梨幼树到结果初期春施15N–尿素的利用及其在土壤的残留与损失

2014—2016年,以‘黄冠’梨为材料,采用15N示踪技术研究了从幼树期到结果初期梨树对春季施用氮素的吸收利用及土壤残留与损失情况。研究结果表明,幼树期(2014—2015年)梨树生长以中心干和粗根等树体骨干结构建立为主,生长量相对较小;进入结果初期(2016年)后树体生长表现为树体骨干结构建立为主,枝梢等营养器官生长与产量形成并存,生长量大幅增加。整个试验期间,树体贮藏器官的标记氮素吸收量较大,其中幼树期中心干吸收量最大,结果初期粗根吸收量最大。0~100 cm土层标记氮素残留量随土层深度和施用年限增加逐渐降低,其中,施用标记氮素后第1年(2014年),土壤标记氮素残留量较高,残留率达63.61%,梨幼树对标记氮素利用率仅为3.25%。随后两年(2015—2016年)土壤残留量较低,树体对标记氮素利用率仅为0.51%和0.80%。试验结束时,幼树期到结果初期梨树对标记氮素的累计利用率为4.57%,土壤标记氮素残留量为20.34%,损失率达75.07%。

Utilization of N-urea Applied in Spring for Pear Trees and Its Residual in Soil and Loss from the No-bearing Stage to the Young Bearing Stage

To investigate the uptake and utilization of nitrogen and its residual and loss in the soil of‘Huangguan’pear trees during the no-bearing stage to the young bearing stage,the growth of various organs and the uptake,residual and loss of labeled nitrogen at 0–100 cm soil layers were studied during the years of 2014–2016 with 15 N tracer technique.The results showed that the growth of pear trees in the no-bearing stage(2014–2015)mainly displayed in the growth of the central trunk and coarse root with a lower growth rate.However,it showed that the establishment of tree structure,the growth of vegetative organs such as branches and shoots,and the formation of yield and quality coexisted in the young bearing stage.During the whole experiment period,the amount of labeled nitrogen absorbed by the storage organs of the tree was larger,among which absorption of the central trunk’s uptake was the largest in the no-bearing stage,while the amount of labeled nitrogen absorbed by the coarse roots was the largest among all tested organs in the young bearing stage.After the application of labeled nitrogen in the first year(2014),the utilization rate of labeled nitrogen was 3.25%for the pear trees,while the residual rate of labeled nitrogen in 0–100 cm soil layer was higher accounting for 63.61%.In the following two years(2015–2016),the residual amount of soil was lower,and the utilization rate of labeled nitrogen for pear trees was only 0.51%and 0.80%.By the end of the experiment,the utilization rate and residual rate of labeled nitrogen was 4.57%and 20.34%respectively,however,the three-year loss rate was as high as 75.07%.