冷冻胁迫下磷肥对紫花苜蓿根颈含水量及氨基酸代谢的影响

Effects of Phosphate Fertilizer on Root Crown Water Content and Amino Acid Metabolism of Alfalfa under Freezing Stress

在科尔沁沙地,以公农1号紫花苜蓿为供试品种,采用大田试验,对紫花苜蓿施用重过磷酸钙和磷酸二铵,磷肥(P_(2)O_(5))施用量分别为0、100、200、300和400kg/hm^(2),越冬前期挖取紫花苜蓿根颈,人工模拟冷冻(-20℃)和冷藏(4℃)处理,分析紫花苜蓿根颈的相对电导率、含水量(自由水和束缚水)和氨基酸(游离氨基酸和脯氨酸)含量的变化。结果表明,低温冷冻较低温冷藏处理自由水含量降低,相对电导率、脯氨酸和束缚水含量升高。低温冷冻处理下施用300kg/hm^(2)磷肥的紫花苜蓿根颈相对电导率较低,且施用重过磷酸钙显著低于磷酸二铵;而脯氨酸和束缚水含量较高,且施用重过磷酸钙显著高于磷酸二铵。相关性分析表明,在低温冷冻处理下,施用重过磷酸钙紫花苜蓿根颈的相对电导率与自由水含量呈显著正相关(P<0.05),与束缚水含量呈极显著负相关(P<0.01)。在科尔沁沙地秋季施用300kg/hm^(2)(P_(2)O_(5))有利于紫花苜蓿安全越冬,重过磷酸钙优于磷酸二铵。

In Horqin Sandy Land,taking Gongnong No.1 as the test alfalfa variety,a field experiment was conducted to explore the effects of calcium triple superphosphate(TSP)and diammonium phosphate(DAP)on alfalfa.The application rates of P_(2)O_(5) were 0,100,200,300,400 kg/hm^(2),respectively.In the early stage of overwintering,alfalfa root crowns were collected and treated under artificially simulated freezing(-20℃)and cold storage(4℃)conditions to analyze the changes of relative conductivity,water(free water and bound water)content and amino acid(free amino acid and proline)content.The results showed that compared with cold storage condition,low temperature freezing treatment had lower free water content and higher relative conductivity,and contents of proline and bound water.Lower relative electrical conductivity and higher contents of proline and bound water of alfalfa root crown were observed under low temperature freezing treatment with addition of 300 kg/hm^(2) phosphate fertilizer.Furthermore,under above condition,the relative conductivity with TSP addition was lower than that of DAP addition,and the contents of proline and bound water in TSP addition was higher than those of DAP addition.The correlation analysis revealed that under low temperature freezing treatment,the relative conductivity of alfalfa root crown with TSP addition was positively correlated with the free water content(P<0.05)and negatively correlated with the bound water content(P<0.01).In conclusion,the application of 300 kg/hm^(2)(P_(2)O_(5))in Horqin Sandy Land in autumn was beneficial to the safe overwintering of alfalfa,and TSP addition had better effect than DAP addition.