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- Author or Editor: D. A. Smittle x
- Journal of the American Society for Horticultural Science x
Abstract
Rabbiteye blueberry [Vaccinium ashei (Reade)] production is increasing rapidly and growers of large plantings are converting rapidly from hand harvesting to machine harvesting. In three tests conducted during 1985, machine-harvested ‘Climax’ and ‘Woodard’ blueberries were softer and had higher moisture loss and decay than handpicked fruit after 1, 2, or 3 weeks of storage at 3°C. For both cultivars, berry firmness remained relatively constant during storage, whereas decay and weight loss increased. Berries of ‘Climax’ were firmer, less acidic, and developed less decay than ‘Woodard’. These results will assist in identifying the best fresh-market berries for export from the United States to Western Europe.
Abstract
Mechanically shelled southern peas (Vigna unguiculata (L.) Walp cv. Purple Hull Pinkeye) were stored at temperatures of 5°, 25° and 45°C for 3, 6 and 12 hours. Quality changes were minimal with 5° storage and increased with prolonged storage at higher temperatures. Changes consisted of decreases in percentage green seed, total chlorophyll, sugar, starch and protopectin and increases in water-soluble pectin, Calgon-soluble pectin and seed discoloration. Total solids, hemicellulose and cellulose contents were not affected by storage treatments. A response curve relating the rate of loss of green seed to storage temperature was developed which will assist in the coordination of harvesting-transport-processing operations for the maintenance of a high quality product.
Abstract
‘Dixie’ squash (Cucurbita pepo L. var. condensa) were subjected to factorial combinations of 2 irrigation levels, 4 N treatments, and 3 tillage methods on a Lakeland sand soil during 1978, 1979, and 1980. The greatest marketable fruit yield resulted from a combination of applying irrigation at 0.3 bar soil water tension, applying 22.5 kg N/ha through the irrigation system at 2, 3, 4, 5, and 6 weeks after planting, and preparing the seedbed by moldboard plow tillage. Yields were reduced 3 to 16% by either reducing the N rate, allowing a greater soil water tension before irrigating, or by the use of subsoil-bed or disk-harrow tillage system. A combination of subsoil-bed tillage and application of irrigation at 0.6 bar soil water tension resulted in the greatest yield when squash received a single N application after planting.
Abstract
Summer squash (Cucurbita pepo L. cv. Dixie hybrid) were grown in drainage lysimeters under closely controlled and monitored soil water regimes. Variables included three irrigation treatments, three growing seasons, and two soil types. Marketable fruit yield was greatest and production cost per kilogram of marketable fruit was least when squash was irrigated at 25 kPa of soil water tension. Yields were greatest for the spring season of production and least for the fall season. Regression equations are provided to describe the relationships of water use to plant age and to compute daily evapotranspiration : pan evaporation ratios (crop factors) for squash irrigated at 25, 50, and 75 kPa of soil water tension during the spring, summer, or fall production season.
Abstract
Root growth of cucumber (Cucumis sativus L.) was not greatly restricted by soil strength less than 500 kPa (5 bars). Root growth was inhibited 80% at a soil strength of 850 kPa. Mechanical compaction produced by a tractor wheel resulted in a 50% reduction of tissue NO3 at comparable soil NO3 levels, a 25 to 35% yield reduction, and a decrease in fruit length/diameter ratio. The effects of soil compaction could be partially alleviated by increasing the rate of nitrogen fertilization; however, a 3-fold increase in N fertilization did not completely counteract the effect of compaction on cucumber yield. A system for cucumber seedbed preparation which reduces soil compaction is presented.
Abstract
In field experiments, yields of pepper (Capsicum annum L.) were obtained by more frequent irrigation, nitrogen topdressings, and increased plant population. The highest marketable yield resulted when sufficient N was added to maintain soil NO3–N levels between 20 (spring) and 30 (fall) ppm. In both seasons, the number of N topdressings was doubled in order to raise the soil NO3–N maintenance levels from 10 to 20 ppm or from 15 to 30 ppm. Yield increases were influenced by frequent irrigation only when additional N was applied to maintain a higher soil NO3–N. Populations greater than 27,000 plants/ha increased marketable yields in spring and fall by 2.8 and 7.1 MT/ha respectively.
Abstract
Removal of 20% of the seed of a commercial ‘Poinsett’ seed lot in a vertical air column increased the mean thickness and weight of the remaining seed. Fruit yield was increased by use of thicker, heavier seed when yield potential was not limited by high soil strengths. Seed grading effect on cucumber yield was less when either soil compaction or climactic conditions reduced yield potential. A combination of both yield limiting factors eliminated seed grading effect. Yield response to source of nitrogen was different when cucumbers were grown on compacted and noncompacted seedbeds. An interaction of seed grade, nitrogen source and seedbed compaction on marketable fruit yield was found.
Abstract
Two snap bean cultivars, ‘Galagreen’ and ‘Eagle’, were grown in rainfall sheltered irrigation plots as spring and fall crops. Pod yield of snap beans irrigated when the soil water tension reached 25 kPa (0.25 bar) averaged 11.9 MT/ha. Application of irrigation at soil water tensions of 50 kPa (0.5 bar) and 75 kPa (.75 bar) reduced yield by 41% and 48%, respectively. The reduction in water use was proportionately less than yield decreases, resulting in water use efficiencies of 0.62, 0.45 and 0.40 MT of pods/cm of water for the 25, 50 and 75 kPa irrigation treatments. Water use by the cultivars was similar, but pod yield and water use efficiency of ‘Eagle’ was greater than ‘Galagreen’. Pod yields were reduced when plants were subjected to a 75 kPa soil water stress during pre-blossom, blossom or pod development growth stages. The relationships of snap bean water use (ET) to evaporation from an open pan (PA) were established throughout growth. The crop factor value (ET/PA) varied with plant age and irrigation regime.
Abstract
Plant and root growth and root distribution of ‘Dixie’ squash (Cucurbita maxima Duch.) were reduced by mechanical soil compaction of a Tifton loamy sand soil. Soil atmospheric O2 and CO2 concentrations were not affected by soil compaction. Marketable fruit yield was reduced 46 to 58% by increased soil strength produced by tractor wheel traffic. Nitrogen from Ca(NO3)2 produced greater yields in non-compacted plots and smaller yields in compacted plots than NH4NO3.
Abstract
Inhibition on phenolase activity by blanching or restriction of exposure to oxygen greatly reduced the rate of internal corrosion of tinplated cans by sweet potatoes independent of variety effect or nitrate concentration of the raw product.
When phenolase activity was not inhibited, the severity of can corrosion varied widely among varieties of sweet potatoes. Varieties which caused more can corrosion had a high phenolase activity and a high nitrate concentration. ‘Nemagold’ and ‘California 20-51D’ sweet potatoes, which have a relatively low phenolase activity, did not accumulate high nitrate concentrations or severely corrode cans when ammonium nitrate fertilization of 1,000 lb./acre was applied. Ammonium nitrate fertilization greatly increased nitrate accumulation and can corrosion by ‘Goldrush’ sweet potatoes.