灌溉、施磷量及AM真菌对紫花苜蓿产量和水磷利用效率的影响

为探究灌溉、施磷量和丛枝菌根（Arbuscular mycorrhizal，AM）真菌对紫花苜蓿（Medicago sativa.L）产量和水分及磷素利用效率的影响，本研究设置调亏灌溉（RDI）和定额灌溉（QI）2个灌溉处理，施磷肥0（P₀），60（P₁），120（P₂）和180 kg·hm^-2（P₃）4个肥力梯度，以及AM （土壤不灭AM真菌）和-AM （土壤灭AM真菌）2种处理。对紫花苜蓿产量、磷含量、磷吸收量和水分利用效率指标测定，并进行相关性分析和差异比较。结果表明：紫花苜蓿平均总产量在QI和RDI下分别为14 487.08 kg·hm^-2，13 395.23 kg·hm^-2，QI与RDI相比产量高出8.1%，但其水分利用效率降低了24.3%。与不施磷处理相比，施磷处理下紫花苜蓿总产量提高15.40%～39.96%。平均总产量在AM处理和-AM处理下分别为14 938.47 kg·hm^-2，13 450.22 kg·hm^-2，AM处理与-AM处理相比产量高出11.1%。综合来讲，QI+P₂+AM处理下（即灌溉量14 000 m³·hm^-2、施磷量120 kg·hm^-2和土壤不灭AM真菌），紫花苜蓿总干草产量最高17 343.69 kg·hm^-2，总吸磷量最高为51.46 kg·hm^-2，RDI+P₂+AM处理组的水分利用效率最高为1.64 kg·m^-3。

Effects of Irrigation,Phosphorus Application and AM Fungi on Yield and Water and Phosphorus Use Efficiency of Alfalfa

In order to explore the effects of irrigation, phosphorus application and arbuscular mycorrhizal (AM) fungi on the yield, water and phosphorus use efficiency of Alfalfa (Medicago sativa. L), experiment was designed including two irrigation treatments of regulated deficit irrigation (RDI) and quota irrigation (QI), four fertility gradients of phosphorus fertilizer (0 (P₀), 60 (P₁), 120 (P₂) and 180 kg·hm^-2 (P₃)), and two treatments of AM (soil inactivation of AM fungi) and -AM (soil inactivation of AM fungi). The yield, phosphorus content, phosphorus absorption and water use efficiency of alfalfa were measured, and the correlation analysis and difference comparison were carried out. The results showed that the average total yield of Alfalfa under QI and RDI were 14 487.08 kg·hm^-2 and 13 395.23 kg·hm^-2, respectively. Compared with RDI, the yield of QI was 8.1% higher, but its water use efficiency decreased by 24.3%. Compared with no phosphorus treatment, the total yield of Alfalfa under phosphorus treatment increased by 15.40%~39.96%. The average total yield of AM treatment and -AM treatment were 14 938.47 kg·hm^-2 and 13450.22 kg·hm^-2, respectively. The yield of AM treatment was 11.1% higher than that of -AM treatment. Generally speaking, under QI+P₂+AM treatment (i.e. irrigation amount of 14 000 m³·hm^-2, phosphorus application amount of 120 kg·hm^-2 and soil not killing AM fungi), the total hay yield of alfalfa was the highest, 17 343.69 kg·hm^-2, the total phosphorus uptake was the highest, 51.46 kg·hm^-2, and the water use efficiency of RDI+P₂+AM treatment group was the highest, 1.64 kg·m^-3.