| The surface mulching has many functions, such as storage and preservation of soil moisture, regulation of soil temperature, improving soil water and heat conditions, and so on. Aiming at the present situation that soil management of rain-fed jujube orchards focuses on “clean cultivation”, grass and branches mulching measures were applied in jujube production. Based on the method of artificial simulation experiment, this paper researched the influence of grass and branches mulching measures on soil moisture and temperature, transpiration of rain-fed jujube and water use efficiency. In addition, this paper also analyzed the relationship between jujube transpiration rate and air temperature(Tair), relative air humidity(RH), wind speed(Vwind), photosynthetically active radiation(PAR), 0-25 cm soil temperature(Tsoil). There were four treatments in this study, namely whole jujube branches mulching(WJBM), jujube branches mulching + strip white clover coverage(JBM+SWC), whole white clover coverage(WCC) and clean cultivation(CC). Through two years of simulation study, the main results were obtained as follows:(1) Whole jujube branches mulching had the strongest water retention capacity, whose soil moisture remained at a high level overall, and increased by 2.69%(2013), 2.23%(2014) than CC on average. Significant(P<0.05) and highly significant(P<0.01) differences existed between WJBM and JBM+SWC, WCC, respectively in 2013. Highly significant difference(P<0.01) existed between WJBM and JBM+SWC, WCC in 2014. In the two experimental years, the average soil moisture content in the 0-70 cm layer for the four treatments from April to August generally followed the order: WJBM>JBM+SWC>CC>WCC; while from September to October, the order was WJBM>JBM+SWC>WCC>CC.(2) The amplitude of average soil temperature in 0-25 cm layer in CC was maximum, WJBM showed flat variation trend, and seasonal amplitude was minimum. Significant difference(P<0.05) existed between WJBM and CC in 2013, WJBM showed good effect of regulating soil temperature. Grass and branches mulching measures had the function of heat insulation in low temperature season, and they could effectively control the shallow soil temperature to make soil thermal environment remain relatively stable in high temperature season. Vertical variation of soil temperature in 0-25 cm layer in each treatment on sunny day showed a decreasing trend; the temperature of each soil layer in CC was higher overall, and the amplitude was relatively large; WJBM was significantly lower than other treatments, and the variation trend was smooth. Significant(P<0.05) and highly significant(P<0.01) differences existed between WJBM and CC respectively in 2013 and 2014. Vertical variation of soil temperature in 0-25 cm layer in four treatments on cloudy day in 2013 had no obvious regularity, and the performance was different from each other; while it showed a decreasing trend on cloudy day in 2014, and the amplitude was relatively small, there was no significant difference among the four treatments.(3) The diurnal variation of jujube stem sap flow velocity in each treatment in sunny showed a typical broad curve, while in cloudy, it showed a multi-peak wavy curve, and the trends were basically consistent. The monthly average stem sap flow velocity for the four treatments from April to August followed the order: WJBM>JBM+SWC>CC>WCC; while from September to October, the order was WJBM>JBM+SWC>WCC>CC. In the two experimental years, highly significant difference(P<0.01) existed between WJBM and WCC, and significant difference(P<0.05) existed between WJBM and JBM+SWC in 2014. Jujube stem sap flow velocity in the four treatments were negatively correlated with RH, while positively correlated with Tair, Vwind, PAR and Tsoil overall. PAR was the dominant driving factor affecting jujube transpiration.(4) During the different growth period of jujube, transpiration ratio and water use efficiency in WJBM were significantly higher than other treatments. Significant difference(P<0.05) existed between WJBM and JBM+SWC, WCC in 2013, and the difference was highly significant(P<0.01) in 2014. The average leaf area index of jujube in four treatments in 2014 followed the order: WJBM(1.02)>CC(0.96)>JBM+SWC(0.93) >WCC(0.84). Jujube stem diameter increment in WJBM was maximum in the four treatments, while it was generally low in grass mulching treatment. Highly significant difference(P<0.01) existed between JBM+SWC, WCC and WJBM, CC in 2013, and the difference between WCC and WJBM was significant(P<0.05) in 2014.(5) Branches coming from dwarf trimming of jujube were used for mulching in this study, they not only had the effect of straw mulching, but also saved the material, reduced transportation cost and reduced construction difficulty. Meanwhile, jujube branches achieved multiple goals, such as storage and preservation of soil moisture, regulation of shallow soil temperature, promoting the transpiration of jujube, improving the utilization of soil water and the water use efficiency of jujube and so on. They had a certain reference value for efficient utilization of rainwater resources in rain-fed jujube orchard. |
PDF Full Text Request