Screening of rice (Oryza sativa L.) germplasm for response to Water stress conditions at reproductive stage

Drought is one of the most hazardous abiotic stresses that can cause considerable yield losses mainly in rainfed and minor irrigated ecosystems in Sri Lanka. Identification of drought tolerant rice germplasm and drought linked traits in those germplasm are essential in developing drought tolerant varieties. Present study was conducted to screen 46 rice germplasm (34 traditional, 4 improved, 7 exotic accessions and one wild relative of rice) for response to drought under induced water stressed condition at reproductive stage which is the most critical stage for drought stress. One plant house trial and two field trials were conducted for germplasm screening. Plant house trail was established using one meter long PVC pipes in a Randomized Complete Block Design with two replicates. Water stress was induced at early booting stage while control treatment was maintained under unstressed condition. Drought linked above ground traits and root traits were investigated. Tested rice germplasm significantly varied with respect to drought linked traits. Different adaptation mechanisms were shown by different accessions for their survival under water stressed condition. Oryza eichingari, Podi Niyanwee, Goda Heenati (4049), Al Wee (4919), Al Wee(4023), Mada Al Galle, Bg 300, Kinadang Patang, Ld 12-38 performed comparatively better under drought stressed conditions at reproductive stage. Suwandel, Rathnawalu, Nona Bokra and Rathu Heenati showed significantly inferior performances under drought conditions. Correlation analysis revealed that the spikelet fertility, harvest index, grain weight and spikelet per panicle significantly contributed to yield stability under drought stressed conditions. High correlation was observed between spikelet fertility and delayed leaf rolling. No significant correlations were observed between yield and root traits. Selected accessions can be utilized as donor parents for development of high yielding rice varieties for low moisture stress conditions.