不同水盐处理对苜蓿耗水、品质及产量的影响

Effects of Different Water and Salt Conditions on Water Consumption, Quality and Yield of Alfalfa

为探索河套灌区不同盐分土壤苜蓿生长的适宜水分展开盆栽试验,设置3个水分水平、3个盐分水平和1个对照处理CK,监测不同水盐处理苜蓿现蕾期至初花期土壤贮水变化量、品质及产量。结果表明:(1)相同盐分条件下,植株株高、地上生物量、地下生物量、耗水量及干草产量随灌水量的增加而增大,但苜蓿的增产效应明显降低;相同水分条件下,随盐分增加,苜蓿耗水量及地下生物量整体呈现先增大后减小的变化趋势。土壤含盐量超过3 g/kg,土壤中剩余水分显著增加,且随灌水量增加逐渐增加。(2)土壤含盐量1~3 g/kg,水分胁迫有利于提高苜蓿粗蛋白含量;其中低水处理粗蛋白含量均显著高于中水及高水处理(p<0.05);含盐量3~4 g/kg,盐分改变水分胁迫阈值,中水处理粗蛋白含量显著高于低水与高水处理(p<0.05)。盐分与水分胁迫下,植株体内氨基酸含量增加,其中F3W1处理氨基酸含量最大,为20.90%。对各游离氨基酸及粗蛋白含量进行相关性分析,其中甘氨酸、蛋氨酸与粗蛋白相关性不显著;其他氨基酸与粗蛋白均呈显著正相关(p<0.05)。(3)土壤盐分1~2 g/kg,苜蓿的水分利用效率随灌水量增加而降低,土壤盐分超过2 g/kg,苜蓿水分利用效率随灌水量呈现先增大后减小趋势。土壤含盐量1~2 g/kg,水分70%~75%θf,干草产量增加,水分利用效率提高;土壤含盐量2~3 g/kg,水分70%~85% θf,水分利用效率提高干草产量减小,但差异不显著;土壤含盐量3~4 g/kg,水分85%θf以上,苜蓿干草产量增加。该研究结果初步可为盐渍化农田苜蓿种植及合理灌溉提供理论依据。

In order to explore the suitable water content of different salt soils of slfalfa in the Hetao Irrigation District, a pot experiment was carried out. Three water levels, three salt levels and one control (CK) are set up to monitor the changes of soil water storage, quality and yield of alfalfa from the bud stage to the initial flowering stage. The results showed that: (1) Plant height, aboveground biomass, underground biomass, water consumption and hay yield increased with the increase of water under the same salt conditions. But with the increase of irrigation amount, the increasing effect of irrigation on the yield of alfalfa was significantly reduced. Under the same water condition, the water consumption and the underground biomass increased with the increase of salt and then decreased. If the soil salinity was more than 3 g/kg, the water storage in the soil increased significantly, and gradually increased with the increasing irrigation amount. (2) When the soil salt content was 1~3 g/kg, water stress was beneficial to increase the content of crude protein. The content of crude protein in low water treatment was significantly higher than that in middle water and high water treatment (p<0.05). When the salt content was 3~4 g/kg, the soil salt changed the water stress threshold. The crude protein content of the treated water was significantly higher than that of the low water and high water treatment (p<0.05). Under the salt and water stress, the amino acid content of the plant increased, and the F3W1 treated amino acid content was the largest, which was 20.90%. Under the same salt condition, the amino acid content decreased stepwise with the increase of water content. Correlation analysis of each free amino acid and crude protein content showed that the correlation between glycine and methionine was not significant, but the correlation between other amino acids and crude protein was positively correlated (p<0.05). (3) When the soil salinity was in the range of 1~2 g/kg, and the water use efficiency of the water was decreasing. But when the soil salinity exceeded 2 g/kg, and the water use efficiency increased first and then decreased with the inceasing irrigation amount. When the soil salinity was 1~2 g/kg, and the water content was 70%θf^75%θf, both the yield of hay and water use efficiency were increased. When the soil salinity was 2~3 g/kg, the water content was 70%θf ~85%θf, the water use efficiency was improved, the hay yield was decreased, but it is not significant. When the soil salt content was 3~4 g/kg, and the water content was above 85%θf, alfalfa production was increased. The results of this study could provide a theoretical basis for the cultivation and rational irrigation of salinized farmland.