硅对向日葵水分利用效率的影响

Effects of Silicon on water use efficiency in sunflower with solution culture

以向日葵(HelianthusannuusL.cv.G101)为试验材料,研究了硅对营养液培养的向日葵生长和水分利用效率的影响。结果表明,施硅显著增加向日葵的水分利用效率,对向日葵生物量、叶面积的影响不大,却使最大展开叶的SPAD值显著增加;施硅显著降低了向日葵叶片背面的蒸腾速率以及叶片导度,而对叶片正面的蒸腾速率和叶片导度影响不大。同时,施硅向日葵木质部汁液的流速显著降低,体内硅含量增加。表明叶片蒸腾速率、叶片导度、木质部汁液流速的降低是硅提高向日葵水分利用效率的主要原因。

Effects of silicon on growth and water use efficiency （WUE） in sunflower（ Helianthus annuus L. cv. G101 ） plants were studied with hydroponic experiment. The objectives of this study were to find the effect of silicon on water use efficiency of sunflower plants, which is mainly through water loss from leaves and water transport in xylem. Under hydroponic experimental condition, water use efficiency was calculated in terms of dry matter produced per unit of water consumption. The transpiration rate and leaf conductance of plants with （1.5 mmol/L silicic acid） or without Si application were measured using LI-1600 steady state prometer. Flow rate of xylem sap was evaluated by calculating the volume of xylem sap per hour. The results showed that WUE of plants treated with 1.5 mmol/L silicic acid was 34% higher than that of plants without Si application. Silicon application did not significantly improve plant growth and leaf area, but significantly increase the SPAD value of the largest leaf. Silicon application significantly decreased the transpiration and leaf conductance of abaxial leaf epidermis, but had no effect on that of adaxial leaf epidermis. Comparing the flow rate of solutes in xylem vessels in plants treated with and without Si found that the flow rates in Si-treated plants was much lower than that in plants without treated with Si, which was due to the increase of affinity for water in xylem vessels induced by silica deposits in vessels. These results indicated that the increase of WUE was mainly resulted from the reduction of leaf transpiration and flow rate of xylem sap in xylem vessels induced by Si application.