Effect of spacing and irrigation on seed production of a CMS-based pigeonpea hybrid

The study was conducted to determine agronomic practices for optimizing hybrid'seed production of a CMS-based pigeonpea hybrid ICPH 2671. The hybrid seed is produced by crossing ICPA 2043 (female parent) and ICPR 2671 (male parent). Seed set on the male-sterile plants occur due to pollen transfer from male to female parents and was mediated by insects. The treatments included two row ratios involving 4 male-sterile ICPA 2043:1 male-fertile ICPR 2671 (restorer) and 3 female: 1 male; two irrigation frequencies (14 and 21 days interval); and seven plant spacings. The study revealed that the spacing of 75 cm x 30 cm with irrigation at every 14 days (5 irrigations during flower initiation till pod development) in the row ratios of 4:1 (2357 kg ha') as well as 3:1 (2699 kg ha'') produced the highest yield. Results also revealed that the differences between the row spacing of 75 cm and 150 cm were significant for seed yield while the effect of irrigation frequencies and row ratios were non-significant for yield and yield contributing characters of ICPA 2043. Under high density, the plants were tall with erect branches, because of high inter-plant competition for light and produced relatively less biomass and seed yield. On the contrary under low densities, the plants were comparatively shorter and sturdier with semi-spreading branches and greater individual plant yield, biomass, stem thickness, and pods plant"'. Such increases in low density, however, did not help plants to compensate and produce high seed yield that was obtained under closer spacings. The yield advantage at closer spacing was 30-60% more than that of wide spacing