Physiological responses of inoculated and uninoculated peanuts under saline stress

Abstract This work evaluated the effects of water salinity on the physiological indices in inoculated and non-inoculated peanut plants. The study was carried out in a protected environment at the seedling production unit (UPMA) at Campus das Auroras, at the University for International Integration of the Afro-Brazilian Lusophony (UNILAB), Redenção, Ceará. The experimental design used was in a completely randomized (CRD), with treatments in a factorial arrangement, 5x2, referring to the five salinity levels of the irrigation water - CEa: 0.5, 1.5, 3, 4.5, and 6.0 dSm-1, and inoculated and non-inoculated plants with a mix of rhizobia SEMIA 630, lot 0810, and SEMIA 6144, lot 0312, from Bradyrhizobium sp., isolated, with four replications. Recommended fertilization was done for phosphorus (62.5 kg ha-1 of P) and potassium (50 kg ha-1 of K) to supply the nutritional needs of the plants. The nutritional effect caused by symbiosis with Bradyrhizobium sp. favored inoculated plants to present greater tolerance to salt stress. The availability of nitrogen collaborated to increase the efficiency of plant physiological mechanisms. Uninoculated plants, even with a higher amount of chlorophyll and CO2, were not efficient in the photosynthetic rate. Saline stress affected photosynthesis, transpiration, stomatal conductance, internal CO2 concentration, water use efficiency, and chlorophyll; however, with less intensity when inoculated with Bradyrhizobium sp. The increase in salinity on irrigation water increased the leaf temperature.

摘要 本研究评估了灌溉水盐度对接种与未接种根瘤菌的花生植株生理指标的影响。本实验在塞阿拉州雷登新市非裔巴西葡语国家国际融合大学（University for International Integration of the Afro-Brazilian Lusophony，UNILAB）奥罗拉校区的幼苗生产单元（UPMA）的受控环境中开展。本研究采用完全随机设计（Completely Randomized Design，CRD），设置5×2因子排列的处理组：分别为5个灌溉水盐度水平（CEa：0.5、1.5、3、4.5、6.0 dSm⁻¹），以及接种与未接种慢生根瘤菌属（Bradyrhizobium sp.）混合菌剂的植株，该混合菌剂由批号为0810的SEMIA 630菌株与批号为0312的SEMIA 6144菌株复配而成，每组设置4次重复。试验按推荐方案施加磷肥（每公顷62.5千克磷素）与钾肥（每公顷50千克钾素），以满足植株的营养需求。与慢生根瘤菌属菌株共生所产生的营养效应，可提升接种植株的盐胁迫耐受性；有效氮素供给可增强植株生理机制的运作效率。未接种植株即便拥有更高的叶绿素含量与胞内二氧化碳浓度，其光合速率仍较低下。盐胁迫会对光合作用、蒸腾作用、气孔导度、胞内二氧化碳浓度、水分利用效率及叶绿素含量产生负面影响，但接种慢生根瘤菌属菌株可显著缓解该胁迫的影响强度。灌溉水盐度升高会导致叶片温度上升。