Heterosis and genetic variability studies in G. hirsutum for yield, yield contributing characters and fibre quality parameters under rainfed conditions

Abstract

Twenty one intra hirsutum conventional hybrids with six checks were studied for yield and fibre quality parmeteres to draw Genetic variability, heritability, genetic advance and standard heterosis in randomized block design under rainfed condition at Cotton Research Station, Nanded during 2019-20. The hybrids were sown in two replications with two rows having spacing 90 x 60 cm and 6 mtrs each row. For varietal check spacing was used 60 x 30 cm and that of Bt hybrid check 120 x 45 cm. The results pertaining to genetic parameters viz., phenotypic coefficient of variation (PCV), genotypic coefficient of variation (GCV), broad sense heritability (h2) and genetic advance as per cent of mean for Seed cotton yield (SCY), Lint yield (LY), Ginning out turn (GOT), Boll weight (BW), Seed index (SI), Lint index (LI), Number of bolls per plant (NB/P), Number of monopodia per plant (NM/P), Number of sympodia per plant (NS/P), Plant height (PH), Days to 1st flower intiation (DF), Days to 50% flowering (50% DF), Days to first boll bursting (DBB), Upper half mean length (UHML), Micronaire (MIC), Bundle strength (BS) were estimated in the twenty seven genotypes. The value of phenotypic coefficient of variation (PCV) is greater than genotypic coefficient of variation (GCV) indicated that the apparent variation is not only due to genotypes but due to the influence of environment also. The highest magnitude of both PCV and GCV were observed by the seed cotton yield (24.67 and 22.00) and lint yield (24.73 and 21.47). Heritability estimate was high for seed cotton yield, lint yield, boll weight, days to 50% flowering, Days to first boll bursting, upper half mean length and bundle strength. This suggested the greater effectiveness of selection and improvement to be expected for these characters in future breeding programmes as the genetic variance is mostly due to the additive gene action. Ginning out turn percentage, Plan height and days to first flowering depicted moderate estimates of heritability. In the present investigation both high heritability and high genetic advance was observed for seed cotton yield and lint yield characters indicating the preponderance of additive gene action in the inheritance of this trait. Per se performance results were statistically significant for seed cotton yield (kg/ha). The hybrid NHH 1235 (2069 kg/ha) depicted significant superior seed cotton yield over higher yielding check NHH 44 BG II (1688 kg/ha) and NHH 715 (1672 kg/ha), whereas hybrid NHH 912 (1911 kg/ha) including NHH 1235 was found superior over hybrid check NHH 250 (1575). As many as five hybrids viz., NHH 1235 (2069 kg/ha), NHH 912 (1911 kg/ha), NHH 916 (1879 kg/ha) NHH 892 (1641 kg/ha) and NHH 964 (1604 kg/ha) recorded significant superiority for seed cotton yield over check, NHH 44 NBt (1288 kg/ha), whereas 6 and 4 hybrids depicted significant superiority over another hybrid check NCS 145 and varietal check NH 615, respectively. The higher yielding intra hirsutum hybrid NHH 1235 (714 kg/ha) recorded highest lint yield followed by NHH 912 (692 kg/ha) and NHH 916 (672 kg/ha). Ginning outturn was ranged from 32.57 (NHH 1230) to 38.09 per cent (NHH 968) amongst the hybrids under testing. The highest yielding hybrid NHH 1235 recorded ginning outturn (34.40%). The range for Upper Half Mean Length (UHML) was ranged from 24.6 (NHH 892) to 28.2 mm (NHH 916). The hybrid NHH 908 recorded lowest micronaire (4.00 ug/inch) to maximum by NHH 992 (4.91 ug/inch). Bundle strength was ranged from 23.1 (NHH 937) to 26.9 g/tex (NHH 916) amongst the hybrids under testing. Standard heterosis calculated in the testing hybrids depicted the significant positive heterosis in two hybrids viz., NHH 1235 and NHH 912. In general, performance of hybrids NHH 1235 (2069 kg/ha) and NHH 912 (1911kg/ha) was found excellent for seed cotton yield, better ginning outturn (around 34 to 36%) and medium fibre properties (26 to 27 mm UHML, micronaire below 5 ug/inch and bundle strength around 24 to 26 g/tex).