Abstract
Rice is considered a strategic crop for many countries around the world, being the main cash crop for farmers. Water shortage stress occurrence as a result of climate change is among the main threats challenging rice breeders in the last few decades. In the current study, 19 Fn-lines were developed from four populations by crossing a reverse thermo-responsive genic male sterile (rTGMS) line, M.J.5460S, with the three high-quality Egyptian commercial cultivars Giza177, Sakha105, Sakha106 and the promising line GZ7768 as male parents. These newly developed lines, along with their parents, and two water shortage stress-tolerant international genotypes (Azucena and IRAT170), were cultivated under water-shortage stress conditions and compared with their performance under well-watered conditions. Results indicated that the yielding ability of the 19 newly developed lines exceeded those for the two Egyptian parents (Giza177 and Sakha105) under well-watered conditions. The lines M.J5460S/GIZA177-3 and M.J5460S/GIZA177-12 were the best performing genotypes under water shortage stress conditions. The genetic and heritability in broad sense estimates indicated that direct selection for grain yield (GY) under water-shortage stress is highly effective in the current study. Molecular marker analysis revealed that M.J5460S/GIZA177-3 had accumulated the quantitative trait loci (QTL)s, on the chromosomes 2, 3, and 9, which contribute to GY under water-shortage stress from their high yielding tolerant ancestor, M.J5460S. It could be concluded that those lines are high yielding under both well-watered and water-stress conditions harboring several QTLs for yield enhancement under both conditions and that the markers RM555, RM14551, RM3199, RM257, RM242, and RM410 are among the markers that could be used in marker-assisted selection (MAS) breeding programs for such stress condition.
Highlights
Production of enough food under limited resources of land and water is considered to be the main approach to secure food for those countries facing reduced arable land and water scarcity, especially those undeveloped ones
New lines have been developed by crossing four different Egyptian genotypes with an rTGMS line, and subsequent selections of the lines under normal condition across generation was conducted since the well-watered condition is the major target in rice breeding and, as in most cases, high yielding lines can still give high to moderate yield under drought conditions [17,27] unless the caused reduction was very high
Fn rice lines generated from 4 crosses (I-IV) by crossing a reverse thermo-responsive genic lines generated from 4 crosses (I-IV) by crossing a reverse thermo-responsive genic male male sterile line, M.J. 5460s with the three high-quality Egyptian cultivars sterile line, M.J. 5460s with the three high-quality Egyptian cultivars Giza177, Giza177, Sakha105, Sakha106, and the promising line GZ7768, as male parents (Table 5)
Summary
Production of enough food under limited resources of land and water is considered to be the main approach to secure food for those countries facing reduced arable land and water scarcity, especially those undeveloped ones. Securing food with such a method consider a manner for sustaining agriculture and achieving the worldwide sustainable development goals of the 2030 Agenda stated by the United Nations in their 2015 summit. Water scarcity is considered one of the main threats facing global rice production since it requires standing water during the cropping season for the best performance. 50% or more of the cultivated rice area is projected to suffer from water stress, causing significant losses in rice productivity [5]
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