Breeding drought tolerant rice for shallow rainfed ecosystem of eastern India

Padmini Swain,Anitha Raman,S.P Singh,Arvind Kumar

doi:10.1016/j.fcr.2017.05.007

Abstract

In shallow rainfed rice agro-ecosystems, drought stress can occur at any growth stage and can cause a significant yield reduction. During recent years, some rice varieties possessing tolerance of reproductive-stage drought stress have recently been developed. Tolerance of vegetative-stage drought stress is also required to improve rice productivity in drought-prone regions. In this study, we evaluated a set of rice breeding lines for their response to a range of different types of vegetative-stage drought stress in order to propose standardized phenotyping protocols for conducting vegetative-stage drought stress screening trials and also to identify genotypes combining tolerance of vegetative- and reproductive-stage drought stress. A soil water potential threshold of −20kPa during the vegetative stage was identified as the target for effective selection under vegetative stage with grain yield reduction of about 50% compared to irrigated control trials. Genotypes identified as showing high yield under reproductive-stage drought stress were not necessarily the genotypes showing best performance under vegetative-stage drought stress. Genotypes IR72667-16-1-B-B-3, IR78908-126-B-2-B, and IR79970-B-47-1 showed tolerance of both vegetative-stage and reproductive-stage drought stress. For most, the genotypes that were best under vegetative stage drought or even vegetative stage+reproductive stage drought were different from the genotypes that were best under reproductive stage drought. Based on the cultivar superiority measure, IR69515-6-KKN-4-UBN-4-2-1-1-1 and IR78908-126-B-1-B were the stable genotypes (indicated by low Pi) under both irrigated control and severe vegetative stress conditions, genotypes IR83614-203-B and IR78908-80-B-3-B were stable under irrigated control conditions and moderate stress, whereas IR72667-16-1-B-B-3 was stable under both moderate and severe vegetative-stage stress conditions.

Highlights

Drought is the most important factor limiting rice productivity in the rainfed rice agro-ecosystem (Huke and Huke, 1997; Pandey and Bhandari, 2009)
In the 2008 and 2009, in directseeded trials in Cuttack, gravimetric soil moisture declined to lower levels in the severe stress treatments (8–9% (−60 kPa)) than in the moderate stress treatments (16–12% (−25 kPa)) due to 38 days later irrigation of the severe stress treatment compared to the moderate stress treatment (Table 4)
IR72667-16-1-B-B-3, IR78908-126-B-1B, and IR79970-B-47-1 performed well under both vegetative- and reproductive-stage drought stress, and were the most stable yielding under both moderate and severe vegetative-stage stress. These results indicate the involvement of the different plant traits responsible for resistance at the two stages and the distinct response of rice genotypes to vegetative-stage and reproductive-stage drought stress, and suggest that some genotypes can show tolerance to both stages of drought stress

Summary

Introduction

Drought is the most important factor limiting rice productivity in the rainfed rice agro-ecosystem (Huke and Huke, 1997; Pandey and Bhandari, 2009). Climate change is predicted to increase the frequency and severity of drought, which will likely result in increasingly serious constraints to rice production worldwide (Wassmann et al, 2009). Drought can occur at any stage of the rice crop in any year in rainfed areas. Modern rice varieties are highly sensitive to drought stress at seedling, vegetative, and reproductive stages and even mild drought stress can result in a significant yield reduction in rice (O'Toole, 1982; Torres and Henry, 2016). Drought reduces leaf formation and tillering, which subsequently reduces the development of panicles per plant, causing a yield loss; whereas, at reproductive stage, drought causes a reduction in the number of grains per panicle, increases grain sterility, and reduces grain weight (Pantuwan et al, 2002)

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Discussion

Conclusion