SCREENING OF DROUGHT TOLERANT GENOTYPES IN RICE (Oryza sativa L.)

Abstract

An experiment was conducted at the Department of Genetics and Plant Breeding Laboratory of Hajee Mohammad Danesh Science and Technology University, Dinajpur during Aman season of 2017. Here, twenty five rice genotypes including 20 land races were screened to investigate them against different levels of osmotic stress on germination and seedling morphological characteristics. The osmotic stress conditions were created in laboratory conditions using three different treatments of Mannitol (C6H14O6) with a control such as water potential (Ψ) i.e., 0, -5, -10, and -15 bars. The experiment was laid out in completely randomized design (CRD) with three replications. Several parameters such as germination percentage, germination rate, seedling vigor index, number of roots, shoot length, root length, total length of the plant, shoot fresh weight, root fresh weight, total fresh weight, root dry weight, shoot dry weight and total dry weight were studied. Most of the traits were evaluated at 14 days after sowing of seeds on all experimental genotypes. The genotypes differed significantly for all traits. Furthermore, the treatment effects were also significant for all studied traits. It was revealed that with decrease of water potential germination percentage, germination rate, seedling vigor index, number of roots, shoot length, root length, total length of the plant, shoot fresh weight, root fresh weight, total fresh weight, root dry weight, shoot dry weight and total dry weight were decreased in most of the genotypes. According to some genetic parameter studied, there was significant variability existed among the genotypes for the all characters. Here, high heritability along with high magnitude of genetic advance in percentage of mean was recorded among most of the traits. Considering all the characters for all genotypes when these raised in vitro up to seedling stage without any drought stress (T0), it was found that the genotype BRRIdhan71 stood first position in performance and was closely followed by Manikmodhu, Laxmilata. When these genotypes were exposed under low moisture stress (T1), the genotype BRRI dhan71 showed superior performance among other genotypes in respect of all the traits, which was followed by Begunbahar, Kadamoni Burikatari. In ease of mild moisture stress (T2), the genotype Burikatari exhibited greater performance for all studied traits that was followed by BRRI dhan71, Begunbahar. When the genotypes exposed to severe stress conditions (T3), it was observed that the genotype Burikatari performed best among all the genotypes for maximum germination percentage, seedling vigor index shoot length, root length, number of roots, fresh shoot weight, dry root weight and total length. According to the ranking based on all treatments and studied traits, the genotypes Burikatari and Begunbahar were found as superior among the all genotypes. These landraces could be designated as drought tolerant from the study it. This finding could be confirmed by further in vivo or field condition research as well as marker assisted breeding research. Therefore, Burikatari and Begunbahar could be helpful to find out drought tolerant gene and to develop drought tolerant variety.