Weed Management in Apple Cv. Royal Delicious by Using Different Orchard Floor management Practices

ABSTRACT

In this study, 19-year-old apple orchard at Arabal, Shalimar, Jammu and Kashmir, India, was selected during 2015 and 2016. Forty-five trees were treated with paddy straw mulch, paddy straw mulch followed by glyphosate @ 2.0 l ha⁻¹, oxyflourfen @ 1.0 l ha⁻¹, oxyflourfen @ 1.0 l ha⁻¹ followed by glyphosate @ 2.0 l ha⁻¹, atrazine @ 3.0 kg ha⁻¹, atrazine @ 3.0 kg ha⁻¹ followed by glyphosate @ 2.0 l ha⁻¹, pendimethalin @ 2.0 l ha⁻¹, pendimethalin @ 2.0 l ha⁻¹ followed by glyphosate @ 2.0 l ha⁻¹, bicolor polythene mulch, cowpea, white clover, clean cultivation, farmer practices, zero weeds and control. Three replications were maintained in a randomized complete block design. Minimum weeds (0.0) and weed control efficiency (100%) were recorded in zero weeds, bicolor polythene mulch and in paddy straw mulch followed by glyphosate. High levels of soil nutrients, large annual shoot extension (49.3 and 50.2 cm) and leaf area (77.83 and 78.57 cm⁻²) with maximum fruit yield (82.03 and 80.60 kg/tree) were recorded in paddy straw mulch followed by glyphosate during 2015 and 2016, respectively. Paddy straw mulch followed by glyphosate can be used for effective weed control with improved yield and growth characters of apple.

KEYWORDS:

• Apple
• straw mulch
• polythene mulch
• cover crop
• herbicides
• yield
• weeds
• macronutrients

Introduction

Apple (Malus x domestica Borkh.) is one of the most important temperate fruit grown in the northwestern Himalayas at an elevation range of 1,500–2,700 m above mean sea level (amsl). Apple is the principal fruit crop of the Jammu and Kashmir (J & K) state in terms of the area and production. The J&K state is the largest apple-producing region in the country with the productivity of 10.27 t/ha (Anonymous, 2016), however, the potential yield of apple is 30–40 t/ha. Several factors including weed management are important components in increasing the productivity of apple with better fruit quality and yield. Timely weed management practices play an important role in the successful cultivation of the crop. Removal of nutrients by weeds showed a great impact on the availability of nutrients to the crop, thus, affecting its dry matter accumulation. It has been reported that about 36–42 per cent losses may occur due to inadequate management of weeds in apple (El-Metwally and Hafez, 2007). Tree growth is greatly influenced by the use of different organic and inorganic mulch materials. Mulches retain moisture, add organic matter to the soil, regulate soil temperature and increase fruit quality to a great extent (Bhardwaj and Kumar, 2012; Prakash et al., 2007). However, information on the use of different floor management practices in apple cultivation is lacking in J & K. Therefore, the present study was carried out to study the effect of different practices of orchard floor management on weeds, growth characteristic and soil nutrient status.

Materials and Methods

Geographical Location of Experimental Site

Kashmir is characterized by a temperate climate. Winters are severe; extending from December to March and the temperatures often go below freezing point during this period. The valley is mostly covered with snow during the winter months. The altitude of Kashmir valley ranges between 1500–2500 m amsl. The mean maximum and minimum temperatures of the valley are 24.5°C and 1.2°C, respectively, with a relative humidity of 43.90 per cent. The normal precipitation is 650 mm mostly received during March-May. The experimental fields were situated at an elevation of 1611 m amsl and lie at 34° 09ʹ N latitude and 74° 52ʹ E longitude. During the experimentation period, the maximum average temperature was 20 and 23°C and minimum mean temperature was 6°C and 8°C during 2015 and 2016 with the total precipitation of 839 mm and 427 mm, respectively.

Experimental Details

The experiment was carried out on a 19–20 year-old apple cv. Royal Delicious grafted on Maharaji seedling in an orchard located at Shalimar, Srinagar, Jammu and Kashmir, India. Trees were spaced 5 × 5 m apart and were grown in sandy loam soil with flood irrigation. The fertilization and irrigation were applied as recommended. Thinning out of bloom and fruit were not followed. The soil had the pH of 6.41, electric conductivity of 0.342 dSm⁻¹, Organic carbon of 0.781%, and macro and micronutrients (nitrogen-363.9 kg ha⁻¹, phosphorous-21.77 kg ha⁻¹, potassium-238.4 kg ha⁻¹, calcium-2302.1 kg ha⁻¹, magnesium-596.7 kg ha⁻¹, zinc-1.11 ppm, iron-62.81 ppm, copper-2.05 ppm, and manganese-37.69 ppm). The treatments included paddy straw mulch (T₁), paddy straw mulch followed by glyphosate @ 2.0 l ha⁻¹ (T₂), oxyflourfen @ 1.0 l ha⁻¹ (T₃), oxyflourfen @ 1.0 l ha⁻¹ followed by glyphosate @ 2.0 l ha⁻¹ (T₄), atrazine @ 3.0 kg ha⁻¹ (T₅), atrazine @ 3.0 kg ha⁻¹ followed by glyphosate @ 2.0 l ha⁻¹ (T₆), pendimethalin @ 2.0 l ha⁻¹ (T₇), pendimethalin @ 2.0 l ha⁻¹ followed by glyphosate @ 2.0 l ha⁻¹ (T₈), bicolor polythene mulch (T₉), cowpea (T₁₀), white clover (T¹¹), clean ultivation (T₁₂), farmer practices (T₁₃), zero weeds (T₁₄) and Control (T₁₅). Three replications were maintained for each treatment with three trees per replication in a randomized complete block design

The application of farmyard compost and the first application of chemical fertilizer was done in the third week of March. The application of mulches (paddy straw mulch 10 cm thick and polythene mulch 250 µm), sowing of white clover and cowpea were done during the last week of March when the research work was started. Cowpea was plowed into the soil after 48 days. The commercial formulations of oxyflourfen, atrazine, pendimethalin and glyphosate herbicide were applied as a directed spray with a high volume of power knapsack sprayers. The oxyflourfen, atrazine and pendimethalin were applied as pre-emergence herbicides during the last week of March, whereas, glyphosate was applied as post-emergence herbicide during the last week of June. Weeding in zero weeds was done at frequent intervals while the weeding in clean cultivation was done at 30 days’ interval throughout the study.

Weed Studies

The weeds were collected from the experimental plot and classified into monocots and dicots. One-meter square quadrant was randomly thrown in each tree basin. Monocot and dicot weeds under the quadrant were counted. The data was taken at the interval of 30 days after treatment untill harvesting. The weed samples from 1 m² quadrant in each tree basin were carefully cut and oven dried at 60°C to a constant weight, the total dry matter accumulation of weeds m⁻² was recorded and expressed in g m⁻². Weed control efficiency was calculated, using the weed dry matter weight per treatment on the basis of formula given by Kondap and Upadhyay (1985);

$\mathrm{W}\mathrm{C}\mathrm{E}\left(\mathrm{\%}\right)=\frac{\left(\mathrm{D}\mathrm{W}\mathrm{C}-\mathrm{D}\mathrm{W}\mathrm{T}\right)}{\mathrm{D}\mathrm{W}\mathrm{C}}\times 100$

Where,

WCE = Weed control efficiency

DWC = Dry weight of weeds from control plot

DWT = Dry weight of weeds from treated plot

Growth Characteristics

To measure the shoot extension growth and leaf area, 15 shoots from current season’s growth of each plant were selected from all the 4 geographical directions and top of the tree (3 from each) randomly. The length of each shoot was measured from the point of growth initiation with the help of measuring tape. Twenty-five leaves were collected from the middle portion of the branch on all four directions randomly from each experimental tree during August and the leaf area was measured using a leaf area meter (Systronics, Leaf Area Meter-211). The results were expressed in centimeter square.

Yield Parameters

Fruit set was estimated from an examination of three uniform limb units per tree evenly spaced around the tree. Very low, weak and shaded limbs were avoided. The fruit set and retention was obtained by counting the number of fruits on each tagged limb and calculated by using the formula suggested by Westwood (1978);

$\mathrm{P}\mathrm{e}\mathrm{r}\mathrm{c}\mathrm{e}\mathrm{n}\mathrm{t}\mathrm{f}\mathrm{r}\mathrm{u}\mathrm{i}\mathrm{t}\mathrm{s}\mathrm{e}\mathrm{t}=\frac{\mathrm{N}\mathrm{o}\mathrm{o}\mathrm{f}\mathrm{f}\mathrm{r}\mathrm{u}\mathrm{i}\mathrm{t}\mathrm{s}\mathrm{a}\mathrm{t}\mathrm{p}\mathrm{e}\mathrm{a}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{g}\mathrm{e}}{\mathrm{N}\mathrm{o}\mathrm{o}\mathrm{f}\mathrm{f}\mathrm{l}\mathrm{o}\mathrm{w}\mathrm{e}\mathrm{r}\mathrm{s}}\times 100$

$\mathrm{P}\mathrm{e}\mathrm{r}\mathrm{c}\mathrm{e}\mathrm{n}\mathrm{t}\mathrm{f}\mathrm{r}\mathrm{u}\mathrm{i}\mathrm{t}\mathrm{r}\mathrm{e}\mathrm{t}\mathrm{e}\mathrm{n}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}=\frac{\mathrm{N}\mathrm{o}.\mathrm{o}\mathrm{f}\mathrm{f}\mathrm{r}\mathrm{u}\mathrm{i}\mathrm{t}\mathrm{s}\mathrm{a}\mathrm{t}\mathrm{h}\mathrm{a}\mathrm{r}\mathrm{v}\mathrm{e}\mathrm{s}\mathrm{t}}{\mathrm{N}\mathrm{o}.\mathrm{o}\mathrm{f}\mathrm{f}\mathrm{r}\mathrm{u}\mathrm{i}\mathrm{t}\mathrm{l}\mathrm{e}\mathrm{t}\mathrm{s}\mathrm{a}\mathrm{t}\mathrm{p}\mathrm{e}\mathrm{a}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{g}\mathrm{e}}\times 100$

The matured fruits were harvested by hand from each tree, weighed by a field balance and the yield was recorded in kilograms (kg).

Soil Parameters

Soil Temperature

Soil temperature (°C) of each experimental treatment was recorded at a depth of 0–15 cm with the help of digital soil thermometer. The first reading was taken at the interval of on last week of March and subsequent readings at 15 days’ intervals. The final reading was recorded at the time of harvesting and soil moisture was recorded at 0–15 cm depth by oven-dry method and expressed in per cent (%).

Soil pH, Electrical Conductivity and Organic Carbon

The soil pH was determined in 1:2.5 soil: water suspension using pH meter (ME 885: Max Electronics, Haryana, India) with a glass electrode as described by Jackson (1973). The electrical conductivity was measured in the supernatant solution of 1:2.5 soil: water suspension using digital conductivity meter (ME 885: Max Electronics, Haryana, India). The organic carbon content was determined by Rapid titration method as suggested by Walkley and Black (1934).

Soil Nutrient Content

The nitrogen content was determined by alkaline potassium permanganate distillation method as described by Subbaiah and Asija (1956), phosphorus content of the soil was extracted by using 0.5 N sodium bicarbonate at pH 8.5 (Olsen et al., 1954), potassium was extracted with neutral 1 N ammonium acetate at 1:5 soil to extract ratio and the content of potassium was estimated by Flame photometer (ME 881: Max Electronics, Haryana, India) (Jackson, 1973). The calcium and magnesium contents were determined by versenate titration method (Jackson, 1973).

Statistical Analysis

The data recorded under study were subjected to statistical analysis according to randomized complete block design. The statistical analysis of the data was carried out as per the method described by Gomez and Gomez (1984). The treatment effects were tested at 5 per cent level of significance.

Results and Discussion

Identification of Weed Flora (Monocot/Dicot)

The predominant weed flora in the apple orchard was identified and grouped as monocots and dicots. The major predominant weed population consisted of Sorghum halepense (L.) Pers., Agropyron repens L., Cyperus rotundus L., Cynodon dactylon L., Amaranthus viridis L., Bidens pilosa L., Chenopodium album L. and Trifolium repen L. The detail of different weeds found in the experimental field are presented in Table 1. These results are in congruence with the earlier reports (Lipecki et al., 2004; Lisek, 2014).

Table 1. Predominant weed species in experimental orchard of apple cv. Royal delicious.

Botanical name	Family	English name	Common name
A. Monocot weeds
Agropyron repens L	Poaceae	Quack grass	–
Avena fatua L.	Poaceae	Wild oat Jai	–
Cynodon dactylon L.	Poaceae	Bermuda grass	Dramun
Cyperus rotundus L.	Cyperaceae	Nut sedge	–
Digitaria sanguinalis L.	Poaceae	Crab grass	–
Setaria glauca (L.) Beauv.	Poaceae	Yellow fox tail	Shaol gasa
Poa annua	Poaceae	Blue grass	Mahi ghass
Sorghum halepense (L.)	Poaceae	Johnson grass	Druham
B. Dicot weeds
Ageratum conyzoides L.	Asteraceae	Bill goat weed	–
Amaranthus viridis L.	Amaranthaceae	Pig weed	Lisa
Portulaca oleracea	Portulacaceae	Common purslane	Nunner
Chenopodium album L.	Chenopodiaceae	Dowlamp bat	Von palak
Convolvulus arvensis L.	Convolvulaceae	Field bind weed	Thrier
Euphorbia hirta L.	Euphorbiaceae	Pod spurge	–
Plantago major L.	Plantaginaceae	–	Veuth gulla
Sonchus arvensis L.	Asteraceae	Milkwood	Daudhi
Trifolium repens L.	Fabaceae	White clover	–

Weed Population

During 2015, the weed population was significantly affected by different orchard floor management practices across the time period (Table 2). After 150 days of treatment, the lowest weed population was recorded under zero weeds (1.0 m⁻²) and bicolor polythene mulch followed by paddy straw mulch followed by glyphosate (6,1 m⁻²). The highest number of weed population was recorded under control (43.1 m⁻²) on 30 days after treatment. The interaction effect of different treatments and days after treatment was significant, with lowest total weed population in zero weeds (1.0 m⁻²) and bicolor polythene mulch from 30 to 150 days, followed by paddy straw mulch followed by glyphosate from 30 days to 120 days after treatments. The highest total weed population was recorded in un-weeded control at 90 days (44.3 m⁻²) after treatment.

Table 2. Weed control by different orchard floor management practices on total weed population (m⁻²) of apple cv. Royal Delicious during 2015.

Treatments		Days after treatment					Mean
		30	60	90	120	150
T1	Paddy straw mulch (10 cm thick)	1.0 (0.0)	7.4 (76.7)	8.4 (100.0)	8.4 (100. 0)	8.2 (66.7)	6.5 (68.7)
T2	Paddy straw mulch (10 cm thick) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	6.1 (25.2)	2.0 (5.0)
T3	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence)	17.7 (340.0)	27.8 (800.0)	32.7 (1066.7)	30.3 (916.7)	30.3 (810.0)	27.8 (786.7)
T4	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	16.0 (260.0)	17.2 (264.0)	1.0 (0.0)	1.0 (0.0)	6.6 (31.8)	8.4 (111.2)
T5	Atrazine @ 3.0 kg ha^−1 (pre-emergence)	18.7 (350.0)	33.7 (1133.3)	34.1 (1160.0)	30.9 (956.7)	30.8 (843.3)	29.6 (888.7)
T6	Atrazine @ 3.0 kg ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	13.7 (266.7)	17.4 (269.3)	1.0 (0.0)	1.0 (0.0)	6.7 (32.5)	8.0 (113.7)
T7	Pendimethalin @ 2.0 l ha^−1 (pre-emergence)	18.4 (340.0)	31.6 (1000.0)	33.7 (1133.3)	31.0 (963.3)	30.9 (805.0)	29.1 (848.3)
T8	Pendimethalin @ 2.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	12.5 (233.3)	16.81 (250.0)	1.0 (0.0)	1.0 (0.0)	7.2 (38.7)	7.0 (104.4)
T9	Bicolor polythene mulch (250 µm)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)
T10	Cowpea (green manure)	12.0 (121.3)	8.9 (62.7)	9.1 (65.4)	8.6 (58.3)	8.4 (55.0)	9.4 (72.5)
T11	White clover (cover crop)	15.2 (333.3)	15.6 (243.3)	14.5 (209.7)	13.5 (183.3)	13.5 (140.0)	14.5 (221.9)
T12	Clean cultivation (weeding at 30 days interval)	14.5 (210.0)	9.5 (126.7)	11.7 (136.3)	5.4 (66.7)	6.1 (50.0)	9.4 (117.9)
T13	Farmer practices (Hoeing during March and May)	1.0 (0.0)	17.3 (300.0)	26.3 (693.3)	32.7 (1066.7)	28.3 (800.0)	21.1 (572.0)
T14	Zero weeds (weeding at frequent intervals)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)
T15	Control (no weeding)	43.2 (1866.7)	44.0 (1933.3)	44.3 (1966.7)	43.8 (1916.7)	40.0 (1600.0)	43.1 (1856.7)
	Mean	12.5 (288.1)	16.7 (430.6)	14.7 (435.4)	14.0 (437.7)	15.0 (353.2)
C.D (p ≤ 0.05)
Treatments	=	2.4
Days	=	1.5
Treatments × Days	=	5.8

Note: The data shown on weed population follows square root transformation. The figures in parentheses are original values.

During 2016, weed population was significantly lowest under zero weeds and bicolor polythene mulch (1.0 m⁻² each)) followed by paddy straw mulch followed by glyphosate (2.0 m⁻²) (Table 3). The highest weed population was recorded in the un-weeded control (42.0 m⁻²). The lowest weed population was recorded on 30 days (12.4 m⁻²) after treatment. The interaction effect of orchard floor management practices and days after treatment indicate that the lowest weed population was recorded under treatments zero weeds and bicolor polythene mulch (1.0 m⁻², each) from 30 to 150 days, farmer practices on 30 days and paddy straw mulch followed by glyphosate, oxyflourfen followed by glyphosate, pendimethalin followed by glyphosate from 90 to 120 days after treatment. Our results are in agreement with the findings of earlier workers (Chatha and Chanana, 2007; Shankar et al., 2014; Singh and Bal, 2013). The lowest weed population in zero weeds was due to frequent weeding in this treatment. However, reduced weed population under mulching treatments may be attributed to the absence of sunlight coupled with the physical barrier provided by bicolor polythene mulch and paddy straw mulch to the emerging weeds. The action of the herbicides in suppressing weed growth is starvation of the weeds due to lack of photosynthesis, the formation of secondary phytotoxic substances, alteration in protective carotenoids related reaction and the involvement of photo-oxidative pigments (Ashton and Crafts, 1981).

Table 3. Weed control by different orchard floor management practices on total weed population (m⁻²) of apple cv. Royal Delicious during 2016.

Treatments		Days after treatment					Mean
		30	60	90	120	150
T1	Paddy straw mulch (10 cm thick)	1.0 (0.0)	5.4 (66.7)	10.0 (143.3)	8.4 (100.0)	7.3 (75.0)	6.4 (77.0)
T2	Paddy straw mulch (10 cm thick) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	5.6 (20.8)	2.0 (4.2)
T3	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence)	16.1 (266.7)	26.3 (690.0)	28.6 (816.7)	28.5 (810.0)	27.0 (731.7)	25.3 (663.0)
T4	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	14.1 (200.0)	15.2(203.0)	1.0 (0.0)	1.0 (0.0)	6.0 (25.0)	7.5 (85.6)
T5	Atrazine @ 3.0 kg ha^−1 (pre-emergence)	18.1 (333.3)	28.7 (823.3)	31.4 (983.3)	31.2 (973.3)	29.9 (896.7)	27.9 (802.0)
T6	Atrazine @ 3.0 kg ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	16.3 (266.7)	17.4 (267.8)	1.0 (0.0)	1.0 (0.0)	6.5 (30.0)	8.4 (112.9)
T7	Pendimethalin @ 2.0 l ha^−1 (pre-emergence)	16.3 (266.7)	25.8 (663.3)	30.1 (903.3)	28.9 (833.3)	27.0 (726.7)	25.6 (678.7)
T8	Pendimethalin @ 2.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	16.8 (283.3)	18.0 (287.0)	1.0 (0.0)	1.0 (0.0)	6.4 (28.0)	8.6 (119.8)
T9	Bicolor polythene mulch (250 µm)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)
T10	Cowpea (green manure)	11.6 (113.0)	8.7 (59.8)	9.1 (65.9)	8.5 (57.0)	8.5 (55.8)	9.3 (70.3)
T11	White clover (cover crop)	16.3 (266.7)	11.8 (200.0)	12.1 (210.0)	12.1 (176.7)	12.1 (146.7)	12.9 (200.0)
T12	Clean cultivation (weeding at 30 days interval)	18.3 (336.7)	9.8 (133.3)	9.5 (130.0)	9.2 (116.7)	8.5 (100.0)	11.1 (163.3)
T13	Farmer practices (Hoeing during March and May)	1.0 (0.0)	17.8 (316.7)	27.1 (733.3)	26.9 (733.3)	26.5 (700.0)	19.9 (496.7)
T14	Zero weeds (weeding at frequent intervals)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0. 0)
T15	Control (no weeding)	36.5(1689.3)	43.2 (1866.7)	44.2 (1950.0)	43.2 (1866.7)	42.7 (1826.7)	42.0 (1877.5)
	Mean	12.4 (268.2)	15.4 (371.8)	13.9 (395.7)	13.5 (377.8)	14.4 (357.6)
C.D (p ≤ 0.05)
Treatments	=	2.5
Days	=	1.6
Treatments × Days	=	6.2

Note: The data shown on weed population follows square root transformation. The figures in parentheses are original value.

Dry Weight of Weeds

The different orchard floor management treatments resulted in significant variation with respect to the dry weight of weeds during both the study period (Tables 4 and 5). Significantly minimum dry weight was observed under zero weeds and bicolor polythene mulch (1.0 g m⁻², each), followed by paddy straw mulch followed by glyphosate (1.8 g m⁻² and 1.6 g m⁻²). Maximum weed dry weight was found in un-weeded control (29.1 and 29.9 g m⁻²) during 2015 and 2016, respectively. Further, the lowest weed dry weight was recorded on 30 days (8.2 and 8.5 g m⁻²), which was at par with all other days of observation. However, highest weed dry weight was recorded on 60 and 90 days after treatments (11.0 and 10.7 g m⁻²) during 2015 and 2016, respectively. The interaction effect of different treatments and days after treatments also showed significant variation for weed dry weight. The lowest dry weight of weed was obtained in treatments zero weeds and bicolor polythene mulch from 30 to 150 days followed by paddy straw mulch followed by glyphosate (1.0 g m⁻²) from 30 days to 120 days (1.0 g m⁻², each) during both the study years.

Table 4. Weed control by different orchard floor management practices on weed dry weight (g m⁻²) of apple cv. Royal Delicious during 2015.

Treatments		Days after treatment					Mean
		30	60	90	120	150
T1	Paddy straw mulch (10 cm thick)	1.0 (0.0)	5.3 (37.0)	6.5 (57.7)	6.0 (47.3)	4.0 (33.3)	3.4 (35.1)
T2	Paddy straw mulch (10 cm thick) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	4.2 (10.3)	1.8 (2.0)
T3	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence)	11.6 (134.7)	17.8 (317.0)	24.9 (621.7)	22.2 (491.7)	19.5 (380.0)	19.2 (389.0)
T4	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	10.5 (109.3)	11.7 (115.1)	1.0 (0.0)	1.0 (0.0)	4.6 (13.3)	5.8 (47.5)
T5	Atrazine @ 3.0 kg ha^−1 (pre-emergence)	12.2 (148.7)	21.2 (450.0)	25.7 (658.3)	22.3 (496.7)	19.9 (396.7)	20.3 (430.1)
T6	Atrazine @ 3.0 kg ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	9.0 (109.7)	12.0 (120.0)	1.0 (0.0)	1.0 (0.0)	4.7 (13.8)	5.5 (48.7)
T7	Pendimethalin @ 2.0 l ha^−1 (pre-emergence)	11.5 (133.3)	20.7 (428.0)	25.7 (662.0)	22.5 (505.0)	23.7 (564.0)	20.8 (458.5)
T8	Pendimethalin @ 2.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	8.8 (112.7)	11.9 (118.3)	1.0 (0.0)	1.0 (0.0)	4.7 (13.7)	5.4 (49.0)
T9	Bicolor polythene mulch (250 µm)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)
T10	Cowpea (green manure)	8.2 (51.4)	5.3 (18.2)	6.5 (30.5)	6.3 (28.4)	6.3 (27.7)	6.5 (31.2)
T11	White clover (cover crop)	10.6 (160.3)	10.6 (111.3)	10.0 (100.0)	9.3 (86.7)	8.0 (63.7)	9.7 (104.4)
T12	Clean cultivation (weeding at 30 days interval)	9.7 (93.7)	6.5 (57.3)	7.2 (52.0)	3.8 (28.3)	3.9 (18.7)	6.2 (50.0)
T13	Farmer practices (Hoeing during March and May)	1.0 (0.0)	11.3 (128.3)	20.6 (425.0)	20.9 (441.0)	19.9 (397.0)	14.7 (278.3)
T14	Zero weeds (weeding at frequent intervals)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)
T15	Control (no weeding)	26.4 (698.0)	28.3 (802.0)	32.5 (1058.0)	30.6 (933.3)	27.7 (770.0)	29.1 (852.3)
	Mean	8.2 (116.8)	11.0 (180.2)	11.0 (244.3)	10.0 (203.9)	10.2 (180.1)
C.D (p ≤ 0.05)
Treatments	=	1.6
Days	=	1.0
Treatments × Days	=	3.9

Note: The data shown on weed population follows square root transformation. The figures in parentheses are original values.

Table 5. Weed control by different orchard floor management practices on weed dry weight (g m⁻²) of apple cv. Royal Delicious during 2016.

Treatments		Days after treatment					Mean
		30	60	90	120	150
T1	Paddy straw mulch (10 cm thick)	1.0 (0.0)	4.3 (40.0)	7.0 (65.0)	6.2 (52.7)	4.7 (22.3)	4.6 (37.0)
T2	Paddy straw mulch (10 cm thick) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	4.2 (10.0)	1.6 (2.0)
T3	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence)	11.0 (121.7)	17.5 (306.7)	20.2 (410.0)	19.3 (371.0)	18.5 (343.3)	17.3 (310.5)
T4	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	10.6 (111.7)	12.0 (120.2)	1.0 (0.0)	1.0 (0.0)	4.6 (12.9)	5.8 (49.0)
T5	Atrazine @ 3.0 kg ha^−1 (pre-emergence)	12.4 (153.3)	19.0 (360.0)	22.0 (483.3)	20.4 (416.7)	20.0 (400.0)	18.8 (362.7)
T6	Atrazine @ 3.0 kg ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	11.3 (127.7)	12.4 (130.0)	1.0 (0.0)	1.0 (0.0)	4.6 (13.3)	6.1 (54.2)
T7	Pendimethalin @ 2.0 l ha^−1 (pre-emergence)	11.1 (123.3)	17.2 (296.0)	20.8 (433.3)	19.1 (365.0)	18.4 (340.0)	17.3 (311.5)
T8	Pendimethalin @ 2.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	11.6 (134.0)	12.2 (127.2)	1.0 (0.0)	1.0 (0.0)	4.7 (13.5)	6.1 (54.9)
T9	Bicolor polythene mulch (250 µm)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)
T10	Cowpea (green manure)	7.3 (40.2)	5.1 (16.5)	6.2 (26.8)	6.5 (30.8)	6.5 (30.0)	6.3 (28.9)
T11	White clover (cover crop)	11.6 (135.0)	9.1 (116.7)	10.9 (119.7)	8.7 (89.3)	8.0 (63.7)	9.7 (104.9)
T12	Clean cultivation (weeding at 30 days interval)	10.9 (119. 3)	6.3 (52.7)	7.0 (64.3)	6.2 (51.7)	5.3 (36.7)	7.1 (51.4)
T13	Farmer practices (Hoeing during March and May)	1.0 (0.0)	11.1 (123.7)	18.4 (340.0)	19.6 (383.3)	19.1 (366.7)	13.8 (242.7)
T14	Zero weeds (weeding at frequent intervals)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)	1.0 (0.0)
T15	Control (no weeding)	24.7 (608.7)	31.5 (993.3)	32.3 (1042.0)	31.3 (982.0)	29.7 (879.3)	29.9(699.1)
	Mean	8.5 (111.1)	10.7 (178.9)	10.0 (199.0)	10.5 (182.8)	10.1 (168.7)
C.D (p ≤ 0.05)
Treatments	=	1.6
Days	=	1.0
Treatments × Days	=	4.0

Note: The data shown on weed population follows square root transformation. The figures in parentheses are original values.

Zero weeds, both mulches and herbicides had a significant effect on the dry weight of weeds on all sampling dates. The lowest dry weight was observed in zero weeds and bicolor mulch followed by treatment paddy straw mulch followed by glyphosate across all the time periods. These results are in accordance with the findings of earlier workers (Kaundal et al., 1995; Kaur and Kaundal, 2009). Bicolor polythene mulch and paddy straw mulch followed by glyphosate gave better results with a minimum dry weight of weeds due to partially anaerobic conditions for the survival of weed species, thus, finally resulted in very low weed density and least fresh and dry weight of weeds. The present observations are in conformity with the findings of Meena (2013).

Weed Control Efficiency

The weed control efficiency was significantly influenced by treatments and days after treatments during both the years of study (Table 6). Among different treatments, zero weeds and bicolor polythene mulch showed the highest weed control efficiency (100.0%, each). However, the weed control efficiency of paddy straw mulch followed by glyphosate and paddy straw mulch (99.7 and 96.5%, respectively) was at par with the treatments zero weeds and bicolor polythene mulch. The highest weed control efficiency (81.5%) was obtained at 60 days after treatments during 2015. During 2016, maximum weed control efficiency was observed in zero weeds and bicolor polythene mulch (100.0%) and was at par with the paddy straw mulch followed by glyphosate (99.8%) and paddy straw mulch (96.1%). During both the years, the interaction effect of different treatments and days after treatments was significant, with highest weed control efficiency under zero weeds and bicolor polythene mulch from 30 to 150 days, paddy straw mulch followed by glyphosate from 30 to 120 days, oxyflourfen followed by glyphosate, atrazine followed by glyphosate and pendimethalin followed by glyphosate from 90 to 120 days after treatment (100%, each). The lowest weed control efficiency was recorded in control (0.0%) across the time period during 2015 and 2016.

Table 6. Weed control by different orchard floor management practices on weed control efficiency (%) of apple cv. Royal Delicious during 2015 and 2016.

Treatments		Days after treatment 2015						Days after treatment 2016
		30	60	90	120	150	Mean	30	60	90	120	150	Mean
T1	Paddy straw mulch (10 cm thick)	100.0	96.3	94.0	94.7	97.3	96.5	100.0	95.3	94.3	95.3	95.7	96.1
T2	Paddy straw mulch (10 cm thick) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	100	100.0	100.0	100.0	98.7	99.7	100.0	100.0	100.0	100.0	98.9	99.8
T3	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence)	80.0	68.3	60.7	62.3	61.3	66.5	80.3	60.7	41.3	47.3	50.3	56.0
T4	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	80.0	85.6	100.0	100.0	98.3	92.8	84.3	87.9	100.0	100.0	98.5	94.1
T5	Atrazine @ 3.0 kg ha^−1 (pre-emergence)	74.7	63.7	53.7	57.3	54.3	60.7	79.0	44.0	38.0	47.0	49.0	51.4
T6	Atrazine @ 3.0 kg ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	78.7	85.0	100.0	100.0	98.2	92.4	83.7	87.0	100.0	100.0	98.4	93.8
T7	Pendimethalin @ 2.0 l ha^−1 (pre-emergence)	80.0	70.0	58.3	62.7	61.0	66.4	80.0	46.7	37.0	46.0	26.3	47.2
T8	Pendimethalin @ 2.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	76.0	85.2	100.0	100.0	98.2	91.9	82.7	87.2	100.0	100.0	98.5	93.7
T9	Bicolor polythene mulch (250 µm)	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
T10	Cowpea (green manure)	93.0	98.0	97.0	97.0	92.0	95.0	93.0	98.0	89.0	91.0	93.0	92.8
T11	White clover (cover crop)	73.3	89.0	88.3	90.7	93.0	86.9	78.7	86.0	90.7	90.7	91.3	87.5
T12	Clean cultivation (weeding at 30 days interval)	78.0	95.0	94.0	94.7	96.0	91.5	86.7	92.7	95.0	97.0	97.3	93.7
T13	Farmer practices (Hoeing during March and May)	100.0	87.0	67.3	61.0	58.3	74.7	100.0	83.7	60.0	53.3	48.7	69.1
T14	Zero weeds (weeding at frequent intervals)	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0	100.0
T15	Control (no weeding)	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0	0.0
	Mean	80.9	81.5	80.9	81.4	80.4		83.2	77.9	76.4	77.8	76.4
C.D (p ≤ 0.05)		2015	2016
Treatments	=	3.50	4.59
Days	=	2.21	2.90
Treatments × Days	=	8.57	11.25

Zero weeds, mulches and herbicides had a significant effect on weed control efficiency on all sampling days. After 150 days of treatments, maximum weed control efficiency was recorded in zero weeds and bicolor polythene mulch, followed by treatment paddy straw mulch followed by glyphosate. The un-weeded control had the lowest weed efficiency across the time periods. The present results were in line with the earlier reports in which maximum weed control efficiency was observed in various floor management techniques (Chatha and Chanana, 2007; Kaith and Bhardwaj, 2011; Kaur and Kaundal, 2009).

Growth and Yield Parameters

Annual Shoot Extension Growth

The annual shoot extension growth during 2015 and 2016 was significantly influenced by different treatments (Figure 1). Maximum annual shoot extension growth was recorded with paddy straw mulch followed by glyphosate (49.3 and 50.2 cm) and was at par with the paddy straw mulch (48.7 and 50.0 cm) and cowpea (48.3 and 48.6 cm) during 2015 and 2016, respectively. Whereas, minimum annual shoot extension growth (was recorded under un-weeded control (45.2 and 45.1 cm) during 2015 and 2016, respectively. The increased annual shoot extension growth due to paddy straw mulch was associated with the suppression of weed growth that increased the availability of moisture as a result of minimum losses due to evaporation from the soil surface and addition of extra organic matter and nutrients to the soil. The results are in consonance with the finding of Kaith and Bhardwaj (2011), who reported maximum shoot growth under glyphosate in apple. The highest annual extension shoot growth with white clover, cowpea and paddy straw mulches in combination with herbicides has also been reported by different workers in apple (Hipps et al., 2004), plum (Singh et al., 2004), grapevine (Krohn and Ferree, 2005) and cherry (Bhat, 2015).

Figure 1. Weed control by different orchard floor management practices on annual shoot extension growth of apple cv. Royal Delicious during 2015 and 2016. C.D.(p ≤ 0.05) 1.70(2015) 1.63(2016).

Leaf Area

Our results showed that leaf area was significantly affected by different treatments during 2015 and 2016 (Figure 2). Among different treatments, maximum leaf area was recorded in paddy straw mulch followed by glyphosate (77.83 cm² and 78.57 cm²), however, it was at par with the leaf area in paddy straw mulch (76.56 cm² and 77.23 cm²) and cowpea (75.89 and 76.77 cm²) during 2015 and 2016, respectively. Minimum leaf area (70.33 cm² and 70.00 cm²) was observed under un-weeded control, during 2015 and 2016, respectively. These results confirm the reports of Singh and Bal (2013), who observed the maximum leaf area of ber in polythene mulch and paddy straw mulch treatments.

Figure 2. Weed control by different orchard floor management practices on leaf area of apple cv. Royal Delicious during 2015 and 2016. C.D.(p ≤ 0.05) 2.83 (2015) 2.98 (2016).

Final Fruit Set and fruit Yield

Final fruit set was significantly affected by different treatments of weed management (Figure 3). Among different treatments, maximum final fruit set (64.8 and 63.9%), paddy straw mulch (64.7 and 63.0%) and cowpea (64.3 and 63.6%) during 2015 and 2016, respectively. Minimum final fruit set was recorded under un-weeded control (60.0 and 58.3%, during 2015 and 2016, respectively). Different weed management practices had a significant effect on fruit yield during both the years of investigation (Figure 4). Among different treatments, maximum fruit yield per tree (82.03 and 80.60 kg) was obtained with paddy straw followed by glyphosate, paddy straw mulch (80.43 and 79.93 kg) and cowpea (79.13 and 78.00 kg), respectively, during 2015 and 2016. Minimum fruit yield per tree (68.17 and 65.10 kg) was recorded under un-weeded control during both the years of study. The increase in fruit yield per plant was directly related to the reduced crop-weed competition. which conserved the soil nutrient and soil water contents and ultimately favored better yield performance under different weed control treatments. The present results are in line with the findings of Khokhar and Sharma (2000), who reported that grass mulch followed by a single application of glyphosate was highly effective in controlling weed growth and resulted in the highest fruit yield with good quality nuts in almond. Further, mulching along with post-emergence herbicide glyphosate enabled the plant roots to expand more in feeding zone for higher nutrient uptake of water and nutrients and increased the fruit yield through their moderating effect on the hydrothermal regimes of the soil in pome and stone fruits (Das et al., 2016; Khokhar and Sharma, 2000; Meena et al., 2015). Our results are further supported by the findings of Kumar and Bal (2005), who reported that glyphosate-based weed management resulted in the highest guava fruit yield per plant.

Figure 3. Weed control by different orchard floor management practices on final fruit set of apple cv. Royal Delicious during 2015 and 2016. C.D.(p ≤ 0.05) 1.30 (2015) 1.21 (2016).

Figure 4. Weed control by different orchard floor management practices on fruit yield of apple cv. Royal Delicious during 2015 and 2016. C.D.(p ≤ 0.05) 1.14(2015) 1.42(2016).

Soil Parameters

Soil Moisture

During 2015, the highest soil temperature and moisture were observed by the treatment with paddy straw mulch followed by glyphosate (26.16%) which was statistically at par with paddy straw mulch (26.12%) followed by bicolor polythene mulch (25.19%) (Table 7). Data pertaining to the weed control by different orchard floor management practices effect of different orchard floor management practices on recorded during 2015 and 2016 are presented in reveals that during Across the time periods, the maximum soil moisture content was recorded after 105 days of treatment (26.24%). The interaction effect of treatments and days after treatments indicate that paddy straw mulch showed maximum soil moisture (28.27%) followed by paddy straw mulch followed by glyphosate (28.20%) at 15 days after treatment. The examination of data pertaining to soil moisture content during 2016, paddy straw mulch followed by glyphosate had maximum soil moisture content (26.01%) which was statistically at par with paddy straw mulch (25.95%) and bicolor polythene mulch (25.09%). However, maximum soil moisture content (26.05%) was recorded on 15 days followed by 105 days (24.37%). The interaction effect of treatments and days after treatments indicate that the paddy straw mulch on 15 days recorded highest soil moisture content (28.03%) which was statistically at par with paddy straw mulch followed by glyphosate and bicolor polythene on 15 days, paddy straw mulch from 75 days to 105 days and paddy straw mulch followed by glyphosate from 90 days to 105 days.

Table 7. Weed control by different orchard floor management practices on soil moisture (%) at 0–15 cm depth (15 days’ interval) of apple cv. Royal Delicious during 2015 and 2016.

Treatments		Soil moisture (%) at 0–15 cm depth (15 days interval)
		15 DAT*		30 DAT		45 DAT		60 DAT		75 DAT		90 DAT		105 DAT		120 DAT		135 DAT		150 DAT		Mean
		2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016
T1	Paddy straw mulch (10 cm thick)	28.27	28.03	27.50	27.00	27.03	25.77	25.93	25.50	27.23	27.07	27.50	27.53	27.70	27.80	25.00	25.57	23.60	24.03	21.43	21.23	26.12	25.95
T2	Paddy straw mulch (10 cm thick) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	28.20	27.90	27.70	26.93	27.03	26.93	25.83	25.77	27.13	26.93	27.50	27.27	27.97	27.53	25.17	25.87	23.67	24.07	21.37	20.87	26.16	26.01
T3	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence)	25.63	25.37	22.90	23.07	21.87	21.07	21.60	21.07	23.43	22.60	23.73	23.37	26.23	23.60	23.97	23.17	22.10	22.10	20.70	20.63	23.22	22.61
T4	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	26.40	26.00	22.57	22.33	21.83	21.37	21.33	20.97	23.20	22.50	23.43	23.17	26.17	23.30	23.57	21.50	20.90	20.63	17.97	17.90	22.74	21.97
T5	Atrazine @ 3.0 kg ha^−1 (pre-emergence)	25.57	26.50	22.97	22.83	22.10	20.90	21.60	21.13	23.47	22.80	23.63	23.33	26.23	23.53	24.00	23.37	22.13	22.13	20.87	20.50	23.26	22.70
T6	Atrazine @ 3.0 kg ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	26.10	25.83	23.07	22.83	21.83	21.40	21.37	20.93	23.27	22.53	23.40	23.23	26.23	23.47	23.50	21.43	20.80	20.57	17.90	17.73	22.75	22.00
T7	Pendimethalin @ 2.0 l ha^−1 (pre-emergence)	25.87	25.30	22.07	22.93	21.80	21.20	21.67	21.00	23.67	22.77	23.77	23.43	26.33	23.67	24.00	23.03	22.03	22.13	20.70	20.63	23.19	22.61
T8	Pendimethalin @ 2.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	25.10	26.09	22.73	22.80	21.73	21.13	21.17	21.03	23.10	22.40	23.40	23.27	26.17	23.30	23.37	21.37	20.87	20.63	17.90	17.80	22.55	21.98
T9	Bicolor polythene mulch (250 µm)	27.10	27.87	26.77	25.90	25.43	24.67	24.93	24.10	25.60	25.73	25.77	26.17	25.97	26.22	24.97	24.93	23.77	24.03	21.63	21.23	25.19	25.09
T10	Cowpea (green manure)	27.07	26.10	21.53	21.23	21.17	20.87	21.07	21.17	23.07	22.77	23.10	23.53	25.97	23.63	23.43	21.57	20.83	20.73	17.93	17.80	22.52	21.94
T11	White clover (cover crop)	25.67	25.79	23.17	23.13	22.77	23.13	22.57	23.00	24.57	24.33	24.67	24.83	26.43	24.90	24.17	23.53	22.20	22.07	20.93	20.53	23.72	23.52
T12	Clean cultivation (weeding at 30 days interval)	25.57	23.80	20.83	21.77	20.83	19.03	19.63	18.87	21.63	20.47	21.83	22.37	24.57	22.57	21.93	19.97	19.90	18.17	16.77	16.63	21.35	20.37
T13	Farmer practices (Hoeing during March and May)	25.33	24.93	23.13	23.17	22.70	21.60	22.50	21.40	24.50	22.73	24.80	24.20	26.33	24.67	24.00	23.67	22.13	22.13	20.87	20.53	23.63	22.90
T14	Zero weeds (weeding at frequent intervals)	25.83	25.70	21.53	22.80	20.77	20.27	20.47	20.00	22.47	21.90	22.73	22.43	24.87	22.73	23.43	20.87	20.70	20.53	17.87	17.63	22.07	21.49
T15	Control (no weeding)	24.20	25.57	23.13	23.23	22.90	21.57	22.50	21.23	24.37	22.93	24.80	24.13	26.37	24.70	24.03	23.63	21.90	22.13	20.83	20.60	23.50	22.97
		26.13	26.05	23.44	23.46	22.79	22.06	22.28	21.81	24.05	23.36	24.27	24.15	26.24	24.37	23.90	22.90	21.84	21.74	19.71	19.48
C.D (p ≤ 0.05)		2015	2016
Treatments	=	0.95	0.95
Days	=	0.68	0.89
Treatments × Days	=	1.38	1.23
*DAT = Day after treatments

Mulching with paddy straw mulch followed by glyphosate recorded highest soil moisture content, which was statistically at par with paddy straw mulch and bicolor polythene mulch on 120 days and 45 days after treatments during 2015 and 2016. These results are in conformity with the finding in fruits such as anola (Pande et al., 2005; Rao and Pathak, 1996; Singh et al., 2010), apple (Raina, 1991) and plum (Sharma and Kathiravan, 2009). Increased soil moisture content below the mulches in various mulches treatments might be due to the reduction in soil surface evaporation, increased infiltration percolation capacity of soil and suppression in extreme fluctuation of soil temperature thus retaining the soil moisture in the soil for a longer duration. These results are also in line with Negi (2013) who stated that the general improvement in soil moisture status was likely a consequence of both improved infiltration capacity and reduced evaporation. Bhardwaj and Kumar (2012) reported that black polythene mulch acts as an insulating barrier, which checks evaporation from the soil surface and conserves soil moisture. Similar findings were obtained by several researchers (Chandel et al., 2010; Walsh et al., 1996), who reported comparatively higher soil moisture contents in different mulches over un-mulched trees. Raina (1991) also reported that mulches act as a cover for the soil to prevent moisture loss through evaporation and transpiration by weeds aerial parts. Moisture loss was higher under clean basin management, zero weeds and herbicidal treatments, perhaps, because of bare soil surface which caused water loss due to higher evaporation during summer months. In un-weeded plants, higher weed population might have extracted more moisture for their growth and development.

Soil Temperature

The soil temperature at 0–15 cm depth was significantly influenced by the various weed management treatments during 2015 and 2016 (Table 8). In 2015, maximum soil temperature was recorded with bicolor polythene mulch (20.9°C) followed by zero weeds and clean cultivation (19.8°C, each). Further, significantly maximum soil temperature was recorded on 105 days (24.1°C) closely followed by at 90 days (23.8°C) after treatment during 2016 and 2015, respectively. The treatments and days interaction effect was also significant. During 2015, maximum soil temperature was recorded under bicolor polythene mulch on 90 days (23.8°C) and was at par with the temperature on 105 days and 135 days (23.6°C, each) under the same treatment. In 2016, soil temperature showed the same trend as in 2015 with bicolor polythene mulched soil having significantly higher soil temperature (21.8°C) followed by the clean cultivation and zero weeds. Soil temperature also varied significantly during different days of observation and the maximum mean soil temperature was recorded on 75 days (22.6°C) and minimum mean soil temperature was recorded on 15 days (14.6°C). Among treatments and days after treatments interaction, maximum soil temperature was recorded under bicolor polythene mulch (24.1^oC) on 105 days and was at par with the same treatment on 90 days (23.9°C).

Table 8. Weed control by different orchard floor management practices on soil temperature (^oC) at 0–15 cm depth (15 days’ interval) of apple cv. Royal delicious during 2015 & 2016.

Treatments		Soil temperature (^oC) at 0–15 cm depth (15 days interval)
		15 DAT*		30 DAT		45 DAT		60 DAT		75 DAT		90 DAT		105 DAT		120 DAT		135 DAT		150 DAT		Mean
		2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016	2015	2016
T1	Paddy straw mulch (10 cm thick)	14.2	14.1	15.0	17.2	19.3	19.4	17.0	22.1	18.0	22.2	21.5	22.3	22.3	22.5	22.0	21.8	21.2	20.6	20.3	20.1	19.1	20.2
T2	Paddy straw mulch (10 cm thick) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	14.4	14.3	15.5	17.5	19.1	19.4	17.7	22.0	18.3	22.2	21.4	22.2	21.6	21.8	21.3	21.7	21.1	20.5	20.2	20.2	19.1	20.2
T3	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence)	14.0	14.7	15.4	17.6	20.0	20.0	19.0	22.4	19.2	22.6	22.5	22.2	22.2	22.5	21.9	21.9	20.4	19.9	19.7	19.7	19.4	20.4
T4	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	14.8	14.7	16.2	17.6	20.1	19.7	18.9	22.6	19.1	22.7	22.1	22.1	22.1	22.6	21.6	22.1	21.2	20.6	20.3	20.6	19.6	20.5
T5	Atrazine @ 3.0 kg ha^−1 (pre-emergence)	14.8	14.9	15.6	17.5	19.3	19.9	18.1	22.6	18.2	22.6	21.5	22.0	21.4	22.1	20.9	21.9	20.9	20.5	20.3	19.9	19.1	20.4
T6	Atrazine @ 3.0 kg ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	14.3	14.6	16.4	17.5	20.1	19.8	18.5	22.7	18.9	22.7	22.3	22.4	22.4	22.8	21.8	21.8	21.1	20.5	20.3	20.1	19.6	20.5
T7	Pendimethalin @ 2.0 l ha^−1 (pre-emergence)	14.9	14.6	15.4	17.8	20.0	19.8	18.4	22.3	18.5	22.5	22.0	21.9	21.8	22.0	21.1	21.6	20.9	20.2	20.1	20.1	19.3	20.3
T8	Pendimethalin @ 2.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	14.1	14.7	16.1	17.7	20.0	19.8	18.7	22.5	19.0	22.5	22.8	22.3	22.9	22.6	21.7	22.7	21.1	20.6	20.3	20.5	19.7	20.6
T9	Bicolor polythene mulch (250 µm)	15.3	15.1	17.4	18.1	20.9	21.3	19.7	23.1	19.9	23.5	23.8	23.9	23.6	24.1	22.4	23.1	23.6	23.0	22.4	22.5	20.9	21.8
T10	Cowpea (green manure)	14.5	14.6	15.9	17.6	20.1	19.6	18.4	22.2	19.2	22.2	22.4	21.5	22.0	21.6	21.7	20.9	20.8	20.4	19.8	20.3	19.5	20.4
T11	White clover (cover crop)	14.8	14.5	15.6	17.6	18.9	19.6	17.8	22.4	18.8	22.5	21.9	22.1	22.5	22.4	21.8	22.2	20.4	19.7	19.2	19.5	19.2	20.3
T12	Clean cultivation (weeding at 30 days interval)	14.9	14.8	16.7	17.7	20.1	19.9	18.9	22.5	19.2	22.6	22.2	22.3	22.4	22.7	21.9	22.6	21.3	20.5	20.6	20.4	19.8	20.6
T13	Farmer practices (Hoeing during March and May)	14.7	14.5	15.4	17.4	18.8	19.7	18.3	22.3	18.7	22.4	22.5	22.3	22.3	22.6	21.7	21.7	20.3	19.6	19.5	19.9	19.2	20.2
T14	Zero weeds (weeding at frequent intervals)	14.9	14.7	16.6	17.6	19.9	19.9	18.6	22.6	19.0	22.7	22.9	22.8	23.0	23.1	21.6	21.7	21.2	20.6	20.5	20.4	19.8	20.6
T15	Control (no weeding)	14.7	14.5	15.9	17.8	18.9	19.5	18.0	22.8	18.5	22.5	21.9	22.0	21.5	21.6	21.5	21.7	20.8	19.9	19.8	20.0	19.2	20.2
Mean		14.6	14.6	15.9	17.6	19.7	19.8	18.4	22.5	18.8	22.6	22.2	22.3	22.3	22.4	21.7	22.0	21.1	20.5	20.2	20.2
C.D (p ≤ 0.05)		2015	2016
Treatments	=	0.17	0.13
Days	=	0.21	0.11
Treatments × Days	=	0.58	0.42

*DAT = Day after treatments

An increase in soil temperature under bicolor mulches may be attributed to the fact that these mulches absorb more radiation from the sun and transmit more heat to the upper layer of soil as compared to organic mulches. These results are in line with the earlier reports that also found an increase in soil temperature with polythene and straw mulches (Liu et al., 2014; Sharma and Kathiravan, 2009). Walsh et al. (1996) found higher soil temperature under cultivation as compared to straw mulch in apple. Mulches reduce the temperature fluctuation at night, condensation on the underside of the mulch absorbs the longwave radiation emitted by the soil thereby slowing the cooling of the soil (Kumar et al., 1990; Teodorescu et al., 2013).

Minimum soil temperature under paddy straw mulch may also be due to the thick grass cover provided by the mulch, thereby, preventing atmospheric heat to reach the soil surface. Greenham (1953) reported that organic mulches generally insulate the orchard soil, thus, lessen orchard soil temperature variability, reducing daily and annual temperature extremes. Therefore, mean soil temperatures beneath mulch in summer are frequently lower under organic mulches (Gormley et al., 1973). Mean monthly temperature at 10 cm depth below a 10 cm thick straw cover have frequently been 1ºC and 2°C less than those beneath bare soil in the summer months, while during winter similarly measured temperature could be 1°C higher under straw mulch relative to the bare soil (Weller, 1969). Similar results were reported by Zhou et al. (2014), who observed that soil water content increased in the plots treated with organic mulch due to the slow soil temperature increase in spring. Organic matter mulch treatments decreased the peak temperature of orchard soil in the summer and increased the minimum soil temperature in the fall.

Soil pH and Electrical Conductivity

Differential levels of soil pH were observed under different treatments during 2015 and 2016 (Table 9). During 2015, highest pH (6.71) was recorded in clean cultivation followed by zero weeds (6.62) and minimum pH (6.41) was recorded under un-weeded control. During 2016, a similar trend was observed with respect to the effect of different orchard floor management practices on soil pH. These findings are supported by Neilsen and Neilsen (2003), who reported that living mulches i.e., white clover and cowpea were most likely associated with the changes in soil pH as a result of differences in N mineralization rates. Billeaud and Zajicek (1989) reported that mulching with four types of organic mulches significantly decreases soil pH in a soil composed of fine sandy loam. Duryea et al. (1999) also found that mulches decreased soil pH.

Table 9. Weed control by different orchard floor management practices on chemical properties of orchard soil of apple cv. Royal Delicious during 2015 and 2016.

Treatments		pH		EC (dSm^−1)		Organic Carbon (%)
		2015	2016	2015	2016	2015	2016
T1	Paddy straw mulch (10 cm thick)	6.55	6.57	0.341	0.341	0.796	0.803
T2	Paddy straw mulch (10 cm thick) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	6.58	6.59	0.341	0.341	0.798	0.806
T3	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence)	6.43	6.44	0.342	0.342	0.785	0.783
T4	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	6.50	6.52	0.342	0.343	0.790	0.795
T5	Atrazine @ 3.0 kg ha^−1 (pre-emergence)	6.41	6.40	0.343	0.343	0.782	0.782
T6	Atrazine @ 3.0 kg ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	6.51	6.52	0.342	0.343	0.785	0.787
T7	Pendimethalin @ 2.0 l ha^−1 (pre-emergence)	6.43	6.43	0.342	0.342	0.783	0.782
T8	Pendimethalin @ 2.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	6.50	6.50	0.342	0.342	0.785	0.792
T9	Bicolor polythene mulch (250 µm)	6.53	6.54	0.341	0.341	0.786	0.784
T10	Cowpea (green manure)	6.45	6.43	0.342	0.342	0.794	0.796
T11	White clover (cover crop)	6.42	6.41	0.343	0.344	0.785	0.787
T12	Clean cultivation (weeding at 30 days interval)	6.71	6.73	0.344	0.345	0.761	0.756
T13	Farmer practices (Hoeing during March and May)	6.44	6.44	0.343	0.343	0.784	0.783
T14	Zero weeds (weeding at frequent intervals)	6.62	6.65	0.343	0.344	0.769	0.765
T15	Control (no weeding)	6.41	6.40	0.342	0.342	0.781	0.776
C.D.(p ≤ 0.05)		0.08	0.08	NS	0.003	0.007	0.009

Soil electrical conductivity was not significantly affected by different treatments during 2015, however, the effect was significant during 2016 (Table 9). Highest electrical conductivity was observed under clean cultivation (0.344 and 0.345 dSm⁻¹) and the lowest electrical conductivity was recorded under bicolor polythene mulch (0.341 dSm⁻¹), paddy straw mulch followed by glyphosate and paddy straw mulch during both the years of study. No significant differences were observed in soil electrical conductivity in 2015 and the least significant difference was observed among different treatments during 2016 (Table 9). The result is in conformity with the finding of Negi (2013) and Ni et al. (2016), who reported a non-consistent variation in soil pH under different orchard floor management systems. Similar results were reported by Tukey and Schoff (1963) and Schuricht et al. (1983) who did not observe any significant differences in soil pH under mulches and herbicide treatments.

Soil Organic Carbon

A significant variation in organic carbon under different weed control treatments was observed during both the years of study (Table 9). Maximum organic carbon was recorded with paddy straw mulch followed by glyphosate (0.798 and 0.806%) and was at par with that of the paddy straw mulch (0.796 and 0.803%) and cowpea (0.794 and 0.796%) respectively, during 2015 and 2016. Minimum organic carbon was recorded under clean cultivation during 2015 and 2016 (0.761 and 0.756%, respectively). Organic carbon of soil was maximum under paddy straw mulch followed by glyphosate, which was at par with paddy straw mulch and cowpea. The results are in accordance with those of Atucha et al. (2011), who reported that organic matter content of soil in the apple was much greater in the mulched treatment through decomposition of mulches. The results are also in agreement with the finding of Laurent et al. (2008), who recorded higher microbial soil respiration rates under mulch treatment compared with the pre-emergence herbicides treatment. They attributed the enhanced microbial activity to the increased carbon cycling in soil. Further, Shylla et al. (1998) reported that application of herbicides in Santa Rosa plum decreased the organic carbon content of soil by 21.08 per cent, over hay mulch, probably, due to effective weed control which reduced the inputs of organic matter of soil and recycling of nutrients. A similar decrease in organic matter under herbicide management has been reported by Robinson (1982). Higher organic carbon content under cover crops as compared to herbicides application was observed by Miller et al. (1963).

Soil Nutrients

Soil macronutrients contents (N, P, K, Ca and Mg) are highly important for the growth and development of the plants and any imbalances can have a drastic effect on the yield. The available nitrogen content of the soil was markedly influenced by various orchard floor management practices during both the years of study (Table 10). Maximum available nitrogen content was recorded under paddy straw mulch followed by glyphosate (405.1 and 410.9 kg ha⁻¹), in cowpea treated floor (403.2 and 408.9 kg ha⁻¹) and in paddy straw mulch (403.0 and 407.3 kg ha⁻¹), respectively during 2015 and 2016. The minimum available nitrogen content was recorded under un-weeded control (363.9 and 363.1 kg ha⁻¹) during 2015 and 2016, respectively.

Table 10. Weed control by different orchard floor management practices on soil available macronutrient status of apple cv. Royal Delicious during 2015 and 2016.

Treatments		N (Kg ha^−1)		P (Kg ha^−1)		K (Kg ha^−1)		Ca (Kg ha^−1)		Mg (Kg ha^−1)
		2015	2016	2015	2016	2015	2016	2015	2016	2015	2016
T1	Paddy straw mulch (10 cm thick)	403.0	407.3	22.28	22.30	262.0	265.5	2527.4	2540.8	637.8	638.8
T2	Paddy straw mulch (10 cm thick) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	405.1	410.9	22.31	22.33	262.7	265.8	2532.2	2547.5	638.0	639.8
T3	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence)	366.1	365.3	21.96	21.97	241.0	241.3	2374.6	2383.3	600.9	600.0
T4	Oxyflourfen @ 1.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	395.4	400.0	22.25	22.27	257.7	259.9	2509.1	2520.9	627.0	629.0
T5	Atrazine @ 3.0 kg ha^−1 (pre-emergence)	365.7	365.0	21.93	21.93	238.8	239.6	2362.4	2371.0	598.2	593.9
T6	Atrazine @ 3.0 kg ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	395.0	398.0	22.20	22.22	257.0	258.4	2504.1	2514.8	620.4	622.0
T7	Pendimethalin @ 2.0 l ha^−1 (pre-emergence)	364.8	364.4	21.93	21.94	239.1	240.3	2375.0	2384.6	600.2	597.3
T8	Pendimethalin @ 2.0 l ha^−1 (pre-emergence) followed by glyphosate @ 2.0 l ha^−1 (post-emergence)	395.7	399.3	22.23	22.24	257.1	258.7	2511.0	2520.3	620.9	621.0
T9	Bicolor polythene mulch (250 µm)	401.1	402.7	22.23	22.25	257.7	260.2	2525.7	2539.2	626.5	628.2
T10	Cowpea (green manure)	403.2	408.9	22.28	22.31	260.1	265.0	2526.7	2540.2	637.1	638.5
T11	White clover (cover crop)	395.0	397.5	22.27	22.28	256.6	260.3	2462.7	2476.0	629.0	631.2
T12	Clean cultivation (weeding at 30 days interval)	393.0	394.6	22.20	22.26	254.4	255.8	2485.0	2503.5	612.7	613.0
T13	Farmer practices (Hoeing during March and May)	368.0	368.2	22.16	22.17	242.7	244.4	2383.7	2394.7	602.4	600.8
T14	Zero weeds (weeding at frequent intervals)	394.2	395.9	22.21	22.22	255.6	256.0	2493.2	2508.6	623.2	624.9
T15	Control (no weeding)	363.9	363.1	21.77	21.78	238.4	237.8	2322.4	2322.1	596.7	583.1
	C.D.(p ≤ 0.05)	3.9	4.0	0.03	0.06	2.9	3.3	7.1	8.7	6.0	6.8

Soil nutrient status showed increased levels under different orchard floor management practices. The available nitrogen content in soil was found maximum under paddy straw mulch followed by glyphosate (405.1 and 410.9 Kg ha⁻¹) and was at par with cowpea (403.2 and 408.9 Kg ha⁻¹) and paddy straw mulch (405.1 and 410.9 Kg ha⁻¹), respectively, during 2015 and 2016. The increase in available nitrogen is mainly attributed to efficient weed control, increase in organic matter content and high soil moisture under mulching and herbicidal combination treatment. The results obtained are in consonance with the findings of Yogesh and Hiremath (2014) and Meena et al. (2015). Maximum available nitrogen in soil was observed under pre-emergence herbicides treatment followed by post-emergence herbicides in apple soil (Atucha et al., 2011). Similarly, Rao and Pathak (1998) reported the highest available nitrogen content in the soil in paddy straw mulch treatment followed by in sugarcane trash in aonla cv. Francis field. Maintenance of a vegetative cover, or “living mulch” can reduce the nutrient loss and retain available soil N, and or contributing additional N through residue decomposition (Sanchez et al., 2003; Yao et al., 2005). In addition, root exudates and decaying residues from cover crops contribute labile carbon compounds that stimulate microbial activity responsible for enhanced nutrient retention and cycling (Wardle et al., 2001).

All the orchard floor management practices influenced the available phosphorous content in the soil. It was observed that, the available phosphorous content in soil was significantly higher under paddy straw mulch followed by glyphosate (22.31 and 22.33 kg ha⁻¹), cowpea (22.28 and 22.31 kg ha⁻¹), paddy straw mulch (22.28 and 22.31 kg ha⁻¹) and white clover (22.27 and 22.28 kg ha⁻¹), respectively, during 2015 and 2016. However, minimum available phosphorus content was recorded under un-weeded control (21.77 and 21.78 kg ha⁻¹) during 2015 and 2016, respectively.

Maximum phosphorous content was recorded with paddy straw mulch followed by glyphosate, paddy straw mulch and cowpea. Our results are in agreement with earlier findings in plum (Shylla et al., 1998) and peach (Meena et al., 2015). They reported a higher amount of available phosphorus in soil under hay mulch which was possibly added to the soil by decomposition of hay. Straw mulch increased soil available phosphorus as compared to the clean cultivation or clean cultivation with cover crops in various fruits (Boynton et al., 1952). The increased available soil phosphorous under mulches treatments may be due to the increased microbial activity, fast decomposition and mineralization of mulches in the presence of nitrogen and elimination of competitive weeds. Similar results were reported by Khokhar and Sharma, 2000).

Further, soil potassium content was significantly influenced by various orchard floor management practices during both the years of study (Table 10). Maximum available potassium content was recorded with paddy straw mulch followed by glyphosate (262.7 and 265.8 kg ha⁻¹), paddy straw mulch (262.0 and 265.5 kg ha⁻¹) and cowpea (260.1 and 265.0 kg ha⁻¹), respectively, during 2015 and 2016. Minimum available potassium content was recorded under un-weeded control (238.4 and 237.8 kg ha⁻¹) during 2015 and 2016, respectively. This can be attributed to the increased available moisture and decomposition of mulches that added organic matter thereby nutrient to the soil. The results are in line with the findings of Rao and Pathak (1998) and Meena et al. (2015) who reported the highest available potassium content in soil under paddy straw mulch in aonla. The higher available potassium content in the tree basin was directly associated with the rapid decomposition of organic mulches. Borthakur and Bhattacharya (1992) reported a similar response with organic mulch in guava. Further, a higher amount of available soil potassium has been reported under hay mulch in plum (Shylla et al., 1998). The increase in available soil potassium with cowpea can be due to its fast and determinate growth habit leading to the enhanced organic carbon content of soil and nutrient availability (Bana, 2009; Dwivedi et al., 2005; Pooniya et al., 2012).

The available calcium content of the soil showed significant variation with different orchard floor management practices during 2015 and 2016 (Table 10). Maximum available calcium content was recorded with paddy straw mulch followed by glyphosate (2532.2 and 2547.5 kg ha⁻¹), paddy straw mulch (2527.4 and 2540.8 kg ha⁻¹), cowpea (2526.7 and 2540.2 kg ha⁻¹) and bicolor polythene mulch (2525.7 and 2539.2 kg ha⁻¹), respectively, during 2015 and 2016. Minimum available calcium content was recorded under un-weeded control (2322.4 and 2322.1 kg ha⁻¹) during 2015 and 2016, respectively.

Further, magnesium content of the soil was significantly influenced by various weed control treatments during both the years of study (Table 10). Maximum available magnesium status was recorded under paddy straw mulch followed by glyphosate (638.0 and 639.8 kg ha-1), cowpea (637.1 and 638.5 kg ha-1) and paddy straw mulch (637.8 kg and 638.8 kg ha-1), during 2015 and 2016, respectively. Minimum available magnesium was observed under un-weeded control (596.7 and 583.1 kg ha-1) during 2015 and 2016, respectively.

Maximum available calcium and magnesium content were recorded under paddy straw mulch followed by glyphosate treatment, paddy straw mulch and cowpea treatment. However, minimum available calcium and magnesium contents were recorded under un-weeded control. The present results are in accordance with those of Mengel and Kirkby (1987) who reported an increase in the concentration of calcium under mulched conditions due to more microbial activity that rendered an organic fraction of calcium into available form. Similarly, Tiquia et al. (2002) observed that mulching increased the total microbial biomass together with the soil cation exchange capacity (CEC), soil calcium and soil organic matter when compared to the bare surfaces. Mulching increased the available calcium and magnesium concentration in plum orchard (Shylla et al., 1999) and apple orchard (Bhutani et al., 1994). Mulch and mulch + compost tea treatments resulted in significantly higher soil calcium and magnesium concentrations compared to the control treatments (Kotze, 2012).

In conclusion, application of paddy straw mulch followed by glyphosate appreciably reduced the weed growth and increased the soil quality, which, in turn increased tree growth and development.

Acknowledgments

We thank University Grants Commission for Rajiv Gandhi National Fellowship for funding of this research and division of fruit science and agronomy for assistance, comments and suggestions in research.

Disclosure statement

No conflict of interest.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the University Grants Commission under grant No. F1-17.1/2015-16/NFST-2015-17-ST-JAM-676/(SA-III/WEBSITE)