DISCONTINUOUS HYDRATION ON THE GERMINATION OF Mimosa caesalpiniifolia AND Pityrocarpa moniliformis SEEDS UNDER WATER STRESS

ABSTRACT The use of discontinuous hydration cycles can act in improving seed germination and seedling initial growth under water stress. In this context, the objective of this study was to evaluate the effect of discontinuous hydration on the germination of Mimosa caesalpiniifolia and Pityrocarpa moniliformis seeds under water stress. For this, seeds of these species were subjected to 0 (without hydration), 2 and 4 hydration cycles (18 h) and dehydration (12 and 18 h, respectively), with subsequent germination under water stress simulated for osmotic potentials of 0.0 (distilled water), -0.2, -0.4, -0.6 and -0.8 MPa. Seedlings were evaluated using tests of germination, germination speed index, mean germination time and seedling length. Discontinuous hydration in M. caesalpiniifolia and P. moniliformis seeds hampers germination and vigor of seedlings under water stress up to -0.6 MPa. However, the use of two cycles in P. moniliformis favors germination under more severe water stress (-0.8 MPa).

摘要
在水分胁迫条件下，采用间断补水循环可改善种子萌发与幼苗初始生长表现。在此研究背景下，本研究旨在评估间断补水对水分胁迫下Mimosa caesalpiniifolia与Pityrocarpa moniliformis种子萌发的影响。为此，供试物种的种子分别接受0次（无补水）、2次及4次补水循环（单次时长18小时）与对应脱水处理（脱水时长分别为12小时与18小时），随后在渗透势分别为0.0 MPa（蒸馏水）、-0.2、-0.4、-0.6及-0.8 MPa的模拟水分胁迫条件下开展萌发实验。本研究通过萌发率、萌发速度指数、平均萌发时间及幼苗长度等指标对幼苗进行评价。在渗透势最高达-0.6 MPa的水分胁迫环境中，对M. caesalpiniifolia与P. moniliformis种子实施间断补水处理，会抑制其种子萌发与幼苗活力；然而，针对P. moniliformis采用2次补水循环处理，可在更严苛的-0.8 MPa水分胁迫下促进其种子萌发。