INVESTIGATING THE ROLE OF PHENOTYPIC PLASTICITY IN TERMINAL HEAT STRESS TOLERANCE IN WHEAT (Triticum aestivum L.)

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dc.contributor.advisorBahuguna, Rajeev Nayan
dc.contributor.authorPARMESHWAR, PADILE GANESH
dc.date.accessioned2023-10-21T13:03:59Z
dc.date.available2023-10-21T13:03:59Z
dc.date.issued2022
dc.description.abstractThe global mean temperature is increasing at a rapid pace due to atmospheric warming. Consequently, heat stress events are becoming more frequent and severe and affecting global food production. For the current study, we gave grown thirty wheat genotypes at two (timely and late) sowing dates and two planting densities viz. optimum and low density (LD) resulting in three treatments viz. Control, terminal heat stress (HT), and terminal heat stress with low planting density (LD+HT). Genotype HD-2967 was used as a check variety for heat stress tolerance. Timely sowing in control treatment was done on 26th Nov, 2021 while for the HT and LD+HT treatments, sowing was delayed by 19 days. Late sowing of genotypes exposed them to a higher temperature of 6.6 oC and 4.5 oC at flowering and active grain filling stages, respectively. As a result, a reduction in the grain yield of up to 59 % and biomass reduction of up to 55 % were observed under HT conditions. Conversely, 15 days reduction in total crop duration and 10 days reduction in grain filling duration has been under HT condition, which was a crucial determinant of seed weight, and grain yield. There was significant (P<0.05 to <.001) genetic diversity observed for traits across the genotypes. Key traits that contributed to yield loss under heat stress were reduced spike weight, grains per spike (seed set) and spikelet fertility. Correlation analysis of traits showed that there was a significant negative correlation between canopy and spike temperature with yield and yield components. In general, spike temperature was significantly higher than canopy temperature across the treatments. Moreover, higher spike temperature was negatively correlated with spikelet fertility, seed set and seed weight. Canopy cover was observed as helpful in maintaining a lower canopy and spike temperature. On the other hand, traits such as tillering ability, SPAD, relative water content and spike weight were positively related to yield and biomass accumulation under control and LD+HT conditions. Lower spike temperature with a better canopy cover was crucial to maintain a high grain number under reproductive heat stress. A significant variation was noted in the phenotypic plasticity where all the traits measured showed higher variations under low planting density. Moreover, genotypes under low density showed higher yield per plant due to better space and light helping accumulate more biomass and dense canopy. Low density helped in maintaining a higher seed set and fertility ratio in responsive genotypes under reproductive heat stress. However, low density did not show similar effectiveness under heat stress at the grain filling stage, as the minimum temperature was the dominant factor where a merely cooler canopy was ineffective. The cumulative response index for 8 key traits showed a wider range in phenotypic plasticity in wheat genotypes, which can be utilized in crop improvement programs for terminal heat stress tolerance.
dc.identifier.otherM/BPP/561/2020-21
dc.identifier.urihttps://krishikosh.egranth.ac.in/handle/1/5810199625
dc.keywordsInvestigating the role
dc.keywordsPhenotypic plasticity
dc.keywordsTerminal heat
dc.keywordsStress tolerance
dc.keywordsWheat
dc.keywordsTriticum aestivum L.
dc.language.isoEnglish
dc.pages62+i-vii (Bibliography)
dc.publisherDr.RPCAU, Pusa
dc.subPlant Physiology
dc.themeInvestigating the role of phenotypic plasticity in terminal heat stress tolerance in wheat (Triticum aestivum L.) .
dc.these.typeM.Sc
dc.titleINVESTIGATING THE ROLE OF PHENOTYPIC PLASTICITY IN TERMINAL HEAT STRESS TOLERANCE IN WHEAT (Triticum aestivum L.)
dc.typeThesis
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