Cultivar and Plant Arrangement Effects on Yield and Fruit Quality of Bell Pepper

Singleand double-row arrangements of a fixed population (one plant every 0.285m) were compared in factorial combination with two (2002) or five (2003) cultivars for effects on yield and fruit quality of bell pepper (Capsicum annuum L.). Arrangements for 2002 were S30, single rows 0.95 m apart, plants within rows 30 cm apart; D30, 1.9 m between centers of double-row beds, double rows 30 cm apart on beds, plants within rows 30 cm apart; S37.5, single rows 0.76 m apart, plants within rows 37.5 cm apart; and D37.5, 1.52 m between centers of double-row beds, double rows 24 cm apart on beds, plants within rows 37.5 cm apart. Only the S30 and D30 arrangements were used in 2003 after 2002 results showed almost no differences between S30 and S37.5 or between D30 and D37.5. Choice of cultivar was more critical in Texas, where X3R Wizard consistently outperformed King Arthur , than in Oklahoma. Single rows resulted in more full-season total marketable fruit weight than double rows in three experiments out of four, primarily as a result of an increased weight of U.S. No. 1 fruit with single rows. Average weight per marketable fruit was consistently unaffected by plant arrangement. Single rows also resulted in a greater full-season weight of sunburned fruit than double rows in two experiments out of four. Cultivar · plant arrangement interactions were not evident in Oklahoma and never involved full-season marketable fruit weights at either location in either year. Given the tested population, a single-row arrangement is likely to result in increased full-season production of U.S. No. 1 bell pepper fruit compared with a double-row arrangement, despite an increased potential for sunburned fruit with single rows. In a competitive marketplace, total yield may be less important than yield of a highquality, premium product. Selection of adapted cultivars and appropriate cultural practices are important steps toward this goal. Many studies have been published on plant populations for bell peppers (Ahmed, 1984; Batal and Smittle, 1981; Gaye et al., 1992; Locascio and Stall, 1994; Stoffella and Bryan, 1988). Specific recommendations for optimal plant population density vary. One reason may be that, as pointed out by Willey and Heath (1969), plant population density consists not only of plant number, but also plant arrangement. Plant arrangement has received relatively little attention in the solanaceous fruits and particularly in bell pepper. In theory, equidistant spacing of plants within the row and between rows (that is, an arrangement approaching a square) should maximize the yield per plant by optimizing canopy exposure to light and by providing a more uniform area for water and mineral uptake by the roots compared with standard rectangular planting (Sayre, 1959). Sayre (1959) compared tomatoes (Lycopersicon esculentum Mill.) in twin rows with those in standard single rows at similar plant population densities and found that the pattern in which the plants were more equally spaced produced the largest yield. Sayre (1959) also reported plants in the twin rows produced a high-quality crop with few fruit defects. This was attributed to plants having grown more erect in the twin rows and shading the fruit better than in the single rows. The current study was designed to determine whether different arrangements of a given plant population would affect yield of premium (U.S. Fancy and U.S. No. 1) bell pepper fruit. The comparison of singleand double-row arrangements also tested the hypothesis that use of double rows might reduce the number of cull fruits. Yield and grade-out of different cultivars were also examined, and possible cultivar · plant arrangement interactions were tested. Materials and Methods Studies were conducted at the Oklahoma Vegetable Research Station, Bixby, and at the Texas Agricultural Experiment Station, Uvalde, in 2002 and 2003. The soil at Bixby was a Severn very fine sandy loam [coarse– silty, mixed (calcareous), thermic Typic Udifluvent]. The soil at Uvalde was a Uvalde silty clay loam (fine–silty, mixed, hyperthermic Aridic Calciustoll). No plastic mulches were used at either location. Weeds were controlled with herbicides supplemented by hand and machine cultivation. Plant water requirements were met with rainfall supplemented by overhead sprinkler irrigation at Bixby and by surface drip irrigation at Uvalde. Standard foliar insecticides, fungicides, and bactericides were applied as needed. The bell pepper cultivars King Arthur and X3R Wizard were used both years. Additional cultivars in 2003 were Boynton Bell, Karma, and Lafayette. Transplants were commercially grown in 2002 and grown onsite in 2003. In both cases, transplants were produced in flats with inverted pyramid cells (200 cells per flat; volume, 18 cm per cell). Singleand double-row arrangements of a fixed population (one plant every 0.285 m) were compared. This population was chosen as a rough average of recommended plant population densities for Oklahoma and Texas. Arrangements for 2002 were S30, single rows 0.95 m apart, plants within rows 30 cm apart; D30, 1.9 m between centers of double-row beds, double rows 30 cm apart on beds, plants within rows 30 cm apart; S37.5, single rows 0.76 m apart, plants within rows 37.5 cm apart; and D37.5, 1.52 m between centers of double-row beds, double rows 24 cm apart on beds, plants within rows 37.5 cm apart. Only the S30 and D30 arrangements were used in 2003 after 2002 results showed almost no differences between S30 and S37.5 or between D30 and D37.5. The experimental design was a split plot. In 2002, arrangements were main plots in a 4 · 4 Latin square; cultivars were subplots. In 2003, cultivars were main plots in a randomized complete block with four replications; arrangements were subplots. Plot lengths varied by plant arrangement. In 2002, single-row treatments had 32 plants per row (16 per cultivar). Double-row treatments had 20 plants per row (10 per cultivar). In 2003, S30 had 16 plants per row and D30 Received for publication 8May 2006. Accepted for publication 30 July 2006. The Oklahoma portion of this research was supported in part under project H-2026. Appreciation is extended to the U.S. Department of Agriculture for a grant (CSREES 2003-34402-13647 ‘‘Designing Foods for Health’’) for partial funding in Texas. Approved for publication by the director, Oklahoma Agricultural Exp. Sta. The information given in this publication is for educational purposes only. Mention of a trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product, nor does it imply approval or disapproval to the exclusion of other products or vendors that may also be suitable. Professor. To whom reprint requests should be addressed; e-mail [email protected] HORTSCIENCE VOL. 41(7) DECEMBER 2006 1565 JOBNAME: horts 41#7 2006 PAGE: 1 OUTPUT: October 24 18:51:51 2006 tsp/horts/127877/01605