Nitrates content in table potato tubers under the influence of herbicides and biostimulants

Figures & data

Table 1. Factors in the conducted field experiment.

Factor I – three table potatoes cultivars: Bartek, Gawin, Honorata (Level 3)
Factor II – five methods of application of herbicides and biostimulants (treatments) (Level 5)
1. Control object – mechanical weed control until and after potato emergence – without herbicides or biostimulants 2. Harrier 295 ZC (linuron + chlomazon) at a rate of 2.0 l ha^−1 (BBCH 07) 3. Harrier 295 ZC (linuron + chlomazon) at a rate of 2.0 l ha^−1 (BBCH 07), and growth regulator Kelpak SL* at a rate of 2.0 l ha^−1 (BBCH 13-18) 4. Sencor 70 WG (metribuzin) at a rate of 1.0 kg ha^−1 (BBCH 08) 5. Sencor 70 WG (metribuzin) at a rate of 1.0 kg ha^−1 (BBCH 08) and growth regulator Asahi SL** at a rate of 1.0 l ha^−1 (BBCH 13-18)

*Kelpak SL (algae extract from Ecklonia maxima − auxins and gibberellins)

**Asahi SL(sodium para-nitrophenol, sodium ortho-nitrophenol, sodium 5-nitroguaiacol)

Table 2. Chemical properties of soil before the establishment of the field experiment in the study years.

	Year and value
	2012		2013		2014
Soil parameter	Value	Category	Value	Category	Value	Category
pH, KCl	5.6	Lightly acidic	5.6	Lightly acidic	6.35	Neutral
Organic matter, g kg^−1	15	-	16	-	18.7	-
Available P, mg kg^−1	68.6	High	73.4	High	110	Very high
Available K, mg kg^−1	149.4	Very high	129	High	149.4	Very high
Available Mg, mg kg^−1	50	High	51	High	56	High

Table 3. Meteorological data in the study years according to Zawady Meteorological Station.

Years	Months						April-September
	April	May	June	July	August	September
Air temperature (°C)							Mean
2012	8.9	14.6	16.3	20.7	18.0	14.1	15.4
2013	7.4	15.3	18.0	19.0	18.8	11.7	15.0
2014	9.8	13.5	15.4	20.8	18.1	14.1	15.3
Long-term mean (1987–2000)	7.8	12.5	17.2	19.2	18.5	13.1	14.7
Precipitation (mm)							Sum
2012	29.9	53.4	76.2	43.0	51.0	11.4	264.9
2013	36.0	105.9	98.8	91.3	15.0	94.3	441.3
2014	45.0	92.7	55.4	10.0	105.7	26.3	335.1
Long-term mean (1987-2000)	38.6	44.1	52.4	49.8	43.0	47.3	275.2

Table 4. Nitrate content (mg kg⁻¹ FM) of potato tubers in response to herbicide and biostimulant application.

	Cultivar			Mean
Herbicide and biostimulant	Bartek	Gawin	Honorata
Control	151.3	146.0	140.8	146.0
Harrier 295 ZC	152.9	149.5	147.6	150.0
Harrier 295 ZC + Kelpak SL	154.0	151.6	149.5	151.7
Sencor 70 WG	155.3	147.7	150.5	151.1
Sencor 70 WG + Asahi SL	156.7	149.9	151.8	152.8
Mean	154.0	148.9	148.0	150.3

Note: LSD_0.05 for: cultivar = 3.6; for herbicide and biostimulant = 4.0; cultivar × herbicide and biostimulant interaction was non significant.

Table 5. Nitrate content (mg kg⁻¹ FM) of potato cultivars as affected by temperatures and rainfall in 2012, 2013 and 2014.

Herbicide and biostimulant	Year and cultivar
	2012			2013			2014			Mean
	Bartek	Gawin	Honorata	Bartek	Gawin	Honorata	Bartek	Gawin	Honorata
Control	161.9	160.2	159.7	143.7	130.0	117.7	148.3	147.7	145.0	146.0
Harrier 295 ZC	162.5	161.8	161.0	146.3	136.7	135.0	150.0	150.0	146.7	150.0
Harrier 295 ZC + Kelpak SL	163.6	163.2	163.0	146.7	140.0	137.3	151.7	151.7	148.3	151.7
Sencor 70 WG	165.8	161.4	164.0	150.0	131.7	140.7	150.0	150.0	146.7	151.1
Sencor 70 WG + Asahi SL	166.4	164.6	165.0	150.3	135.0	142.7	153.3	150.0	147.7	152.8
Mean, cultivar	164.0	162.2	162.5	147.4	134.7	134.7	150.7	149.9	146.9	150.3
Mean, year	162.9			138.9			149.2			150.3

Note: LSD_0.05 for: cultivar = 3.6; for herbicide and biostimulant = 4.0; for year = 3.6; cultivar × herbicide and biostimulant interaction was non significant.

Table 6. Analysis of variance for nitrate content in three potato cultivars subjected to five herbicide and biostimulants applications in 2012, 2013 and 2014.

Sources of variation	Degrees of freedom	Sum of squares	Variance	F	F Critical value	LSD0.05
Cultivars	2	947.9484	473.9742	11.4913	3.880	3.615*
Years	2		6545.0516	158.683	3.880	3.615*
Cultivars × Years	4	822.2524	205.5631	4.9838	3.260	6.261*
Error I	12	494.9529	41.2461
Herbicide and biostimulants	4	737.0677	184.2669	6.5147	2.500	4.67*
Cultivars × Herbicide and biostimulants	8	261.8701	32.7338	1.1572	2.070	6.017
Herbicide and biostimulants × Years	8	314.1043	39.2630	1.3881	2.070	7.045
Cultivars × Herbicide and biostimulants × Years	16	384.1179	24.0074	0.8487	1.790	10.422
Error II	72	2036.5000	28.2847

*Significant at the 0.05 level.

Table 7. Daily human consumption of nitrates (mg) with 266 g potato^a as affected by herbicides, biostimulants and cultivars. Means across 2012–2014^b.

Herbicide and biostimulant	Cultivar			Mean
	Bartek	Gawin	Honorata
Control object	40.2	38.8	37.5	38.8
Harrier 295 ZC	40.7	39.8	39.3	39.9
Harrier 295 ZC + Kelpak SL	41.0	40.3	39.8	40.4
Sencor 70 WG	41.3	39.3	40.0	40.2
Sencor 70 WG + Asahi SL	41.7	39.9	40.4	40.7
Mean	41.0	39.6	39.4	40.0

^aMean per capita consumption of potato tubers is 97 kg year⁻¹ in Poland in 2017 (Potato Market. Status and perspectives 2017).

^bAcceptable daily intake (ADI) of nitrates is 200 mg day⁻¹ (Regulation of the Minister of Health 2003, Commission Regulation (EC) 2006).

Regulation of the Minister of Health of January 13. 2003. On the maximum levels of chemical and biological impurities that may be found in food, food ingredients, allowed additives, processing aids or on the surface of food. Dz. U. No. 37, item 326. Warsaw, 2411–2439. (in Polish).

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Commission Regulation (EC) No 1881/2006 of 19 December. 2006. Setting maximum levels for certain contaminants in foodstuffs (Text with EEA relevance) (OJ L 364, 20.12.2006, p. 5).

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