Rice Breeding for Drought Tolerance Under the Changing Climate Scenario

Abstract

Rice (Oryza sativa L.) is one of the most important staple food crops for about two third of the world’s population. Rice is cultivated in diverse ecosystems extending from rainfed upland to deep water. The rainfed rice covers ~45 % of the world’s rice area. In a rainfed ecosystem, the recurrent event of drought has been attributed as the major reason to the low productivity. Present speculations regarding higher frequency of drought event along with a 1.1–6.4 °C rise in average global soil surface temperature by the end of this century pose an alarming threat to the production and productivity of rice posing a question mark to the food security of Asia. Drought is the greatest single yield-reducing factor among all other stresses influencing more than 23 M ha area of South and Southeast Asia. Out of the total 20.70 M ha located in India, ~16 M ha of area falls in eastern India including 6.3 M ha of upland and 7.3 M ha of lowland areas, which are highly susceptible to drought condition. Rice crop is very susceptible to soil moisture deficit and high-/low-temperature stresses, particularly at the reproductive stage. The majority of the existing high-yielding and traditional varieties of rice in the eastern part of India are very susceptible to moisture stress (drought). The majority of the high-yielding as well as traditional varieties of rice cultivated in the eastern part of India are very susceptible to moisture stress (drought). Farmers of drought-prone areas require such type of rice varieties that give them with high yield in years of normal rainfall and sustainable good yield in drought years. In this scenario, 42 advanced rice breeding lines were evaluated under drought stress at the reproductive stage with the objective of identifying drought stress-tolerant genotypes. The effect of drought stress on morphophysiological and biochemical traits was also studied. In the study, significant yield reduction was noticed almost in all rice genotypes under drought stress condition in comparison to control (non-stress). The varying responses of genotypes to the applied drought stress condition indicate its drought tolerance capacity. Grain yield was varied from 1.26 to 4.76 t/ha and 2.47–7.48 t/ha under stress and control condition, respectively. Based on preliminary screening, rice genotypes, viz., IR88867-4-1-1-4 (4.76 t/ha), IR88964-24-2-1-4 (4.73 t/ha), and IR88867-9-1-1-4 (4.55 t/ha), showed tolerance to drought at the reproductive stage as compared to check varieties Lalat (2.42 t/ha), IR64 (2.04 t/ha), and Sahbhagi Dhan (2.87 t/ha). Reproductive-stage drought also caused a decline in relative water content (RWC), membrane stability index (MSI), and plant biomass and an increase in grain sterility. These drought stress-tolerant rice genotypes may be cultivated in large areas of rainfed ecology where the occurrence of reproductive-stage drought is very frequent, especially in eastern India.