Abstract
Selection and breeding for drought tolerance in rice have always been one of the leading objectives for rice breeders in water-deficient farming areas. In the present study, we applied the potential of recombinant inbred lines (RILs) population, which were derived from cross Shahpasand (Iranian landrace) and IR28, for the development of drought-tolerant rice lines. One hundred fifty-two lines along with five check varieties were investigated from 2017 to 2019 under non-stress and drought stress conditions. The yield reduction caused by drought based on overall mean during 2017, 2018, and 2019 were estimated to be 89.40, 57.95, and 35.31%, respectively. Using different statistical methods, certain lines, including L33, L90, and L109, which are considered as the best lines in most environments, were found to be promising for being utilized to increase rice drought tolerance. The averages of grain yield of the above-mentioned lines were respectively 6.45, 5.80, and 5.70 t ha−1 under non-stress condition, and respectively 2.77, 2.66, and 2.59 t ha−1 under drought stress condition. The yield reduction of the selected lines were significantly lower than that of others indicating the significant transgressive segregation. The results revealed using the combination of the best identified tolerance and susceptibility indices and GT-biplot are effective methods for screening superior lines. However, their utilization is not easy and requires specialized packages. For the first time, we introduced a new composite index as a combination of significant indices (CSI). CSI is in the form of a linear function of indices which effectiveness is determined by their correlation coefficient with grain yield. According to our results, using CSI, the identified rice drought-tolerant lines were in high agreement with those obtained by other methods, demonstrating that CSI is a simple but reliable composite index.
Highlights
Selection and breeding for drought tolerance in rice have always been one of the leading objectives for rice breeders in water-deficient farming areas
A significant variation and transgressive segregation were observed in the recombinant inbred lines (RILs) population
Grain yield in the rice RILs of the cross between (SH × IR28) clearly indicated a tendency for improvement, and significant transgressive segregation was observed in both directions under non-stress and drought stress conditions
Summary
Selection and breeding for drought tolerance in rice have always been one of the leading objectives for rice breeders in water-deficient farming areas. The results revealed using the combination of the best identified tolerance and susceptibility indices and GT-biplot are effective methods for screening superior lines. Their utilization is not easy and requires specialized packages. Janwan et al.[5] investigated 271 F7 RILs derived from a cross between KDML105 and CH1, and developed by the SSD method and five check varieties They identified three lines which were significantly high yielding as compared to the best check variety (CNT1) based on transgressive segregation. Kumar et al.[7] reported that 17 high-yielding drought-tolerant varieties were developed from IRRI’s drought breeding programs, which were released in different countries of South and Southeast Asia and Africa. Conventional and molecular approaches were applied in order to develop these varieties
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