WATER AND SALT STRESSES ON GERMINATION OF COWPEA ( Vigna unguiculata cv. BRS Tumucumaque) SEEDS

ABSTRACT The objective of this work was to evaluate seeds of cowpea, cultivar BRS Tumucumaque, subjected to different water stresses induced by polyethylene glycol (PEG-6000) and mannitol and different salt stresses induced by NaCl and CaCl2 solutions. The water and salt stresses was evaluated in laboratory using completely randomized experimental designs in 2x6 factorial arrangements, with six osmotic potentials (0.0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa) and two stress inducers for each experiment, with four replications of 50 seeds. The percentage of germination, germination speed index, root and shoot lengths and seedling fresh weight were evaluated at the tenth day (end of the evaluation period). The simulated water stress showed effects on the cowpea seed germination and seedling initial growth by decreasing the rates of the variables evaluated, which had greater effect in treatments with PEG-6000. The salt stress induced by NaCl showed greater effect on the variables evaluated than that induced by CaCl2, due to the sodium toxicity in the salt chemical composition.

摘要 本研究旨在评估经聚乙二醇（polyethylene glycol，PEG-6000）与甘露醇（mannitol）诱导的不同水分胁迫，以及经氯化钠（sodium chloride，NaCl）、氯化钙（calcium chloride，CaCl₂）溶液诱导的不同盐胁迫下，豇豆品种BRS Tumucumaque的种子生长表现。本试验在实验室采用完全随机试验设计，以2×6析因安排开展：设置6个渗透势梯度（0.0、-0.2、-0.4、-0.6、-0.8、-1.0 MPa），两类胁迫试验各设置2种胁迫诱导剂，每组处理设置4次重复，每次重复使用50粒种子。于评估周期结束的第10天，测定种子发芽率、发芽速度指数、根长、芽长及幼苗鲜重。模拟水分胁迫可降低各测定指标的数值，进而抑制豇豆种子萌发及幼苗初期生长，其中PEG-6000处理的抑制效果更为显著。氯化钠（NaCl）诱导的盐胁迫对各测定指标的影响显著强于氯化钙（CaCl₂）诱导的盐胁迫，这源于该盐化学成分中钠离子的毒性效应。