Abstract
Three research trials were performed over two spring seasons to assess the performance of bell pepper (Capsicum annuum) cultivars in southern Georgia, USA. Studies were conducted in commercial production fields in Echols and Lowndes counties, which are major bell pepper production areas in Georgia, USA. Eleven cultivars were evaluated, and 10 newer bell pepper cultivars with improved disease resistances for bacterial leaf spot races 1 to 10, tomato spotted wilt virus, and/or phytophthora were compared with ‘Aristotle’, which historically was the most widely grown bell pepper hybrid in the southeastern United States. Our goal was to determine how the new and improved cultivars compared with ‘Aristotle’ for total yield, fruit size distribution, and unmarketable defects in the absence of disease pressure. There were significant differences in fruit size, marketable fruit, and culls between cultivars contrasting their adaptability for production in southern Georgia. The top performers for yield and preferred fruit size for fresh market bell pepper spring production in southern Georgia were ‘Autry’, ‘Standout’, and ‘Antebellum’. Yields and fruit size distribution of these cultivars were similar to ‘Aristotle’ but may be preferred in certain situations due to additional disease resistance. The cultivar, SV 3255 also had higher yields and low defects but had smaller average fruit sizes.
The United States produced 10.4 million cwt of bell peppers (Capsicum annuum) nationwide in 2022; the State of Georgia ranked third in the country, contributing nearly 10.5% of the total production with 1.09 million cwt, demonstrating the crop’s economic significance for the state [US Department of Agriculture (USDA), National Agricultural Statistics Service (NASS) 2023a, 2023b]. After sweet corn (15.9%), watermelon (13.2%), and onion (12.6%), bell pepper was the fourth leading vegetable crop in Georgia for 2021 contributing 11.5% of the production value (University of Georgia, Center for Agribusiness and Economic Development 2024). The counties with the greatest production areas in 2021 were Echols (49%), Colquitt (19%), and Lowndes (10%), highlighting the predominance of this crop in the southern part of the state.
In southern Georgia, complete resistance to all known bacterial leaf spot races, Phytophthora, and tomato spotted wilt virus (TSWV) is desired, because these diseases can be problematic in some locations, during certain times of the year under the right environmental conditions. Resistant cultivars are the most effective method to reduce infection in disease-prone areas (Keinath 2019). Besides disease resistance, cultivars must have good yield potential and stability for a given environment. Cultivars may not be well-suited to a given environment, resulting in low fruit set and fruit that exhibit higher levels of physiological disorders or deformities that reduce marketable yields. The most important fruit defects encountered in these experimental trials are poor fruit shape, blossom-end rot (BER), and sunburn. Inadequate pollination leads to misshapen, flattened, or formation of fruit with a long tapered appearance (Ernest 2023). In addition, at fruit set and development, during the late spring when conditions are hot and dry, BER is a major problem in southern Georgia, USA (Westerfield et al. 2022). BER appears as sunken gray to black, leathery patches encircling the pepper fruit's pistil scar (blossom-end), which leads to the early ripening of fruit and makes it commercially unmarketable (Olle and Bender 2009; Taylor and Locascio 2004). Sun-exposed bell pepper fruit experiences heat stress, which damages the impacted cells and causes sunburn that ultimately results in fruit rotting (Ngouajio 2011). These disorders impede productivity, and development and are irreversible (Sanchez et al. 2011). Variations in plant genetics make certain cultivars more tolerant or susceptible (Salgotra and Chauhan 2023) to these physiological disorders. This research screened currently available commercial bell pepper cultivars for adaptability, high yields, ideal fruit size distribution, and most desired fruit qualities to make cultivar recommendations for the mature green fresh market sector within major production regions of southern Georgia, USA.
Materials and methods
Experimental site and design
The research trials were carried out at different farms in Echols, GA, USA, in Spring 2022 and 2023 as well as in Lowndes, GA, USA, in Spring 2023. Trials were transplanted on 4 Apr and 29 Mar in growers’ fields at Echols during 2022 and 2023, respectively. The Lowndes trial was transplanted on 21 Mar 2023 (Table 1). The weather data for the year 2022 and 2023 has been presented in Fig. 1. Treatments were arranged in a randomized complete block design with four replications. Plants were managed according to grower standards, which typically include weekly prophylactic pesticide applications (Sparks and Riley 2024). The bed tops were covered with black plastic mulch at all trials, and the field was watered through drip irrigation. Bell pepper seeds were sown in 242-count trays 6 weeks before transplanting. Transplants were grown at a local commercial greenhouse. Planting densities were 14,520 to 14,931 plants/acre configured with raised beds spaced 5 to 6 ft apart in the center. There was a double row of pepper plants on top of the bed and within-row spacing was 12 to 14 inches. Each experimental plot consisted of 20 plants. Irrigation regimes varied between different farms with 1 to 3 drip irrigation cycles/day of 30 min to 1 h per irrigation event throughout the week as required by the crop. Fertilizer rates varied between 200 and 400 lb nitrogen/acre. Phosphorous and potassium applications were made based on recommendations from a preplant soil analysis. A quarter of total nitrogen was applied pre-plant as a granular cold while the remaining liquid nitrogen (7-0-7) was applied weekly after transplanting through the irrigation system.
Sowing, transplant, and harvest dates of three bell pepper cultivar trials in southern Georgia, USA, between Mar and Jun 2022 and 2023.
Experimental material
Ten bell pepper cultivars (Antebellum, Autry, Green Machine, Nitro, Playmaker, SV3255, Tarpon, Boca, Prowler, and Standout) were compared with a standard check Aristotle for adaptability to production in southern Georgia, USA. Seeds of all cultivars were purchased from Seedway, LLC, Hall, NY, USA (Table 2).
Seed source and disease resistance in 11 bell pepper cultivars screened across three trials in southern Georgia, USA, between Mar and Jun 2022 and 2023.
Harvests
A total of two harvests were conducted ≈1 week apart (Table 1). Ten plants from the center of each plot were harvested. Fruit was graded according to USDA standards (USDA 2005) and sized by industry guidelines. Marketable fruit were sized into four categories: medium, large, extra-large, and jumbo. The estimated number of fruit/bushel box (estimated to be 28 lb) was 30 for jumbo, 40 for extra-large, 50 for large, and 60 for medium. A Market Maker Mechanical Grader (Tew Manufacturing Corp., Penfield, NY, USA) was used to separate fruit by width using the following cutoffs: 3 inches for medium, 3.5 inches for large, 4 inches for extra-large, and >4 inches for jumbo. The percentage of marketable fruit was calculated by dividing the total number of marketable fruit by the total number of fruit (marketable + unmarketable) and multiplying by 100 (Kumari et al. 2024).
Physiological disorders
A total of six fruit physiological disorders, including, silvering (Fig. 2A), pancaking (Fig. 2B), pointy (Fig. 2C), misshapen (Fig. 2D), BER (Fig. 3A), and sunburn (Fig. 3B), were encountered in the trials and recorded. Fruit was further sub-categorized into those that can be used for processing or choppers (silvering, pancaking, pointy, and misshapen) and culls (BER and sunburn). Fresh market consumers may not prefer fruit in the chopper category, although it can be used for processing purposes, whereas the cull fruit is completely unmarketable and discarded. Cultivars that are least affected by physiological disorders in the region have more yield stability and are preferred for cultivation.
Statistical analysis
Data were analyzed using statistical software (JMP Pro 17; JMP Statistical Discovery LLC, Cary, NC, USA) for analysis of variance to determine significant differences between cultivars. Replication and trial were treated as random variables. Mean separation was performed using Tukey’s honestly significant difference test (P < 0.05).
Results
Number of marketable fruit/plant
Cultivars exhibited significant differences in the number of jumbo, extra-large, and medium bell pepper fruit per plant, whereas there were no differences in large fruit (Table 3). The highest number of jumbo-sized bell peppers were yielded by ‘Standout’ (0.49 fruit/plant) and ‘Playmaker’ (0.48 fruit/plant), which were significantly higher than ‘Nitro’ (0.14 fruit/plant). All the other cultivars had no difference among them. ‘Autry’ (0.92 fruit/plant) and ‘Standout’ (0.80 fruit/plant) had the highest numerical number of extra-large fruit. All other cultivars had similar numbers of extra-large fruit/plant (ranging from 0.47 to 0.74 fruit/plant), whereas Prowler (0.28 fruit/plant) had the least. ‘Autry’ (0.73 fruit/plant), ‘Playmaker’ (0.75 fruit/plant), and ‘Green Machine’ (0.73 fruit/plant) had the lowest number of medium fruit/plant, whereas ‘SV 3255’ (1.62 fruit/plant), ‘Prowler’ (1.40 fruit/plant), ‘Nitro’ (1.38 fruit/plant), and ‘Boca’ (1.38 fruit/plant) had the most medium fruit.
Marketable fruit size distribution per plant of 11 bell pepper cultivars conducted across three trials in southern Georgia, USA, between Mar and Jun 2022 and 2023.
Chopper
There was a statistically significant difference in total chopper (choice) percentages among cultivars (Table 4). ‘Prowler’ (49.64%) had the highest number of chopper fruit, whereas ‘SV 3255’ (25.44%) was least affected by these disorders. The percentage of specific types of chopper fruit (pancaked, pointed, and misshaped) was statistically significant. ‘Green Machine’, ‘Standout’, and ‘Tarpon’ did not show any silvering in fruit, whereas other cultivars had very low levels of silvering. Pancake (flat) shape fruit deformation was highest in ‘Green Machine’ (18.04%) and lowest in ‘Prowler’, ‘Antebellum’, and ‘Boca’ (5.38%, 5.53%, and 7.56%, respectively). Furthermore, ‘Prowler’ (15.74%) had the highest percentage of tapered (pointed) bell pepper fruit, while ‘Aristotle’ (9.45%) displayed a moderate percentage of pointy fruit/plant. ‘Green Machine’ (1.89%), ‘Standout’ (2.39%), and ‘Autry’ (2.91%) had the lowest percentage of pointed fruit. Misshaped fruit formation was maximum in ‘Prowler’ (28.40%). ‘Antebellum’ (21.68%), ‘Aristotle’ (21.80%), and ‘Playmaker’ (21.22%) had moderate levels of misshaping in fruit.
Statistical analysis of physiological disorders categorized as choice and culls for 11 bell pepper cultivars conducted across three trials in southern Georgia, USA, between Mar and Jun 2022 and 2023.
Cull
The total number of culls and specifically BER-affected fruit/plant differed significantly between cultivars (Table 4). ‘Prowler’ (1.62%) had the lowest percentage of total cull fruit/plant and ‘Autry’ had the most (12.94%). The biggest contributing factor to cull fruit was BER; thus, trends among cultivars for BER and total cull fruit were almost similar.
‘Prowler’ (1.22%) was found with the lowest incidence of BER, and ‘Autry’ (11.82%) was severely affected by this physiological disorder. Sunburn was not prevalent and did not display any significant differences between cultivars (Table 4).
Marketable, unmarketable, and percentage marketable fruit
Cultivars were significantly different for total (marketable + unmarketable) fruit/plant; however, marketable, unmarketable, and percentage marketable fruit/plant were not significantly different (Table 5). The total number of fruit/plant was highest in ‘Prowler’ (6.37), which was similar to all other cultivars except Boca, Tarpon, and Playmaker (4.95, 4.71, and 4.63, respectively). Marketable fruit/plant ranged from 2.55 to 3.80 and unmarketable fruit/plant ranged from 1.80 to 3.23. The percentage of marketable fruit/plant ranged from 49.04% to 66.62%. The marketable fruit percentage was more than 60% for ‘Tarpon’, ‘Boca’, and ‘SV3255’ (63.18%, 64.65%, and 66.62%, respectively).
Marketable, unmarketable, and percentage marketable fruit/plant of 11 bell pepper cultivars conducted across three trials in southern Georgia, USA, between Mar and Jun 2022 and 2023.
Number of bushel boxes/acre
The number of bushel boxes/acre was significantly different for jumbo, extra-large, and medium-sized bell peppers among cultivars (Table 6). The highest number of jumbo-size bell peppers were seen in ‘Standout’ (238 bushel boxes/acre) and ‘Playmaker’ (234 bushel boxes/acre). ‘Nitro’ had the least jumbo yield (69 bushel boxes/acre), whereas the other cultivars performed moderately (ranging from 97 to 230 bushel boxes/acre). In addition, Autry (332 bushel boxes/acre) and Standout (290 bushel boxes/acre) had the most boxes of extra-large-size bell peppers, having similar yields as all other cultivars except Prowler (102 bushel boxes/acre), which had the lowest number of extra-large bell pepper boxes. For large-sized bell peppers, there were not any significant differences between cultivars. SV 3255 had the highest number of medium-sized bell peppers (392 bushel boxes/acre), which was similar to all other cultivars except Autry, Playmaker, Green Machine, and Aristotle (178, 182, 184, and 228 bushel boxes/acre, respectively).
Yield and fruit size distribution for the number of bushel boxes/acre of 11 bell pepper cultivars conducted across three trials in southern Georgia, USA, between Mar and Jun 2022 and 2023.
There was no statistical difference in the total number of bushel boxes/acre. Total yield ranged from 1145 (‘SV3255’) to 836 bushel boxes/acre (‘Playmaker’). However, four cultivars, SV3255 (1145 bushel boxes/acre), Aristotle (1095 bushel boxes/acre), Standout (1051 bushel boxes/acre), and Autry (1019 bushel boxes/acre), exhibited a yield of more than 1000 bushel boxes/acre.
Discussion
There were notable differences among the cultivars in our trial for yield, fruit size, and general adaptability. The most important traits for choosing a cultivar are marketable yield potential and yield stability (Barchenger et al. 2018; Hong et al. 2020). Furthermore, large and extra-large bell pepper fruit are favored by fresh market consumers. In addition, jumbo fruit is preferred over medium-sized fruit by producers because it takes fewer jumbo fruit to fill boxes, resulting in higher total yields. Jumbo fruit that is too big under ideal conditions serves as insurance during adverse conditions that cause fruit sizes to shrink (Thuy and Kenji 2015), ensuring growers have an adequate supply of extra-large- and large-sized fruit. The average production of bell peppers per acre in Georgia, USA, is 1143 bushel boxes (USDA, NASS 2024). In this research, only ‘Autry’ had higher than the average state yield.
In this study, several cultivars exhibited promising results. ‘Standout’ had a higher number of jumbo sizes, extra-large-sized fruit, total marketable yield per plant, and total yield in boxes per acre along with lower levels of silvering, pointy, and sunburned fruit. ‘SV 3255’ had the highest number of marketable, percentage marketable fruit/plant, and total yield in boxes/acre with the lowest number of chopper fruit/plant. However, it had a higher number of medium-sized fruit with a moderate number of jumbo-size, and large and extra-large fruit. ‘Aristotle’ and ‘Autry’ yielded a higher number of extra-large, large-size, and comparatively lower medium-size bell peppers along with a greater number of total boxes/acre. However, ‘Autry’ had a higher percentage of pancaking and BER disorders. ‘Boca’ and ‘Tarpon’ had the least number of unmarketable fruit along with higher percentages of marketable fruit/plant indicating their adaptability to the southern Georgia production region (Kumari et al. 2024).
According to Kathayat and Rawat 2019, environmental factors and nutrient deficiencies are the main causes of physiological disorders such as pointy fruit; silvering or skin separation; misshapen, pancaking, or flat-shaped fruit; BER, and sunburn. In southern Georgia, spring-grown peppers, sunburn, and BER are major concerns, particularly in the latter part of the season when temperature, sunlight, and higher transpiration demands occur, exacerbating these problems. In most cases, BER is caused by environmental factors that result in inadequate calcium uptake and absorption (Prieto et al. 2007; Taylor and Locascio 2004).
Vegetables and fruit growing in regions with higher temperatures are prone to sunburn, which is also a problem for spring-produced peppers in Georgia, USA. Fruit quality is seriously compromised by sunburn, rendering them unmarketable (Racsko and Schrader 2012) due to photooxidative browning and necrosis damaging the cultivar’s profitability (Kabir 2019; Kabir et al. 2022; Maughan et al. 2017). The most prevalent chopper defect in this study was misshaped fruit and the most common cull defect was BER, both of which considerably decreased yields in the bell pepper cultivars tested.
Conclusion
This experiment demonstrated an extensive spectrum of variations in fruit size, marketable yields, and physiological disorders. Cultivars SV 3255, Standout, Autry, and Antebellum are our top recommendations for fresh market bell pepper producers in southern Georgia, USA, during the spring season, based on adaptability, yield, and fruit size distribution. These performed as well as ‘Aristotle’, which was a standard check and the market leader for many years because of its yield consistency, stress tolerance, and wide adaptability. These newer cultivars may be preferred over Aristotle by growers seeking additional disease resistance. ‘Tarpon’ had additional Phytophthora resistance and consistent performance, but lower overall total yield potential.
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