甘蔗硝酸还原酶活性与氮素营养的关系

对福引79-9、福引82-41和闽糖70-611三个品种分别施以不同量的氮肥后,各品种的+1叶硝酸还原酶活性(NRA)与+3叶含氮量的变化规律极其相似,不施氮处理的+1叶NRA和+3叶含氮量随蔗株株龄的增长而持续下降;施氮处理在施肥后几天,+1叶NRA和+3叶含氮量逐渐上升至最高峰,以后则随株龄的增长而下降。从施氮后+1叶NRA和+3叶含氮量出现最高峰起,各时期的+1叶NRA和+3叶含氮量的高低顺序(除闽糖70-611 9月11日Nl的+3叶含氮量略高于N2外)为施氮多的处理>施氮少的处理>不施氮的处理。3个品种3种施氨水平下的+1叶NRA与+3叶含氮量均呈极显著正相关。可见,+1叶NRA与+3叶含氨量一样能反映出蔗株的氮素营养状况。但+1叶NRA因品种和株龄而有很大变化,不适用于氮素营养诊断。

NITRATE REDUCTASE ACTIVITY IN SUGARCANE AS RELATED TO NITROGENOUS CONDITION

Three cultivars (Fuyin 79-9, Fuyin 82-41 and Mintang 70-611) were applied with 3 levels of nitrogen. After the application of nitrogen, the variation of+1 leaf nitrate reductase activity (NRA) in each cultivar was very similar to that of+3 leaf nitrogen content. Both+1 leaf NRA and+3 leaf nitrogen content in non-fertilized treatment constantly decreased with plant age. In fertilized treatments,+1 leaf NRAs and+3 leaf nitrogen content increased several days after fertilizing, then a maximum appeared. After this, they constantly decreased with increasing plant age too, and the order of+1 leaf NRA and+3 leaf nitrogen content was N_2 treatment>N_1 treatment>N_0 treatment (+3 leaf nitrogen content of Mintang 70-611 assayed on September 11 was not included). There were all very significant positive correlations between+1 leaf NRAs and+3 leaf nitrogen contents in 3 cultivars applied with 3 levels of nitrogen. It was suggested that+1 leaf NRA could show nitrogenous condition of sugarcane plant. But it could not be properly used to nitrogen diagnosis because of its great variations with cultivars and plant age.