Abstract
Drought is one of the major abiotic stresses affecting wheat yield. A recurrent selection program was conducted to improve the drought tolerance and yield of bread wheat using drought tolerant advanced breeding lines from a drought tolerant x susceptible cross (HI 1500 x HUW 510). The parental lines were evaluated for yield, biomass and harvest index (HI) in addition to the drought adaptive traits like Canopy Temperature (CT), chlorophyll content and Normalized Difference Vegetative Index (NDVI). After three rounds of recurrent selection, the half sib progenies exhibited a marked reduction in CT, chlorophyll content and biomass; whereas improvement was noted for yield, HI and NDVI. Drought tolerance of the half-sib population appeared enhanced as indicated by drought indices and grain yield. Compared to base population, half-sibs showed better HI, grain filling and a significant (17.1%) increase in grain yield under water stress conditions. Cooler canopies and increased early vigour might have contributed to drought tolerance. A favourable combination of gibberellin sensitive and insensitive Rhtalleles was observed in the recombinant progenies. However, increased yield under water stress had a negative trade off in reduction of biomass. The study also identified potential lines with high yield and drought tolerance for subsequent varietal development for water limited areas.
Highlights
Climate change and shrinking water resources have catapulted drought as the most important abiotic stress affecting the productivity of field crops world-wide [1]
After three rounds of recurrent selection, the half sib progenies exhibited a marked reduction in Canopy Temperature (CT), chlorophyll content and biomass; whereas improvement was noted for yield, harvest index (HI) and Normalized Difference Vegetative Index (NDVI)
The data from Semi Arid Wheat Yield Trials (SAWYT) in South Asia over the years using lines bred at CIMMYT, Mexico using conventional and physiological trait (PT) approaches has shown that PT lines were superior yielding with higher grain yield and cooler canopy temperatures (CT) [10]
Summary
Climate change and shrinking water resources have catapulted drought as the most important abiotic stress affecting the productivity of field crops world-wide [1]. Wheat (Triticumaestivum) is an important food crop in India often seriously affected by high temperatures and water stress. Due to the large genotype x environment interactions and low heritability, selection for improved performance under drought conditions based on grain yield alone is considered to be ineffective [7]. In such situations it is advocated that secondary traits with increased genetic variance under stress conditions can be incorporated to increase selection efficiency provided such traits have high heritability, greater adaptive value and relatively easy to measure [8,9]. The data from Semi Arid Wheat Yield Trials (SAWYT) in South Asia over the years using lines bred at CIMMYT, Mexico using conventional and physiological trait (PT) approaches has shown that PT lines were superior yielding with higher grain yield and cooler canopy temperatures (CT) [10]
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