Please use this identifier to cite or link to this item: http://krishikosh.egranth.ac.in/handle/1/5810127463
Authors: PURUSHOTHAMA M
Advisor: Pramod kumar
Title: Induction of Heat Tolerance by Modulating the Xanthophyll Cycle Activity in Wheat (Triticum aestivum L.)
Publisher: DIVISION OF PLANT PHYSIOLOGY ICAR – INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI
Language: en_US
Type: Thesis
Agrotags: null
Keywords: Wheat, Ascorbic acid, Calcium Nitrate, Violoxanthin de epoxidase, Relative water content, NPQ, Membrane stability index.
Abstract: Wheat crop is very sensitive to heat stress. In India, as a result of delayed harvesting of sugarcane and rice crops, often late sown wheat crop is exposed to heat stress. At very high temperature photosynthetic machinery is badly damaged. Since photosynthesis is fundamentally associated with biomass and yield therefore, heat stress causes reduction in crop yield. Plant carotenoids protects photosynthetic apparatus under heat stress by scavenging reactive oxygen species, quenching triplet chlorophyll and dissipating excess energy in the form heat via xanthophyll mediated non-photochemical quenching (NPQ). Xanthophyll cycle reversible inter-conversion of violaxanthin to zeaxanthin plays important role in photoprotection. Therefore, it was hypothesized that heat tolerance and yield may be improved by modulating the xanthophyll cycle activity using xanthophyll cycle activators. Thus, present study was undertaken using two contrasting wheat varieties viz. HD 2329 and HD 3086 for analyzing physio-biochemical alterations to gain insight into the mechanism of heat tolerance mediated by modulated xanthophyll cycle activity and to explore the possibility of xanthophyll cycle activators in improving growth and yield under high temperature conditions. Heat stress was imposed by delaying the sowing date i.e normal (23rd Nov 2018) and late sown (8th Jan 2019). Present study comprised two main treatments (Normal and Late sown conditions) and four sub treatments (Foliar application of ascorbic acid (10 mM), calcium nitrate (60 mM), DTT (3mM), water (control) at booting (before anthesis) stage). Results of the present study showed decrease in photosynthesis, Fv/Fm, Y II, RWC, MSI, Chla , Chlb, total Chl, total Car, anthocyanin, growth parameters, yield & its components and increase in transpiration rate, stomatal conductance, NPQ, ascorbic acid, proline, lipid peroxidation, H2O2, activity of antioxidant enzymes (SOD, CAT, POX, GR, APX), zeaxanthin, and VDE gene expression under late sown heat stress condition. Application of ascorbic acid and Ca(NO3 )2 restricted lipid peroxidation and H2O2 formation thus improved membrane stability and relative water content under heat stress. Foliar application of ascorbic acid and Ca(NO3 )2 enhanced the photosynthesis, transpiration, stomatal conductance, Fv/Fm, Y II, NPQ, level of Chla , Chlb, total Chl, total Car, zeaxanthin, lutein, ascorbic acid, proline, activity of antioxidant enzymes (SOD, CAT, POX, GR, APX), improved density of pigments profile and VDE gene expression particularly under late sown heat stress condition. Foliar application of ascorbic acid and Ca(NO3 )2 significantly enhanced the yield and its components, partitioning towards economic sink and also improved heat tolerance index and heat yield stability index and reduced the value of heat susceptible index. From the present study, it may be concluded that xanthophyll cycle activators modulated xanthophyll cycle activity and enhanced the yield and induced the heat tolerance in wheat by improving photosynthetic activity, antioxidant activity, growth, membrane stability, stay green characteristics and by reducing reactive oxygen species.
Description: T-10080
Subject: Plant Physiology
Theme: Induction of Heat Tolerance by Modulating the Xanthophyll Cycle Activity in Wheat (Triticum aestivum L.)
These Type: M.Sc
Issue Date: 2019
Appears in Collections:Theses

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