ABSTRACT

Moisture stress is one of the most important constraints for crop production in arid regions. Cowpea is a vital food legume that has been cultivated in tropical and sub-tropical regions where water is scarce. Rhizobia inoculation confers resistance to water stress legumes. Two-year field experiments were conducted to assess the carbon assimilation and water use efficiencies of inoculated cowpea varieties at three sites. The treatments consist of four varieties and three levels of Bradyrhizobium inoculation arranged in a factorial randomized complete block design with four replications. The nitrogen (% N) and carbon (% C) concentrations in plant shoots were obtained directly from the mass spectrometric analysis. The results revealed considerable variation for shoot % N and % C, shoot growth, and δ¹³C among the varieties. Similarly, Bradyrhizobium significantly affected plant growth, % C, C and N contents, C/N ratio, and carbon isotope discrimination of the shoot. For instance, C and N contents and the C/N ratio increased by 28, 24, and 31%, respectively, due to Bradyrhizobium inoculation. In general, these results indicated that physiological performances such as carbon assimilation and water use efficiency of the crop could be, significantly improved when effective Bradyrhizobium strains and the best performing varieties are selected.

摘要

水分胁迫是干旱地区作物生产的最重要制约因素之一。豇豆是一种重要的食用豆类，已在缺水的热带和亚热带地区种植。根瘤菌接种赋予了豆科植物对水分胁迫的抵抗力。进行了为期两年的田间试验，以评估三个地点接种的豇豆品种的碳同化和水分利用效率。处理由四个品种和三个水平的慢生根瘤菌接种组成，采用因子随机完全区组设计，四次重复。植物枝条中的氮 (% N) 和碳 (% C) 浓度直接从质谱分析中获得。结果显示，芽 % N 和 % C、芽生长和 δ 存在相当大的变化品种中^{13 ℃。}同样，慢生根瘤菌显着影响植物生长、% C、C 和N 含量、C/N 比以及枝条的碳同位素鉴别。例如，由于接种慢生根瘤菌，C 和 N 含量以及 C/N 比分别增加了 28%、24% 和 31% 。In general, these results indicated that physiological performances such as carbon assimilation and water use efficiency of the crop could be, significantly improved when effective Bradyrhizobium strains and the best performing varieties are selected.