施磷深度对低温胁迫苜蓿根颈糖类物质含量及抗寒性的影响

Effects of phosphate fertilizer application depth on carbohydrate content and cold resistance of alfalfa root crown under low temperature stress

【目的】探讨磷肥施用深度对低温胁迫处理苜蓿根颈活力和糖类保护物质的影响,旨在为苜蓿抗寒高产栽培中磷肥的高效管理提供依据。【方法】以‘北极熊’紫花苜蓿作为供试材料,采用大田试验,磷肥(P_(2)O_(5))施用量为225 kg/hm^(2),设置5个磷肥施用深度处理,分别为施于地表和距离地表7.5,15.0,22.5,30.0 cm,分别以S_(0)、S_(1)、S_(2)、S_(3)、S_(4)表示,以不施用磷肥作为对照(CK),于封冻前期对以上5个处理苜蓿根颈进行4,-10,-20和-30℃低温胁迫处理,测定不同处理苜蓿的根颈活力和糖类物质(可溶性糖、果糖、蔗糖、淀粉)含量,分析不同低温胁迫处理下苜蓿根颈活力与糖类物质含量的相关性。【结果】在同一磷肥施用深度处理下,随着胁迫温度的降低,苜蓿根颈活力持续降低,可溶性糖、果糖、蔗糖含量则呈先增加后降低的变化趋势,且均以-20℃下最高,淀粉含量则呈先降低后增加的变化趋势,且在-20℃下最低。在同一胁迫温度下,不同磷肥施用深度处理的苜蓿根颈活力以及可溶性糖、果糖、蔗糖和淀粉含量均明显高于CK,其中以S_(2)处理的上述指标总体高于其他处理。相关性分析表明,在不同低温胁迫处理下,苜蓿根颈活力与可溶性糖、果糖、蔗糖和淀粉含量均呈正相关。【结论】施用磷肥能提高低温胁迫苜蓿的根颈活力,其中磷肥施用深度为距离地表15.0 cm处理最有利于提高苜蓿糖类物质含量,增强苜蓿根颈活力,提高苜蓿抗寒性。

【Objective】This study explored the effects of phosphate fertilizer application depth on root crown vitality and carbohydrate protective substance content of alfalfa under low temperature stress to provide basis for efficient management of phosphate fertilizer in cold-resistant and high-yield cultivation of alfalfa.【Method】With Gibraltar alfalfa as test material,the field experiment was adopted with phosphate fertilizer(P_(2)O_(5))application rate of 225 kg/hm^(2).The 5 depth treatments included ground surface and 7.5,15.0,22.5 and 30.0 cm from the ground surface and they were expressed as S_(0),S_(1),S_(2),S_(3) and S_(4),respectively.No phosphate fertilizer application was used as the control(CK).In the early stage of freezing,the root crown was treated with 4,-10,-20 and-30℃low temperature stress.Then,root crown vigor and sugar contents(soluble sugar,fructose,sucrose and starch)were determined and correlations between them were analyzed.【Result】With same phosphate fertilizer application depth,the root crown vitality of alfalfa decreased continuously with the decrease of temperature.The contents of soluble sugar,fructose and sucrose showed a trend of first increasing and then decreasing with peaks at-20℃,while starch content showed opposite trend with the lowest value at-20℃.With same stress temperature,the root crown vitality and soluble sugar,fructose,sucrose and starch contents of alfalfa in different phosphate fertilizer treatments were significantly higher than those of CK,and treatment S_(2) was the best.Correlation analysis showed alfalfa root crown vigor was positively correlated with soluble sugar,fructose,sucrose and starch contents.【Conclusion】Phosphate fertilizer increased the root crown vitality of alfalfa under low temperature stress and the suggested application depth of phosphate fertilizer was 15.0 cm from ground surface.