Indian researchers have bred rice lines that combine four separate drought-tolerance genes and yield 36 to 82% more than their parent variety under water stress, according to a study in the Indian Journal of Genetics and Plant Breeding reported by Global Agriculture.

The work, by scientists at Malla Reddy University in Hyderabad, the ICAR-Indian Institute of Rice Research, Central Agricultural University in Umiam and the ICAR-National Institute for Plant Biotechnology in New Delhi, evaluated 40 breeding lines developed by QTL pyramiding, in which several genetic regions linked to a trait are combined in one plant by marker-assisted conventional crossing rather than genetic engineering. The lines carried combinations of the drought-yield QTLs qDTY2.1, qDTY3.1, qDTY1.1 and qDTY2.2 in the background of DRR Dhan 50, a widely grown Indian variety.

Five lines stood out: QTV 108-4, QTV 108-3, QTV 189-2, QTV 128-4 and QTV 105-1, which delivered the 36-82% grain-yield gains over unmodified DRR Dhan 50 under drought stress. High heritability and genetic-advance values for the underlying traits suggest the improvements should carry reliably into later generations through ordinary selection.

Because the method relies on breeding rather than transgenic modification or gene editing, the resulting varieties avoid the regulatory hurdles that have slowed genetically engineered crops in India, where Bt cotton remains the only approved GM crop and no GM food crop has been cleared. The study also identified spikelet fertility and harvest index as the secondary traits most closely tied to protecting yield under water stress, giving breeders measurable selection targets, and principal-component analysis showed that the first two components explained close to half the genetic variation among the 40 lines.

Rainfed rice covers vast areas of eastern and central India and much of the rice land of Africa and South-East Asia, where dry spells are among the biggest constraints on farm income. A breeding route that lifts yield by more than a third under drought using only conventional crossing offers a template other rice programmes could adopt quickly, without biosafety approvals or public-acceptance hurdles. The findings land in a kharif season in which several Indian states have reported large rainfall deficits, the kind of year such varieties are meant for.

Source: Global Agriculture