Effect Of Simulated Precipitation Patterns Change On Seedlings Growth And Root Morphological Characteristics Of Nitraria Tangutorum

In order to reveal the characteristics of soil moisture change under different precipitation patterns, and then to explore the reaction and adaptation mechanism of seedlings growth and root morphological characteristics to various precipitation patterns. a simulated experiment was conducted to examine the effect of precipitation(increased by 30%, reduce 30%, unchanged) and precipitation interval(increase, unchanged) on the soil moisture, seedlings growth and root morphological characteristics of N. tangutorum seedlings, which can not only provided a basis theoretical to N. tangutorum scrub vegetation degradation, and accelerate the desert region recovery, but also added a new theoretical basis for the change of precipitation patterns of desert plants. The results were as followings:(1) The soil moisture content increased with the increase of precipitation, especially in the prolonged precipitation interval of large rainfall events, the increase of soil moisture is more obvious. Compared with the high frequency of small precipitation events, the less frequency of large precipitation events had a greater contribution to soil moisture. Changes in soil and average monthly precipitation water content were consistent, with the increase of average precipitation, the soil water content increased. When the average precipitation reached the maximum in the month of September, the average soil water content of the 6 different treatments was also the largest, reaching 7.2%, compared to 5.6% in July and 5% in August were higher than 28.5%, 44%; In October, when the average precipitation was the least, the soil water content did not sharply decreased, the soil moisture was higher than July and August, reaching 6.0%.(2) The N.tangutorum seedling growth was effected by precipitation and precipitation interval, all biomass is caused by precipitation, in spite of total precipitation and precipitation interval are closely related, but there was no significant interaction between organs. The same precipitation condition, the soil moisture content was significantly increased, then the height, crown, basal diameter and biomass were accumulated by extend precipitation interval, especially the leaf biomass increased by 81%, so that the above biomass growth is far greater than below biomass, root-shoot ratio decreased. The same precipitation interval, precipitation decreased 30% had no significant effect on stem and below biomass, but the leaf, above biomass and total biomass were significantly 67%, 48%, 27%, the root-shoot ratio significantly increased by 74%; precipitation increase 30% had no significant effect on all biomass. Therefore, appropriate increase the precipitation and precipitation interval is helpful to N. tangutorum seedlings growth and promote the restoration of vegetation.(3) The root morphological characteristics were influenced by total precipitation and precipitation interval, and the total precipitation plays a more significant role than the precipitation interval. The same precipitation condition, the main root length, root diameter, root volume and root surface area were decreased, total root length and root biomass were increased by extend precipitation interval, and the root length and surface area will be greatly increased to the original 1.61 times and 2.03 times in high precipitation, but the difference was not significant. The same precipitation interval conditions, the others root morphological indexes of N. tangutorum were all increased with soil content increased, expected the main root length. The main root length was significantly increased by 86%, the total length, diameter, volume and surface area were significantly decreased, SRL and SRA basically unchanged in reduced by 30% precipitation conditions. The SRA were significantly decreased by 29.38%, the other index differences were not significant. The main root length was largest in the case of low precipitation, others in high precipitation conditions, which indicated extreme heavy precipitation events could promote the root growth of N. tangutorum seedlings.(4) The total length, diameter, volume and surface area were significantly positive correlation, and the correlation coefficient was greater than 0.8, which indicated they have a greater impact on the root morphological. There is positive correlation between root surface area and total root length, and the correlation coefficient was 0.9, which indicated increasing the total root length will significantly increase the absorption area of the root, promoting root growth. So the N. tangutorum seedlings can adjust the morphological plasticity to improve the competitiveness to adapt to environmental changes.