Genetic diversity of African’s rice (Oryza glaberrima Steud.) accessions cultivated under iron toxicity

Abstract

Iron toxicity stress is one of the most important constraints to rice production in Togo. Although several methods were explored to control this stress, the best one is still the genetic control through the use of tolerant or resistant varieties. Our hypothesis is that African’s rice, Oryza glaberrima, accessions contain sources of tolerance or resistance to the iron toxicity stress. Thus, the aim of this study was to determine the level and the structure of the African’s rice, Oryza glaberrima, genetic diversity and to identify tolerant genotypes. Two hundred and four (204) accessions obtain from Africa Rice genebank and eight control varieties were evaluated under iron toxicity conditions using alpha lattice design with three replications. There was significant variability among accessions for height of mature plants and weight of 1000 seeds. The coefficient of variation values ranged from 10.56% for the 50% flowering to 77.47% for the sterility rate. The principal component analysis (PCA) with all the measured characteristics revealed that the first four axes accounted for 59.93% of the total variability. The coordinates of the variables showed that, six (6) accessions (T30, T60, H60, Tf, yield and Tox60) are associated to the factor F1 with an eigenvalue of 2,81. A high correlation between 50% flowering and plant height, fertile tillers and number of tillers, sterility rate and total number of seeds and yield were also observed. The accessions were divided into three (3) distinct groups. Sixty (60) accessions and four (4) controls (CG14, IR64, Azucena Whyte and NERICA L-20) identified as tolerant genotypes were clustered together in Group 3. These tolerant accessions could be exploited in the rice breeding program for the tolerance to iron toxicity stress.