Effects of warming and precipitation reduction on physiological characters of dominant psammophytes’ seeds in Horqin sandy land, northeast China

Abstract

Seeds are generally sensitive to environmental change and the reactive oxygen species (ROS) generated during their development cause oxidative stress leading to oxidative damage in seeds. Therefore, it is essential to understand the physiological and biochemical changes associated with seed development. The seeds physiological responses of Artemisia scoparia, Lespedeza davurica, and Cleistogenes squarrosa to simulated warming and rainfall reduction in sandy grassland were studied. The seed malondialdehyde (MDA) and proline content of C. squarrosa was significantly affected by warming. The rainfall reduction obviously impacted the proline level of three plants. However, the combined stress of warming and drought had no significant effect on the seed MDA and proline contents of three psammophytes. With decreasing rainfall gradient in natural temperature, seed MDA and proline content were increased by 50.0 and 49.8% in A. scoparia and 30.8% and 41.3% in C. squarrosa, respectively. When precipitation was reduced by 60%, the increasing values were A. scoparia > L. davurica > C. squarrosa. The separate effects of warming and drought had an obvious influence on the seed enzyme activity of A. scoparia, but only significantly affected the seed peroxidase (POD) activity of L. davurica, while the combined effect of two factors had no significant effect on many seed enzyme activities of three psammophytes. Whether it’s warming or not, more than 40% precipitation deficit had a great influence on seed cellular superoxide dismutase (SOD) activity of L. davurica and C. squarrosa, and the increase of seed SOD activity in C. squarrosa is greater than that of L. davurica. At natural temperature, higher than 40% rainfall reduction had a significant influence on seed POD activity of three psammophytes, and compared with the natural precipitation, with descending order was A. scoparia > L. davurica > C. squarrosa. The variation trend of seed catalase (CAT) of C. squarrosa under severe water deficit stress was decreased by 94.4%, and opposite to that of A. scoparia under combined effect of warming and precipitation reduction, increased by 73.0%. Correlation result indicated that temperature (T) was significant in A. scoparia and C. squarrosa, precipitation (W) was significant in L. davurica based on the Monte Carlo test (p = 0.034, 0.028, 0.016).