【作者】 周源；

【导师】 马履一；

【作者基本信息】 北京林业大学 ， 森林培育， 2009， 博士

【摘要】 107杨具有速生、质优、抗病等特点,已成为北方地区最主要的速生丰产林树种。特别是随着107杨大面积的种植,对107杨苗木需求量增大,对107杨苗木的经营管理也提出了更高的要求,但目前并没有科学的107杨苗木经营管理模式,尤其是对基于107杨苗木水肥需求规律的精准水肥灌溉制度研究很少。本研究选择107杨最适生的北京地区,进行了不同苗龄型苗木耗水及养分变化规律研究试验。研究了不同苗龄型的107杨苗木主要生长季的生长节律、光合特性、体内养分变化规律,采用盆栽称重法和以热平衡为原理的Dynamax包裹式茎流测量系统和自动气象站,分析了107杨苗木耗水特性,结果表明:（1）用logistic方程拟合107杨幼苗年生长时期变化和107杨幼苗总N、P、K、C元素含量变化效果显著,相关系数皆在0.95以上,并划分为3个阶段。（2） 107杨I_1-0苗木净光合速率的生长季进程为双峰曲线,从4月萌芽开始,净光合速率不断上升,5月底就达到了较高的净光合速率,8月初净光合速率达到全年最高,与苗高和地径在7月底生长最快相一致,8月底出现一个低谷,但9月份由于天气凉爽,净光合速率又回升,到了10月,净光合速率Pn又下降。（3） 107杨I_1-0苗和107杨I_1（2）-0苗日均耗水量与叶面积、苗高、地径呈极显著正相关,进行偏相关分析对日均耗水量的影响从大到小的次序为地径、苗高、叶面积。环境因子对107杨I_1-0苗和107杨I_1（2）-0苗日均耗水量的影响从大到小的次序均为光合有效辐射、大汽水势、相对湿度、风速、温度、饱和水汽亏。偏相关分析不同天气条件下环境因子对液流速率的影响从大到小的次序有所不同:晴天为光合有效辐射、空气温度、空气相对湿度、土壤含水量;雨天为光合有效辐射、空气相对湿度、土壤含水量、空气温度;阴天为光合有效辐射、空气相对湿度、空气温度、土壤含水量;经过回归系数检验,回归方程都达到了极显著水平。（4） 107杨幼苗在4-6月份土壤蒸发占4-6月份蒸散的百分比很高,特别是4-5月份占95%以上,所以如何降低土壤蒸发量是苗木生长前期节水的主要突破点;而107杨幼苗在9月份耗水占4-9月份苗木总耗水的43%～47%,占4-9月份总蒸发蒸散的27%～31%,107杨幼苗通常在9月中旬苗木封顶后采取控水控肥措施,以促进苗木木质化,提高苗木质量,所以在9月份开展控水试验,以降低107杨幼苗9月份的耗水量,是苗木生长后期节水的主要突破点。（5） 107杨I_1-0在落叶前含总N量9.157克,总P量0.883克,总K量5.352克;107杨I_1（2）-0在落叶前含总N量7.462克,总P量0.745克,总K量4.198克。更多还原

【Abstract】 Populus×euramericana cv."74/76" is an ideal tree species with the characteristics of short rotation,fast growth,excellent quality and anti-disease.With the spreading of Populus×euramericana cv."74/76",higher-standard management measure and more saplings are required.However,there is no scientific management model of Populus×euramericana cv. "74/76" at present,especially few research on precise irrigation based on water use and nutrients requirement of the sapling.In provinces of Beijing,most suitable for the growth of Populus×euramericana cv. "74/76",the trias of the water use and nutrition dynamics for the different age of saplings were studied about growth rhythem,photosynthetic characteristic,nutrition dynamics.The pot weighting,heat balance Dynamax packaged sap flow measuring system and automatic weather recording system,were employed to analyse the relationships of water use with test meteorological factors.The results showed that:（1） The logistic model can reflect on the most significant level the relation of the element content（C,N,P,K） and the growing time（T）and the effective accumulated temperature（K）,and the relation of the root collar diameter,shoot height,total leaves area and the growing time（T）and the effective accumulated temperature（K） respectively,of which the correlation is significant and all the correlation coefficients are higher than 0.95.Based on the equation,they can be divided into three periods.（2） The net photosynthetic rate for seasonal variations shows two peaks,which are in early August and in the end of September.The second peak is caused by the cool weather.（3） There is a significant positive correlation between average daily water use and root collar diameter,shoot height,leave areas.The analyse of partial correlation showed that the root collar diameter and the photosynthetically effective radiation were always the dominant factor affecting the average daily water use for Populus×euramericana cv."74/76" I_1-0 and Populus×euramericana cv."74/76" I_1（2）-0.The partial correlation analyse of the effect on SFD by meteorological factors showed different order among sunny days,clondy days and rainy days.Tested by regressive coefficient,the regressive equation showed most significant level between SFD and meteorological factors.（4） Soil evaporation accounted for a high percentage of evapotranspiration during major growth season,especially more than 95%in April and May,so how to reduce soil evaporation is a major breakthrough in water-saving.In September water use accounts for 43%～47%of total water use in major growth season,and also accounting for 27%～31%of the total evaportransperation.Measures to control water and fertilizer were taken to promote sapling lignification and improve the quality of saplings in mid-September,so the trial of reducing the water use in September,is a major breakthrough in water-saving.（5） Nutrients concentrations in the I_1-0 of Populus×euramericana cv."74/76" in a growing season,is N 9.15712 g,P 0.882676 g,K5.351916 g,respectively.And nutrients concentrations in the I_1（2）-0 of Populus×euramericana cv."74/76" in a growing season,is N 7.462 g,P 0.745 g,K4.198 g,respectively.更多还原