Screening of rice land races for drought tolerance (Oryza sativa L.)

Rice is the staple food for over half of the world population. The current unprecedented climate change scenario poses a severe threat to national food security. As a result, the development of climate-resilient genotypes is necessary to boost rice yield in India and alleviate food scarcity due to rising population demand. Though drought is one of the complex quantitative traits highly influenced by the environment, it is necessary to better understand the attributes and mechanisms of drought tolerance. Landraces with a broad genetic base serve as a hub of novel traits contributing to drought tolerance. In the present investigation, a total of 22 traditional rice landraces collected from different agro-climatic zones of Tamil Nadu were screened to observe their responses to induced moisture stress under in vitro and in vivo conditions. The traditional rice land races, along with drought-tolerant (Anna 4) and drought-susceptible (IR 64) checks, were screened for drought tolerance. The genotypes used were Vadan Samba, Orissa Kuttai, Thanga Samba, Kalapath, Kattuyanam, Boodhakali Karupam, Kangam Samba, Keerai Samba, Kollan Samba, Chinnar, Manam Kuruvai, Kasthuri Samba, Sivan Samba, Sinkar, Manisamba, Kaalanamak, Madumulungi, Karudan Samba, Athur kichili Samba, Chengalpattu Sirumani Samba, Karuthakar, Rathasali, Vasanal Seraka Samba, Sivappu Kavuni, along with Anna 4 and IR 64. The land races were evaluated under moisture stress using polyethene glycol (PEG) with three different concentrations, 5 %, 10 % and 20 % and a control. The land races that showed tolerance to PEG germination were Keerai Samba, Vadan Samba, Sinkar and Kollan Samba. The rice land races were subjected to proline estimation. The land-races Madumulungi, Garudan Samba, Kasturi Samba and Keerai Samba showed drought tolerance. The land races screened under field conditions exhibit drought and tip drying under induced moisture stress, adapting the drought avoidance mechanism. Molecular screening was also done with SSR markers viz. RM71, RM520, RM256, RM217 and RM431, out of which RM256 showed polymorphism among the genotypes. The molecular characterisation confirmed that Madumulungi, Garudan Samba, Kattuyanam, Keerai Samba, Kannan Samba and Manag Kuruvai showed the presence of a resistant allele with 127 bp. These identified drought-tolerant landraces can be used as a donor parent in further breeding programs to develop drought-tolerant varieties.