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In 1998–99, experiments were conducted to evaluate current fertility practices with plant-bed onions. In experiments in 1998 and 1999, a factorial experiment of preplant 5–10–15 and CaNO3 sidedressing indicated that CaNO3 had a significant effect on foliar nitrogen levels. CaNO3 also had an effect on stand count in 1998, but not in 1999. CaNO3 and 5–10–15 had an effect on plant height in both 1998 and 1999, with an interaction between 5–10–15 and CaNO3 in 1999. In 1999, transplants were also evaluated on an acceptability scale with 5–10–15 and CaNO3 rates resulting in significant differences in transplant acceptability. Postseedling applications of high phosphorus fertilizer were also evaluated. There were no consistent improvements in transplant growth with applications of high phosphorus fertilizers, such as 18–46–0 or 10–34–0, either on soils with very high residual phosphorus (242 lb/acre) or medium residual phosphorus (50 lb/acre). In addition, variety was not a factor in these responses.

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The stigmatic secretions of pomaceous flowers serve as a natural medium not only for pollen, but also for the pathogen Erwinia amylovora (Burr.) Winslow et al. and other microorganisms. To understand the microecology on the stigma, exudates from cultivars of pear (Pyrus communis L.), apple (Malus pumila P. Mill.), and crab apple [Malus mandshurica (Maxim.) Kom.] were analyzed for free sugars and free amino acids as available carbon and nitrogen sources. Extracts were obtained at different stages of anthesis by submerging and sonicating stigmas in water. Certain free sugars (glucose and fructose) and free amino acids (proline, asparagine, glutamic acid, and glutamine) were consistently predominant and increased during anthesis. Apple stigma extracts were also analyzed for polysaccharides and proteins. Of major components identified for apple, free sugars made up 4.5% by mass; polysaccharides (composed of arabinose and galactose), 49.6%; and proteins, 45.9%. The two largest components are likely present as glycoproteins. This may be the first report on characteristics of rosaceous stigma exudates that includes the identity of specific free sugars, free amino acids, and polysaccharide subcomponents. Discussion includes the comparison of pomaceous stigma exudates to those of other plants and the microecological implications.

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Preplant levels of 5N-4.4P-12.4K (-5S or -9S) and sidedress applications of CaNO3 were evaluated in onion (Allium cepa L.). In addition, high phosphorus fertilizers 18N-20.1P-0K (diammonium phosphate) and liquid 10N-14.8P-0K were evaluated on sites with and without high residual phosphorus levels as well as their interaction with onion cultivars. Sidedress applications of CaNO3 had a significant effect on plant height and an interaction with preplant 5N-4.4P-12.4K fertilizer. There was a linear increase in plant height with increasing applications of 5N-4.4P-12.4K from 0 to 1569 kg·ha-1 with the CaNO3 applications. Neither 5N-4.4P-12.4K nor CaNO3 applications affected stand count. 5N-4.4P-12.4K fertilizer had significant linear effects on tissue potassium and sulfur. Tissue nitrogen and calcium increased with CaNO3 applications while phosphorus, potassium, and sulfur decreased. CaNO3 also had a positive effect on suitability for transplanting. There was an interaction effect between 5N-4.4P-12.4K and CaNO3 for tissue phosphorus levels. There was a linear decrease in tissue phosphorus levels with increasing amounts of 5N-4.4P-12.4K fertilizer with the sidedress CaNO3 treatments. High phosphorus fertilizers applied directly after seeding had no effect on plant stand or plant height either on soils with or without high residual phosphorus in 1998. In 1999, 10N-14.8P-0K fertilizer had a significant effect on plant height while 18N-20.1P-0K did not. Based on this study, we conclude that additional applications of high phosphorus fertilizers applied post seeding are not required due to the relatively warm conditions found in southeast Georgia in September. There were differences between cultivars, but cultivar× high phosphorus fertilizer interactions were nonsignificant.

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A 3-year study on the effects of growth stimulants on yield, bulb size, bulb quality, and storability of short-day onions (Allium cepa L.) was conducted at three locations. Treatments included 2-hydroxypropanoic acid, humic acids, humic acids in conjunction with micronutrients, and two formulations of cytokinin applied as a transplant dip and/or plant spray. There were no differences between 2-hydroxypropanoic acid and an untreated check at two different farm locations for onion yield, equatorial bulb diameter, or percent jumbos [≥3 inches (≥7.6 cm)] in 1997. Comparisons between untreated checks, 2-hydroxypropanoic acid, humic acids as a transplant dip or plant spray, and humic acids with micronutrients, all applied as transplant dip or plant spray, indicated there were no differences among treatments for yield, pungency, soluble solids, equatorial bulb diameter, or percent marketable bulbs after 6 months in controlled atmosphere storage in 1997-98. In a final experiment, these treatments were evaluated in a factorial arrangement using the short-day onion cultivar Pegasus and a mixture of cultivars WI-609 and WI-3115, which are referred to as Wannamaker cultivar mix. `Pegasus' displayed higher yield and lower soluble solids than the Wannamaker cultivar mix. Treatment with humic acids and micronutrients, or cytokinins resulted in greater percent marketable bulbs after 4.5 months of controlled atmosphere storage compared to the untreated check. No differences were observed among the treatments for pungency or bulb size. In addition, there was no treatment by cultivar interaction.

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Afield study of organic production of tomato (Lycopersiconesculentum Mill.) in high-tunnels was conducted in 2004. `Mountain Fresh' was transplanted 31 Mar.; `Ultra Sweet' and `Sun Leaper' were transplanted on 21 July. The primary objective was to determine the feasibility of obtaining two crops of fresh-market tomatoes by starting plants 4–8 weeks earlier than the average last spring-killing frost, and extending the growing season 4–6 weeks past the average first fall-killing frost. Plants were started at weekly intervals for 4 weeks in both seasons. Data and observations were recorded on the yield of marketable fruits, plant growth and development, and plant health. Other objectives were to evaluate: 1) the benefits of using a selective UV-blocking film on plant growth and development, disease events; and 2) compost amendments on soil improvement and disease control. Major cultural challenges included water management, soil texture/drainage, prevention of chilling injury, plant support, and adequate ventilation. Major disease/pest challenges involved stalk rot caused by Sclerotinia sclerotiorum in the spring, powdery mildew in spring and late summer, Alternaria and Septoria leaf blight in late summer, and aphids, tomato hornworm, corn earworm, and beet army worm also in late summer. In addition, macrofaunal intrusions by fox, mice, and birds occurred sporadically. Poor drainage and stalk rot in the spring necessitated relocating the tunnels to an uninfested site with better drainage. The fall crop yielded high numbers of marketable quality fruits, well beyond the 15 Oct. average killing frost date. The results suggest that with improved management, there is a considerable potential for profitable extended-season production of organic tomatoes in this region.

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