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  • Author or Editor: D. R. Walker x
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Abstract

Concentration of endogenous ethylene was higher in Ag+-treated cuttings of sweet potato (Ipomoea batatas Lam.) than in the control or in cuttings subjected to 48°C for 2 minutes. When leaf tissue was dipped in 0, 125, 250, or 500 mg/liter Ag+, endogenous ethylene was increased by the 250 and 500 mg/liter treatments. When equal concentrations of NO3– were applied to cuttings as KNO3, Ca(N)O3)2, or AgNO3, only AgNO3 increased the endogenous ethylene content.

Open Access

Abstract

Temperature treatments influenced inception, intensity and termination of rest in peach trees [Prunus persica (L.) Batsch]. A substance that affected the response was translocated within the trees. The time of leaf abscission in the fall was related to duration and intensity of rest in ‘Gleason Elberta’ peach leaf terminal buds. An August application of 100 ppm gibberellic acid (GA3) and warm field temperatures delayed defoliation and extended rest.

Open Access

A `Montmorency' sour cherry planting was established on 20 clonal rootstocks in April, 1987, as part of the NC-140 cherry rootstock trial. After 5 seasons scion/rootstock combinations showed a 2.5-fold range in trunk circumference. During the fifth season there was a 6-day range in bloom date, a 4-fold range in growth rate, a 7.5-fold range in yield and a 3-fold range in yield efficiency as influenced by rootstock. Trees on GM 9 were the smallest, had the lowest yields, smallest fruit and were among the lowest in yield efficiency. Mahaleb has been the standard cherry rootstock in Utah. Rootstocks whose trees were comparable or exceeded those on mahaleb in both yield and yield efficiency during the fifth season included 148-1, 196-13 and M×M 2. Differences were also observed in root sucker tendency.

Free access

Calcium chloride (CaCl2) enhances turgidity and quality of postharvest sour cherry, Prunus cerasus L., fruit. Mechanisms by which plasma membrane (PM) ATPase maintains the electrochemical gradient in cell turgor were studied in isolated PM vesicles isolated from tapwater-, CaCl2- and chelated amino acid-calcium-treated Montmorency sour cherry fruit. Electron microscopy and periodic-chromicphosphotungstic acid staining indicated 85-90% closed PM vesicles. Protein activity associated with the PM was four times higher in both Ca treatments than in untreated cherries. ATPase activity was insensitive to NO3 and NaN3, but inhibited by vanadate, indicating absence or low levels of tonoplast and mitochondrial ATPases. PM vesicles exhibited a pH jump in the presence of acridine orange (A493-530nm). Cherry fruit appeared to have a PM ATPase similar to that of other plant species. Generation of a positive membrane potential across the PM was dependent upon ATP.

Free access

Abstract

A mathematical model relating environmental temperatures to rest completion of 2 peach cultivars has been developed. The model equates temperatures to effective chill-units, such that, one can predict when rest will or has been completed with a high degree of accuracy.

Open Access

Abstract

Two processing lines of bean (Phaeolus vulgaris L.), WIS. HBR 40 and WIS. HBR 72, were released in 1970. They combine, for the first time, resistance to both race 1 and race 2 of the bean halo blight disease caused by Pseudomonas phaseolicola (Burkh.) Dows.

Open Access

Abstract

Electron micrographs of ‘Gleason Elberta’ peach flower buds, Prunus persica (L.). Stobes, during rest indicated only moderate metabolic activity prior to December 20. In the December 27 collection, however, a single membrane-bound body (microbody or lysosome) and rough endoplasmic reticulum (RER) were present. Also, the Golgi bodies (dictyosomes) were nearly mature. Heterochromatin disappeared on January 3. By the end of February the number of mitochondria, Golgi bodies, and vesicles had increased markedly. During the first week of March, large nucleopores were observed in the nucleus. These data indicated that bud cells were changing at cold temperatures during winter. Organellar changes were compared to the predicted date for end of rest (13).

Open Access

The Sun Grant Initiative is a new Act of Congress (Sec. 9011 of Title IX of the Farm Security and Rural Investment Act) that reflects a new vision for the future in agriculture. The Sun Grant Initiative is driven by a national consortium of land grant universities, in coordination with the U.S. Department of Agriculture and the U.S. Department of Energy. The mission of the Sun Grant Initiative is to 1) enhance national energy security through development, distribution, and implementation of biobased energy technologies; 2) promote diversification and environmental sustainability of America's agriculture through land-grant based research, extension, and education programs in renewable energy and biobased products; and 3) promote opportunities for biobased economic diversification in rural communities. Bioenergy produced on American farms represents an opportunity to both reduce dependence on imported oil and provide a significant source of income to American farmers.

Free access

Abstract

A model has been developed that relates the stages of spring bud development of ‘Redhaven’ and ‘Elberta’ peaches (Primus persica (L.) Batsch) to an accumulation of growing degree hours following rest completion. The accumulation of growing degree hours is based on a lower limit of 4.5°C and an upper limit of 25°.

Open Access

Abstract

The environment created by ventilating a greenhouse with mine-air was suitable for the production of high quality spray chrysanthemums (Chrysanthemum morifolium Ramat.) and snapdragons (Antirrhinum majus L.) from mid-February through November without any additional energy requirement. The environment created in the greenhouse from December to February was extremely humid and favored botrytis development and physiological problems which reduced crop quality.

Open Access