Cytogenetics and Crop Improvement Studies in Pigeonpea [Cajanus cajan (L.) Millsp.]: A Review

Pigeonpea has 2n= 2x= 22 chromosomes with length ranging from 5.73±1.15 μm to 10.92±2.69 μm. The largest long arm of chromosome pair (q) was 6.22±1.05 μm, while the shortest measured 3.37±0.83 μm. The longest short arm chromosome pair was 4.70±1.65 μm, while the shortest measured 2.37±0.43 μm. Metacentric and submetacentric chromosomal shapes exist in pigeonpea, but metacentric dominating. Pigeonpea’s karyotypic formula is 2n= 2x= 9m+2 sm. In pigeonpea, regardless of maturity groups, the main and foremost goal is to breed for higher yield/area/time. Resistance to diseases including wilt, sterility mosaic, phytophthora and alternaria blights, as well as insect pests like pod borers and pod flies, is being bred for. Resistance to abiotic stresses like drought tolerance can be achieved by osmotic adjustment (OA), dehydration tolerance and relative water content (RWC). Reduced Na and Cl translocation from root to stem, osmoprotectants and the optimal leaf area index (LAI) for salinity tolerance. Many outstanding varieties has been developed in pigeonpea through germplasm selection, pedigree breeding, mutation breeding and Heterosis breeding.