苹果植株硝酸还原酶(NR)研究初报

STUDY ON THE NITRATE REDUCTASE ACTIVITY OF APPLE TREES IN ORCHARD

田间耕作条件下苹果短枝型品种与普通型品种的硝酸还原酶活性（ＮＲＡ）分析表明：ＮＲ普遍存在于根系与叶片中，但皮层没有检测到，其活性以根系最高；ＮＲＡ的周年变化动态与植株的３次根系活动高峰相一致，说明其与根系旺盛的土壤Ｎ吸收有关。追施硝态氮（ＮＯ３—Ｎ）能显著提高ＮＲＡ，但高剂量的铵态氮（ＮＨ４—Ｎ）并未造成ＮＲＡ的下降；ＮＲＡ在两类品种间存在差异，短枝型品种的ＮＲＡ高于其相应的普通型品种，表明前者的耐肥性较高。

Two apple cultivars“starking”and“starkrimson”which were under the same conditions(age,rootstock,field)were fertilized with two forms and three levels of nitrogen in early spring in orchard.The nitrate reductase activity (NRA)in the various organs of the trees were measured:NR had been detected generally in fine roots,shoot and spur leaves;and of all of them,fine roots NRA was the highest ,then the second was in shoot leaves,and the lowest was in spur leaves;but NRA was not detected in shoot cortex.The annual variations of NRA in roots were correlation to the three times of new roots developments .Applying NO 3-N could significantly increase the NRA,but high level of NH 4-N had no toxicity to the apple plants in the soil.At last,NRA was different in two kinds of cultivars,NRA in“starkrimson” the spur-type apple tree was higher than in “starking”.