Sand Burial, Rather than Salinity or Drought, Is the Main Stress That Limits the Germination Ability of Sophora alopecuroides L. Seed in the Desert Steppe of Yanchi, Ningxia, China

Abstract

Global change and environmental pollution have reawakened ecologists to the great threat of multi-stress interactions to different growth stages of plants. Sophora alopecuroides L., a dune plant, has been widely studied for its medicinal components and strong salinity tolerance. S. alopecuroides seeds, obtained from the desert steppe of Yanchi, Ningxia, China, were used to analyze the effects of sand burial, salinity, drought, and their interactions on seed germination (germination percentage, germination energy, and germination index). The results showed that sand burial and salinity stress had significant effects on the seed germination ability of S. alopecuroides, and drought stress had no significant effect, but the interaction of the three stresses had a significant effect. Under different drought-stress treatments, the interaction of no sand burial and a certain degree of salinity stress significantly improved the germination ability of S. alopecuroides, and the overall intensity of the effects of the three stresses showed that sand burial > salinity > drought. Considering the germination percentage, germination energy, and germination index of S. alopecuroides under various stress interactions, the treatment of no sand burial × 1% soil saline-alkali content × 18–20% soil water content was adopted to maximize the germination ability of S. alopecuroides. In the desert steppe area of Yanchi, Ningxia, sand burial stress was still the most limiting factor for seed germination of S. alopecuroides, and soil saline-alkali content should be increased moderately, and soil moisture should be ensured to obtain the best germination ability.

Functional Trait Responses of Sophora alopecuroides L. Seedlings to Diverse Environmental Stresses in the Desert Steppe of Ningxia, China

“…Researchers have noted that the environmental context is a key element in ecological studies, and when environmental stress factors become too extreme, situations may arise where no seedlings can survive, regardless of their ecological traits [ 18 ]. The latest research on the germination characteristics of S. alopecuroides seeds under different stress conditions found that sand burial is the most critical stress limiting seed germination [ 20 ]. A thick layer of sand can induce seed dormancy; however, even if seeds are successfully activated, seedlings might fail to germinate due to an inability to break through the sand layer [ 22 ].…”

“…Dominant among these are S. alopecuroides , Astragalus melilotoides , and Stipa caucasica subsp. glareosa [ 20 , 33 ]. Our experimental setup aimed to closely mimic these natural conditions, providing valuable insights into the adaptive mechanisms of S. alopecuroides in its native habitat.…”

“…The specific methods for the pre-treatment of S. alopecuroides seeds before germination can be found in the paper published by Zhao et al [ 20 ]. In June 2022, we initiated our experiment with the preparation of S. alopecuroides seeds, using plastic flowerpots measuring 16.5 cm in height and 13.5 cm in diameter as planting containers.…”

“…First, similar to the variability in traits during the adult phase of plants [ 19 ], we believed that plant traits also underwent specific changes during the seedling stage under different stress conditions. Second, due to the varying tolerance levels of S. alopecuroides seeds during germination to different stresses [ 20 ], we believed that the intensity of the effect of different stresses on the traits of S. alopecuroides seedlings also varied.…”

Salinity tolerance at the germination stage of Senegalese varieties of peanut, cowpea, millet and sorghum

“…The germination parameters were determined with reference to the work of ( [8]; [12]; [18]; [19]; [20])…”