Abstract:

Regulated deficit drip irrigation (RDDI) can not only save water during vegetative growth stage, but also increase the yield of alfalfa (Medicago sativa L.). In order to learn about effects of regulated deficit drip irrigation (RDDI) on biomass allocation of alfalfa, a field experiment was carried out. The results showed that the branching stage of regulated deficit drip irrigation (RDDI) alfalfa should grasp the appropriate degree of water deficit:In degree of 60% FC and 14 d deficit duration, drought stress was formed at the branching stage of alfalfa; when the water deficit was 80% FC, more photosynthate was distributed to the alfalfa biomass of the ground, meanwhile, the appropriate increase of the deficit duration was more conducive to the elongation growth of alfalfa root and improved the utilization of water. During the period of branching, the regulated deficit drip irrigation (RDDI) was adjusted, and the deficit degree and duration were maintained at about 80% FC and 14~21 d, respectively, which could achieve the purpose of saving water and promoting the growth of alfalfa in Beijing area.

Key words: Alfalfa, Regulated deficit drip irrigation, Deficit degree, Deficit duration, Water use efficiency

摘要：

本研究的目的在于探讨紫花苜蓿营养生长期调亏滴灌对其节水效果的影响，增加其产量的作用。在北京对分枝期苜蓿品种“皇冠”进行调亏程度和调亏历时对其生长的研究。结果发现，秋播苜蓿进行调亏灌溉应把握适当的调亏度，在调亏度达60% FC、调亏历时为14 d时，土壤水分对苜蓿形成干旱胁迫；在调亏度达80% FC时，光合同化物更多向苜蓿地上部分配，同时适当增加调亏历时改变苜蓿根系形态可塑性，有利于其根系伸长生长，提高其水分利用效率。适当的将调亏度与调亏持续时间分别维持在80% FC左右和14~21 d，更能实现北京地区苜蓿节水促生长的目的。

关键词: 紫花苜蓿, 调亏灌溉, 调亏度, 调亏历时, 水分利用效率