Effect of temperature during flowering on seed formation of Stylosanthes humilis

Abstract

A Greenvale line of Stylosanthes humilis was grown in controlled environment cabinets and subjected to various temperature treatments after commencement of flowering. Seed yield was maximal (8.0 g per plant) at 31/31�C; it reduced to 6.3 g at a 24�C nyctotemperature, and to 1.0, 1.2, and 0.06 g per plant at day/night temperatures of 31/17, 24/17, and 17/17� respectively. Few seeds were formed at a 10� nyctotemperature. The rate of inflorescence differentiation was positively related to nyctotemperature; seed formed per inflorescence was apparently maximal at a 24� nyctotemperature and sensitive to low phototemperature. The whole-plant yield of this annual plant was highest at 31/17 and 24/17�, in which treatments flowering was reduced. Some ecological implications are discussed.