Physiological and bio-chemical drought responsive mechanisms in rice genotypes
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Date
2021-07-30
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Department of Plant Physiology, OUAT, Bhubaneswar
Abstract
Drought is a major abiotic threat that affects rice production. The experiment entitled
“Physiological and bio-chemical drought responsive mechanisms in rice genotypes” was
conducted during the dry season -2018 and dry season -2019 at Crop Physiology and
Biochemistry Division, ICAR-National Rice Research Institute, Cuttack, India. Droughttolerance screening of 100 diversified rice genotypes including four controls
(Sahabhagidhan,Vandana as tolerant control and IR 64, IR 20 as susceptible control) was
conducted during the dry season -2018 at the vegetative stage based on physiological traits
such as drought score (DS), drought recovery score (DRS), SPAD Chlorophyll Meter
Reading (SCMR), Normalized Difference Vegetation Index (NDVI) value, Relative Water
Content (RWC) and chlorophyll fluorescence (Fv/Fm) in the field condition. After screening,
14 genotypes were selected for drought tolerance capacity viz., five genotypes (Parijata, IC
516313, IC 516130, ARC 10376 and IC 516008) as tolerant, four genotypes (IC 516149,
Pathara, Lalat and IR 36) as moderately tolerant, two genotypes (Satabdi and Naveen) as
moderately susceptible and Prasad as susceptible genotype including two controls
(Sahabhagidhan and IR 64 as tolerant and susceptible control). These fourteen genotypes
were further grown in pot experiment during dry season -2019 for detailed physiological,
biochemical and molecular assessments under control and water stress conditions and all data
were recorded at flowering stage. Simultaneously, these genotypes were grown in the field for
evaluation for reproductive stage drought tolerance. The genotypes Parijata, IC 516130, IC
516008, IC 516149 and Sahahagidhan showed higher values of leaf area, total root length,
specific root length (SRL), leaf photosynthetic rate, stomatal conductance, transpiration rate,
water use efficiency (WUE), photochemical efficiency of photosystem II (Fv/Fm) and
membrane stability index compared to susceptible genotypes Prasad and IR 64. However,
higher antioxidant activity (Superoxide dismutase (SOD), Catalase (CAT) and Peroxidase
(POX)), higher proline accumulation with lesser malondialdehyde (MDA) content in tolerant
genotypes was the well-adapted mechanism under water stress condition. Genes encoding
antioxidant enzymes, such as OsCuSOD, OsFeSOD OsMnSOD, OsCATC, OsPOX1 and
OsPOX2 had higher expression levels in the tolerant genotypes (IC 516130) compared to
susceptible genotypes (Prasad) at flowering stage under water stress. At reproductive stage,
the genotypes Parijata, IC 516130, IC 516008 and IC 516149 possessed the higher grain yield
along with higher biomass accumulation, spikelet fertility percentage, panicle number per m2
with lesser relative yield reduction (below 50%) over susceptible genotypes. Based on these
results, three genotypes Parijata, IC 516130 and IC 516008 were identified as tolerant to both
vegetative and reproductive stage drought and can be used as parent donors in drought
breeding programs of rice.