Linking phenology, harvest index and genetics to improve chickpea grain yield

Abstract

Phenology is critical to crop adaptation. We grew 24 chickpea genotypes in 12 environments to analyse: the environmental and genotypic drivers of phenology; associations between phenology and yield; and phenotypes associated with allelic variants of three flowering related candidate loci: CaELF3a; a cluster of three FT genes on chromosome 3; and a region on chromosome 4 with an orthologue of the floral promoter GIGANTEA. A simple model with 3 genotype-specific parameters explained the differences in flowering response to daylength. Environmental factors causing flower abortion, such as low temperature and radiation and high humidity, led to a longer flowering-to-podding interval. Late podding associated with poor partition to grain, limiting yield in favourable environments. Sonali, carrying the early allele of Caelf3a (elf3a), was generally the earliest to set pod, had low biomass but the highest harvest index. Genotypes combining the early variants of GIGANTEA and FT orthologues FTdel, where a deletion in the intergenic region of FTa1-FTa2 was associated with slow development, usually featured early reproduction and high harvest index, returning high yield in favourable environments. We emphasise the importance of pod set, rather than flowering, as a target for breeding, agronomic, and modelling applications.