DEVELOPMENT OF BLAST (caused by Pyricularia oryzae) RESISTANT FINE AROMATIC RICE LINE THROUGH CROSSING TECHNIQUE

Abstract

This field research work offers an account of the generating blast resistant fine aromatic rice over June to December 2016 in Dinajpur using landraces viz., BRRI dhan 34 as susceptible, Zotakatari and Kalijira as resistant cultivars following Randomized Complete Block Design with three replications. Data were assessed on plant height (cm), number of leaves in mother tiller, length of leaf blade and sheath (cm), number of effective tillers, panicle length (cm), spikelet per panicle, number of spots, length and width of the largest spot (mm), percent leaf blast severity, number of death leaf, yield (g) and 1000-grain weight (g) where data were collected at 25 DAT, 45 DAT and 65 DAT. The results indicated that BRRI dhan 34 received the highest number of tillers per plant 19.07, 28.20 and 29.20, length of leaf blade 52.10 cm, 56.97 cm and 60.80 cm, number of spots per plant 84.1, 89.8, and 94.47, number of death leaf per plant 3.60, 5.06 and 6.20 at 25, 45 and 65 DAT, respectively. BRRI dhan 34 also showed the highest number of effective tillers per plant 23.93, panicle length 25.2 cm, number of spikelet per panicle 153.3, 1000-grain weight 27.52g and yield per plant 3.251g. The mean squares of the three cultivars exhibited strong and significant differences for most of the characters including number of tillers per plant, number of leaves in mother tiller, length of leaf sheath and blade (cm), plant height (cm), panicle length (cm), spikelet per panicle, number of spots per plant, 1000- grain weight (g) and yield per plant (g). The genotypic variance (Vg), phenotypic variance (Vp), genotypic coefficient of variation (GCV), phenotypic coefficient of variation (PCV), heritability, genetic advance (GA) and genetic advance (GA%) were estimated where the PCV values were higher than corresponding GCV values for number of tillers per plant, number of leaves in mother tiller, length of leaf sheath and blade, plant height, number of spots per plant, length and width of the largest spot, and number of death leaf per plant. Very high phenotypic and genotypic coefficients of variation were found in number of spots per plant. In comparison with others, the number of tillers per plant (99.62), length of leaf sheath (99.89), plant height (99.92), number of spots per plant (99.95) and number of death leaf per plant (99.08) showed high heritability. Number of tillers per plant showed significant and positive correlation with length of leaf blade (r=0.426***), plant height (r=0.230*), number of death leaf per plant (r=0.303**), number of spots per plant (r=0.740***), width of the largest spot (r=0.306**), spikelet per panicle (r=0.544***), yield (r=0.559***), panicle length (r=0.411***), 1000-grain weight (r=0.564***) and number of effective tillers per plant (r=0.257*). Plant height exhibited highly significant positive relation with number of spots per plant (r=0.138*), width of the largest spot (r=0.313**). Number of spots per plant exhibited highly positive significant correlation with width of the largest spot (r=0.31199**), panicle length (r=0.328**) and yield per plant (r=0.619***). Spikelet per panicle showed highly significant positive correlation with yield per plant (r=0.710***), panicle length (r=0.462***), 1000-grain weight (r=0.436***) and number of effective tillers per plant (r=0.178*). The direct and indirect effects were partitioned among the nine phenotypic characters as well as among the disease parameters. Among the phenotypic characters, the highest positive direct effect was revealed on spikelet per panicle (0.554) on yield followed by number of effective tillers per plant (0.16) on yield. Spikelet per panicle also revealed higher positive indirect effect via number of tillers per plant (0.299), panicle length (0.255) and 1000- grain weight (0.243) on yield. Among the disease parameters percent leaf blast severity showed positive direct effect (0.369) on yield. Again percent leaf blast severity revealed highest indirect effect on yield via number of spots per plant (0.251). In crossing, the number of unsuccessful pollinated panicle was higher (95%) than the number of successful pollinated panicle (5%). The message come out from the study suggesting the best route in breeding program for developing disease resistant fine aromatic rice where the number of spots exhibited highly transmissible character resulting highly significant correlation coefficients with genetically effective in yield contributing linkage.