Response of chickpea genotypes to low temperature stress during reproductive development

Low temperature at flowering is a major constraint to improved yield of chickpea in many regions of the world. In particular, cool dryland environments such as southern Australia, parts of the Indian sub-continent and the Mediterranean would benefit from cultivars with the ability to flower and set pods early in the growing season before soil moisture becomes a limiting factor. This paper demonstrates that low temperature (less than 15 °C) affects both the development and function of reproductive structures in the chickpea flower. Aspects of the male and the female gametophyte phases of development are described. Comparisons between chilling sensitive genotypes are made to identify the likely causes of flower abortion. The function of pollen derived from chilling sensitive plants is clearly affected most by low temperature stress, particularly the growth of the pollen tubes down the style before fertilisation occurs. In contrast, pollen tubes derived from chilling tolerant plants continue to grow down the style under low temperature stress. Although other stages of development and function were affected by low temperature, including sporogenesis, pollen germination, and the stigma, none were correlated to the phenotype of the mother plant. The implications of the findings for chickpea improvement programmes are discussed.