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  • Author or Editor: Gordon S. Howell x
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Abstract

Field death of dormant primary buds of Vitis labrusca L. cv. Concord may be effectively simulated by in situ puncture with an aluminum needle super-cooled by liquid N2. This allows the subsequent development of the secondary buds for studies of their growth and productivity.

Open Access

Abstract

The acclimation and deacclimation rates of wood and flower buds of tart cherry were determined over 2 seasons and related to the time of defoliation that occurred as the result of pathogenic infection or hand removal during the first year of study. Early leaf loss resulted in delayed acclimation in the fall and more rapid deacclimation in the spring. The end result was reduced bud survival and decreased fruit set. The effects of early defoliation carried over into the second year.

Open Access

Abstract

It has been necessary for perennial plants to develop systems for sensing and reacting to environmental parameters. Their survival and perpetuation is determined, in large measure, by the timing of vital processes in relation to favorable and unfavorable cycles of environment. While the regulation of flowering by environmental stimuli has been extensively researched little is known about the control of cold acclimation. Recent studies show striking similarities between the control mechanisms for flowering and cold acclimation in temperate zone plants.

Open Access

Abstract

Survival data for cold stressed blueberry flower buds are used to demonstrate application of the Spearman-Kärber (S-K) method for estimating T50. Quantal responses are used. The S-K method determines the T50 for buds stressed over a range of temperatures which produce 0 to 100% bud survival. The general equation can accommodate data containing unequal temperature intervals and unequal numbers of observations per temperature treatment. A single statistic, S, can be calculated using a second equation which is an unbiased indicator of the variance of the temperature-percent survival curve around the T50 point. The major advantages of the S-K method are speed, adaptability to computer programming, and accuracy with small sample sizes. Agreement is within 0.5°C of graphically determined T50 values.

Open Access

Abstract

The reliability and convenience of 5 viability tests were evaluated. Growth and tissue browning were the most reliable tests, but they required considerable time and were qualitative. Triphenyl tetrazolium chloride (TTC) reduction and specific conductivity were satisfactory for grape, but TTC was not as reliable as specific conductivity for cherry and raspberry. Neither test proved satisfactory for strawberry.

A second exotherm always indicated living stems and the absence of a second exotherm accurately predicted stem death. Freezing curves for raspberry showed the stems to be 5 degrees hardier than the control growth tests indicated.

Open Access

Abstract

Variability of cluster weight, soluble solids, and titratable acidity of ‘Concord’ grapes (Vitis labruscana Bailey) was quantified with respect to several fixed and random factors. All 3 measurements were affected by cluster position while only cluster weight and soluble solids were affected by sunlight exposure. Estimates of variance components indicated that the greatest percentage variability was among vines. Variance components were used to examine efficient sampling plans that would detect a specified difference at a selected level of Type I error. Graphs illustrate various schemes of sample allocation which would achieve the desired level of precision.

Open Access

Abstract

Radical pruning rejuvenated highbush blueberries (Vaccinium australe Small) which had become excessively large and unproductive. The method returned poorly productive bushes (less than 3,390 kg/ha or 1.5 tons/acre) to superior production (11,300 kg/ha or 5 tons/acre) in 2 years. After 4 years, yields were greater yet (18,080 kg/ha or 8 tons/acre).

Open Access