A PhilRice study is developing breeding lines that can produce high yielding drought-tolerant rice varieties based on root traits to improve upland rice production.
Rainfed upland areas can poorly accumulate water because of uneven slope location, absence of bunds, and lower water- holding capacity of the soil.
“The plan is to let the rice plant have the ability to avoid dehydration, basically, to access whatever water source there is through its roots,” said Dr. Roel R. Suralta, study lead.
Results of the study showed that under upland drought condition, deep and think nodal roots are not the only root traits that contribute to rice productivity. Traits such as maintenance in nodal root production, deep nodal rooting ability, greater nodal root length ratio, and greater lateral root development also help.
According to Suralta, lateral root branching increases the size of contact with soil for greater water and nutrient uptake. When combined with maximum rooting depth, it may maximize the plant’s ability to avoid dehydration caused by drought.
“If the plant cannot develop its maximum rooting depth, deep nodal root development, and branching ability, there’s a chance that it will have poor adaptability to upland drought condition,” Suralta explained.
The researchers used Double Haploid Lines (DHLs) from a cross between a drought tolerant and a high yielding rice variety developed together by IRRI and the International Center for Tropical Agriculture.
Among the DHLs evaluated, one DHL showed higher dry matter production and yield under upland drought because of its ability to produce greater number of nodal roots, high lateral root branching ability, and maximum rooting depth.
Suralta hopes that breeders will use the chosen DHL as a parent to produce high yielding drought-tolerant upland rice varieties.