Chickpea Plant Ideotype Development for Semi-Arid Subtropical Climates to Assist Plant Breeding.

Empirically, plant breeders attempt to increase crop productivity by focusing their selection criteria on yield. However, this approach faces many challenges because of the low heritability for yield. Plant ideotype breeding which attempts to construct a model plant with the desired morphological and physiological traits augments empirical breeding. Selection of a combination of plant characters which can act through additive gene action can enhance crop productivity in the target environment. A plant ideotype gives plant breeders a structural framework to target in a defined environment. Terminal drought is a major problem in semi-arid subtropical climates due to the rapid warming experienced in spring causing huge yield losses. However, in some years there is sufficient in season moisture to produce higher yields. A model plant in this type of environment should show plasticity and produce high yield in seasons with higher rainfall and limit yield losses under terminal drought in drier years.

In this study, 30 chickpea genotypes comprising both kabuli and desi types were evaluated under well watered (irrigated) and water stress (rainfed) conditions at the International Grains Research Centre in Narrabri, northwest NSW, Australia. Chickpea genotypes Sonali and Tyson emerged as drought tolerant on the stress susceptibility index scoring 0.68 and 1.13 respectively, whereas, Amethyst and Genesis 079 were susceptible with values of 1.85 and 1.73. Trait association and regression analysis showed that early ground cover, plant canopy closure throughout the reproductive phase which intercepts the photosynthetic active radiation and early flowering were essential drought tolerance traits. Under well watered conditions, early maturity, plant canopy cover and high light interception at flowering, low disease pressure and small leaves were important. These responses were used to construct an ideotype for chickpea yield and adaptation in northwestern NSW to assist cultivar development.