Association of grain-filling characteristics with grain weight and senescence in wheat under warm dry conditions

Abstract

Abstract Two field experiments were conducted in the 1980/81 and 1981/82 growing seasons to study the association of grain filling parameters with final kernel weight and test weight in three durum (Triticum turgidum, L.) and two bread wheat (Triticum aestivum, L.) cultivars. The time of complete senescence of foliage and maximum grain weight were also investigated. Data on grain-filling rate (GRF), grain-filling duration (GFD) and leaf senescence were obtained from successive samples. Temperatures above a daily average of 19.3°C during the grain-filling period reduced the GFD in 1980/81 by an average of 1.6 days per degree increase in temperature and resulted in about 6% reduction in grain yield compared to the 1981/82 season. The durum wheat cultivars showed higher GFRs than the bread wheat cultivars, suggesting differences in photosynthetic rates and/or lower respiration rates. The greater kernel weights found in some cultivars were associated with higher GFRs. Plant senescence was largely dependent on air temperature. Moreover, termination of grain filling and senescence of foliage occurred independently and were cultivar specific. It is suggested that under warm dry conditions, wheat cultivars with high GFRs and short GFDs could produce higher yields. They should be harvested, however, before the complete loss of green coloration in order to prevent shattering.