Effect of Temperature on Time from Planting to Flowering in Virginia Type Peanuts (Arachis hypogaea L.)1

Abstract Field studies with a planting date variable were utilized to determine an empirical relation between time from planting to first flowering of NC2, NC5, and Florigiant peanuts and minimum and maximum daily temperatures. Two basic types of curvilinear response functions and two heat unit systems, which used linear functions, were compared on the basis of days missed by each prediction. The mathematical expression of the data that gave the least days missed was the daily fraction of time to flowering being the sum of quadratic functions for minimum and maximum temperature. The rate of slope change was greater at the higher end of the temperature range. The relation between time to flowering and minimum temperature was more curvilinear that that for maximum temperature except at higher temperatures. Minimum temperatures below 43° F lengthened the time to flowering for the three varieties. Varietal differences appeared to be expressed more by the relation with daily maximum than with daily minimum temperatures. The expressions calculated should be more accurate for prediction purposes than a linear heat unit system, plus they tend to describe the individual responses to changes in minimum and maximum temperatures. A certain lack of fit for the relation still exists, indicating perhaps some other measure, such as solar radiation, should also be included.