交替灌溉对山黧豆叶片气体交换和土壤水分以及产量指标的影响

改变土壤根系的分布以汲取深层土壤水分的能力是植物避免干旱的主要策略。山黧豆是一种抗逆性强的豆类作物，该研究通过起垄条播控制性沟灌的方式，设置传统灌溉(FI)、交替灌溉(PRD，灌水量减少50%)和不灌溉(NI)3种处理模式，探索不同灌溉模式对播种后不同时期山黧豆土壤水分、根系分布、叶片气体交换、水分利用效率和籽粒产量的影响。结果表明：(1)在FI、PRD和NI处理下，山黧豆的根系分别有89.8%、86.9%和84.9%生长在0~20 cm的表层土壤中；干旱胁迫使PRD和NI处理下深层土壤中根系的比例提高至13.05%和15.07%。(2)在整个生育期内，土壤干旱显著降低了山黧豆叶片的净光合速率、蒸腾速率和气孔导度；在种植后60 d时，PRD和NI处理下叶片的瞬时水分利用效率分别较FI处理显著提高了21.4%和14.9%。(3)干旱胁迫显著降低了山黧豆植株高度、第一豆荚高、平均结荚数和豆粒数以及地上部和根系的干重，但显著增加了根冠比；PRD处理对豆荚长度、豆荚重和每荚豆粒重没有显著影响；PRD和NI处理下山黧豆平均籽粒产量分别比FI处理显著降低了53%和63%。研究发现，在干旱胁迫条件下，山黧豆能够通过提高深层土壤中根系的比例、更多吸收深层土壤水分、显著增加根冠比以及显著提高生殖生长期叶片的瞬时水分利用效率，减轻干旱胁迫对自身生长的影响。该研究结果可为山黧豆在旱区推广种植提供理论依据。

Effect of Alternate Irrigation on Leaf Gas Exchange, Soil Moisture and Yield Indexes of Lathyrus sativus

Changing the distribution of soil roots to absorb deep soil water may be an important strategy for plants to avoid drought. Lathyrus sativus is a kind of legume crop with strong stress resistance. We explored the effects of different irrigation modes (Full irrigation, FI; Partial root drying, PRD; No irrigation, NI) on soil moisture, root distribution, gas exchange, water use efficiency and yield of Lathyrus sativus at different periods after sowing. The results showed that: (1) 89.8%, 86.9% and 84.9% of the roots of L. sativus grew in 0-20 cm topsoil under FI, PRD and NI treatments, respectively. Drought stress increased the proportion of roots in deep soil to 13.05% and 15.07% under PRD and Ni treatments, which provided guarantee for roots to absorb deep soil water and avoid the influence of drought on L. sativus. (2) During the whole growth period, soil drought significantly reduced the net photosynthesis, transpiration and stomatal conductance; At 60 days after planting, PRD and NI treatment significantly improved the instantaneous water use efficiency of leaves, which was 21.4% higher than that of the control (FI treatment) and 14.9% higher than that of NI treatment. (3) The drought reduced plant height, first pod height, average pod number and seed number of L. sativus. Drought also led to a significant decrease in aboveground biomass and root system, but a significant increase in root shoot ratio; PRD treatment had no significant effect on pod length, pod weight and seed weight per pod. Drought reduced the average grain yield loss of PRD and NI reached 53% and 63%. The study found that under drought stress conditions, L. sativus could alleviate drought by increasing the proportion of roots in the deep soil, absorbing more water in the deep soil, significantly increasing the ratio of root to shoot, and significantly improving the instantaneous water use efficiency of leaves in the reproductive growth period. These results provide a reference for the cultivation of L. sativus in arid areas.