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D.R. Evert and D.A. Smittle

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.

Open access

D. A. Smittle and E. D. Threadgill

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.

Open access

D. A. Smittle and L. E. Scott

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.

Open access

D. A. Smittle and R. E. Williamson

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.

Open access

D. A. Smittle and S. J. Kays

Abstract

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.

Open access

K. M. Batal and D. A. Smittle

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.

Open access

W.R. Miller and D.A. Smittle

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.

Open access

J. R. Stansell and D. A. Smittle

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.

Open access

D. A. Smittle and M. J. Hayes

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.

Open access

D. R. Evert and D. A. Smittle

Abstract

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.