Heterosis over environments in crosses involving indica and tropical japonica rice cultivars

Abstract

The discovery of wide compatibility genes in rice recently shifted the emphasis on enhancing heterosis from intervarietal hybrids to intersubspecific hybrids. We therefore studied the nature and magnitude of heterosis in inter- and intrasubspecific crosses involving improved tropical japonica (J) parents (BSI 10 [P1], BSI 16 [P2], B4116 [P3], and B4122 [P4]) and indica (I) parents (Govind [P5], Manhar [P6], Pant Dhan 4 [P7], Sarjoo 52 [P8], Pant Dhan 12 [P9], and Narendra 359 [P10]). We evaluated all 45 hybrids and parents in a randomized complete block design under environments with optimum sowing and high fertility (E1), optimum sowing and optimum fertility (E2), and late sowing and high fertility (E3). We studied 10 agronomic traits, including harvest index and grain yield, for heterosis, heterobeltiosis, and standard heterosis using Pant Dhan 4 as the standard variety.