ROLE OF SULFUR IN IMPROVING MORPHOLOGICAL, PHYSIOLOGICAL AND YIELD PERFORMANCE OF RICE PLANT (Oryza sativa L.) UNDER SALT STRESS

Abstract

Salt stress adversely affects the growth and development of rice plants. Sulfur plays diversified roles to regulate plant physiology. Sulfur application can be helpful in inducing salt tolerance in plants. An experiment was carried out at the net house and Plant Physiology Laboratory of the Department of Agricultural Botany, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh from November 2018 to May 2019 to study the effects of different salinity levels on the morphological, physiological and yield performance and the role of sulfur in improving the above mentioned traits of rice plant under salt stress. Oryza sativa L. cv. BRRI dhan67 plants were subjected to various levels of salinity (0, 8, 12 dSm -1 ) and sulfur (0, 3, 6 Kg S ha -1 ). In this experiment, the treatments consisted of three different salinity levels viz. N 0 = without salt (0 dSm -1 , N 2 = 12 dSm -1 , and three different levels of sulfur viz. S 0 = 0 Kg S ha -1 ), N 1 , S 1

and S 2 = 6 Kg S ha -1 . A randomized complete block design was followed as experimental design with three replications. Treatments were given at 15 days after transplanting (DAT). Data were recorded at different DAT following the standard procedure. The results showed that all the morphological (plant height, no. of tillers, leaf area), physiological (relative water content, K + content, chlorophyll content indicated by SPAD value, dry weights), yield attributes (panicle length, spikelet fertility, no. of effective and non-effective tiller, no. of filled and unfilled spikelets panicle -1 , 1000 grain wt.) and yield (grain and straw yield) parameters were reduced significantly (P ≤ 0.05) under salt stress except membrane stability index (MSI%), Na + content and, no. of non-effective tillers, days to flowering, no. of unfilled spikelets panicle -1 . Under salt stress plants grown in control condition (N 0 ) performed best whereas worst performance of all parameters was recorded from N 2 treated plants. Supplementary sulfur fertilization (3, 6 Kg S ha -1 ) improved all the morphological, physiological and yield contributing characters significantly with the best performance found in N 0 S 2 treatment. Supplemental S treatment decreased the root and shoot Na + content and improved the K + content which reduced the toxic effects of salt stress. Supplemental S also improved the relative water content and leaf MSI% and chlorophyll content in salt affected rice plants. The combinations of salinity and sulfur significantly influenced almost all the morphological, physiological and yield contributing characters, compared to salt affected plants alone. In every case N 1 S 1 , N 1 gave better result than N 1 S 0 and N 2 treatment (6 Kg S ha -1 S 1 , N 2 S 2 gave better result than N 2 S 0 = 8 dSm = 3 Kg S ha S 2 . In most of the parameters, S 2 ) showed better salinity mitigating potential than S 1 treatment (3 Kg S ha -1 ) even at higher level of salt stress (N 2 treatment). Therefore, supplemental sulfur induced improvement of physiology, growth and developmental processes contributed to improve the grain yield which are the indications for improved salt tolerance in rice plants. -1 -1 S 0 S 0