STUDIES ON STABILITY FOR YIELD AND PHYSIOLOGICAL TRAITS ACROSS RICE GROWING ENVIRON
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Date
2015
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Acharya N.G. Ranga Agricultural University, Guntur
Abstract
The present investigation was carried out with 21 rice genotypes at the College Farm of Agricultural College, Mahanandi of Acharya N. G. Ranga Agricultural University during kharif 2014 to identify stable genotypes across kharif seasons, in addition to assessment of variability, genetic parameters, character association and path coefficients for yield, yield components and physiological characters. The experimental material was sown in randomized block design with three replications during the three seasons of study, namely early kharif, normal kharif and late kharif. Observations were recorded on five randomly selected plants for yield, yield components and physiological characters. The data was subjected to standard statistical procedures for drawing of valid conclusions and interpretations. Analysis of variance (ANOVA) for early kharif, normal kharif and late kharif revealed highly significant differences among the genotypes for all characters studied in all the three seasons, indicating the existence of sufficient variation among the genotypes studied. Pooled analysis revealed significant mean squares due to genotypes and seasons for grain yield and the yield component traits studied in the present investigation, indicating the existence of significant variation among the genotypes studied in addition to considerable seasonal variance. Highly significant genotype x season interaction was also observed for the various traits, indicating a variable response of the genotype to the different seasons studied. Further, a perusal of the results on seasonal indices for grain yield and yield component traits also revealed variable response of the seasons to the different traits studied. Normal kharif was observed to be congenial for productive tillers
per plant, filled grains per panicle, SPAD chlorophyll meter reading (SCMR), dry matter production at harvest, CGR, RGR and grain yield per plant, while early kharif was noticed to be conducive for panicle length. In contrast, late kharif was observed to be suitable for days to maturity, plant height and 1000 seed weight. A perusal of the results on stability ANOVA revealed the significance of seasons+ (genotypes x seasons) interaction for all traits studied. Further partitioning of the season + (genotype x season) component into season (linear) revealed the significance of season (linear) component for all the traits, except, CGR, indicating the significance of differences between seasons and their influence on the genotypes for expression of these traits. Genotype x season (linear) was also observed to be significant for all the characters studied indicating that the genotypes were diverse for their regression response to change with the season. The mean squares for pooled deviation (non-linear) were also significant for all characters indicating that both linear and non-linear components contributed to the genotype x season interaction observed for various traits in the present investigation. An analysis of the results on the stability parameters, namely, mean (X), regression coefficient (bi) and deviation from regression coefficient (S2di) revealed greater number of genotypes with wider adaptability across seasons for various traits studied, compared to genotypes adapted to specific season (poor / favourable). Eight genotypes (MTU 11371-44-1-1, MTU 11320-30-1-1, KNM 604, WGL 678, BPT 2615, JGL 21078, RNR 11442 and RNR 11718) were noticed to possess high grain yield per plant in addition to non-significant regression coefficient (bi=1) and deviation from regression (S2di=0). Among these, RNR 11718, MTU PS 8-7-1-1 and MTU 11371-4-1-1 were identified as potential genotypes suitable for cultivation across the paddy growing kharif seasons prevalent in the zone. The genotype, BPT 2671, however, had recorded high grain yield per plant, in addition to bi>1 and S2di=0, indicating its suitability for favourable season alone, namely, normal kharif under the scarce rainfall zone conditions of Andhra Pradesh. The studies on genetic parameters of variability revealed high range combined with moderate GCV and PCV, in addition to high heritability and high genetic advance as per cent mean in the present study for filled grains per panicle, indicating the preponderance of additive gene action and therefore scope for improvement of the trait through selection. A perusal of the results on character associations and path co-efficients revealed phenotypic and genotypic correlations and path co-efficients of similar direction and significance. The genotypic correlations and path co-efficients were also in general higher than phenotypic correlation and path co-efficient values for almost all the characters, indicating the masking effect of environment on these traits. The results also revealed high residual effect for both phenotypic and genotypic path co-efficients, respectively, indicating that variables studied in the present investigation explained only about 77 (phenotypic) and 71 (genotypic) per cent of the variability in grain yield and therefore, other attributes, besides the characters studied are contributing for grain yield per plant. A detailed analysis of the direct and indirect effects revealed high positive direct effect of 1000 seed weight followed by filled grains per panicle on grain yield per plant. These traits had also recorded highly significant and strong positive association with grain yield per plant. High direct effects of these traits therefore appear to be the main factor for their strong association with grain yield. Hence, these traits should be
considered as important selection criteria in all rice improvement programmes and direct selection for these traits is recommended for yield improvement. RNR 11718, MTU PS 8-7-1-1 and MTU 11371-44-1-1 are identified as stable and widely adaptable genotypes for cultivation across seasons, in addition to BPT 2671 for cultivation during normal kharif season only, under the scarce rainfall zone conditions of Andhra Pradesh. Further, filled grains per panicle and 1000 seed weight are identified as potential selection criteria for effective improvement of grain yield in rice.
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D5364
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