Genotypic and environmental interaction in advanced lines of rice under salt-affected soils of Punjab

Sixteen genotypes developed through hybridization and mutation breeding techniques were evaluated during the year 2003-04 on nine locations covering most of the area of Punjab province including Faisalabad, Toba Tek Singh and Jhang. NIAB-IRRI-9, Jhona-379 salt tolerant genotypes and super Basmati, a salt sensitive variety were included as standard checks. The tested material [six genotypes] was generated by crossing fine varieties of rice viz. Basmati-370 and Basmati-385 with three coarse varieties of rice viz. NIAB-IRRI-9, Jhona-349 and NIAB-Rice-1. The mutants [seven mutants] were derived by gamma irradiation of rice varieties, Basmati-370 and Basmati-385. The nine sets of experiments were conducted in the naturally high saline sodic soils having EC range of 9.2-18.13 d/Sm pH=8.65-9.50, and SAR=20.7-37.15. The seed yield data collected at maturity and stability parameters were computed to know genotypic x environment interaction and varietals performance. The combined analysis of variance showed highly significant variance in case of varieties, locations and varieties x locations interaction. Varieties and varieties x Environment [Lin] also showed highly significant differences. It means that genotypes exhibited different behavior in different locations / environments which is due to their different genetic make up. The behavior may be cross over [in which significant change in ranking occurs from one environment to another] or cross over nature [in which case the ranking of genotype remains constant across environments and the interaction is significant because of change in the magnitude of response] depending upon the ranking order of genotypes performance under different environment. In our study, only super Basmati behavior was of almost non cross over nature, while others had cross over type of interaction. Based on overall mean seed performance, mutant NIAB-Rice-4 and DM-38/88 produced significantly the highest grain yield [5.6 t/ha] followed by mutant line NIAB-Rice-5 [5.4 t/ha] and NIAB-rice-2 [5.3 t/ha]. The lowest performing genotype was super Basmati [3.0 t/ha]. The coarse variety Jhona-349 produced [4.8 t/ha] grain yield. Mutant line DM-38/88 showed significant regression co-efficient differences from unity while mutant line NIAB-Rice-4 showed non significant difference of regression co-efficient from unity. Mutant line, NIAB-Rice-4 also showed non significant difference of standard deviation to regression co-efficient from zero. All the three parameters of stability i.e. overall mean seed yield, regression co-efficient and standard deviation to regression, provided clear evidence that mutant line NIAB-Rice-4 produced maximum stable yield compared to super Basmati