设施栽培油桃对叶面施15N的吸收、分配特性研究

以设施栽培的5年生早红珠油桃/山毛桃为试材,应用15N示踪技术研究油桃叶片对15N-尿素的吸收及运转特性。结果表明,叶片施用15N-尿素标记叶吸收主要发生在叶片涂抹15N-尿素后6.h内,平均吸收速率为0.204mg/(g.h);标记叶中15N吸收量24.h达到最高,新梢和梢顶嫩叶15N含量在施用15N-尿素48.h达到最高,下部叶15N含量很低,没有明显的峰;处理168.h各器官中15N含量为标记叶梢顶嫩叶新梢下部叶;试验结束时分配势Ndff(即各器官N含量来自化肥N所占的百分率)为标记叶中最高,然后依次为梢顶嫩叶、新梢、下部叶。这说明氮素迅速被吸收并运到嫩梢和嫩叶中,从而促进这些新生器官的形态建造,可起到以N增C的作用。不同叶面处理的试验还表明,正面和背面全部涂抹的叶片15N含量最高,只涂抹叶片背面次之,涂抹正面最低。设施栽培油桃叶片可迅速吸收尿素,其吸收量早晨明显优于中午和下午,因此设施油桃栽培管理中于早晨进行叶面施尿素,且正反面兼顾,N素的吸收利用效果最好。

Study of the absorption and distribution characteristics of 15N-urea applied to leaves of nectarine planted in greenhouse

This research was carried out in a greenhouse in 2005.Mature trees of "Zaohongzhu" nectarine/wild peach were fertilized in spring with ¹⁵N-labelled urea via leaf,and the nitrogen absorption and distribution characteristics were studied using isotope ¹⁵N.The uptake of ¹⁵N by leaves mainly occurred during the first 6 hours following application of urea.The mean rate of absorption during this period was 0.204 mg/(g·h).The content of ¹⁵N 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 followed this order: 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: treated leaves>younger leaves>new shoots>older leaves.The result suggested that the distribution of absorbed N was mainly translocated to the younger leaves and new shoots.Thus foliar application of N accelerated growth and formation of newly organs.¹⁵N absorption was greatest in leaves with both abaxial and adaxial leaf surface treatments,followed by abaxial leaf surface treatment and adaxial leaf surface treatment.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 sprayed to both abaxial and adaxial leaf surfaces in the morning.