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- Author or Editor: Brian A. Kahn x
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.
Three lodging-resistant (LR) and 3 lodging-susceptible (LS) paprika pepper (Capsicum annuum L.) lines were grown from transplants at Bixby, Okla., in 1983. Stem diameter at ground level and number of lodged plants were determined monthly from July through November. Stem diameter increased gradually through 14 Oct. and then leveled off. Number of lodged plants increased sharply between 14 July and 15 Aug., and increased slowly thereafter. On all but the 1st date (14 July), stem diameter was negatively correlated with number of lodged plants. On each date, LR lines averaged larger in stem diameter and lower in number of lodged plants than LS lines. Sample plants were harvested on 28 Oct. On the average, LR plants had larger stem diameters at soil level, greater root weights, and lower shoot:root ratios than LS plants but did not differ from LS plants in shoot weight, number of marketable red pods, and cellulose and lignin content in the lowermost 8 cm of central axis stem tissue. Results should aid in breeding for lodging resistance in paprika pepper.
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.
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.
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.
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.
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.
Field experiments were conducted in Oklahoma in 1993 and 1994. Cowpeas [Vigna unguiculata (L.) Walp.] were grown using either noninoculated seed and 23 kg·ha–1 of preplant nitrogen (N) fertilizer (conventional) or Rhizobium-inoculated seed and no preplant N fertilizer (reduced input). Sample plants were excavated at first pod set and analyzed for nodulation and root morphology. Additional plants were harvested at the green-shell stage to determine seed yield and plant N concentration. Conventional and reduced input cowpeas did not differ in dry weight of root mass components, total root dry weight, shoot dry weight, shoot: root ratio, nodule distribution among root morphological components, total nodule fresh weight, plant N concentration, or green-shell seed yield. Most of the nodule fresh weight generally was associated with nodules on the basal and lateral roots. Results indicate that cowpea root characteristics are not necessarily altered by the presence or absence of added N fertilizer at a given location.
Studies were conducted to examine the effects of pruning treatments applied to spring-transplanted bell peppers (Capsicum annuum L.) on marketable fruit yield in late summer and fall. Control plants were set in the field in early May 1997 (Oklahoma) and Apr. 1998 (Oklahoma and Texas) and harvested weekly into October (Oklahoma) or periodically into December (Texas). In 1997, all four treatments (involving height and method of pruning) reduced total marketable fruit weight, but differences among treatments were nonsignificant. In Oklahoma in 1998, plants were mowed on 27 July at an average height of ≈24 cm. Mowed plants produced less total marketable fruit weight but more U.S. Fancy fruit than did control plants, while weight of U.S. No. 1 fruit was not affected. In Texas in 1998, plants mowed on 4 Sept. at a height of ≈20 cm produced more than twice the weight of U.S. No. 1 fruit and fewer cull fruit than did control plants. Nonpruned transplants set in the field in Summer 1998 (both Oklahoma and Texas) produced low marketable yields. Maintaining spring-transplanted bell peppers is a viable technique for fall pepper production, and the highest total marketable yields may be obtained if these plants are not mowed. However, mowing offers an opportunity for increased fall production of premium fruit, and mowed plants would be easier to manage than nonpruned plants.
Field studies were conducted in Oklahoma from 2010 to 2012 to develop protocols for fall sweet corn (Zea mays) production. Variables examined included a transgenic cultivar that expresses the CryIA(b) toxin from the bacterium Bacillus thuringiensis (Bt) and its nontransgenic near-isoline, seeding rates and planting dates, and various insecticide regimens. We found that, in eastern Oklahoma, a suitable planting window would correspond roughly to the last 2 weeks in July. Within this favorable period and given timely irrigation, it was possible to sow corn to an acceptable stand. A seeding rate ≈1½ times the desired final stand of one plant/ft appeared to be satisfactory. Use of a cultivar (GSS-0966) with genetic resistance to lepidopteran pests was a critical factor for successful production of fall sweet corn. Efforts to produce a crop with a nontransgenic cultivar using insecticides with relatively low mammalian toxicity were unsuccessful. Our experiments support previous recommendations for applying supplemental insecticides to transgenic Bt sweet corn to potentially increase production of “premium” ears by reducing the percentage of ears with severe insect damage (damage >1½ inches from the cob tip). We demonstrated that a spray schedule that rotated two insecticides with intermediate mammalian toxicity (carbaryl and permethrin) was as effective in reducing severe insect damage to ears of ‘GSS-0966’ as a similar schedule that rotated two highly toxic insecticides (esfenvalerate and methomyl).