Maize is a low-temperature (LT)-sensitive plant and its physiological responses towards LT of temperate regions developed is an adaptive trait. To further our understanding about the response of maize to LT at the physiological and photosynthesis level, we conducted Infrared Gas Analysis (IRGA using LICOR6400-XT in 45-day-old grown two maize genotypes, one from temperate region (Gurez-Kashmir Himalayas), viz., Gurez local (Gz local), and another from tropics (Gujarat), viz., GM6. This study was carried out to evaluate the underlying physiological mechanisms in the two differentially temperature-tolerant maize genotypes. Net photosynthetic rate (A/P_N), 18.253 in Gz local and 25.587 (µmol CO₂ m⁻² s⁻¹) in GM6; leaf conductance (gs), 0.0102 in Gz local and 0.0566 (mmol H₂O m⁻² s⁻¹) in GM6; transpiration rate (E), 0.5371 in Gz local and 2.9409 (mmol H₂O m⁻² s⁻¹) in GM6; and water use efficiency (WUE), 33.9852 in Gz local and 8.7224 (µmol CO₂ mmol H₂O⁻¹) in GM6, were recorded under ambient conditions. Also, photochemical efficiency of photosystem II (PSII) (F_v/F_m), 0.675 in Gz local and 0.705 in GM6; maximum photochemical efficiency (F_v′/F_m′), 0.310234 in Gz local and 0.401391 in GM6; photochemical quenching (qP), 0.2375 in Gz local and 0.2609 in GM6; non-photochemical quenching (NPQ), 2.0036 in Gz local and 1.1686 in GM6; effective yield of PSII (ФPSII), 0.0789 in Gz local and 0.099 in GM6; and electron transport rate (ETR), 55.3152 in Gz local and 68.112 in GM6, were also evaluated in addition to various response curves, like light intensities and temperature. We observed that light response curves show the saturation light intensity requirement of 1600 µmol for both the genotypes, whereas temperature response curves showed the optimum temperature requirement for Gz local as 20 °C and for GM6 it was found to be 35 °C. The results obtained for each individual parameter and other correlational studies indicate that IRGA forms a promising route for quick and reliable screening of various stress-tolerant valuable genotypes, forming the first study of its kind.

玉米是一种低温（LT）敏感植物，其对温带地区LT的生理反应是一种适应性性状。为了进一步了解玉米在生理和光合作用水平上对 LT 的反应，我们使用 LICOR6400-XT 对生长 45 天的两种玉米基因型进行了红外气体分析（IRGA，一种来自温带地区（古雷斯-克什米尔喜马拉雅山脉） , 即 Gurez local (Gz local), 另一个来自热带 (Gujarat), 即 GM6。本研究旨在评估两种不同耐温玉米基因型的潜在生理机制。净光合速率 ( A / P _N ), 18.253 in Gz local and 25.587 (µmol CO ₂ m ^-2  s ^-1) 在 GM6 中；叶电导 (gs)，在 Gz 局部为 0.0102，在 GM6 中为0.0566 (mmol H ₂ O m ^-2  s ^{-1 )；}蒸腾速率 (E)，在 Gz local 中为 0.5371，在 GM6 中为 2.9409 (mmol H ₂ O m ^-2  s ^-1 )；在环境条件下记录了 Gz local 中的 33.9852 和 GM6 中的 8.7224 (µmol CO ₂ mmol H ₂ O ^{-1 ) 和水利用效率 (WUE)。}此外，光系统 II (PSII) ( F _v / F _m )的光化学效率，Gz local 为 0.675，GM6 为 0.705；最大光化学效率 ( F _v ′/ F _m')，在 Gz 本地为 0.310234，在 GM6 为 0.401391；光化学猝灭 (qP)，Gz 局部为 0.2375，GM6 为 0.2609；非光化学猝灭 (NPQ)，Gz local 为 2.0036，GM6 为 1.1686；PSII（ФPSII）的有效产量，在 Gz local 为 0.0789，在 GM6 为 0.099；除了各种响应曲线（如光强度和温度）外，还评估了 Gz 局部的 55.3152 和 GM6 的 68.112 和电子传输速率 (ETR)。我们观察到光响应曲线显示两种基因型的饱和光强度要求为 1600 µmol，而温度响应曲线显示 Gz local 的最佳温度要求为 20 °C，而 GM6 的最佳温度要求为 35 °C。