ESTIMATION OF THE GENETIC DIVERSITY OF REPRESENTATIVE RICE (Oryza sativa L.) GERMPLASM IN MEXICO USING MORPHOLOGICAL DESCRIPTORS

Abstract

Genetic diversity is the foundation of crop improvement, and understanding it allows for the systematic organization of plant genetic resources to optimize plant breeding programs. A total of 112 accessions representative of rice (Oryza sativa L.) germplasm in Mexico were evaluated to estimate their genetic diversity based on morphological traits. The evaluated materials included drought-tolerant lines, drought-tolerant lines combined with resistance to Pyricularia oryzae, the IR8 variety, and varieties released by the National Institute of Forestry, Agricultural, and Livestock Research (INIFAP). A completely randomized block design was used over two years of evaluation, and analysis of variance, Tukey’s mean comparisons (p ≤ 0.05), principal component analysis, and K-means cluster analysis were performed using the statistical software packages RStudio 4.3.3 and SAS Studio 3.81. Highly significant statistical differences (p < 0.01) were found between rice genotypes and between evaluation environments. The genotype × environment interaction was highly significant for most variables. The test for comparison of means revealed the high genetic diversity of the evaluated rice genotypes. Principal component analysis revealed that the variables total and productive number of stems, as well as days to flowering and to maturity, contributed most to the overall variability. Cluster analysis grouped the evaluated materials into four clusters; two of these clusters contained the rice cultivars with the greatest intergroup dissimilarity and the greatest intragroup similarity. The evaluated accessions of rice germplasm in Mexico possess a broad genetic base.