Response Of Sweet Potato Growth To Soil Permeability In Different Soil Texture And Water Conditions

Soil permeability as one of important physical characters of soil had great effect on the plant growth and water use, especially for plants’ root expanding. Soil texture and soil water were important factors for soil permeability. In this study, responses of photosynthetic characteristics 、leaf nutrition content、daily transpiration and yield of sweet potato to soil permeability in different soil textures and soil water conditions were observed through a pot experiment, and the main conclusions were given as follows:1. Soil permeability had great effect on the transpiration rate and water use efficiency of sweet potato, but no effect on photosynthetic rate. The transpiration rate decreased as the soil permeability increased, but the water use efficiency increased. There was significant difference in photosynthetic rate and transpiration rate between two soil water conditions, and it’s higher in high water condition than that of low water condition. However, there was no significant difference of photosynthetic rate 、transpiration rate and water use efficiency in loam soil and sandy soil. In addition, it was found that the effects of soil permeability on the transpiration rate and water use efficiency were related to soil compositions. Permeability in sandy soil showed no effect on photosynthetic rate, transpiration rate and water use efficiency. However, the transpiration rate and water use efficiency in high water condition and low condition in loam soil decreased 42.6% and 43.6%, 33.4% and12.9%, respectively. The effects of soil permeability on the photosynthetic characteristics were also related to the growth period of sweet potato, resulting in various response patterns.2. Soil permeability only had significant effect on the content of nitrogen of sweet potato leaf, but no effect on phosphor and potassium content, and the nitrogen content increased as the soil permeability increased. Soil water had no effect on these three elements in sweet potato leaves, soil texture only had effect on the content of phosphor. Also, the effect of soil permeability related to soil texture not to soil water condition. For example, soil permeability had great on the content of nitrogen and potassium in lower water condition for loam soil, and affected the content of phosphor and potassium significantly in higher water condition. But permeability of sandy soil showed no effect on the content of nitrogen、phosphor and potassium content. In addition, the content of nitrogen, phosphor and potassium varied significantly in different growth period and decreased for time. Soil permeability had no effect on the content of nitrogen, phosphor and potassium in different growth period.3. All of soil permeability, soil texture, soil water treatments and the coefficient effects had significant effect on the daily transpiration of sweet potato. The daily transpiration was higher in high water condition than that of low water condition, and higher in loam soil than that of sandy soil. The daily transpiration in 2 permeability holes was significantly higher than that of other permeability holes. In addition, daily transpiration showed significant difference in growth period and higher in rooting period and root expanding period.4. The yield of sweet potato had significant difference in different soil permeability and water condition but not in soil texture. It was found that the effect of permeability on yield related to soil texture not for soil water. For example, the yield was more in higher water condition than that of lower water, and the highest yield reached at the 2 holes of permeability. Daily transpiration and yield had significant positive relations, and the yield increased as daily transpiration increased.