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PHYSIOLOGICAL APPROACHES FOR HIGH TEMPERATURE TOLERANCE IN RICE GENOTYPES

KrishiKosh

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Title PHYSIOLOGICAL APPROACHES FOR HIGH TEMPERATURE TOLERANCE IN RICE GENOTYPES
Ph.D.
 
Creator CHANDRAKALA J. U.
 
Contributor Dr. Madan Pal
 
Subject High temperature, 24-EBL, Salycylic acid, Calcium, Photosynthesis, Pigments, Chlorophyll fluorescence, Rice
 
Description T-8809
Three signalling molecules viz. salicylic acid, chloride and brassinosteroid
were exogenously applied at pre-anthesis stage to investigate their role in ameliorating
high temperature effects on CO2 assimilation, chlorophyll fluorescence and
photosynthesis pigments and their correlation with grain yield in two contrasting rice
genotypes (Pusa Sugandh-5 and Nerica L-44). Three different concentrations of salicylic
acid (SA) (0.1, 0.25, 0.5 mM), calcium (Ca) (10, 50, 100 mM of CaCl2) and
brassinosteroid (BR) (0.5, 1, 1.5 ppm of 24-Epibrassinolide) were applied thrice through
foliar spray at pre-anthesis stage. After foliar spray, one set of plants was exposed to
high temperature stress (36 oC ±1.7 oC) using temperature tunnel for a period of two
weeks. High temperature significantly decreased the net photosynthetic rate (PN),
photosynthetic water use efficiency (PWUE), stomatal conductance (gs), total
chlorophyll content as well as relative efficiency of PS II photochemistry (Fv/Fm) in
both the genotypes. Transpiration water loss (E) and internal CO2 concentration (Ci)
increased under high temperature stress. Lower concentration of SA (SA1 and SA2) and
Ca (Ca1 and Ca2) improved PWUE by enhancing PN and reducing E as well as Ci.
Similarly, all three concentrations of BR showed alleviation of high temperature stress
effects on photosynthetic activity. The amelioration effect of signalling molecules for
high temperature stress effects were more pronounced in PS-5 compared to Nerica L-44.
Regression analysis indicated involvement of these molecules to nullify the effects of
high temperature stress on PN in relation with grain yield per plant in both rice genotypes
and was significant in PS-5. It may be concluded that application of above signalling
molecules may negate the high temperature stress induced reductions in PSII efficiency,
PWUE, chlorophyll pigments and gaseous exchange in rice at pre-anthesis stage.
 
Date 2016-08-17T13:37:40Z
2016-08-17T13:37:40Z
2013
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/72747
 
Format application/pdf
 
Publisher IARI, DIVISION OF PLANT PHYSIOLOGY