Phenotyping Drought-Induced Morpho-Physiological Changes and Genetic Diversity Among Pigeon Pea ( Cajanus cajan (L.) Millsp.) Genotypes

Drought stress at reproductive stages is mainly responsible for low yield in pigeon pea especially in semi-arid regions. Understanding genetic makeup at the phenotypic and genotypic level for stress tolerance-related traits is critical for the selection of diverse parental lines and in designing the breeding program for genetic enhancement of the crop. In view of this, we assessed the responses of different pigeon pea genotypes under irrigated and drought stress conditions for two consecutive years through morpho-physiological characterization and genotyping using SSR markers for assessing diversity at the genomic level. The study revealed high genetic diversity for morpho-physiological traits of which photosynthesis and water use efficiency were found to be useful in screening for drought tolerance. Cluster and PCoA analysis revealed diverse genotypic groups by stress tolerance and maturity duration. Genotyping using genic and genomic SSRs revealed 109 unique alleles with an average of 2.09 alleles per marker with the average polymorphic information content (PIC) value of 0.28 and a range of 0.09 to 0.60 between genotypes. This study helped in identifying diverse genotypes with stress tolerance and provide an insight for the selection of parental lines for using them in the genetic enhancement program in pigeon pea.