Identification of Superior Segregants for Drought Tolerance and Productivity Traits in Backcross Inbred Lines (BILs) Derived from NERICA Introgression under Rainfed Ecosystem
2. Barwale Foundation, Hyderabad, AP, India
Author Correspondence author
Rice Genomics and Genetics, 2013, Vol. 4, No. 3 doi: 10.5376/rgg.2013.04.0003
Received: 05 Feb., 2013 Accepted: 15 Mar., 2013 Published: 08 May, 2013
The aim of this study was to identify promising genotypes for upland rice ecosystem especially in drought prone areas. Backcross inbred line (BC1F6) developed from inter varietal cross of Swarna X NERICA were evaluated under water stressed environment for physiological and productivity related traits in the pot experiment. The result showed a clear expression of donor (NERICA) genome on the background of the recurrent parent (Swarna) in the BILs evaluated. Performance of BILs is generally lower under water stressed treatment when compared with non-stressed treatment for all the traits studied except leaf temperature which was higher under water stressed condition. Except for traits like leaf area and plant height, percentage reduction in performance of BILs for physiological and productivity component traits under water stress treatment are generally lower than the recurrent parent Swarna indicating their superiority over recurrent parent for drought tolerance.
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Performance of BILs was generally lower under water stressed treatment than non-stressed treatment for all the traits studied except leaf temperature which was higher under water stressed condition. Reaction of plant to water stress is complex, it involves physiological, morphological and biochemical changes within the plant tissue. The initial responses to drought stress occur at the leaf level in response to stimuli generated in the leaf itself or elsewhere in the plant and they have a negative influence on carbon assimilation and growth (Chaves et al., 2002). The combine effect of various reactions within the plant tissues culminate in the actual behaviour of plant to drought stress (Pereira and Chaves, 1993).
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Top 20 superior BILs (Table 4) that showed lowest percentage reduction in important component traits like relative water content, chlorophyll content, leaf temperature and leaf area under water stress will be suitable as breeding material for drought tolerance. It has been reported that under conditions of water stress, plants are often subjected to a high temperature, which increases their vulnerability to light stress and consequently the photo inhibition (Shahenshah et al., 2010). When carbon dioxide ï¬xation is limited, the rate of active oxygen formation increases in chloroplasts as excess excitation energy, which would either become manifest as oxidative damages to the plant or would result in activation of defence and repair mechanisms which could prevent such damage from occurring (Shahenshah et.al., 2010). The decrease in chlorophyll content under drought stress has been considered a typical symptom of oxidative stress and may be the result of pigment photo-oxidation and chlorophyll degradation. A decrease in the relative water content (RWC) in response to drought stress has been noted in wide variety of plants as reported by Shakeel et al., (2011). RWC related to water uptake by the roots as well as water loss by transpireation (Shakeel et al., 2011). Identification of superior drought tolerant rice genotypes is achievable through genetic manipulation for these physiological traits.
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