猕猴桃树对氮素吸收、利用和贮存的定量研究

为了探明猕猴桃树对氮素吸收、利用和贮存规律，为确定合理的施肥量和施肥时期提供依据，以10年生秦美猕猴桃树为试材，采用彻底刨根，分解取样的方法，研究了年周期各器官的生物量、氮含量和氮累积量变化动态。结果表明，猕猴桃整株生物量全年增加了12.14 kg/plant，在果实生长期（5月18到9月8日）增加较快，增加量为7.99 kg/plant。氮素在猕猴桃树的根、茎、叶、果及皮层和木质部的分布为:根、叶、果实＞茎；皮层＞木质部；冬季氮的贮存部位是根和茎的皮层，并且主要贮存在茎的皮层。年周期猕猴桃树体总吸氮量为216.78 kg/hm2，进入果实收获期以后和结果前共吸收33.75 kg/hm2，整个果实生长期吸收183.03 kg/hm2，分别占总吸氮量的15.57%和84.43%。5月18日到7月9日和7月9日到9月8日两个阶段吸收的氮素量分别占总吸氮量的53.13％和31.30％，据此计算得猕猴桃的合理施氮量为N 412.91 kg/hm2（产量40 t/hm2)；推荐在休眠期结束前施基肥 N 64.29 kg/hm2，座果前追施壮果肥 N 219.38 kg/hm2，果实膨大末期追施促稍肥 N 129.24 kg/hm2。

Study on absorption, utilization and storage of nitrogen of kiwifruit tree

To find out the law of absorption,utilization and storage of nitrogen in kiwifruit tree,and to provide facts for nitrogen nutrition analysis and for reasonable fertilizing amounts and their application periods,a field experiment were conducted for analyzing yearly biomass,nitrogen content and its accumulation at different parts of kiwifmit trees (Actinidia Deliciosa cv.Qinmei kiwifruit)which are cultivated about 10 years.The results show that yearly biomass in- crease rate is about 12.14 kg/plant,and the rapid increase period is at the plant's fruit growth season(from May 18 to September 8)and the dry matter increment is about 7.99 kg/plant.Nitrogen contents of roots,leaves and fruits are larg- er than that of stems,respectively.Nitrogen content of cortex is larger than that of xylem.During the winter time,nitro- gen is mainly stored in the cortex of roots,and the next is the cortex of stems.Yearly total nitrogen absorption amount is 216.78 kg/ha.Among this amount,183.03 kg/ha nitrogen is absorbed during the fruit growing period,and 33.75 kg/ha nitrogen is absorbed from other periods,accounting for 84.43% and 15.57% of total nitrogen uptake respective- ly.In the fruit growing period,about 53.13% and 31.30% of total nitrogen uptake are absorbed from May 18 to July 9 and from July 9 to September 8.The yearly suggested total nitrogen application amount is 412.91 kg/ha,while 64.29 kg/ha of nitrogen is applied as base fertilizer in forced dormancy period of the plant,and 219.38 kg/ha is used as top- dressing just before the fruit period,and the rest of 129.24 kg/ha is also applied as topdressing in the last days of the rapid growing phase of the fruit.