Abstract
Impact of elevated temperature on physiological and biochemical changes were evaluated in 5 commercial sugarcane genotypes and 2 wild species clones at two different growth phases. The study revealed that heat stress decreased chlorophyll content, chlorophyll stability index (CSI), SPAD value, maximum quantum efficiency of PSII photochemistry (Fv/Fm ratio), leaf gas exchange parameters, relative water content (RWC), and activities of nitrate reductase (NR), sucrose-metabolizing enzymes (SPS, SS, AI, NI) in all the genotypes and species clones. In contrast, elevated temperature induced an increase in proline, total phenolics content (TP), antioxidant enzyme activities (SOD and POX), lipid peroxidation (LP), membrane injury index (MII) and soluble sugar content in all clones. Principal component analysis based on physiological heat tolerance indexes could clearly distinguish sugarcane genotypes into three heat tolerance clusters. Noteworthy in comparison to the heat-sensitive varieties, sugarcane genotype that possessed higher degrees of heat tolerance Co 99004 displayed higher chlorophyll content, CSI, antioxidant enzyme activities, NR activity, RWC, total phenols, sucrose-metabolizing enzymes, soluble sugar content and leaf gas exchange and lower level of lipid peroxidation and membrane injury index.
Highlights
Sugarcane is an important industrial crop used for sugar and bio-energy
Heat stress had shown the adverse effect on chlorophyll content, chlorophyll stability index (CSI) and SPAD value of sugarcane genotypes at formative phase (FP) and grand growth phase (GGP) are presented in Tables 1 and 2
In the present study, when the crop was exposed to heat stress at 45 ± 2 °C, a significant decrease in chlorophyll content, CSI and SPAD value were observed in all the genotypes, suggesting structural damage to the chloroplast in sugarcane genotype due to the high-temperature
Summary
Sugarcane is an important industrial crop used for sugar and bio-energy. It is one of the world’s major C4 crops that mainly grow in the tropic and sub-tropic regions. The rise in temperature even by a single degree beyond the threshold level is considered as heat stress in plants (Hasanuzzaman et al 2013). Increases in temperature may cause yield declines between 2.5% and 10% across a number of agronomic species throughout the twenty-first century (Hatfield et al 2011). The unfavorable temperature may significantly affect photosynthesis, respiration, water balance, and membrane stability of leaves reported by Kaushal et al (2016)
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