The Effects of Mother Tree Size and Flowering Period on Salt Tolerance of <i>Tamarix Austromongolica</i> Seeds in the Yellow River Delta

Abstract

<i>Tamarix austromongolic</i>a is a two-season flowering plant with a spring and summer flowering period and both flowering periods produce viable seeds, with flowering extending from mid-May to October and seed maturation from mid-June to October. In order to reveal the germination pattern of <i>T. austromongolica</i> seeds in the Yellow River Delta region, this study investigated the salt tolerance of seeds of different age mother trees during the spring and summer flowering periods in the region. Spring and summer flowering seeds of different ground diameter mother trees in the <i>T. austromongolica</i> forest in the region were collected and subjected to seed germination experiments under different concentrations of NaCl solution. The results showed that the diameter grade of the mother tree had a significant impact on seed germination, but had no significant effect on early seedling growth (except for the root length of offspring seedlings during the summer flowering period). As the diameter level of the mother tree increases, the germination rate, germination index, and vitality index of seeds during the spring flowering period first increase and then decrease, with the highest values observed at a ground diameter of 10.0-19.9cm. However, the above indicators of summer flowering seeds gradually decreased with the diameter increasing. There were significant differences in salt tolerance of seeds during different flowering periods. The germination rate and germination index of spring flowering seeds significantly decreased between 11‰ and 15‰, but the effect of salt concentration on summer flowering seed germination was not significant. For the early growth of seedlings, as the salt concentration increased, the root length and seedling height of seed offspring seedlings during spring and summer flowering periods decreased after being higher than 5‰. Compared with spring flowering seeds, summer flowering seeds had higher germination ability and seedling weight under salt stress. Therefore, the salt tolerance of the seeds of <i>T. austromongolica</i> was determined by the size of the mother tree and the flowering period, which is an important strategy for its adaptation to the Yellow River Delta region.