Gas exchange and organic solutes in forage sorghum genotypes grown under different salinity levels

ABSTRACT Adaptation of plants to saline environments depends on the activation of mechanisms that minimize the effects of excess ions on vital processes, such as photosynthesis. The objective of this study was to evaluate the leaf gas exchange, chlorophyll, and organic solute in ten genotypes of forage sorghum irrigated with solutions of different salinity levels. The experiment was conducted in a randomized block design, in a 10 x 6 factorial arrangement, with three replications, using ten genotypes - F305, BRS-655, BRS-610, Volumax, 1.015.045, 1.016.005, 1.016.009, 1.016.013, 1.016.015 and 1.016.031 - and six saline solutions, with electrical conductivity (ECw) of 0, 2.5, 5.0, 7.5, 10 and 12.5 dS m-1. The photosynthetic activity in forage sorghum plants reduces with increasing salinity, and this response was found in the ten genotypes evaluated. The chlorophyll and protein contents were not affected by salinity, whereas carbohydrates and amino acid contents increased with increasing ECw. Soluble sugars are essential for osmoregulation of forage sorghum due to its high content in leaves.摘要：植物对盐渍环境的适应性，依赖于激活相关机制以缓解过量离子对光合作用等生命过程的不利影响。本研究旨在评估采用不同盐度溶液灌溉的10个饲用高粱基因型的叶片气体交换、叶绿素及有机溶质含量。本试验采用随机区组设计，设置10×6的析因处理组合，共3次重复；供试材料为10个饲用高粱基因型：F305、BRS-655、BRS-610、Volumax、1.015.045、1.016.005、1.016.009、1.016.013、1.016.015及1.016.031，灌溉溶液为6种不同盐度的水溶液，其初始电导率（electrical conductivity, ECw）分别为0、2.5、5.0、7.5、10及12.5 dS·m⁻¹。随盐度升高，饲用高粱植株的光合活性显著降低，且该响应在所有供试的10个基因型中均存在。叶绿素及蛋白质含量不受盐度胁迫影响，而碳水化合物与氨基酸含量则随ECw升高而显著上升。由于叶片中可溶性糖含量较高，其对饲用高粱的渗透调节具有关键作用。