Morphometric Analysis for Intraspecific Diversity of Oryza sativa cv. ‘Shamim’ Populations (Morphotypes) from Southern Iran

Understanding morphometric diversity in rice (Oryza sativa L.) is essential for improving genetic resources, enhancing breeding efficiency, and supporting conservation strategies. This study examines intraspecific and inter-population morphological variation in Oryza sativa cv. “Shamim” from 15 populations across southern Iran, in Fars (Rostam) and Kohgiluyeh and Boyer-Ahmad (Basht) regions. A total of 150 specimens (10 per population) were sampled in mid-November, with whole plants collected as herbarium vouchers. Fourteen quantitative traits, spikelet number, seed weight, awn length, panicle traits, culm length, blade dimensions, plant height, internode metrics, grain length, and width, plus eight qualitative traits, were measured using standard procedures. Habitat factors like altitude, soil pH, and electrical conductivity varied significantly, driving phenotypic differences. Correlation analyses showed strong links among traits: spikelet number positively correlated with ligule length, culm length, blade length, plant height, panicle length, and weight; awn length negatively correlated with internode number. The strongest correlation was between culm and plant height, indicating integrated stature. PCA and UPGMA clustering grouped the 15 populations into four clusters: first (P02, P10, P07, P03, P04, P12, P01, P13) with low genetic distance; second (P05, P09, P06, P15, P08); and independent (P14, P11) showing greater divergence. Key differentiating traits included spikelet number, seed and panicle weight, awn and panicle length, glume length, culm and blade dimensions, plant height, internode number, and grain attributes. Results highlight substantial diversity in Iranian “Shamim” populations, likely due to environmental variation and adaptation. These findings aid in selecting divergent parents for breeding to boost yield, adaptability, and conserve local rice resources.