Experimental study on salt tolerance of seeds of four annual plants during germination

The seeds of four annual herbaceous plants, Bassia dasyphylla, Halogeton arachnoideus, Agriophyllum squarrosum, and Eragrostis pilosa, were selected for treatment in a study of relative germination rate, relative germination potential, germination index, and other indicators to analyze their differing salt tolerance under different concentrations of NaCl solution. The following results were found: 1) the germination rate of seeds gradually decreased with increasing NaCl concentration, and peak germination was achieved within 3 days in distilled water, while the germination was basically absent on day 7 in NaCl solution. 2) When the concentration of NaCl solution increased gradually, the germination rate and germination potential of the four plant species first increased, then decreased. The germination rate and germination potential of the same plant's seeds varied significantly (P < 0.05) in different concentrations of NaCl solution. Salt content had the greatest influence on the germination rate and germination energy of the H. arachnoideus seed, followed by E. pilosa, while the other two species exhibited the smallest change. 3) Under the condition of increasing salt stress, the germination index of the four plant species showed a declining trend, with B. dasyphylla activity index being significantly higher than that of the H. arachnoideus, A. squarrosum, and E. pilosa; the salt stress had the greatest detrimental effect on the germination index and vigor index of E. pilosa. When the NaCl solution concentration reached 2.1%, the seedling vigor index was reduced to a minimum. 4) The length of seedlings of the 4 plant species first increased with the increase of salt concentration and then decreased rapidly, thus a suitable concentration of salt promoted the growth of seedlings. Low concentration NaCl solution had a strong influence on the length of E. pilosa seedlings, while high concentration NaCl had a greater influence on the length of B. dasyphylla, H. arachnoideus, and A. squarrosum seedlings. According to the analysis of various indicators, the combined salt tolerance of the four annual plant seeds in the germination period and be ordered: A. squarrosum > B. dasyphylla > E. pilosa > H. arachnoideus. Accounting for germination rate, germination energy, seedling length, and other indicators, the optimum concentration of salt solution was 0～0.6% for B. dasyphylla, 0～0.6% for H. arachnoideus, 0～0.9% for A. squarrosum, and 0～0.6% for E. pilosa.