PHYSIOLOGICAL STUDIES ON HIGH TEMPERATURE TOLERANCE IN RICE (Oryza sativa)

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dc.contributor.advisorDr. Y. ASHOKA RANI
dc.contributor.authorVERONICA, N
dc.date.accessioned2018-08-07T09:57:17Z
dc.date.available2018-08-07T09:57:17Z
dc.date.issued2017
dc.descriptionD5411en_US
dc.description.abstractExperiment entitled “Physiological studies on high temperature tolerance in rice (Oryza sativa)” was conducted at ICAR- Indian Institute of Rice Research, Rajendranagar, Hyderabad during kharif 2014, rabi 2014-15, kharif 2015, rabi 2015-16. A set of 60 diverse rice germplasm were screened in kharif 2014 and rabi 2014- 15 for high temperature tolerance. The physiological traits based on which they were screend were membrane thermostability, chlorophyll fluorescence, paraquat tolerance assay, spikelet fertility, grain yield and yield based indices. Based on these genotypes both tolerant and susceptible to high temperature stress were identified. The cell membrane thermostability (MTS) reduced under high temperature by 23.1% over control. However under high temperature, genotypes N22 (80.5%), Rasi (78.9%), IR64 (69.8%), GSR330 (59.4%) and Akshayadhan (61.3%) had a higher MTS whereas it was lower in MTU1001 (20.5%), ADT43 (19.1%), Sumati (18.7%), Pantdhan12 (21.1%) and IR36 (22.4%). Chlorophyll fluorescence traits such as Fv/Fm (maximum quantum yield of PSII), electron transport rate (ETR), effective quantum yield (ΦPSII), co-efficient of photochemical quenching (qP) and co-efficient of non-photochemical quenching (qN) were reduced under high temperature conditions except for an increase in qN of some genotypes. The mean Fv/Fm reduced by 18.3% over control. The maximum Fv/Fm values under high temperature were noted in N22 (0.746), Rasi (0.734) and Khudaridhan (0.726) and minimum in NDR359 (0.335), RNR6378 (0.390) and MTU1001 (0.417). Lesser reduction in ETR was evident in N22 (5.0%), Sonkaichi (6.6%), Khudaridhan (8.6%), Akshayadhan (9.0%), Rasi (9.3%), Assanchidiya (10.5%) and IR64 (11.0%). On the other hand, higher reduction in ETR was in Mahamaya (76.1%), ADT49 (77.6%), MTU1001 (78.0%), ADT43 (78.0%) and WGL14 (79.7%). The ΦPSII under high temperature conditions was the highest in Rasi, N22 and Akshayadhan and the lowest in WGL14, ADT49, MTU1001 and Mahamaya. Paraquat treatment resulted in reduction in chlorophyll a, chlorophyll b and total chlorophyll content. Minimum reduction in the total chlorophyll content was noted in N22 (15.6%), IR64 (16.9%), BPT5204 (17.4%) and Rasi (17.4%). Maximum reduction was in Vandana (74.4%), Sugandhasamba (73.4%) and RPHR517 (64.6%). Regression analysis revealed that there existed a negative association between yield under high temperature and the per cent reduction in chlorophyll content. A reduction in all the yield components (number of panicles m-2, number of grains panicle-1, number of filled grains panicle-1, spikelet fertility, total dry matter, 1000 grain weight and harvest index) and grain yield with a subsequent increase in the number of unfilled grains panicle-1 in both kharif and rabi seasons was observed under high temperature. In both kharif 2014 and rabi 2014-15, maximum spikelet fertility under high temperature was recorded in N22, Rasi, Akshayadhan and IR64 and minimum in IR36, Vandana, ADT43, Sugandhasamba and Sumati. In kharif 2014, the grain yield under high temperature was maximum in N22 (5308.3 kg ha-1), Rasi (5133.3 kg ha-1), Assanchidiya (5083.3 kg ha-1), HKR47 (4816.7 kg ha-1) and TJP82 (4450.0 kg ha-1) and minimum was in Sumati (116.7 kg ha-1), Sugandhasamba (283.3 kg ha-1) and MTU1001 (400.0 kg ha-1). In rabi 2014-15 there was 26.8% reduction in grain yield under high temperature. Maximum yield under high temperature was in Rasi (6400 kg ha-1), Akshayadhan (6266.7 kg ha-1), HKR47 (6233.3 kg ha-1) and IR64 (6133.3 kg ha-1) and minimum was in ADT43 (2516.7 kg ha-1), Vandana (2866.7 kg ha-1) and NDR359 (3950.0 kg ha-1). Based on the grain yield in normal and in high temperature stress conditions, eleven yield based indices were computed and correlation analysis revealed that in kharif 2014, Stress Tolerance Index (STI), Geometric Mean Production (GMP), Mean Production (MP), Yield Index (YI) and Modified stress tolerance index (STIK2) had a significant correlation in both control and heat stress. In rabi 2014-15, besides the above indices Heat resistance index (HI) and Modified stress tolerance index (STIK1) also showed significant correlation. Hence these could be considered as suitable indices. The performance of the genotypes was assessed based on the above screening parameters and 4 genotypes (2 tolerant and 2 susceptible genotypes) were selected. Rasi and IR64 were selected as tolerant genotypes and MTU1001 and ADT43 as susceptible genotypes. N22 and Vandana were taken as tolerant and susceptible checks respectively. In-depth studies were carried out in kharif 2015 and rabi 2015-16 with the selected rice genotypes. Morpho-phenological parameters, physiological parameters, biochemical parameters, yield components and yield along with quality analysis were studied in these six genotypes. An increase in the mean plant height under high temperature in both vegetative and reproductive stages in both the seasons was observed. Tiller number m-2 and stem thickness reduced under high temperature in both the stages in kharif and rabi. Among the genotypes, the reduction was lesser in N22 and Rasi and higher in Vandana and MTU1001. In kharif and rabi the mean days to 50% flowering and days to physiological maturity reduced under high temperature. The shoot and root biomass at vegetative and reproductive stage and total dry matter at harvest reduced considerably due to the impact of high temperature. The mean total dry matter in kharif and rabi reduced by 27.2% and 40.5% respectively. High temperature resulted in the reduction of photosynthetic rate (PN). In kharif season, in both vegetative and reproductive stages higher PN under high temperature was noted in N22 (16.9 and 19.44 μmol [CO2] m-2 s-1 respectively) and Rasi (15.6 and 20.17 μmol [CO2] m-2 s-1 respectively). Lower PN in vegetative stage was in MTU1001 (11.07 μmol [CO2] m-2 s-1) and in reproductive stage in Vandana (13.27 μmol [CO2] m-2 s-1). Similarly in rabi also at both stages, N22 (15.55 and 21.18 μmol [CO2] m-2 s-1 respectively) and Rasi (15.12 and 20.78 μmol [CO2] m-2 s-1 respectively) maintained relatively higher photosynthetic rate under high temperature conditions. Lower PN was in Vandana (10.69 μmol [CO2] m-2 s-1) in vegetative stage and in MTU1001 (12.97 μmol [CO2] m-2 s-1) in reproductive stage. The stomatal conductance (gs) increased under high temperature in N22 and Rasi genotypes which led to subsequent increase in E under high temperature while both gs and E reduced in the susceptible genotypes. There was a reduction in Ci in all the genotypes but under high temperature higher Ci was noted in Rasi and N22. High temperature resulted in the reduction of Fv/Fm, ETR, ΦPSII and qP in all the tested rice genotypes. However the extent varied. The reduction in the observed fluorescence traits was higher in Vandana, MTU1001 and ADT43 and lower in N22 and Rasi. However, qN increased in all the genotypes under high temperature. The chlorophyll content reduced in response to high temperature in both the seasons at vegetative and reproductive stages. Reduction was less in N22 and Rasi and high in MTU1001, Vandana and ADT43. Pollen viability and stigma receptivity were affected due to high temperature stress. The mean pollen viability reduced by 28.3% over control. However, a higher pollen viability and a better stigma receptivity under high temperature was recorded in N22, Rasi and IR64 while, lesser pollen viability and poor stigma receptivity was seen in Vandana, ADT43 and MTU1001. Elevated levels of the leaf antioxidant enzymes, Superoxide dismutase (SOD), Peroxidase (POD) and Catalase (CAT) activity was noted in vegetative and reproductive stage in both the seasons. Higher SOD and CAT activity in reproductive stage was evident in N22 and Rasi. Imposition of high temperature stress significantly reduced the non-structural carbohydrates content in both the stem and leaf sheath. In kharif and rabi, under high temperature NSC’s in stem and leaf sheath was maximum in IR64 in both reproductive stage and at harvest. NSC’s in stem in kharif and rabi, in reproductive stage was minimum in Vandana and at harvest in N22. All the yield components and grain yield were reduced in the tested rice genotypes. A significant reduction in number of panicles m-2, panicle length, panicle weight, number of grains panicle-1, number of filled grains panicle-1, spikelet fertility, 1000 grain weight, grain yield and harvest index was noted in both the seasons. Higher spikelet fertility under high temperature condition in both kharif and rabi seasons was recorded in N22 (75.6 and 70.7% respectively) followed by Rasi (74.2 and 68.7% respectively). The lowest was noted in Vandana (27.5 and 19.03% respectively). The reduction in grain yield was lower in N22 and Rasi and higher in MTU1001. Quality parameters such as amylose content, gel consistency and gelatinization temperature were influenced by high temperature stress. Amylose content reduced in all the tested genotypes in both normal and chalky grains. There was an overall reduction in the GC of the tested rice genotypes. GT increased in Vandana and ADT43 and remained unchanged in other genotypes. A pot culture experiment was conducted to study the interaction of high temperature and water stress in 4 selected rice genotypes (N22, Rasi, Vandana and MTU1001). Plant height increased in response to high temperature (Ht), whereas reduced marginally in water stress treatment (Ws) and combined water stress and high temperature (Ht+Ws). Stem thickness reduced in response to stress and the reduction was maximum in MTU1001 and minimum in Rasi and N22. Compared to control, there was decrease in the number of days to 50% flowering and days to maturity under Ht and Ht+Ws. Shoot biomass and total dry matter reduced in Ws, Ht and Ht+Ws condition in all the genotypes. The extent of reduction in both the stages was higher under combined stress than the individual stresses. The reduction was higher in MTU1001 and lesser in N22 and Rasi. Significant reduction in the PN in both vegetative and reproductive stages in Ws (20.4 and 25.0% respectively), Ht (24.0 and 31.8% respectively) and Ht+Ws (51.8 and 52.3% respectively) was noted. In both the stages higher PN under stress conditions was in N22 and Rasi. gs and E reduced under Ws and Ht+Ws, however increased in N22 and Rasi under Ht conditions. Ci reduced in Ws, Ht and Ht+Ws. Fv/Fm, ETR, ΦPSII and qP reduced in both vegetative and reproductive stages under Ws, Ht and Ht+Ws; whereas qN increased. A higher Fv/Fm, ETR, ΦPSII and qP under stress was noted in N22 and Rasi. Chlorophyll content was also affected by Ws and Ht and the combined stress in all the genotypes at both the stages. The reduction in the total chlorophyll content at both the stages was higher in MTU1001 and Vandana and lower in N22 and Rasi. Relative water content (RWC) reduced drastically in both vegetative and reproductive stage under Ws and Ht+Ws and marginally under Ht. N22 and Rasi maintained a higher RWC under all the stress conditions. The proline content in both vegetative and reproductive stages, increased significantly under Ws (4.5 and 3.9 folds), Ht (2.4 and 2.9 folds) and under Ht+Ws (5.1 and 4.7 folds). Comparitively, N22 and Rasi maintained a higher proline content under stress conditions. Imposition of Ws, Ht and Ht+Ws led to reduction in all the yield components (panicle weight, number of grains panicle-1, filled grains panicle-1, spikelet fertility, 1000 grain weight and harvest index) and grain yield in Ws, Ht and Ht+Ws conditions. In Ws, Ht and Ht+Ws, higher spikelet fertility and lesser reduction in grain yield was in Rasi and N22 whereas lower spikelet fertility and higher reduction in grain yield was in MTU1001.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/5810063602
dc.keywordsPHYSIOLOGICAL, TOLERANCE, RICE (Oryza sativa)en_US
dc.language.isoen_USen_US
dc.pages331en_US
dc.publisherAcharya N.G. Ranga Agricultural Universityen_US
dc.research.problemPHYSIOLOGICAL STUDIES ON HIGH TEMPERATURE TOLERANCE IN RICE (Oryza sativa)en_US
dc.subCrop Physiologyen_US
dc.subjectnullen_US
dc.themePHYSIOLOGICAL STUDIES ON HIGH TEMPERATURE TOLERANCE IN RICE (Oryza sativa)en_US
dc.these.typePh.Den_US
dc.titlePHYSIOLOGICAL STUDIES ON HIGH TEMPERATURE TOLERANCE IN RICE (Oryza sativa)en_US
dc.typeThesisen_US
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