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Kyung-Hwan Yeo*, Jung-Min Son, and Yong-Beom Lee

Plant factory is a new plant production system that enables high quality, year-round, and planned production by controlling the environment. However, the recirculation of the nutrient solution leads to several problems because of unstable condition by nutrient uptake. The concentrations of nutrients in the recirculating solution should be kept at the required levels, since an optimum nutrition is determined by the specific concentrations of an element and mutual ratio to other nutrients in the root zone. Consequently, the nutrient solution is required adjustments based on regular analysis of the drain water and relationships among nutrient uptake, growth stage, and environmental factors for plant quality. This study was conducted to examine the effect of mineral nutritional control by five different methods on growth and photosynthesis of single-stemmed rose `Red velvet' and `Vital' in a plant factory. The nutritional control of nutrient solution was as following: the control of electrical conductivity (EC), N, P, and K elements (NPK), macro elements (M), macro and micro elements (MM) to target ranges in root environment, and the supplement of nutrient solution (S). The growth of single-node cutting rose `Vital' and `Red velvet' was higher in the M and MM than that of other control systems. Although M and MM system showed no significant difference, the photosynthetic rate, stomatal conductance, and transpiration rate were higher than those with other systems. The maximal efficiency of photochemistry (Fv/Fm) was higher in the M and MM control system, which showed the highest root activity. These results could be attributable for modelling the mineral nutritional control system, which reduces the use of fertilizers and increases the productivity of single-stemmed rose.

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Stephen Southwick*

Quality of stone fruit is defined by fruit size, color, firmness, flavor, shape, general appearance, adhesion and size of the stone and fruit surface characteristics (e.g. fuzz, abrasions, pest damage). Cultural practices, such as pruning, nutrition, irrigation, growth regulator usage and pesticide applications can influence these quality characteristics to a greater or lesser extent. Adequate potassium nutrition can improve soluble solids and fruit size in plums. Excess nitrogen fertilization can soften peaches. Well-timed calcium sprays are thought to improve the firmness of sweet cherries, as are applications of gibberellin. Ethylene synthesis inhibitor usage can alter the timing of ripening, reduce early fruit drop and improve storage. Irrigation scheduling is a tool that can be used to regulate final fruit size and firmness, as well as time of maturation. Selective pruning is used to structure a tree's architecture for improved light penetration to improve fruit size and color. These and other production practices will be discussed in relation to how they affect fruit quality in stone fruit.

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Gene E. Lester

Organic and conventional fruits and vegetables contain compounds with important human health promoting effects. Whether fruits and vegetables grown via organic versus conventional production systems are superior in taste and nutrition, at present, is difficult to say with complete certainty. To ascertain possible quality differences and develop a definitive data base, direct comparative studies of organic vs. conventional produce requires following rigorous guidelines which includes 1) appropriate study approaches (retail market vs. farm vs. research center studies), and 2) standardized preharvest production site, harvest procedural, postharvest handling, and analytical methodology constraints.

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Young-Sang Lee, Yong-Ho Kim, and Sung-Bae Kim

To study the effects of chitosan on the productivity and nutritional quality of soybean (Glycine max L.) sprouts, soybean seeds were soaked in solutions containing 1,000 ppm chitosan of low (<10 kDa), medium (50 to 100 kDa), or high (>1,000 kDa) molecular weight, and the respiration, growth, and vitamin C content of the sprouts were subsequently evaluated. Sprouts treated with high molecular weight chitosan exhibited a significant increase in respiration, 5%, within 1 day of treatment. Chitosan effectively increased the growth of the sprouts: sprouts treated with high molecular weight chitosan showed increases of 3%, 1%, 3%, 1%, and 12% in the total length, hypocotyl length, root length, hypocotyl thickness, and fresh weight, respectively, as compared to a control. The growth-improving effects of chitosan were proportional to the molecular weight of the molecule used in the treatment. Chitosan treatment did not result in any significant reduction in vitamin C content or postharvest chlorophyll formation, traits that determine the nutritional and marketing values of soybean sprouts. All these results suggest that soaking soybean seeds in a solution of chitosan, especially of high molecular weight, may effectively enhance the productivity of soybean sprouts without adverse effects on the nutritional and postharvest characteristics.

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Robert K. Prange and Jennifer R. DeEll

137 COLLOQUIUM 3 (Abstr. 012–017) Effect of Preharvest Factors on Postharvest Quality

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Marie-Hélène Michaud, Joseph Makhlouf, Nicolas Tremblay, and André Gosselin

A research project was undertaken in 1990 with the objective of improving both quality and productivity of peas, beans and sweet corn grown and processed in Quebec (Canada). It was conducted with the technical and financial help of five proccessing companies. Cultivar trials were undertaken as part of this project together with an evaluation of commercial practices in the areas of pest control, fertilization and crop management. Samples of fresh and processed products were analysed for nutritional quality and pesticide residues. During this presentation we will show preliminary results of the pesticide residue analyses and will compare fresh and processed products. So far, determination of dimethoate, trifluralin and bentazone (peas), azinphosmethyl and permetrin (beans) and cypermetrin (sweet corn) showed no concentration exceeding the Canadian norm (<0, 1mg/kg), with the exception of a bean field with azinphosmethyl residues. Canning and freezing operations greatly reduced pesticide residues so that all processed samples tested below detectable levels.

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Dharmalingam S. Pitchay*, Jonathan M. Frantz, Jonathan M. Locke, and Charles Krause

Growers tend to over fertilize their plants as a way to minimize the likelihood of encountering nutrient deficiencies that would reduce the quality of their plants. Much of the nutrition literature focuses on the nutritional extremes namely of toxicity and deficiency. Once plants get to this stage, little can be done to correct the problem. Characteristics of plant performance in super-optimal conditions, yet below toxic levels, is less well known, and needs to be developed to help growers identify problems in their production practices before they impact sales. New Guinea Impatiens were grown over a wide range of N, K, and B levels, from 15% to 400% full strength Hoagland's solution for each nutrient after establishing transplanted rooted cuttings in a peat: perlite soilless media. Plants were grown for four weeks during treatment, during which time the flowers were pinched. After only 2 weeks of treatment, plants with 200% and 400% N were significantly shorter than control plants and plants with 15% N. Reflectance measurements and photographs were made twice a week. At the end of the four weeks, plant tissue was analyzed for form of N, root development and structure, and leaf area. Tissue samples were also analyzed with SEM and energy dispersive X-ray analysis to determine changes in nutrient location and tissue structure. This data provides insight into the nutrition economy of plants in general, tests the use of reflectance spectrometry as a method of detecting super-optimal fertilizer concentrations, and will help growers optimize their fertilization requirements to reduce production costs yet maintain high plant quality.

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Harbans Bhardwai and Ron Eitenmiller

Guar or cluster bean (Cyamopsis tetragonoloba (L.) Taubert), a leguminous plant, is grown in many parts of the world for consumption as green beans. However, information on green bean yield and their nutritional quality is lacking. Our objectives were to determine yield potential, optimum harvesting time, and nutritional quality of green guar beans. We planted 10 guar varieties in a RCBD with 4 replications on 1 June 1990 at Fort Valley, Georgia. The guar bean production was recorded at 55, 70, 85, and 100 days after planting (DAP). Significant variation for bean yield existed among genotypes. The bean yield (kg ha-1) varied from 9549 (Kinman) to 1629 (HG-75), at 85 DAP. The highest yield at 100 DAP was recorded for Lewis. The ideal harvesting time, based on degree of yellowness and bean texture, for Durga Jay, Esser, Hall, SPS-119, and Lewis seemed to be 100-115 DAP whereas the beans of Brooks, HG-75, HSB-130, Kinman, and Santa Cruz became tougher and yellow by 100 DAP. A comparison with published results of snap beans and edible-pod peas indicated that green guar beans contained greater amounts of protein, total carbohydrates, vitamin C, calcium, iron, manganese, phosphorus, potassium, and sodium. These results indicate that green guar beans can be a potential alternate source of income for farmers in Georgia and other states.

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Regina R. Melton and Robert J. Dufault

Tomato (L.ycopersicon esculentum Mill.) seedlings were nutritionally conditioned with solutions containing factorial combinations of N at 25, 75, and 225 mg·liter -1, P at 5, 15, and 45 mg·liter-1, and K at 25, 75, and 225 mg·liter -1 to determine the effect of nutritional regimes on tomato transplant growth and quality. As N increased from 25 to 225 mg·liter-1, fresh shoot weight, plant height, stem diameter, leaf number, leaf area, shoot and root dry weights, and total chlorophyll increased. Nitrogen accounted for the major source of variation. Phosphorus effects were significant only in 1988; Pat 45 mg·liter-1 increased fresh shoot weight, plant height, stem diameter, leaf number, and leaf area in comparison to 5 and 15 mg·liter -1. Potassium did not significantly influence any of the growth variables measured in the study. For quality transplant production, nutrient solutions should contain at least N at 225 mg·liter-1, P at 45 mg·liter-1, and K at 25 mg·liter-1.

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Christopher C. Gunter and David Francis

Poster Session 45—Vegetable Nutrition 21 July 2005, 12:00–12:45 p.m. Poster Hall–Ballroom E/F