Effects of NaCl and PEG Stresses on Germination and Seedling Growth of Robinia pseudoacacia Seeds with Different Sizes

【Objective】This paper aims to study the germination regularity of R. pseudoacacia seeds with different sizesunder salt and drought stresses, and propose suggestions on the selection of suitable seed sizes and degree of the stress, in order to provide a theoretical basis for the cultivation of excellent seedlings of R. pseudoacacia.【Method】The seeds of R. pseudoacacia were divided into three categories of sizes（large, medium and small） with the soil sieve, and the range of seed size, thousand grain weight and the imbibition rate of each category were determined. NaCl andpolyethylene glycol 6000（PEG6000）（iso-osmotic conditions of 0,-0.05,-0.15,-0.30 and-0.49 MPa）were prepared to simulate salt and drought stress. Seeds of different sizes were placed in the light incubator for germination test. In this way, the germination characteristics, seedling biomass and root growth of seeds of different sizes were analyzed, and the plasticity indexes of those seeds were compared.【Result】1)The imbibition rate of large seeds