Nonterminal cuttings were taken just after leaf fall (November) from nongirdled shoots and from shoots girdled 7 weeks previously on `Flordaking', `Junegold', and `Harvester' peach trees [Prunus persica (L.) Batsch.]. Cuttings from nongirdled shoots rooted (85%) and survived (72%) better than did cuttings from girdled shoots on the same trees (64% rooting, 49% survival). Total sugar averaged across cultivars was 68 mg·g-1 dry weight in cuttings from nongirdled shoots and 82 mg·g-1 dry weight in cuttings from girdled shoots. Starch averaged 26 mg·g-1 dry weight and was independent of shoot girdling. `Flordaking' had the lowest starch concentration and the highest” percentage of cuttings that rooted and survived. Rooting and survival percentages differed by as much as 90% among trees within each cultivar.
Mechanically harvested southernpeas (Vigna unguiculata (L.) Walp cv. Purple Hull Pink Eye lost substantial green color within 2 – 3 hours after harvest. Color loss was greater at higher temperature. Color changes were more closely related to O2, CO2, acetaldehyde and ethanol concentration in the load atmosphere than to endogenous ethylene concentrations. Solids and total sugar content decreased after harvest and were not affected by product temperature within the range studied. Flavor and off-flavor acceptability ratings were closely related to time from harvest, product temperature and load atmosphere O2 and CO2 concentrations, but were not closely associated with ethylene, acetaldehyde or ethanol concentrations.
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.
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.
The disk, deep turn and rip-bed methods of land preparation resulted in soil strengths of 1000 kPa or greater at depths of 10, 28 and 18 cm, respectively. The disk and deep turn treatments produced a relatively uniform soil strength across the seed bed at all depths while the rip-bed treatment resulted in a channel of low strength soil under the row with relatively high soil strengths 15 cm to each side. Root growth generally followed the same pattern as soil strength. Shelled pea yield was greatest with the deep turn tillage method and lowest with the disk tillage method. The greater yield was due to a combination of a larger yield per plant and a slightly greater plant stand with the deep turn tillage method. Nutrient use efficiency as determined by total nutrient uptake by plants of the rip-bed and deep turn treatments was 40 and 50% greater than those from the disk treatment.
Midshoot peach [Prunus persica (L.) Batsch.] leaves were collected in 1984 and 1985 from phony-diseased [presumably infected with Xylella fastidiosa (Wells et al.)] and healthy trees of several cultivars at intervals during the summer. Leaves were evaluated for specific chlorophyll content, specific leaf weight, and color (lightness, hue, and saturation). The darker green of diseased trees reported previously could not be attributed to the quantitative changes in the leaf characteristics measured in this study. Midshoot leaves from diseased trees were more yellow and less green than midshoot leaves from healthy trees.
‘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.
Seed of snap bean, Phaseolus vulgaris L. cv. Avalanche were separated into 3 length or 3 diameter groups and then each group separated into 3 classes based on aerodynamic properties. The grading procedure resulted in seed grades having large differences in physical characteristics, growth and yield responses. Yield response potential of snap bean was determined primarily by seed weight. A grading method utilizing size grading based on seed diameter followed by aspiration in a vertical air column was the most effective method of eliminating seed with low yield potential.
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.
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.