Validation of dehydration avoidance root plasticity traits of selected germplasm collection under soil moisture deficit

Percentage of drought affected rice areas has approximately doubled from the past years and thus, further reduced the potential rice production. Under such condition, roots play an important role in maintaining plant productivity through the maintenance of higher soil water uptake from the drying soils to support higher transpiration and photosynthesis and consequently, above ground dry matter production. One of the methods for rapid screening of drought resistance is using Line Source sprinkler system (LSS). Using the LSS, germplasm collections were identified as drought resistant (based on the ability to maintain dry matter production) in response to different intensities of drought. The drought resistance of these selected germplasm, however, need to be further studied to validate the contribution of dehydration avoidance root traits to drought resistance and a selected germplasm with validated dehydration avoidance root traits can be recommended for use as a parent for breeding high yielding varieties adapted to drought prone environments. Seven selected rice germplasms from the LSS system were grown under two water treatments such as CWL (continuously waterlogged for 39 days) and PDR (progressive drought, first waterlogged for 14 days and subsequently subjected to progressive soil drying conditions at 10% SMC until 39 days after sowing). Arranged in split plot design (treatments as main plot and genotypes as subplots) with three replications. Statistical analysis showed that there was significant interaction between genotype and water treatments on shoot dry matter production. The shoot dry matter production was significantly reduced by PDR regardless of genotypes. Correlation analyses showed that water use was positively and significantly contributed the higher maintenance of shoot dry matter production during PDR. Among the selected rice germplasms, Belibod showed the ability for greater tolerance to drought based on its less reduction of its shoot drought during progressive soil drying conditions.