|Keywords (Extracted from title, table of contents and abstract of thesis)
rice, oryza sativa l., seed vigor, seed germination, genetic variability, ir 25924-92-1-3, tnau(ad)103, ir31779-19-3-3-2-2, pusa 33, pusa 510
Fifty-seven genotypes of rice (Oryza sativa L.) originating form different regions of the rice growing world were collected from local and foreign sources. These genotypes were planted at National Agricultural Research Center(NARC), Islamabad and Rice Research Institute, Kala Shah Kaku for seed increase.
The seeds form both the sites after breaking the dormancy were tested for different vigor traits viz.,100-seed weight, rate of germination index, alpha amylase activity, dehydrogenate activity, seedling root length, seedling hoot length and seedling dry weigh on 14th day after setting or germination using role towel method Genotypic differences were highly significant for all the traits studied in both the seed sources and a wide range of variability was observed.
Correlations among various traits were detected. in the seeds produced at NARC, Islamabad; the rate of germination index showed significant positive correlation with alpha amylase activity and highly significant negative correlation with 100-seed weight. Seedling shoot length exhibited highly significant and positive correlation with seedling dry weight and 100-sedd weight. The correlation between alpha amylase activity and dehydrogenase activity was non-significant.
In the seeds form RRI, Kala Shah Kaku, rat of germination index showed significant and positive correlation with alpha amylase activity and dehydrogenase activity and a significant negative correlation with 100-seed weight. Seedling root length and shoot length wre positively correlated with alpha amylase activity, dehydrogenase activity and 100-seed weight. Alpha amylase activity showed highly significant and negative correlation with 100-seed weight. Six genotypes viz. IR 25924-92-1-3, TNAU(AD)103, IR31779-19-3-3-2-2, Pusa 33, and Pusa 510 were found superior in respect of majority of the vigor traits
For genetic studies seven genotypes, four high vigor (IR-50, IR 25924-92-1-3, TANU(AD) 103 and IR 31779-19-3-3-2-2) and three low vigor (IR 21820-154-3-2-23, IR 9766-45-2-2 and M148) were selected. These seven genotypes were crossed in a diallel fashion excluding the reciprocals.
F1 seeds were use for vigor test in the laboratory and for filed experiments. Data generated were analyzed following techniques of analysis of variance, combining ability analysis, genetic component analysis. Combining ability analysis indicated the presence of additive type of gene action in all the traits studied except seedling dry weight. Rice genotypes IR 50 25924-92-1-3, TANU(AD) 103 and IR 31779-19-3-3-2-2 were fond better general combiners of rate of germination index. Based on the genetic component analysis, both additive and non-additive components appeared important in the inheritance of most of the traits. The Wr, Vr.graphic analysis indicated over dominance for seedling root length, seedling dry weight and 100-seed weight. Pretrial dominance was observed for rate of germination index at low temperature, seedling shoot length, tillers per plant, plant, panicle length and grain yield per plant. Non-allelic gene interaction appeared playing an important role for in the inheritance of panicle sterility.