Increasing Yield Potential and Yield Stability in Durum Wheat

Abstract

By 2020, wheat production must increase by 40% to meet the global demand. Future crop improvement must emphasize grain yield potential (GYP), yield stability and user preferences in concerted, interdisciplinary approaches. Issues of environmental sustainability must be an integral part of the research agenda. To achieve these goals, crop breeding at CIMMYT aims to protect high genetic yield potential as a prerequisite of broad adaptation through incorporating resistance to abiotic and biotic stresses. For this study, data from maximum yield trials from 1991-99 have been analysed to investigate GYP and associated traits. The analysis revealed that improvements in GYP in modern durum wheat resulted from higher biomass, primarily through an increased number of grains/m2 via an augmented number of spikes/m2 and/or grains/spike. Straw yield, culm weight, spike weight, vegetative growth rate and grain biomass production rate per day increased, while 1000-grain weight decreased. Results from the 1991-93, 1994-96 and 1997-99 periods display higher rates of genetic progress from grain yield, biomass and associated agronomic components in recent years, as well as changes in yield architecture in elite durums over time. In contrast to previous studies, this study showed that harvest index in CIMMYT durum germplasm declined since the early to mid 1970s, and advances in biomass production were largely partitioned into straw, particularly in the 1991-94 period. A comparison of the 3 top-yielding durums with the 3 highest yield bread wheat genotypes over 9 years reflected a trend towards a more uniform balance of yield components. Data covering a range of abiotic and biotic stresses environments suggest that advances in GYP have been combined with improved stress tolerance and input efficiency. Implications and strategies are developed from recent research data in the context of linking to and extending upon modern breeding. Dry matter partitioning, biomass enhancement, empirical and analytical approaches, expansion of the genetic base, stabilizing GYP, and hybrids are considered.