INFLUENCE OF LEAF THICKNESS AND STOMATAL CHARACTERS ON WATER USE EFFICIENCY AND HAPLOTYPE MAPPING FOR VARIABILITY IN STOMATAL CHARACTERS IN RICE
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Date
2022-01-10
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Abstract
Rice is the major food crops which serve as staple food for majority of the world’s population. Uneven rainfall and frequent droughts have brought the necessity to adopt
aerobic cultivation. Water use efficiency (WUE) is an important physiological trait which
determines the growth rates and has relevance under both resource sufficient as well as
deficit conditions. WUE is a complex trait controlled by both photosynthesis and
transpiration. Leaf thickness and stomatal frequency are two important traits that determine WUE through their influence on net assimilation rate (NAR) and mean
transpiration rate (MTR), critical subcomponents of WUE. A study was conducted to
evaluate 150 rice lines to screen for leaf thickness, stomatal frequency and leaf area. A
sub-set of 32 lines were selected from 150 lines which were evaluated in phenomics
facility under two water regimes i.e., well-watered (100% FC) and water-limited (60%
FC) conditions. Leaf thickness was measured as leaf mass area (LMA) and stomatal
frequency was determined using the leaf imprint method. Leaf area and WUE were
strongly related in the selected sub-set. NAR was key determinant of WUE under both
well-watered and water-limited conditions. Leaf thickness played a major role in
determining WUE under water-limited condition, whereas WUE was better explained by
stomatal frequency under well-watered condition. The probable reduction in mesophyll
conductance in thicker leaves might be compensated by having many stomata. Haplotype analyses indicated presence of 3 haplotypes for each gene but were not responsible for phenotypic variation.
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