Early anthesis and delayed but fast leaf senescence contribute to individual grain dry matter and water accumulation in wheat

The physiological process of how anthesis time and leaf senescence patterns affect individual grain weight of wheat has only been partially elucidated. In this study, a recombinant inbred line mapping population of bread wheat (Triticum aestivum L. Forno') and its relative spelt (Triticum spelta L. 'Oberkulmer'), contrasting for phasic development and leaf senescence kinetics, was used to understand the physiological and genetic relationships among anthesis time, leaf senescence, grain filling processes, and individual grain weight. Phenotypic measurements were taken in the field over two growing seasons. The results showed that earlier anthesis and delayed leaf senescence were associated with larger grains. Furthermore, early anthesis and delayed but fast leaf senescence promoted grain filling rate (but shortened its duration), grain water absorption rate and maximum grain water content, while individual grain dry matter and water accumulation displayed strong relationships with individual grain weight. A total of 118 significant quantitative trait loci (QTL) were identified in this mapping population, including six QTL for anthesis dates, 24 for flag leaf senescence, 69 for grain filling traits, and 19 for individual grain weight. Frequent QTL coincidences between these traits were observed on chromosomes 2A, 3B, 4A, 4DL, 5A, 5B, 5DL and 7B. Analysis of allelic effects confirmed the above physiological relationships. Therefore, anthesis time and leaf senescence affect individual grain weight at least partly through their effects on individual grain dry matter and water accumulation, resulting from pleiotropy or tight gene linkages. Slightly early anthesis, and delayed but fast leaf senescence, can be used to maximize individual grain weight and yield potential in wheat. (C) 2015 Elsevier B.V. All rights reserved.