The efficacy of using potting media and fertilizers that are alternatives to conventional materials to produce vegetable transplants needs clarification. Bell pepper, onion and watermelon seed were sown in Container Mix, Lawn and Garden Soil, and Potting Soil, which can be used for organic production in greenhouse transplant production. The alternative media were amended with a 1× rate of Sea Tea liquid fertilizer. Comparisons were made to a system using a conventional potting medium, Reddi-Earth, fertilized with a half-strength (0.5×) rate of a soluble synthetic fertilizer (Peters). Watermelon, bell pepper and onion seedlings were lifted at 3, 6, and 8 weeks, respectively, and heights and dry weights determined. Watermelon were sufficiently vigorous for transplanting regardless of which medium and fertilizer was used. Bell pepper and onion at the scheduled lifting were sufficiently vigorous only if produced with conventional materials. Additional experiments were designed to determine the reason(s) for the weaker seedlings when the alternative products were used. Seedlings maintained in transplant trays, in which media amended weekly with Sea Tea were required to be held for up to an additional 34 days before being vigorous enough for transplanting. Six-week-old bell pepper, or 8-week-old onion, seedlings were transferred to Reddi-Earth in pots and supplied with Sea Tea or Peters fertilizer. Bell pepper treated with Peters were taller and heavier, but onions plants were similar in height and weight regardless of fertilizer used. Other pepper seed were planted in Reddi-Earth and fertilized weekly with Sea Tea at 0.5×, 1×, 2×, or 4× the recommended rate, or the 0.5× rate of Peters. There was a positive linear relationship between seedling height and dry weight for seedlings treated with increasing rates of Sea Tea. Other pepper seed were planted in to Potting Soil, or an organically certified potting medium (Sunshine), and fertilized with a 2× or 4× rate of Sea Tea or a 1×, 2×, or 4× rate of an organic fertilizer (Rocket Fuel), or in Reddi-Earth fertilized with a 0.5× rate of Peters. There was a positive linear relationship between the rate of Rocket Fuel and heights and dry weights of bell pepper seedlings. However, even at the highest rate seedlings were not equivalent to those produced with conventional practices. Plants treated with the 4× rate of Sea Tea were similar to those produced using conventional materials. Use of Sunshine potting medium and the 4× rate of Sea Tea will produce bell pepper seedlings equivalent in height and dry weight to those produced using conventional materials. The 4× rate of Rocket Fuel used in Sunshine potting medium will produce adequate bell pepper seedlings. The original poor showing of seedlings in the alternative potting media appears to be due to fertilization with Sea Tea at a rate that does not adequately support seedling development.
Senescence occurs at the cellular and tissue levels. It is under genetic and environmental control and factors affecting initiation and speed of development of senescence can be passed from parental to F1 plants. This study was conducted in the greenhouse and field to determine how senescence patterns in F1 plants of a shrunken2 sweet corn (Zea mays L.) hybrid compared to those of parental inbreds. Greenhouse grown plants were left intact and field grown hybrids and parental inbreds had one or both reproductive organs removed or were left intact. Senescence patterns in stalk internodes were similar in greenhouse and field grown F1 and inbred plants. Senescence patterns in shank internodes in greenhouse grown plants were different from those of field grown plants. Senescence ratings in stalks increased as developmental stage advanced. Expression of stalk senescence in internodes below the node bearing ears appears to be suppressed by hybrid vigor. In field tests, destruction of the tassel before expansion (decapitation) appears to suppress senescence in internodes above I7, with this effect somewhat dependent on plant developmental stage.
V.M. Russo and Merritt Taylor
Many producers who have used conventional production methods for vegetables, and who want to convert to organic production, will have to pass through a 3-year transition period before their land can be qualified for organic certification. This transition can produce unique challenges. Use of several amendments has received interest for inclusion in organic production. How these affect vegetable production during the transition period was examined. Land was taken from perennial pasture and converted to production of the vegetables: bell pepper (Capsicum annuum L.), cv. Jupiter; processing cucumber (Cucumis sativus L.), cv. Earli Pik; and sweet corn (Zea mays L.), cv. Incredible (se endosperm genotype) using organic materials and methods with comparison made to production using conventional methods. Conventional and transition to organic portions of the field were separated by 25 m with the buffer zone planted with the same sweet corn cultivar used in the experimental plots and minimally maintained by addition of organic fertilizer. To the organic portion of the field, three levels of humates (0, 112, and 224 kg·ha–1) and three levels of corn gluten meal (0, 448, and 896 kg·ha–1) were applied in nine combinations. Yields for all crops were determined for all years. In the first year, bell pepper yields for plants under conventional production were higher than for the plants in the transition plots. In the remaining 2 years, bell pepper yields were similar under the two production systems. In the first 2 years, cucumber yields for plants under conventional production were higher than for the plants under transition to organic production. In the last year, cucumber yields were similar under the two production systems. In all years, sweet corn yields for plants under conventional production were higher than for plants under transition to organic production. Humates and corn gluten meal did not benefit yields of crops. An economic analysis comparing yields, prices, and costs of production of the crops under conventional and the transition to organic indicated that conventional practices generally provided more net revenue than did transition to organic production. Net revenue for the three species under the transition to organic for the 3 years was $2749 for three hectares. Net revenue for the three crops under conventional production for 3 years was $61,821, a difference of $59,072. Costs, yield, and prices will have to be considered when decisions are made concerning the adoption of organic practices.
V.M. Russo and T. Smith
Sweet corn (Zea mays L.) kernels are sinks, and sugars found in kernels must be translocated from a source. Stalk tissues can act as a source and a sink as sweet corn plants age. Quantity and types of sugars present in various sweet corn tissues during plant development are not well documented. Concentrations of fructose, glucose, sucrose, and their total were determined in the ninth stalk internodes (I9) from the 12-leaf stage (V12) to fresh-market maturity (R3) in sweet corn cultivars carrying either the su1se1, su1, or sh2 endosperm genotype. Developing ears were sampled at tassel emergence (VN) and silking (R1). Kernels and cob tissue were sampled separately at blister stage (R2) and R3. Correlation analysis was performed on concentrations of sugars at all developmental stages. In I9, from V12 to R3, levels of fructose and glucose declined and sucrose increased. In developing ears, concentrations of fructose and glucose increased from VN to R1. Concentrations of sugars in cobs in all cultivars were generally the same at R2 and R3. In kernels from R2 to R3 in the su1se1 cultivar, glucose decreased while the other sugars were unchanged; in the su1 cultivar, fructose decreased while levels of the other sugars stayed the same; and in the sh2 cultivar, fructose decreased, glucose was unchanged and sucrose increased. Correlation analysis suggested that the cultivars moved sugars to the kernels differently. The pattern of movement of sugars to kernels was most complex in the su1se1 cultivar than in the su1, which was more comlex than in the sh2 cultivar. Knowing how sugar content changes in the plant may be used to predict sugar content in kernels.
V.M. Russo and C. Biles
Cucumber (Cucumis sativus L.) seed require soil temperature to be around 20C for efficient germination. This hinders early planting in cool soils. This study was conducted to determine how germinating seed of cucumber cultivars Earlipik 14 and Arkansas Little Leaf at 13.9, 15.6, and 20C in the dark affected protein formation. Seed were removed from moist chambers at 0, 12, 24, 48, 72, 84, 96, 120, and 168 h. Germination, defined as the radicle being at least 5 mm long, was determined at each time. Germinated and ungerminated seed was prepared for polyacrylamide gel electrophoresis. At 20C, 90% to 100% of seed had germinated by 48 h. At 15.6C, 20% to 50% of seed germinated by 168 h, and at 13.9C, ≈2% of seed had germinated by 168 h. For seed incubated at 20C, concentrations of proteins at 70.1 kDa decreased, while those at 37.4, 43.4, and 50 kDa increased after 24 h, which corresponded to formation and elongation of the majority of radicles. These changes were expressed later for seed germinated at 15.6 and 13.9C. Identification of the proteins is being attempted. The importance of these proteins in germination and early development will be discussed.
V.M. Russo and B.W. Roberts
Soil conditions may not be adequate for uniform yields when perennial pasture is converted to vegetable production. This occurred with `Pip' bell pepper (Capsicum annuum var. annuum L.) planted in a 0.17-acre field 3 years after conversion from perennial pasture. Depths of the A-horizon and pH levels, as well as concentrations of N, P, and K were variable throughout the field when sampled after the last harvest. Marketable yields from plots established in the field ranged from 4.1 to 14.5 tons/acre. The A-horizon depth, soil pH, and residual N, P, and K levels were correlated with yield at specific A-horizon depths and pH levels. An intensive soil-testing regime likely will be required so that nutrient levels can be maintained to support bell pepper production on soil converted from perennial pasture.
V.M. Russo and A.J. Pappelis
V.M. Russo and J.C. Díaz-Pérez
Heat stress can limit yield in pepper (Capsicum spp.), generally through flower and fruit abortion. A kaolin-based particle film, originally developed to protect fruit trees from insects, has been found to reduce temperatures in tissues of plants. A kaolin-based particle film was tested to determine if it could be used to improve yields of pepper in Oklahoma and Georgia. In Oklahoma, seedlings of a bell pepper, `Jupiter', and a nonpungent jalapeño, `Pace 103', were transplanted at three progressively warmer planting dates from mid-May to mid-July 2002 and 2003, that would ensure that inflorescences would be subject to high day and night temperatures and treated with the kaolin-based particle film. Applications were begun as the first flowers were set and continued through the settings of the first three flushes of flowers on a three-times a week schedule, or on an as needed basis, to determine if the kaolin-based particle film improved yield. In Georgia, the bell peppers `Camelot' and `Heritage VR' were transplanted on 24 Apr. 2003, and treated with the kaolin-based particle film. In addition to yield, physiological measurements and disease incidences were recorded in Georgia. In both locations treatment with water only served as controls. In Georgia, the kaolin-based particle film had no significant effect on net photosynthesis, stomatal conductance, leaf transpiration or leaf temperature, as measured at midday on clear days. In Oklahoma, planting bell pepper after 15 May is not recommended. Planting the nonpungent jalapeño after mid-June can reduce yields. The kaolin-based particle film did not affect yield at either location and is not recommended for use on peppers.
V.M. Russo and T.D. Abney
The effect of soil CO2 on the development of vegetable crops is not well-understood. An inexpensive and simple method for monitoring soil CO2 levels is needed to study those effects. A soil gas extraction apparatus was constructed from polyvinyl chloride (PVC) pipe, tygon tubing, and Plexiglas. The apparatus was placed into soil covered with black plastic or spray-on mulch or left bare. Gas samples were collected twice weekly after canopy closure of eggplant (Solanum melongena L., cv Black Bell) and continued through the last harvest. A vacuum pump was used to pull gas samples from 16 inches (41 cm) below the soil surface for collection in an airtight foil bag. The CO2 levels, recorded over time and between treatments, was determined with detector tubes available commercially and compared to gas chromatography results. Detector tube CO2 levels were comparable to the samples from the same bags measured by gas chromatography. This system was able to monitor differences in soil CO2 levels between treatments and over time.
V. M. Russo, B. W. Roberts and R. J. Schatzer
Trellising was investigated for intensive, small-scale, fresh market cucumber (Cucumis sativus L.) production. Economic feasibility of trellising was examined. The cultivars Dasher II, Marketmore 76, and PetoTripleMech were evaluated using trellising and ground culture at two locations in Oklahoma. The cultivar PetoTripleMech is normally grown as a processing cucumber. Here it was evaluated as a fresh market entry. Trellising significantly improved marketable yield of the three cultivars at both locations in comparison to ground culture. PetoTripleMech yields were equal to, or better than, the fresh market standards Dasher II and Marketmore 76. Average marketable fruit weight was not affected by trellising. Economic analysis indicated that trellising is a viable management system for small-scale cucumber production because the gross and net returns to the producer were increased by 20% and 10% respectively.