Water stress and temperature on germination and vigor of Handroanthus impetiginosus (Mart. ex DC)

ABSTRACT Water availability and temperature are among the main abiotic factors that influence seed germination and vigor, since they act directly on biochemical and physiological processes, which result in the production of the primary root. The objective of this study was to verify the effects of stress on germination and vigor of H. impetiginosus (‘ipê-roxo’) seeds under different temperatures and osmotic agents. The experimental design was completely randomized, in a 6 x 2 factorial scheme (osmotic potentials x temperatures) with four replicates of 25 seeds for each osmotic agent. In order to simulate water stress, polyethylene glycol (PEG 6000) and mannitol solutions were used and distilled water was used as control. Osmotic potentials of 0, -0.2, -0.4, -0.6, -0.8 and -1.0 MPa were evaluated at temperatures of 25 and 30 °C, under 8 h photoperiod. The variables analyzed were: germination, germination speed index, shoot length, root length, and total dry matter of seedlings. Simulated water stress affected seed germination and seed vigor of H. impetiginosus at both temperatures and osmotic agents from -0.6 MPa.

摘要：水分可利用性与温度是影响种子萌发与种子活力的主要非生物因子之一，二者可直接作用于生化与生理过程，进而影响初生根的形成。本研究旨在验证不同温度与渗透介质条件下，胁迫对H. impetiginosus（俗称‘ipê-roxo’）种子萌发与种子活力的影响。实验采用完全随机设计，设置6×2因子组合（渗透势×温度），每个渗透介质设置4次重复，每次重复包含25粒种子。为模拟水分胁迫，本实验采用聚乙二醇（PEG 6000）与甘露醇溶液作为渗透介质，以蒸馏水作为空白对照。实验设置的渗透势梯度为0、-0.2、-0.4、-0.6、-0.8与-1.0 MPa，温度设置为25与30℃，光照周期为8小时。本实验测定的指标包括：种子萌发率、萌发速度指数、幼苗芽长、幼苗根长以及幼苗总干物质量。结果表明，当渗透势达到-0.6 MPa及以下时，模拟水分胁迫会在两种温度条件下均对H. impetiginosus的种子萌发与种子活力产生显著影响。