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Brian A. Kahn

A 2-year study was conducted at Bixby, OK, to examine shoot characteristics of several eggplant (Solanum melongena) cultivars, including the vertical distribution patterns of fruit production, and to examine possible relationships of these traits to aspects of fruit quality. Plants of 11 cultivars of purple-fruited eggplant were field-grown following local production practices. Fourteen harvests of fruit that had reached horticultural maturity were made from 99 plants in each year over a period of ≈45 days per year. On each harvest date, every fruit that was harvested from an individual plant was charted. Before a fruit was severed from the plant, heights were measured from the soil surface to the pedicel attachment and to the blossom end. Each fruit was then weighed and categorized for marketability. On the day after the final harvest, each data plant was measured for height and diameter of the main stem and then severed at soil level for subsequent measurement of shoot dry weight. ‘Classic’, ‘Dusky’, ‘Megal’, and ‘Santana’ were the only cultivars that produced more than 50% marketable fruit in both years. There were no consistent relationships between plant height, stem diameter, or shoot dry weight and fruit quality. For a given cultivar, the fruiting plane was defined as the vertical space in which fruit were found over the course of the harvest period. This was delimited at the top by the mean height above the soil of the point of pedicel attachment and at the bottom by the mean height above the soil of the blossom end. The cultivars differed in fruiting planes, but height of fruit set was relatively unimportant as a determinant of overall fruit quality. Cull fruit usually had blossom ends that were higher off the ground than marketable fruit. The primary reason for cull fruit production was determined for two cultivars: ‘Black Beauty’ had poor fruit color and ‘Black Bell’ was relatively susceptible to fruit rot (primarily caused by Phomopsis vexans). Fruit scarring was found to be a major contributor to cull fruit production. Cultivars differed in fruit scarring in 1 of 2 years, and there was evidence that scarred fruit occurred higher in the crop canopy than marketable fruit.

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Brian A. Kahn

Paprika pepper (Capsicum annuum L.) plants were subjected to a single destructive harvest in either October, November, or December to determine an optimal month for once-over harvest. Studies were conducted at two locations in Oklahoma each year for two years. Total and marketable fruit yields were highest with October harvest dates in three of the four experiments. Marketable fruit red color intensity decreased between the November and December harvest dates at both locations in the second year. It appears that paprika harvest should be completed during October in this region.

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Brian A. Kahn

This review summarizes studies involving intercropping for field production of peppers [Capsicum spp. (typically Capsicum annuum)]. Intercropping is particularly important in developing countries and where arable land is limited. Fruit crops, vegetables, forages, and other crops representing over 12 botanical families have been intercropped with peppers. System recommendations may be affected by whether one is attempting to grow another species as an intercrop in a pepper field or whether peppers are being used as an intercrop in a different primary crop. Other factors such as the timing of the intercrop planting, climatic conditions, and local economics all contribute to the potential success or failure of intercropping with peppers. Although broad recommendations cannot be made, the reviewed studies offer several examples of successful combinations of peppers with other crops.

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Brian A. Kahn

Paprika pepper (Capsicum annuum L.) plants were subjected to a single, destructive harvest in either October, November, or December to determine an optimal month for once-over harvest. Studies were conducted at two locations in Oklahoma each year for 2 years. Total and marketable fruit yields were highest with October harvest dates in three of the four experiments. Marketable fruit red pigment intensity decreased between the November and December harvest dates at both locations in the second year. When the crop is established by transplanting, paprika harvest should be completed during October in the southwestern United States.

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Brian A. Kahn

Growers of turnip `greens [Brassica rapa L. (Rapifera Group)] are accustomed to planting 5.6 to 10 kg of seed per hectare. A study was conducted in 1985 to determine whether reduced plant populations could be used without reducing yield or quality for `Alltop', a hybrid cultivar with relatively expensive seed. A trial planted on 4 Apr. showed that populations could be reduced from 64 to 33 plants/m of row without reducing yield or quality. A second trial, planted on 30 Aug., used populations of 36, 26, and 16 plants/m of row. Again, there were no statistically significant reductions in yield or quality as populations decreased. However, yields from the 36 and 16 plants/m treatments differed by almost 7 t·ha-1, indicating substantial variability. A conservative approach would be to use a population of 33 to 36 plants/m of row (≈ 725,400 plants/ha) to provide a balance between seed costs and yield. This can be achieved by seeding rates of 2.2 to 2.8 kg·ha-1.

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Clydette Alsup and Brian A. Kahn

Cowpea [Vigna unguiculata L. (Walp.)] cover crops were grown in a rotation with broccoli (Brassica oleracea L. var. italica Plenck.), spinach (Spinacia oleracea L.), and turnip greens [Brassica rape L. var. (DC.) Metzg. utilis] to evaluate the legume's ability to remove excess P from soils when poultry litter was used as a fertilizer. Fertilizer treatments were litter to meet each crop's recommended preplant N requirements (1X), litter at twice the recommended rate, and urea at the IX rate as the control. Following the vegetable crops, cowpeas were planted on half of each replication, while the other half was fallowed. The cowpeas were harvested for green-shell seeds and then underwent a simulated haying operation. Soil samples were taken at 0-to 15-cm and 15- to 30-cm depths at the onset of the study and after each crop to monitor plant nutrient levels. The cowpeas effectively lowered soil N levels but not soil P levels. However, there was no consistent evidence of an increase in soil P or K levels with litter applications. All three vegetable crops were successfully grown using poultry litter, although the 1X rate appeared inadequate for maximum production of broccoli and turnip greens.

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Brian A. Kahn and Wendy A. Nelson

Trellised plants of `Oregon Sugar Pod II' and `Snowflake' snow peas (Pisum sativum var. macrocarpon Ser.) were grown in single and double rows on l-m centers at a constant population of 20 plants/m2 in 1988 and 1990. Plants of `Oregon Sugar Pod II' produced a greater number and weight of fresh pods than plants of `Snowflake' in both years. Plants grown in double rows (10 cm within-row spacing) produced a greater number and weight of fresh pods than plants grown in single rows (5 cm within-row spacing) in 1988, but not in 1990. Vine dry weights were greater from plants grown in double rows than from plants grown in single rows in both years. Double rows seemed more promising for home gardeners than for commercial growers because of the increased branching and more widely scattered pod distribution on plants grown in double rows compared with plants grown in single rows.

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Brian A. Kahn* and Daniel I. Leskovar

Single- and double-row arrangements of a fixed population (one plant every 0.285 m2) 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: (1) 1.9 m between centers of double-row beds, rows on beds 30 cm apart, plants within rows 30 cm apart; (2) single rows 0.95 m apart, plants within rows 30 cm apart; (3) 1.52 m between centers of double-row beds, rows on beds 24 cm apart, plants within rows 37.5 cm apart; and (4) single rows 0.76 m apart, plants within rows 37.5 cm apart. Only arrangements (1) and (2) were used in 2003. Row arrangement did not affect marketable fruit production in Oklahoma in 2002, but single rows resulted in a greater weight of fruit with blossom-end rot than double rows. Arrangement (2) resulted in both a greater weight of U.S. No. 1 fruit and a greater weight of sunburned fruit than arrangement (1) in Texas in 2002. `King Arthur' produced more marketable fruit than `X3R Wizard' in Oklahoma in 2002, but the opposite occurred in Texas. Arrangement (2) resulted in a greater weight of U.S. No. 1 fruit than arrangement (1) in both locations in 2003. Arrangement (2) also resulted in greater weights of sunburned (Oklahoma) or total cull (Texas) fruit than arrangement (1) in 2003. `Lafayette' and `X3R Wizard' produced a greater weight of marketable fruit than `Boynton Bell', `Karma', and `King Arthur' in Texas in 2003, but not in Oklahoma. Plant arrangement × cultivar interactions were not evident in Oklahoma and minimal in Texas. Given the tested population, a single row arrangement is likely to result in higher U.S. No. 1 fruit yields than a double-row arrangement, despite an increased potential for cull fruit production with single rows.

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Brian A. Kahn and John P. Damicone

Drip-irrigated, stake-and-weave supported tomato (Lycopersicon esculentum) plots were established in 2005 and 2006. All plots (except controls) were treated with a kaolin particle film product (Surround WP) mixed at 0.5 lb/gal of water and applied with a pressurized hand sprayer. Sprays began after transplanting and were repeated as needed to maintain a particle film on the foliage. Sprays were discontinued either at anthesis, at first green fruit 5 cm in diameter, or at first colored fruit harvest. Multiple hand harvests were made as fruit matured. In 2005, all kaolin treatments reduced marketable fruit number and weight, whereas in 2006 there were no significant effects. Cull fruit weight and average weight per marketable fruit were unaffected by treatments during either year. Results indicate that when applied before harvest begins, Surround may not improve marketable yields of fresh tomatoes.

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Brian A. Kahn and Mark E. Payton

Eggplants (Solanum melongena L.) were grown from transplants in a field study at Bixby, Okla., in 2005. Plants were harvested twice a week for 7 weeks. Data were taken from 3 individual plants per plot × 11 cultivars × 3 replications. The open-pollinated `Black Beauty' was inferior to the hybrids for yield and fruit quality. Patterns of cumulative percent marketable fruit number did not differ for 3 of the 4 cultivars producing the numerically highest (not always statistically highest) marketable fruit weights per plant (`Classic', `Nadia', and `Santana'). `Dusky' was the exception; fruit number peaked relatively early, but it still totaled among the highest for marketable fruit weight per plant. This might be considered an efficient fruiting pattern. Apart from `Dusky', a relatively high cumulative percent marketable fruit number throughout the season tended to be associated with an intermediate to low marketable fruit weight per plant. Two factors usually were responsible for this pattern: relatively low average marketable fruit weight, or high cull production. Despite significant differences in individual marketable fruiting patterns and average fruit weights, one relatively simple curvilinear model gave an excellent estimation of total and marketable eggplant fruit production (respectively) over time. The model was pct = 1/(1+exp(-(a+b*day))), where pct = estimated cumulative percent based on number of fruit, a = intercept, and b = slope.