Testing for potential drought-tolerant lines

Frances Gould, Schultz, Bruce  |  1/24/2017 8:34:09 PM

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Niranjan Baisakh, LSU AgCenter geneticist, at left, selects panicles from test plots in a project designed to develop drought-resistant rice that could withstand periods of dry soil, increasing water usage efficiency. Assisting Baisakh is Christopher Addison, a graduate student who will be taking the lines to the International Rice Research Institute in the Philippines in 2017 where a retractable rain-out shelter will be used to shield research plots from rainfall.

Niranjan Baisakh, an LSU AgCenter plant molecular biologist and geneticist, is working on a project to develop rice that uses less water.

A considerable amount of water is used to grow rice. It requires about 170 gallons of water to produce one pound of rice, Baisakh said.

Currently grown rice varieties in Louisiana need plenty of water to maximize yields. Water shortages happen periodically, which can affect the productivity of a rice crop. And climate change is expected to worsen the availability of quality water for irrigation, he said.

A three-week window last year with nearly no rain allowed good conditions for testing drought-tolerant rice lines during the reproductive stage, but heavy rains interfered with the test in 2016, Baisakh said.

Next year, to grow rice in controlled drought conditions, a graduate student will take the lines to the International Rice Research Institute in the Philippines where a retractable rain-out shelter is used to shield research plots from rainfall.

Rice plants that are denied water respond in multiple ways, Baisakh said. Some die, while others look healthy with tissue tolerance but produce a low amount of grain. Still other plants with drought tolerance show leaf rolling to reduce water loss through evapotranspiration and slightly reduced growth so the plant’s energy is directed to producing grain.

From Baisakh’s tests, the lines that produce the most rice under drought are selected to remain in the breeding program.

From last year’s field screening, Baisakh has selected 21 lines each from several progenies of two crosses between drought-sensitive Cocodrie and two drought-tolerant varieties, Vandana and N22. They are being grown at the Rice Research Station.

These high-yielding, drought-tolerant lines will be genetically compared against drought-sensitive lines to identify genetic markers within the chromosomal regions previously identified to be associated with drought tolerance. Baisakh is using sequencing technology to identify markers to screen for lines with drought tolerance and good yield potential.

He also is screening 420 varieties of a rice diversity panel collected from around the world. They have been planted in the field for validating the drought-tolerance markers and to identify superior lines for incorporating their drought tolerance potential to Louisiana-bred rice cultivars.

Because rice grown in upland conditions is more susceptible to blast disease, Baisakh said, blast resistance is a trait that should be included in the breeding process for drought tolerance.

Development of a suitable variety for the Gulf South will take a few years. “Our goal is to grow these varieties with minimal water,” he said.

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