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  • Author or Editor: Gordon S. Howell Jr. x
  • Journal of the American Society for Horticultural Science x
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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