Abstract
Drought and submergence have been the major constraint in rice production. The present study was conducted to develop high-yielding rice lines with tolerance to drought and submergence by introgressing Sub1 into a rice line with drought yield QTL (qDTY; QTL = quantitative trait loci) viz. qDTY3.1 and qDTY12.1 using marker-assisted breeding. We report here the effect of different combinations of Sub1 and qDTY on morpho-physiological, agronomical traits and yield under reproductive stage drought stress (RS) and non-stress (NS) conditions. Lines with outstanding performance in RS and NS trials were also evaluated in vegetative stage submergence stress (VS) trial to assess the tolerance level. The QTL class analysis revealed Sub1 + qDTY3.1 as the best QTL combination affecting the measured traits in RS trial followed by Sub1 + qDTY12.1. The effects of single Sub1, qDTY3.1 and qDTY12.1 were not as superior as when the QTLs are combined, suggesting the positive interaction of Sub1 and qDTY. Best performing lines selected from the RS and NS trials recorded yield advantage up to 4453.69 kg ha−1 and 6954 kg ha−1 over the parents, respectively. The lines were also found having great tolerance to submergence ranging from 80% to 100%, contributed by a lower percentage of shoot elongation and reduction of chlorophyll content after 14 days of VS. These lines could provide yield sustainability to farmers in regions impacted with drought and submergence while serving as important genetic materials for future breeding programs.
Highlights
Over the past years, farmers have been cultivating high-yielding rice cultivars in their field to obtain higher income and meet the demand for rice
The present study reports the development of drought and submergence tolerant rice lines by combining the drought yield quantitative trait loci (QTL) and Sub1 in the background of UKM5 and IR64-Sub1
We successfully demonstrated the effectiveness of combining qDTY12.1, qDTY3.1 and Sub1 in the background of UKM5 and IR64-Sub1 using marker-assisted selection
Summary
Farmers have been cultivating high-yielding rice cultivars in their field to obtain higher income and meet the demand for rice. Heightening climate change has caused more incidents of drought and flood around the world and is retarding rice production. Drought has been the key concern for food security and caused $28 billion in losses to the crop and livestock industry in Asia from 2003 to 2013 [1]. Farmers in South-East Asian countries especially Laos, Thailand, Malaysia, Philippines and Indonesia were finding it difficult to plant rice in their fields due to water shortages throughout 2019 to early 2020 [2,3,4]. According to Jusop [4], farmers in northern peninsular Malaysia were more worried about the drought that destroyed their rice field than the coronavirus disease 2019 (COVID-19) pandemic. Faulty irrigation equipment in the fields has worsened the condition of drought in 1000 hectares of paddy field in Kepala Batas [5]
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