Physiological Characterization of Diverse Landraces of Rice to Identify Donors for High Temperature Stress Tolerance Bas
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FULL-LENGTH RESEARCH ARTICLE
Physiological Characterization of Diverse Landraces of Rice to Identify Donors for High Temperature Stress Tolerance Based on First Spikelet Opening Time R. Megala1 • P. Jeyaprakash2 • D. Vijayalakshmi1
Received: 12 July 2019 / Accepted: 2 December 2019 Ó NAAS (National Academy of Agricultural Sciences) 2019
Abstract Rice is susceptible to heat stress at flowering, where temperatures above 33 °C during anthesis causes spikelet sterility. Heat-induced spikelet sterility at flowering is associated with reduction in grain yield. So far only N22 has been used as universal donor for heat stress. One of the major traits employed in N22 in mitigating the impact of high temperature is the early morning flowering (EMF). Hence, the present study was designed to identify novel donors from the indigenous landraces of rice available at TNAU. The physiological basis of flower opening time (FOT) showed early flowering lines had higher transpiration rate coupled with low photosynthetic rate and stomatal conductance during anthesis. The transpiration rate also led to a reduction in panicle temperatures in these lines. It was concluded that at the time of anthesis, the panicle temperatures were 24 °C and less which led to advanced FOT. The results revealed that among the 21 lines, seven landraces, namely Thatan samba, Panamara samba, Thooyamali, Norungan, Mattikar, Sornavari and Seakar, flowering (9.30 to 10.00 IST). Hence, the lines Thatan samba, Panamara samba which flowered before 9.40 IST can be used as potential donors of EMF trait to develop heat-tolerant varieties. Keywords Rice Gas exchange parameters Transpiration rate Panicle temperature First spikelet opening time
Introduction India being the topmost rice producer of 43.20 millions of hectares faces shifting of growing seasons due to global warming, which leads to a fall in production by 40% [2]. Among the challenges prevailing in increasing the rice productivity, high temperature stress plays a major role. The surface air temperature is probably expected to increase around 1.4–5.8 °C at the end of the twenty-first century [15]. Mean temperature rise in tropical and subtropical regions during sensitive stages may be harmful for rice production and can drastically reduce grain yield. The & D. Vijayalakshmi [email protected] 1
Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu 641003, India
2
Department of Genetics and Plant Breeding, ADAC&RI, Tiruchirappalli, India
rise in temperature above 38 °C leads to the poor spikelet fertility and reduced yield. In Tamil Nadu, results of the projected climate change over Cauvery basin showed a reduction in rice yield for an increasing trend of maximum, minimum temperatures and rainfall [5]. Till date, N22, an Indian aus variety, has been identified as one of the heat-tolerant accessions and used as check variety for many studies on heat tolerance. Hence, there is a need to identify new genetic donors for heat tolerance. Landraces have inherent
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