MSU Extension Vegetables

A bell pepper cultivar trial was planted at the Southwest Michigan Research and Extension Center (42.081985, -86.354087, Benton Harbor, Michigan). Enza Zaden (EZ), HM Clause (HM), PanAmerican (PA), Seminis (SE), and Sakata (SK) seed companies donated bell pepper cultivars for plastic-mulch bedded and trellised hand harvest. Overall trial quality was excellent, however environmental conditions increased the numbers of choppers during the 2^nd and 3^rd pickings. In the future, we will not pick small fruit because there is no market for them.

Materials and Methods

On 7 April, 15 bell pepper cultivars were seeded into 72-cell trays and raised for 43 days in a greenhouse and 6 days in a shadehouse.

On 29 April lime and fertilizers were preplant incorporated to achieve 40 lb. N, 0 lb. P2O5, 20 lb. K2O, 1 lb. B, 25 lb. S, and 2000 lb. lime per acre (119 lb. 21-0-0-21S, 32 lb. 46-0-0, 28 lb. 0-0-60, 6.5 lb. 0-0-0-15B) in a field size of 0.4 acre. The soil type was a well-drained Oakville fine sand. On 11-12 May, black plastic mulch and drip tape was laid with 6 ft between beds. No fumigation was used.

On 26 May, peppers were planted in a completely randomized design with four replications, two rows per bed, 14 inches apart between rows and 18 inches between holes in-row resulting in 16 plants per bed and a final plant population of 9,680 plants per acre. Two plants of a distinctly different variety were planted on either end of each plot to reduce picking errors between plots.

On 2 June, the fertigation schedule started delivering 5 lb. N and 5 lb. K2O per week (30 lb. 18-0-0-5Ca-1.5Mg, 9 lb. 0-0-60) for 15 weeks. No herbicides were applied. The field was hand-hoed, and diseases were managed with a weekly rotation of standard fungicides. Hornworms and two-spotted spider mites were treated on 29 July, and 2 September, respectively.

Four reps of all cultivars were harvested and measured four times on 4 Aug (70 dap), 17 Aug (83 dap), 25 Aug (91 dap), and 7 Sep (104 dap). We harvested all 16 plants from each dual row plot when the fruits began reaching advanced sizes. Hard-ripe fruit were removed from the plants and sorted and counted by the following sizes for No. 1 quality fruit: Small (< 130 g), Medium (130 – 159 g), Large (160 – 189 g), Extra Large (190 – 229 g), Jumbo (> 230 g). In addition, No. 2 quality fruit (choppers) and culls were counted and weighed. Yield data was analyzed with a both parametric ANOVA and non-parametric Kruskal-Wallis procedures followed by a Least Significant Difference (LSD) calculation.

Fruit per plant, 1-1/9 bushels per acre of each size class, and combined total 1-1/9 bushel per acre yield calculations do not include culls. We determined 1-1/9 bushels per acre with the following equation. 

Results and Discussion

The season was characterized by warmth and dryness, though the peppers harvested 91 days after planting exhibited the stubby growth characteristic of cool temperatures at bud-formation (Table 1). The established transplant stand was near 100%, and plants grew well.

Total clean yield (jumbo + xlarge + large + medium + small + choppers) averaged 955.8 1-1/9 bushels per acre (Table 2). The top five cultivars with the highest combined clean yields of the most profitable size classes (xlarge, jumbo, large) were SE Redfish, SK Mercer, SE Tarpon, PA Remarkabell, and EZ Regulator. The total yield of PA Kickstart and PA 11033 was driven by high proportions of smalls and choppers relative to other more profitable sizes. However, the overall means across all cultivars for each size class were nearly equal, at around 107 1-1/9 bushels per acre for each size class. The five lowest yielders in total 1-1/9 bushels per acre were PA Trailblazer, SK Nitro S10, EZ 9, HM Captain, and PA 11135.

Fruit classified as choppers were often mishappen due to plant architecture or environmental effects and the overall mean across all cultivars was 419.5 1-1/9 bushels per acre. Choppers averaged 45% of the total yield across cultivars, and this ranged from 35% (SE Tarpon) up to 62% (EZ 3), indicating the importance for secondary markets for bell peppers (Table 3).

Cull rates averaged 8% and were between 1% (SE Sailfish) and 29% (EZ 9) (Table 3). The culls were largely due to blossom end rot, and sunscald to a much lesser extent. The five cultivars with the lowest cull percentages were SE Sailfish, PA 11033, SK Mercer, PA Kickstart, and PA Remarkabell. The five cultivars with the highest cull percentages were HM Captain, SE Redfish, EZ Regulator, PA 11135, and EZ 9.

The best overall performer was SK Mercer, with the highest total yield, highest yield across the two middle pickings, the second highest number of marketable fruit per plant, and third smallest cull percentage (5%). Trial observers were attracted to PA 11033 for its bright white color and some sensed that it had a different smell. For one commercial bell pepper grower, this different smell was a concern. But, for one consumer the smell was desirable, and “less vegetal”.

Acknowledgements

Thanks to Cheni Filios, Dennis Thome, Ryan Kingma, Bryan Stuart, and John Schramski at the seed companies; Dave, Rich, Sylvia, Martin, Mina, Ramon, and Jenny at the farm; and Aaron Molter for technical review.