Breeding effects on sensitivity of barley grain weight and quality to events of high temperature during grain filling

Abstract

Temperature is one of the most important factors affecting grain quality in the majority of cereal growing areas. It has been shown that brief periods of high temperature during grain filling can reduce grain weight and quality. However, it is not known whether breeding for increased yields has altered the sensitivity to high temperatures after flowering. Four malting barley cultivars, chosen from previous studies to represent a series of successful breeding releases in Argentina, were sown under field conditions. The high temperature treatments consisted of increasing the spike temperature by about 5 ∘C for 6 h/day (from 10 am to 4 pm) for 20 days starting nine days after flowering (DAF), or for two periods of 10 days each, between 9 to 19 DAF or from 20 to 29 DAF. In all cultivars, grain weight and screening percentages decreased significantly with the treatments. In general, the two more modern cultivars (Q. Pampa and Q. Ayelen) were more sensitive to heat stress than the older ones (Heda and Union). A similar pattern was found for malt extract. Thus it appears that breeding for higher yields has concomitantly increased sensitivity of grain weight (and yield) and quality to the episodes of high temperatures during the grain-filling period in barley.