Evaluation of Strawberry Cultivars in Florida

Abstract

Field studies were conducted over two seasons to examine the performance of strawberry cultivars. During the 2007–2008 season, the cultivars tested were ‘Winter Dawn’, ‘Florida Elyana’, ‘Florida Radiance’, ‘Ruby Gem’, ‘Strawberry Festival’, ‘Treasure’, and ‘Camarosa’; whereas in the 2008–2009 season, ‘Winter Dawn’, ‘Florida Elyana’, ‘Florida Radiance’, ‘Strawberry Festival’, ‘Treasure’, ‘FL 05–73’, and ‘FL 05–107’ were planted. During both growing seasons, ‘Strawberry Festival’ consistently produced the highest early and total fruit numbers among all tested cultivars. Similarly, the same cultivar had the highest early fruit weight. With regards to total fruit weight, ‘Florida Radiance’, ‘Treasure’, and ‘Strawberry Festival’ resulted in the highest values among all cultivars tested during both seasons. There was no consistency on specific cultivars producing the largest early fruit, while ‘Florida Radiance’ and ‘Florida Elyana’ had the largest total weight per fruit during both seasons. These results indicated that ‘Strawberry Festival’ is an adequate choice as a main cultivar for production under Florida's conditions, which could be complemented during low production periods with other promising and late producing cultivars such as ‘Florida Radiance’ and ‘Treasure’.

KEYWORDS:

• Fragaria X ananassa
• ‘Strawberry Festival’
• ‘Winter Dawn’
• ‘Florida Elyana’
• ‘Florida Radiance’
• ‘Treasure’

INTRODUCTION

Strawberry (Fragaria X ananassa Duch.) production in Florida is the second largest in the United States after California, with about 3,360 hectares and gross sales over $330 million (U.S. Department of Agriculture [USDA], 2008). Florida is the largest supplier of strawberries during the winter months in the United States, and the majority of the strawberry production occurs in the west central part of the state. Strawberry yields in Florida have increased over the years due to the use of soil fumigation, raised beds with polyethylene mulch, defined fertilization practices, and planting pest-free stocks from northern nurseries (Galleta, 1997). Some of the benefits of the annual hill system are improved weed control, high early yields and large fruit size, and ease of harvest (Black et al., 2002). The west central Florida strawberry industry sets fresh transplants with active crowns and intact and functional leaves during early October. Ripe fruit is harvested from mid-December until mid-March or later, if the market prices are favorable (Chandler et al., 2002).

The goal of a successful breeding program is to develop cultivars to satisfy market and grower requirements. From the market point of view, among the most important strawberry fruit characteristics are uniform shape, size, firmness, flavor, color, and prolonged shelf life. On the other hand, growers are interested in having cultivars with disease resistance, high yields under different weather conditions, and acceptable yield earliness, which allow them to supply the market when premium prices are available (Santos et al., 2007). Planting different cultivars in the same farm is a common practice among strawberry growers in Florida. The purpose is to complement the production peaks of each cultivar in order to maintain a steady supply through the season, especially during the early part of the fruiting season.

‘Winter Dawn’ is a cultivar with high early yields, large fruit in small plants, and resistance to botrytis (caused by Botrytis cinerea [de Bary] Whetzel) and anthracnose fruit rot (caused by Colletotrichum acutatum Simm.) (Chandler, 2005). ‘Treasure’ is characterized by its earliness, high yield, firm fruit, and long shelf life (Chang, 2002). ‘Strawberry Festival’ is the most used cultivar in Florida, with attractive and firm fruit and long shelf life (Chandler et al., 2000). ‘Camarosa’ produces firm fruit flesh and early season yields (Voth et al., 1994). The latest releases from the University of Florida's breeding program are ‘Florida Radiance’ and ‘Florida Elyana’. The former is resistant to botrytis and anthracnose fruit rot and produces medium to large fruit (Chandler et al., 2009b), whereas the latter has large firm and very flavorful fruit (Chandler et al., 2009a).

There is a current need for cultivars to complement the harvest peaks of ‘Strawberry Festival’, which is the most planted cultivar in Florida (Chandler et al., 2000). However, the performance of the strawberry cultivars needs to be investigated in Florida to determine adaptability and performance among cultivars and advanced breeding lines. The objective of this study was to compare the performance of several strawberry cultivars in west central Florida.

MATERIALS AND METHODS

Two trials were conducted during the 2007–2008 and 2008–2009 strawberry seasons at the Gulf Coast Research and Education Center of the University of Florida, located in Balm, FL. The soil at the experiment site is classified as a Myakka fine sand siliceous, hyperthermic, Oxyaquic Alorthod. The organic matter content and the soil pH of the experiment site were 1.5% and 7.3, respectively, and were measured 4 weeks before transplanting. Planting beds were pre-formed with a standard bedder, 69-cm wide at the base, 61-cm wide on the top, 25-cm high, and spaced 1.22 m apart on centers. The soil was fumigated with 398 kg/ha of methyl bromide + chloropicrin (67/33 v/v). Simultaneously, beds were covered with black high-density polyethylene mulch (0.04-mm thick). No preplant fertilizer was used. Fertilization and pest control were done according the requirements of the crop (Peres et al., 2006). Fertigation was applied through a single-drip tape line (237 L/ha per min; T-tape Systems International, San Diego, CA) buried between 2- and 5-cm deep, and the experimental area was equipped with 15-L/min sprinklers for frost protection and crop establishment.

During the 2007–2008 season, the cultivars tested were ‘Winter Dawn’, ‘Florida Elyana’, ‘Florida Radiance’, ‘Strawberry Festival’, ‘Treasure’, and ‘Camarosa’; whereas in the 2008–2009 season, ‘Winter Dawn’, ‘Florida Elyana’, ‘Florida Radiance’, ‘Strawberry Festival’, ‘Treasure’, ‘FL 05–73’, and ‘FL 05–107’ were planted. The experimental design was a randomized complete block design with four replications. Bare-root strawberry transplants from certified nurseries in Nova Scotia, Canada, were planted October 15, 2007, in double rows 38 cm apart with 20 plants per 7.6 m plot. Sprinkler irrigation was used 8 hr/day for 10 days to ensure plant establishment.

Strawberry marketable fruit weight and number were collected two times per week, beginning in mid-December of each season and using every plant of each plot. A marketable fruit was defined as a fruit without visible blemishes and with at least 75% red skin. Early yield consisted of the cumulative yield from the first six harvests, whereas the total yield included the 24 harvests through the season. The weight per fruit was determining by dividing the fruit weights by the fruit numbers of the early and total yields. Cultivar means were compared with a Fisher's protected least significance difference (LSD) test at the 5% significance level.

RESULTS AND DISCUSSION

2007–2008 Season

There were significant effects of cultivars on the fruit number, fruit weight, and weight per fruit during the 2007–2008 and 2008–2009 seasons. During the first season, the highest early fruit numbers were found in plots planted with ‘Strawberry Festival’ with 243,900 fruit per ha, whereas there were no early fruit number differences among ‘Treasure’, ‘Winter Dawn’, ‘Florida Elyana’, and ‘Camarosa’, ranging between 125,800 and 166,100 fruit per ha (Table 1). However, there were no significant differences among plots planted with ‘Strawberry Festival’, ‘Treasure’, and ‘Winter Dawn’ in the total fruit number during the season, while the lowest number was found in the ‘Camarosa’ plots.

TABLE 1 Comparison of Fruit Number, Yield, and Weight per Fruit of Different Strawberry Cultivars, 2007–2008 Season, Balm, FL, USA

Cultivar	Fruit number(no. × 10^3/ha)		Fruit weight(t/ha)		Weight per fruit (g)
	Early^z	Total	Early	Total	Early	Total
Strawberry Festival	243.9 a	820.6 a	3.5 a	12.7 ab	14.3 c	15.5 b
Treasure	166.1 b	730.7 ab	3.3 a	15.0 a	19.7 a	20.5 a
Winter Dawn	125.8 bc	647.4 ab	1.9 b	11.9 b	15.3 c	18.4 ab
Florida Elyana	137.2 bc	567.4 b	2.4 b	11.5 bc	17.4 b	20.3 a
Florida Radiance	113.8 c	600.0 b	1.9 b	12.2 ab	16.5 b	20.3 a
Camarosa	134.5 bc	399.1 c	2.3 b	8.9 c	16.8 b	22.3 a
^zValues followed by the same letter do not significantly differ at the 5% level according to Fisher's protected LSD test.
∗Significance, P < 0.05.

Early fruit weight was the highest in plots planted with ‘Strawberry Festival’ and ‘Treasure’, ranging between 3.3 and 3.5 t/ha (Table 1). Other cultivars produced early fruit weights between 1.9 and 2.4 t/ha. There were no differences in early fruit weight among the remaining cultivars. Plots planted with ‘Strawberry Festival’, ‘Treasure’, and ‘Florida Radiance’ did not differ in total fruit weight, with yields above 12 t/ha. The lowest total fruit weights were found with ‘Camarosa’ and ‘Florida Elyana’. The heaviest fruit were obtained in plots planted with ‘Treasure’ during the early harvests, averaging 19.7 g per fruit, followed by ‘Florida Elyana’, ‘Florida Radiance’, and ‘Camarosa’, whose fruit ranged between 16.5 and 17.4 g. The smallest fruit were produced by ‘Strawberry Festival’ and ‘Winter Dawn’. Fruit size changed as the planting season progressed, as shown by the season-total weights per fruit. There were no significant differences in the weights per fruit of five out of six cultivars, ranging between 18.4 and 22.3 g per fruit (Table 1).

2008–2009 Season

Plots transplanted with ‘Strawberry Festival’ and ‘Winter Dawn’ resulted in the highest early fruit number, with values of 183,600 and 184,900 fruit per ha, respectively. The lowest early fruit weights were obtained with the advanced line ‘FL 05–107’, and with ‘Florida Elyana’ and ‘Florida Radiance’ (Table 2). However, the advanced line ‘FL 05–107’ produced the highest total fruit number along with ‘Strawberry Festival’, both exceeding 710,000 fruit per ha. In contrast, ‘Winter Dawn’ and ‘Florida Elyana’ had the lowest values for this variable with less than 400,000 fruit per ha.

TABLE 2 Comparison of Fruit Number, Yield, and Weight per Fruit of Different Strawberry Cultivars, 2008–2009 Season, Balm, FL, USA

Cultivar	Fruit number (no. X 10^3/ha)		Fruit weight (t/ha)		Weight per fruit (g)
	Early^z	Total	Early	Total	Early	Total
Strawberry Festival	183.6 a	710.6 a	3.9 a	15.4 b	21.2 b	21.7 b
Treasure	121.2 bc	537.4 b	2.7 b	13.0 bc	22.3 b	24.2 b
Winter Dawn	184.9 a	388.1 c	3.7 a	7.7 d	20.0 b	19.8 bc
Florida Elyana	67.6 d	323.8 c	2.2 b	10.6 c	32.5 a	32.7 a
Florida Radiance	86.6 cd	510.4 b	2.8 b	13.4 bc	32.3 a	26.3 ab
FL 05–73	130.8 b	592.0 b	2.6 b	11.0 c	19.9 b	18.6 c
FL 05–107	69.9 d	787.0 a	2.2 b	21.3 a	31.5 a	27.1 a
^zValues followed by the same letter do not significantly differ at the 5% level according to Fisher's protected LSD test.
Significance, P < 0.05.

‘Strawberry Festival’ and ‘Winter Dawn’ produced the highest early fruit weight among all the cultivars, with 3.9 and 3.7 t/ha, respectively (Table 2). There were no significant differences on early fruit weights among the remaining cultivars, which ranged between 2.2 and 2.8 t/ha. Plots planted with the advanced line ‘FL 05–107’ provided the highest total fruit weights during this season (21.3 t/ha), followed by ‘Strawberry Festival’, ‘Treasure’, and ‘Florida Radiance’, which produced between 13.0 and 15.4 t/ha. The lowest total fruit weights were obtained in plots planted with ‘Winter Dawn’. ‘Florida Radiance’, ‘Florida Elyana’, and the advanced line ‘FL 05–107’ produced the heaviest early and total weights per fruit during the season, ranging between 26.3 to 32.7 g per fruit (Table 2). In most cases, there were no significant differences on early weight per fruit among the remaining cultivars. ‘Strawberry Festival’, ‘Treasure’, and ‘Winter Dawn’ had weight per fruit between 19.8 and 24.2 g.

During both growing seasons, ‘Strawberry Festival’ consistently produced the highest early and total fruit numbers among all tested cultivars. Similarly, the same cultivar had the highest early fruit weight. With regards to total fruit weight, ‘Florida Radiance’, ‘Treasure’, and ‘Strawberry Festival’ resulted in the highest values among all cultivars tested during both seasons. The advanced line ‘FL 05–107’ seemed to be a promising germplasm that produced the highest fruit weight in the 2008–2009 season, but more testing is needed to confirm that result. There was no consistency on specific cultivars producing the largest early fruit, while ‘Florida Radiance’ and ‘Florida Elyana’ had the largest total weight per fruit during both seasons.

These results indicated that ‘Strawberry Festival’ is an adequate choice as a main cultivar for production under Florida's conditions, which could be complemented during low production periods with other promising and late producing cultivars, such as ‘Florida Radiance’ and ‘Treasure’. The performance of the advanced line ‘FL 05–107’ needs to be further investigated because of its elevated total fruit weight during the only season when it was tested.