苹果幼树根系越冬期氮代谢及覆膜效应研究

Root Nitrogen Metabolism and Film-mulching Effects in Young Apple Tree during Overwlntering Period

越冬期苹果根系氨基酸总量和蛋白酶活性在12～l月保持低水平，2月份开始回 升，3～4月增幅最大；冬季地膜覆盖提高了根系蛋白酶活性和氨基酸含量，初冬和初春效果 最明显。氨基酸总量，细根高于粗根；蛋白酶活性，初春粗根高于细根；蛋白质含量于1月份 出现高峰，3月以前粗根高于细根；覆膜对蛋白质含量影响不明显。冬春根中含多种氨基酸， 但以天门冬氨酸、谷氨酸、脯氨酸和精氨酸为主；越冬之后粗根中有3种氨基酸（ASp On、A吧）含量增加，细根中有匕种氨基酸（灿卜On、＊h、％r、G匕川a、＊1、Ik、 LSu。Tyr、Phy、LyS、His）合量增加；两种根内脯氨酸含量均是冬季大于春季。

Amlno tlcld contentand protelnase activity In apple roots remained lowestlevel fromDecember to January. They began to raise In Februaryand the rates ofin-creasing were highest In March to April. Filmmulching Increased protelnase actlvltyandamlno acid content, and It was most significantly at early Winter and early Spring. Thecontent ofamlno acid was higher In thinner roots than that In thicker roots at earlySpring, which was strengthened by him—mulching. Before March, the protein contentwas higher In thicker roots than In thinner roots. The protein content oftwo tyPes ofrootreached the peaks In January. There were various amlno acid In roots In Winter andSpring, andamong them the contentofAsp, Gin, Pro and A werehest. Asp, Ginand Afg contentn thicker rocs Increased after overwlntering. AsP, Gin Thr, Sef,Gly, Ala, Val, Ik, Leu, Tyr, Phe, Lys, and His content In thinner roots Increasedafter overwlntering. The content ofPro was h坞her In Winter than In Spring In two tyPes of