ABSTRACT

Salinity and low nitrogen availability are two major abiotic stresses that often coexist and disturb plant productivity. This study aimed at investigating the combined effects of salinity (0 and 100 mM NaCl) and nitrogen (0.5 and 5.0 mM NH₄NO₃) levels on the morphological parameters, the mineral status, nitrogen use efficiency, photosynthesis, and nitrate reductase (NR, E.C. 1.6.6.1) and glutamine synthetase (GS, EC 6.3.1.2) activities at Sulla carnosa.‎ Salinity enhanced growth rate (66%), the relative growth rate (RGR), root volume (RV), Na⁺ and Cl⁻ accumulations and nitrogen use efficiency (NUE). It had no detrimental effect on photosynthetic assimilation rate (A) and leaf NR and GS activities under high nitrogen level condition. High nitrogen availability under saline condition enhanced growth rate, RGR, shoot/root ratio, photosynthesis activity, NR activity in roots, and the accumulation of NO₃⁻ in different plant organs and all cations and anions in roots. In brief, salinity and high nitrogen availability represented an adequate condition for optimal growth and high Na⁺ and NO₃⁻ accumulations at S. carnosa. This study suggested that S. carnosa could be a suitable forage legume that can be widely cultivated in the discarded, salinized and nitrogen-contaminated agricultural soils.

摘要

盐度和低氮可用性是两种主要的非生物胁迫，它们经常共存并扰乱植物的生产力。本研究旨在研究盐度（0 和 100 mM NaCl）和氮（0.5 和 5.0 mM NH ₄ NO ₃）水平对形态参数、矿物质状态、氮利用效率、光合作用和硝酸盐还原酶（NR）的综合影响, EC 1.6.6.1) 和谷氨酰胺合成酶 (GS, EC 6.3.1.2) 在Sulla carnosa的活动。盐度提高了生长率 (66%)、相对生长率 (RGR)、根体积 (RV)、Na ⁺和 Cl ⁻积累和氮利用效率 (NUE)。它对光合同化率没有不利影响（A) 和高氮水平条件下叶片 NR 和 GS 活性。盐碱条件下的高氮有效性提高了生长速率、RGR、茎/根比、光合作用活性、根中的 NR 活性以及不同植物器官和根中所有阳离子和阴离子中NO ₃ ^{-的积累。}简而言之，盐度和高氮可用性代表了S. carnosa最佳生长和高 Na ⁺和 NO ₃ ^-积累的充分条件。该研究表明，S. carnosa可能是一种适宜的豆科牧草，可在废弃、盐碱化和氮污染的农业土壤中广泛种植。