Studies On The Characteristics Of Absorption, Distribution And Utilization Of Foliar Urea-N In 'Zaohongzhu' Nectarine In Greenhouse

The experiment using the stable isotope 15N-labelled urea was carried out in Shandong Agricultural University of'Zaohongzhu'nectarine in Greenhouse from 2004~2005.The characteristics of 15N absorption,distribution and utilization after 15N-urea daubing on the nectarine leaves in different fruit developing stages under the condition of protected cultivation by using 5-year-old nectarine tree (Prunus persica var. nectarina Maxim.cv. Zaohongzhu/Prunus davidiana Carr. ) were studied.The main results were as follows:1. Most uptake of 15N by leaves occurred during the first 6 hours following application of urea. The mean rate of absorption during these 6 hours was 0.204 mg·g-1·h-1. 15N content in leaves peaked 24 hours after urea application and then decreased, whereas 15N content in younger leaves and new shoots peaked 48 hours and 15N content in older leaves was very low. Moreover, 15N content in different tissues was: treated leaves> younger leaves> new shoots> older leaves. At the end of the experiment (168h), however, mobility of urea-derived N varied with different organs. That was: treated leaves, younger leaves, new shoots and older leaves. The result suggested that the distribution of absorbed N was mainly translocated to the younger leaves and new shoots.Thus foliar application N accelerate growth and conformation of newly organs. 15N absorption was greatest through both abaxial and adxial leaf surfaces, the absorption of abaxial leaf surfaces was the next and that of adxial was the least. Applying foliar 15N-urea during morning resulted in greater absorption of 15N than in the afternoon or at noon. It is clear that mature trees of'Zaohongzhu'nectarine could rapidly absorb urea applied to leaves and maximum N absorption from foliar urea sprays occurred in the morning through both the abaxial and adxial leaf surfaces of nectarine leaves in greenhouse.2. The translocation of foliar 15N-urea applied during different fruit developing stages distributed mainly to the growth centre. 15N absorbed by...