Extreme temperatures affect seedling growth and photosynthetic performance of advanced cotton genotypes

Growth temperature and genotype can influence seedling vigor in cotton (Gossypium hirsutum L.), identifying genotypes that perform well under different extremes may broaden the range of temperatures over which optimum growth could be obtained. To this end, a controlled environment study was conducted to evaluate response advanced breeding lines utility rapid, fluorescence-based measurements (the OJIP test) as indicators plant day/night regimes (20/15, 30/20, 35/25, 40/30 °C). At two weeks after planting, analysis, chlorophyll fluorescence measurements, pigment concentrations were Significant genotype, temperature, interaction effects observed for parameters, some key components thylakoid reactions. Specifically, 35/25 °C treatment had highest values all with genotypic differences primarily being at regime. Energy trapping by photosystem II (PSII) (φPO), intersystem electron transport (φEO), I end acceptor reduction (φRO) significantly affected but each component differed heat sensitivity. All parameters correlated number including quantum efficiencies performance indices. However, strongest positive associations between metrics, φEO exhibiting correlations growth. Our observations indicate rapid assessments potentially used early season responses temperature.