MORPHO-PHYSIOLOGICAL CHARACTERIZATION OF WILD RELATIVES OF RICE CONFERRING TOLERANCE TO SALINITY AND DROUGHT

Abstract

Varietal breakthrough in rice contributed very significantly to the increased rice production in Bangladesh over the years despite of many challenges including abiotic stresses like salinity and drought. However, the recent trend shows a yield ceiling of the varietal improvement of rice, especially under stress condition. The use of untapped resources of wild species of rice against biotic and abiotic stresses is still largely unexplored under Bangladesh context. This study evaluated 40 accessions of wild species of rice through assessing their morpho physiological behaviors and allelic diversity conferring tolerance to salinity and drought stresses. The whole work consisted of four pot experiments and one laboratory experiment conducted during 2018-2020. In the 1st pot experiment 40 accessions under 10 wild species of rice namely Oryza rufipogon, O. alta, O. nivara, O. latifolia, Poterecia coarctata, O. glaberrima, O. longistaminata, O. officinalis, O. punctata and O. barthii were tested to assess their morpho-physiology and yield performance under normal environment where all the accessions showed variable morpho-physiological and yield performances. Based on their morpho-physiological parameters the accessions were distributed into five clusters where cluster IV included the maximum number of accessions (17) followed by clusters III (11), cluster II (5), cluster V (4) and cluster I (3). The principal component analysis (PCA) clearly and concisely explains the genetic diversity of wild rice genotypes. Based on the cluster grouping ten accessions from the ten wild species were further evaluated in the 2ndexperiment under normal condition and their morpho-physiological features were identified. The results summarized that the wild rice genotypes exerted fluctuating result for different morpho physiological traits. The maximum grain yield hill-1 (101.90 g) was distinctly produced by wild rice genotype O. nivara and the minimum grain yield hill-1 (9.00 g) was produced by wild rice genotype O. latifolia. In the 3rd pot experiment the performance of these ten wild species of rice along with two checks FR13A (check variety as drought tolerant) and BRRI dhan29 (check variety as drought sensitive) were evaluated under drought condition of 40-45 % field capacity. Among the tested genotypes O. punctata and O. barthii showed more susceptibility under drought stress. On the other hand, O. latifolia, O. nivara, Poterecia coaractata, O. officinalis and FR13A showed more tolerance capability against drought stress. The 4th experiment was comprised of two factors: 12 rice genotypes (10 wild rice genotypes along with two checks Pokkali as salinity tolerant and BRRI Dhan 29 as salinity sensitive) and 3 salinity levels viz. 0 mM NaCl, 50 mM NaCl and 100 mM NaCl. Potericia coaractata and O. latifolia showed the most tolerance among all the wild rice genotypes used. The allelic diversity analysis of the 10 wild species of rice concluds that the polymorphism information content (PIC) value of each primer pair ranged from 0.16 (O. rufipogon) to 0.37 (O. alta, O. latifolia, O. offficinalis, Portericia coactata and O. nivara) with an average of 0.31. The results reveal that O. alta, O. latifolia, O. offficinalis, Portericia coactata and O. nivara would be the best salt tolerant wild rice genotypes among 12 wild rice genotypes used in the study. The identified traits of the wild species of rice for salinity and drought tolerance would be a valuable resource for their introgression into the modern rice cultivars for future breeding programs to develop salinity and drought tolerant rice cultivars.