Morpho-Reproductive Stability of Rice Landraces Under Water Deficit Across Agroecological Zones of Far-West Nepal

Rice landraces represent a reservoir of genetic diversity with potential for enhancing drought tolerance abilities. This study evaluated the morphological and reproductive responses of twelve rice landraces to drought stress from three agro-ecological regions (low land Tarai, Inner-Tarai, and Mid-hill) Nepal. The landraces were grown under the treatments of regular irrigation, intermittent irrigation, and without irrigation by water after seedling establishment in the farmers' field. The traits such as root and shoot length, shoot-to-root ratio, panicle length, and yield were measured during harvesting time. The data were analyzed using two-way analysis of variance, multivariate principal component analysis, and Pearson correlations to know the variations among the landraces and drought treatments across agro-ecological regions. Trait responses varied significantly among landraces across all regions, whereas treatment effects were not significant in most cases. Traits such as shoot-to-root ratio, panicle length, and grain weight showed relative stability across treatments. However, drought reduced tiller number in the rice Anjana and Lalchand, decreased shoot length in Chamade and Ratomarso, and lowered total grains per panicle in Jhini and Shanti. Principal Component Analysis (PCA) indicated that variation was primarily associated with the landraces rather than treatment effects, with the first two principal components explaining 49.1%, 48.6%, and 43.9% of total variance in the Mid-hill, Inner-Tarai, and Tarai regions, respectively. Yield was positively associated with root length, grain weight, and grains per panicle. Cluster analysis indicated grouping of landraces based on agro-ecological origin, suggesting adaptation to specific environmental conditions. This study identifies locally adapted landraces with consistent performance across different water treatments and provides candidate material for further evaluation and utilization for drought-focused breeding programs.