不同土壤水分条件下硅对紫花苜蓿水分利用效率及产量构成要素的影响

Effect of addition of silicon on water use efficiency and yield components of alfalfa under the different soil moisture

硅是地壳中含量仅次于氧的元素,植物不可能在无硅的环境中生长。通过盆栽试验研究了不同土壤水分条件下硅对紫花苜蓿(Medicago sativa)水分利用效率及产量构成要素的影响。结果表明,在土壤含水量为田间最大持水量的35%和80%的条件下,硅对紫花苜蓿水分利用效率和生物量没有显著影响,而在土壤含水量为田间最大持水量的50%和65%的条件下,硅显著提高了紫花苜蓿水分利用效率和生物量(p<0.05),紫花苜蓿水分利用效率的增幅分别为35%和20%,主要途径为降低叶片蒸腾速率;紫花苜蓿生物量增幅分别为41%和14%,主要通过促进分枝和株高生长,而不受单枝生物量的影响。因此硅对紫花苜蓿水分利用效率和生物量的有益作用与其生长环境中的土壤水分条件密切相关。

As the second most abundant mineral element in the soil, silicon has been found to alleviate the adverse impact of drought in many plant species and increase the water use efficiency in others. If the water use efficiency of alfalfa could be enhanced by simply adding silicate to the soil, this measure could potentially be applied in pasture management to face rising irrigation costs and water demand from inadequate supplies of surface water, together with declining water tables. Therefore, the effects of addition of silicon on the water use efficiency and forage yield component of alfalfa （Medicago sativa L.） were investigated across four soil moisture environments. This study shows that addition of silicon improved water use efficiency of alfalfa under lightly （65% of field water capacity） and moderately （50% of field water capacity） water-stressed conditions, by decreasing the transpiration rate （p〈0.05） but it had no effect on alfalfa water use efficiency under wet （80% of field water capacity） and seriously（35% of field water capacity） water-stressed conditions. This study also indicated that addition of silicon significantly increased the forage biomass by promoting shoot development （p〈0.05） and enhancing the plant height under the moderately water-stressed condition and only by enhancing the shoot development under the slightly water-stress rather than biomass per branch （p〈0.05）. The results of this study suggest that improvement of water use efficiency of alfalfa by added silicon is regulated by soil moisture.