【作者】 常君；

【导师】 杨水平； 姚小华；

【作者基本信息】 西南大学 ， 森林培育， 2008， 硕士

【摘要】 本文就美国山核桃苗木根系生长规律在浙江省建德市美国山核桃苗木扩繁基地进行了多种措施、多种处理试验,试验结果表明,在不同处理下美国山核桃苗木根系各指标、生长指标等均有较大差异。不同接穗美国山核桃苗木根系生物量、根系长度、根系表面积、根系体积、苗木粗度和高度等指标分析结果表明,不同接穗美国山核桃苗木根系之间均存在极显著差异,根系总长均值最大可达2911.36cm,为最小值的1.82倍;根系表面积最大为573.07cm²,为最小值的1.79倍;根系体积差异也比较大,最大可达10.83cm³,是最小值的2.11倍;对不同接穗美国山核桃苗木多个指标相关分析表明,各指标两两之间（极个别例外）均呈极显著相关,其中根冠比分别与嫁接点以上粗度、嫁接点以上长度、地上部分鲜重、地上部分干重呈极显著负相关,其它均呈极显著正相关;不同接穗美国山核桃苗木不同根级之间根系长度、根系表面积、根系体积均存在较大差异,根系长度最大在0.0＜d＜=0.5mm根级,根系表面积最大在1.0＜d＜=3.0mm根级,根系体积最大在d＞3.0mm根级,在同一根级内接穗不同美国山核桃苗木根系长度、根系表面积、根系体积也存在较大差异。不同水分胁迫条件对苗木各指标均表现出显著性差异,苗木高度、地径最小值分别比对照减少了24.17%、16.14%,根系长度、根系表面积与根系体积均随着水分胁迫程度的加深而降低,干旱过程中复水根系长度、根系表面积、根系体积均会显著增长,其值比使用保水剂大,但均小于对照。随着土壤含水量的降低苗木地上、地下部分生物量逐渐减小,复水后,苗木地上、地下部分生物量会有所增加,但仍小于对照;随着水分胁迫程度的加深,美国山核桃叶片脯氨酸含量呈现出急剧增加而后又逐渐下降规律,而在干旱胁迫过程中复水,叶片脯氨酸含量重新恢复到原来的水平。不同容器类型对苗木地径、苗木高度、苗木地上部分和地下部分生物量、苗木根系长度、根系表面积和根系体积均表现出极显著差异,显著水平均在0.0001以上,通过不同一元非线性回归模型对苗木地径、苗木高度进行模拟表明,各回归模型均有较高决定系数,适应性较好。其中地径以Logistic模型拟合效果最佳,苗木高度以幂函数模型拟合效果最佳;以化学截根容器苗木根系长度、根系表面积最大,其次为空气截根容器,普通育苗容器苗木根系长度和根系表面积最小,空气截根容器根系体积最大,其次为化学截根容器,普通育苗容器苗木根系体积最小。去胚尖与否对苗木根系长度、根系表面积和根系体积未表现出显著性差异;通过对去胚尖措施与容器类型各组合不同径级苗木根系长度与大田直播苗根系对比研究发现,容器苗苗木根系长度要显著高于大田直播苗木根系长度,尤其是细根的长度表现得更为明显。截主根措施及不同施肥梯度对苗木地径、高度、新梢长、生物量等都表现出极显著差异,其中均以不截主根各指标较大。中度施肥或高施肥苗木各项指标值较大,不施肥或低施肥各指标值较小,通过对苗木地径、苗木高度、根系体积生长曲线拟合发现,各模型均能较好地对其生长曲线进行拟合,具有较高的适应性,其中,苗木地经以Gompertz等指数模型拟合效果最好,苗木高度以幂函数拟合效果最佳,根系体积以幂函数模型和指数函数模型拟合效果最佳;截主根措施及不同施肥梯度对苗木根系的影响与对地上部分各指标的影响不同,截主根后苗木根系长度、根系表面积、根系体积远远高于不截主根,不同的施肥梯度对苗木根系各指标影响不大。不同无性系苗木地上部分各指标随着种子大小降低而呈现下降趋势,种子大小的不同不仅对肉眼能看到的苗木地径、高度有较大影响,对隐藏在地下的根系也有较大影响。不同基质对苗木地径及苗木高度均有一定的影响,其中以普通育苗容器对苗木地径及高度影响最大,基质类型和去胚尖措施对苗木地径也有一定的影响,对苗木高度未表现出显著性影响;不同基质对美国山核桃苗木根系长度、根系表面积及根系体积影响结果表明,容器种类对地下部分各指标未表现出显著性影响,而基质类型及去胚尖措施对苗木地下部分各指标影响较大,其中以40%泥炭+40%珍珠岩+20%蛭石为基质及去胚尖1/2苗木的根系长度、根系表面积及根系体积最大;通过不同粗细根段播种试验结果表明,以1.2cm＜d＜=1.6cm径级根段播种出苗率最高,0.8cm＜d＜=1.2cm根段播种次之,以0.4cm＜d＜=0.8cm根段播种的出苗率最低,其中以100ppmABT₆溶液浸泡根段出苗率最大。更多还原

【Abstract】 The experiment was conducted in multiplication base of pecan seedling in Jiande,Zhejiang Province,which mainly studied on the root growth rule of pecan seedling.Several measures and many treatments were carried out,and the results showed that there were remarkable differences in the indexes of root and growth rule under different experimental conditions.Analyzing on such indexes as root biomass,root length,root surface area,root volume,root diameter and root height of different grafted pecan seedling,we could concluded that:there were extremely remarkable differences among the roots of different grafted pecan seedling.That was,the maximum of the average total root length can arrive at 2911.36cm,which was 1.82 times the total length of the minimum;the maximum of the root surface area was 573.07cm2,which is 1.79 times the size of the minimum;the differences of root volume were relative large,the maximum is 10.83cm3 equaled to 2.11 times the size of the minimum;correlation analysis on these indexes showed that each two indexes(very few exceptions)showed a significant correlation:root crown had no collation with the root diameter and the root length which was beyond grafted union,the aboveground fresh weight,the underground dry weight;but had significant positive collation with others.Among different root level of different grafted pecan seedling,the root length,root surface area and root volume were different remarkable.The root was the longest in the level of 0.0＜d＜=0.5mm, the root surface area was the biggest in the level of 1.0＜d＜=3.0mm,and the root volume was the biggest in the level of d＞3.0mm.Moreover,although in the same root level,there were relatively differences among root length,root surface area,root volume of various grafted pecan seedlings.Each index of pecan seedling was different dramatically under various water stressing. Comparing with control,the tree height and the minimum of the root diameter were reduced by 24.17%,16.14%respectively,and the indexes of root length,root surface area,the root volume were declining as the water stressing deepening and rising while rewatered,and their value were bigger than that treated by water-retaining,but were still less than the control.In different water stressing conditions,the biomass of aboveground and underground seedlings decreased as the reduction of soil moisture and increased with rewatered,but still less than the control;moreover,as the water stressing deepening,the proline contained in pecan leaves grow rapidly initial and appeared declining trend then,but it would retum to original level with rewatered.Affected on the seedling diameter,seedling height,the biomass of aboveground and underground seedling,root length,root surface area and root volume were affected by the type of container dramatically,and the level of dramatically association was beyond 0.0001.Stimulating the seedling diameter and seedling height with one-factor non-linear regression model,each model had higher decision coefficient and the adaptability was better.For example,Logistic model was preferred for root diameter;exponential model was suitable for root height.The indexes of root length,root surface area and root volume were different in various containers,and the index consequence from high to low was as follows:the former was chemical controlling container,air controlling container,ordinary cultivating container;the latter was air controlling container, chemical controlling,and ordinary cultivating container.Whether removing embryos or not had no dramatically association with root length,root surface area and root volume,comparing the root controlled by removing embryos in different containers with ones cultivated in the field,we found that root in container was longer than that in the field,especially the fine root.Measure of controlling main root and different fertilizer gradients affected the index of aboveground(seedling diameter,seedling height,fresh treetop strength,biomass and so on)and underground(root length,root surface area,root volume).That was,the indexes of underground were higher under controlling the main root than that without controlled,and the fertilizer gradients had little effect on root index.But the effect to the index of aboveground was different from to that underground,especially,the indexes of aboveground were higher under no controlling main root,middle-fertilizing or high fertilizing conditions,and lower under no fertilizing or low fertilizing conditions.Studying on the growth curving fitting of seedling diameter,seedling height and root volume,we found that each model were fitting for the growth curving very well,including Gompertz index model was suitable for root height,exponential model and index model were fitted for root volume.The indexes of aboveground cloning seedling,which appeared decline trend with the size of seed contract,not only had great effect on root diameter and root height,but also had effect on the indexes of underground root.Substrate effected the indexes of seedling diameter and seedling height,especially ordinary cultivating container,substrate types and removing embryos measures had some effect on root diameter,but had no association with root height;studying on the effect of substrate on root length, root surface area,root volume,the results were as follows:the indexes of underground had no association with container types,but effected by substrate types and removing embryos measures, especially using 40%turfs + 40%pearlite + 20%vermiculite as substrate and removing half of embryos,in this condition,the indexes reached the maximum.Studying on sowing with various root diameter,we found that the rate of seedling emergence was highest when the diameter was between 1.2cm and 1.6cm,and lowest when the diameter was between 0.4cm and 0.8cm.更多还原