Mechanism of water potential response to the water-retention agent modified loess and plant roots

The construction of ecological civilization in the arid and semi-arid regions of western China is a key national strategy, in which the efficient utilization of limited water resources is essential for successful ecological restoration. Industrial water retaining agents are widely used to enhance soil water-retention capacity and improve plant growth environments; however, there are differences in the adaptability of different plants to water-retaining agents. To analyze the suitability of adding water-retaining agents to loess for plant growth, the water holding curves of pure water-retaining agents, pure loess, and modified loess with water-retaining agents were measured using the filter method. The water holding curve of the cow tendon root system was tested using a pressure plate apparatus. Comparative analysis of various curves shows that loess improved with water-retaining agents is only suitable for plants with low wilting values and high suction during wilting, such as drought-tolerant plants like sea-buckthorn and caragana microphylla. For plants with high wilting values and low suction during wilting, such as water-loving plants like eleusine indica and bermuda grass, adding water-retaining agents to loess may absorb water from the plant roots, which is not conducive to plant growth. Therefore, adding water-retaining agents to loess can effectively improve the growth environment of drought-tolerant plants; however, it may have adverse effects on the growth of water-loving plants. This study provides scientific basis for ecological restoration in loess areas.