Expansion of Leaf Area Per Plant in Field Bean (Vicia fabia L.) as Related to Daily Maximum Temperature

Abstract

The relative rate of increase of leaf area per plant was measured in field beans (V. faba) from May to Aug. 1966. In the early stages of growth, until the leaf area index (L) reached about 3, the rate was closely related to daily maximum air temperature. Previous results from some other temperate crops suggests that this relation may be general up to the point at which L has about half its final value. Combining the present and previous results the relative rate of leaf area increase (Rl) and daily maximum temperature (T[degree]C) are related by log10 Rl = 0.033T + 2.316 giving a Q10 = 2.1 for the increase of leaf area per plant. When the above expression and actual dally maximum temperatures were used to compare the effects of a warm or cool spring on the increase of leaf area per plant, the calculated time taken to reach L = 2 differed by about 4 days for a mean temperature difference of 2.5[degree] C. The greater temperatures associated with later plantings in the same year would shorten the time to achieve L = 2 by up to 23 days.