Characterization and evaluation of Nepalese rice landraces using agro-morphological traits

Rice (Oryza sativa L.) landraces represent an important reservoir of genetic diversity for crop improvement. To characterize agro-morphological variation, a total of 63 rice landraces were evaluated using qualitative and quantitative descriptors, with the improved variety Lalka Basmati included as a check. Among 29 qualitative traits assessed, basal leaf sheath color, leaf blade intensity of green color, auricle color, flag leaf blade attitude, and culm lodging resistance exhibited the highest variation, whereas ligule shape showed no variation across landraces. Highly significant differences (p < 0.001) were observed for key quantitative traits, including flag leaf length and width, penultimate leaf dimensions, ligule length, culm length and diameter, culm number per plant, panicle number and length, filled grains per panicle, total and productive tillers per square meter, thousand-grain weight, grain dimensions, straw yield, grain yield, and harvest index. Vhadasar (3397 kg ha-1) and Ratin (3396 kg ha-1) were identified as high-yielding landraces with superior harvest indices. High genotypic and phenotypic coefficients of variation coupled with high heritability and genetic advance as a percentage of mean were recorded for flag leaf traits, culm length, culm number per plant, and total tillers per square meter, indicating substantial scope for genetic improvement. Grain yield exhibited significant positive correlations with panicle number per plant, filled grains per panicle, culm number per plant, and grain length and width. Principal component analysis revealed that the first five components explained 73.40% of the total phenotypic variation. Cluster analysis using unweighted pair group method with arithmetic mean (UPGMA) grouped the landraces into eight distinct clusters, reflecting varying degrees of genetic relatedness. The observed level of agro-morphological diversity highlights the potential of these rice landraces for use in selective breeding and genetic improvement programs.