Browsing by Author "Anitha Raman"

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Genetic gain for rice yield in rainfed environments in India
(Elsevier B.V., 2021) Arvind Kumar; Anitha Raman; Shailesh Yadav; S.B. Verulkar; N.P. Mandal; O.N. Singh; P. Swain; T. Ram; Jyothi Badri; J.L. Dwivedi; S.P. Das; S.K. Singh; S.P. Singh; Santosh Kumar; Abhinav Jain; R. Chandrababu; S. Robin; H.E. Shashidhar; S. Hittalmani; P. Satyanarayana; Challa Venkateshwarlu; Janaki Ramayya; Shilpa Naik; Swati Nayak; Manzoor H. Dar; S.M. Hossain; Amelia Henry; H.P. Piepho
The complexity of genotype × environment interactions under drought reduces heritability, which determines the effectiveness of selection for drought tolerance and development of drought tolerant varieties. Genetic progress measured through changes in yield performance over time is important in determining the efficiency of breeding programmes in which test cultivars are replaced each year on the assumption that the new cultivars will surpass the older cultivars. The goal of our study was to determine the annual rate of genetic gain for rice grain yield in a drought-prone rainfed system in a series of multi-environment trials conducted from 2005 to 2014 under the Drought Breeding Network of Indian sites in collaboration with the International Rice Research Institute (IRRI). Our results show a positive trend in grain yield with an annual genetic yield increase of about 0.68 % under irrigated control, 0.87 % under moderate reproductive stage drought stress and 1.9 % under severe reproductive stage drought stress due to breeding efforts. The study also demonstrates the effectiveness of direct selection for grain yield under both irrigated control as well as managed drought stress screening to improve yield in typical rainfed systems. IRRI's drought breeding programme has exhibited a significant positive trend in genetic gain for grain yield over the years under both drought stress as well as favorable irrigated control conditions. Several drought tolerant varieties released from the programme have outperformed the currently grown varieties under varied conditions in the rainfed environments on farmers’ fields. © 2020 The Authors
Rice breeding for yield under drought has selected for longer flag leaves and lower stomatal density
(Oxford University Press, 2021) Santosh Kumar; Santosh Tripathi; Suresh Prasad Singh; Archana Prasad; Fahamida Akter; Md Abu Syed; Jyothi Badri; Sankar Prasad Das; Rudra Bhattarai; Mignon A Natividad; Marinell Quintana; Challa Venkateshwarlu; Anitha Raman; Shailesh Yadav; Shravan K Singh; Padmini Swain; A Anandan; Ram Baran Yadaw; Nimai P Mandal; S. B Verulkar; Arvind Kumar; Amelia Henry
Direct selection for yield under drought has resulted in the release of a number of drought-tolerant rice varieties across Asia. In this study, we characterized the physiological traits that have been affected by this strategy in breeding trials across sites in Bangladesh, India, and Nepal. Drought- breeding lines and drought-tolerant varieties showed consistently longer flag leaves and lower stomatal density than our drought-susceptible check variety, IR64. The influence of environmental parameters other than drought treatments on leaf traits was evidenced by close grouping of treatments within a site. Flag-leaf length and width appeared to be regulated by different environmental parameters. In separate trials in the Philippines, the same breeding lines studied in South Asia showed that canopy temperature under drought and harvest index across treatments were most correlated with grain yield. Both atmospheric and soil stress strengthened the relationships between leaf traits and yield. The stable expression of leaf traits among genotypes and the identification of the environmental conditions in which they contribute to yield, as well as the observation that some breeding lines showed longer time to flowering and higher canopy temperature than IR64, suggest that selection for additional physiological traits may result in further improvements of this breeding pool. © 2021 The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Experimental Biology.