Relevance of grain number and grain weight on barley yield responses to environmental and genetic factors

Abstract

Objective: This study examines the relationships between the two major components of GY (grain number-GN and grain weight-GW), when driven by genetic and environmental factors.Methods: We compiled data of GY and its numerical components (i.e. GN and GW) to generate a large and unbiased database from every single paper having the word “barley” in the title published over 25 years in four prestigious international journals: Field Crop Research, European Journal of Agronomy, Crop Science and Crop and Pasture Science (formerly Australian Journal of Agricultural Research) between January 1996 and December 2021, both inclusive.Results: GN was significantly better correlated with GY than GW, accounting for 86 % of the variation in GY compared to just 13 % for GW. The changes in GY responsiveness to environmental and genetic factors were mainly due to variations in GN, especially in scenarios with high responsiveness. In contrast, low-responsiveness cases showed trade-offs between GN and GW, suggesting compensatory mechanisms that may not accurately reflect competition for resources.Conclusions: The potential to increase barley GY relies heavily on GN, emphasizing the need to optimise conditions during the critical period of GN determination. Implications: Barley crops under typical field conditions are generally not limited by resource availability during grain filling.