Effects of short periods of exposure to high temperature on the phenology and shoot apex development of wheat cv. Sonora 64

Abstract

Wheat (cv. Sonora 64) was exposed to high temperatures (27�C) during six developmental stages and compared with growth of controls at continuous high (27�C) and continuous low (17�C) temperatures. Time from sowing to maturity was reduced more by later exposures to high temperature, especially anthesis to maturity. High temperatures in phases I, IIA and IIB promoted a higher fraction of fertile florets to set grain, but total grain yield was lower because the number of fertile florets per ear and weight of individual grains decreased. The reasons for this response are examined in terms of the flowering apex.