A study on genetic variability, interrelationships among agronomic traits and path-coefficient analysis in pearl millet (pennisetum glaucum (L.) R.Br)

Eighteen pearl millet genotypes werc evaluated for some agronomic traits for one season 2006, at four locations namely El shegaila, El jekka and Beinu (in North Kordofan state), under rainfed conditions; and Shambat, (Khartoum state), under irrigated conditions. The experiment was carried out in a randomized complete block design (RCBD) with four replicatons. Seventeen agronomic traits were studied to estimate phenotypic and genotypic coefficients of variation, heritability, genetic advance ancl percentage genetic advance, interrelationships and path coefficient analysis. Analyses of variance revealed significant difference among genotypes for all agronomic traits studied except plant population/ha. The highest genetic coefficients of variation (GCV%) were detected for grain yield (kg/ha) (31.44%), harvest index (30.96%), dry pancle weight (kg/plot) (28.56%) and grain yield (g/plant) (25.83%). The lowest values for (GCV %) were recorded for plant population/ha ((l.62%) and 1000-seed weight (g) (8.97%). The highest phenotypic coefficients of variation (PCV%) were shown by grain yield (kg/ha) (38.07%.), harvest index (37.89%) and grain yield (g/plant) (35.03%); while the lowest value for PCV% was shown by l000-seed wcight (g) (14.11%) The values of phenotypic eoefficient of variation (PCV %) were higher than their corresponding (GCV%) for a11 agronomic traits studied. High heritability estimates were observed for threshing percentagc (0.75), days to 50% flowering (0.74), and days to 95% maturity (0.73) and dry panicles weight (kg/plot) (0.73). The lowcst heritability estimate was shown for 1000-seed weight (g) (0.39). The predicted genetic advance as percentage of mean (GA %) was found to be very high for grain yield (kg/ha) (53.47%), harvest index (52.2%) and dry panicle weight (kg/plot) (50.13%). The lowest GA % was shown for 1000- seed weight (g) (5.24%). Grain yield (kg/ha) showed significant positive phenotypic correlation coefficients with grain yield (g/plant) (0.83) and harvest index (0.73) and dry panicles weight (kg/plot) (0.64). Significant positive genotypic correlations coefficient were found between grain yield (kg/ha) and grain yield (g/plant) (0.97) and harvest index (0.89), productive tillers/plant (0.61), dry panicles weight (kg/plot) (0.57) panicle length (0.52) and number of panicles/plot (0.51). Negative significant genotypic correlation coefficients were detected for grain yield (kg/ha) with threshing percentagc (-0.82), days to 50% flowering (-0.57) and days to 95% maturity (-0.57). The genotypic correlation coefficients were generally higher than the corresponding phenotypic correlation coefficients, for the traits studicd. Path coefficient analysis indicated that panicle length had the highest direct effect (0.51) on grain yield (g/plant), followed by productive tillers/plant (0.28) and panicle width (0.22). The highest indirect effects on grain yield (g/plant) were shown by 1000-seed weight through productive tillers/plant (0.59), and by number of seeds/panicle through panicle width (0.53). Consequently, panicle length, productive tillers/plant, panicle width, number of seeds/panicle, 1000-seed weight (g), grain yield (g/plant), dry panicles weight (kg/plot) and harvest index can be used as selection criteria for grain yield improvement in pearl millet