杨树用途广泛，是一种多功能的树种，具有速生以及在短轮伐期内提供大量木材的特性，在木材加工业中使用量逐年增加，我国实施了速生丰产林基地建设工程，大力发展杨树速生丰产林来缓解日益尖锐的木材供需矛盾。澳大利亚L．D．Pryor博士选育的3个杨树无性系是适合亚热带地区生长的常绿-半常绿杨树无性系。3个无性系分别为：A-65/27（Populus×euramericana cv.A-65/27）、A-65/31（Populus×euramericana cv.A-65/31）及A-61/186（Populus×euramericana cv.A-61/186）。3个品系的共同特点是：容易扦插繁殖，造林成活率高，生长快，材质好，干形通直，适应南方亚热带地区温暖的气候。推广这3个品系可使我国的杨树栽培区向南扩大到南亚热带，将极大地丰富南方用材林树种资源，改变南方大多数地区用材林以针叶林为主的局面，从而缓解林种单一化所带来的一系列环境问题，减轻对天然林资源保护的压力。但目前国内外关于这三个品系生理生态特性及环境适应性的了解近乎空白，急切需要相关系统研究能够用于指导生产。本研究利用当前植物生理生态领域一系列先进测定仪器Li6400光合作用测定系统、PAM2100叶绿素荧光仪、LI3000C叶面积仪等，对常绿杨3个品系在大田实验条件下的生理生态特性及其基本生长状况进行全面观测和分析，并对影响常绿杨在亚热带推广的2个主要方面的环境因素（干旱、低磷胁迫）下的生长状况及其响应机制做了初步研究，以期为其全面推广提供科学的理论依据。对常绿杨三个品系在福州和泉州的扦插及移栽实验结果表明，三个品系在福州及泉州均能表现为常绿-半常绿，不存在完全的休眠期；扦插成活率达到90%以上，高度和地径年生长动态存在明显的速生期，高度年速生期主要在6、7、8、9四个月，地径速生期集中在8、9、10三个月；光合、蒸腾及水分利用率在不同的月份显示出不同的日变化趋势，是品种特性与外界环境因子共同作用的结果；光合、蒸腾及水分利用率年变化的趋势显示常绿杨3个品系高光合同时伴随着高蒸腾，因此速生时期的水分供应是保证苗木良好生长的关键；从光合特性、生长量及生物量的观测数据来看，两年生移栽苗长势较一年生扦插苗有明显的下降，导致这种现象的原因可能有两个方面，一是苗木自身的问题，虽然扦插当年长势较好，但移栽后无法继续速生，另一方面可能是移栽方式及管理措施的不到位。常绿杨磷素营养实验表明，当磷素浓度较小时，随着磷素供给浓度的不断增大，常绿杨生长量不断增大，但当磷素浓度达到一定程度后，生长量不再随着磷素浓度的增大而增大，个别甚至出现了下降的现象。从本文设置的5个梯度的磷素浓度下常绿杨的形态及生长指标发现，当磷素浓度为0.2722 g/L时已经能满足常绿杨生长对磷的基本需求了。从选择利用耐低营养的高效基因型植物的角度出发，对常绿杨3个品系在低磷胁迫下的生理生态特性进行了研究。结果表明，磷素不足会明显的影响到常绿杨的生长，低磷胁迫下常绿杨高度、地径及生物量明显降低；磷素胁迫下常绿杨光合速率也明显下降，通过对3个品系气孔导度及胞间二氧化碳浓度的变化趋势分析表明，导致光合速率下降的主要原因是非气孔限制因素，叶绿素荧光的测定表明光系统II也受到了一定的影响，这是非气孔限制因素之一。常绿杨三个品系磷素吸收率与苗高生长量、地径生长量、根冠比、干物质积累量、单叶面积、叶绿素含量及光合速率7个指标之间均存着显著相关。用7个指标对常绿杨三个品系磷素营养效率的主分成分析结果表明，A-61/186具有较高磷素利用率，其次是A-65/31和A-65/27。利用气体交换法和叶绿素荧光技术，对常绿杨3个品系干旱胁迫及复水处理后的光合生理变化进行了研究。结果表明，在轻度干旱胁迫下，常绿杨光合速率、气孔导度和胞间二氧化碳浓度值均随干旱胁迫增强而下降，光合速率下降的主要原因是气孔导度下降；而当干旱程度进一步加剧之后，影响光合速率下降的主要原因是非气孔因素，同步叶绿素荧光测定结果表明，旱胁迫的加剧，会使PSII潜在活性中心受损，影响到光合电子传递，这是光合速率下降的一个主要原因。从3个品系经过干旱胁迫一段时间再进行复水后的生长量及生物量来看，与正常供水的植株相比，生长量及生物量明显下降，这说明即便后期供水充足，前期的缺水也会对苗木生长产生不可恢复的影响。 对常绿杨3个品系在大田条件下及两种逆境条件下的表现进行综合分析， A-61/186在三种条件下均表现优于A-65/27和A-65/31，是一个首选栽植的品系，而A-6 5/27和A-65/31在各个件下的表现并不一致，两者之间的差异也较小，所以难以区分优劣。但这种表现只是幼苗期的一个初步结果，关于三个品系优劣性的明确需要进一步研究。

Poplar is a multi-functional tree species with fast-growing and short rotation, and extensively planted in the world. The quantity of Poplar using is increasing year by year in wood processing industry. Hybird Poplar has been identified as one of promising candidates for plantation to fill the increasing gap between the supply and demand of wood in China. Dr L. D. Pryor. of Australia bred three evergreen-semi-evergreen poplar clones which were suitable for growing in the subtropical regions .They are A-65/27(Populus×euramericana cv.A-65/27), A-65/31(Populus×euramericana cv.A-65/31) and A-61/186(Populus×euramericana cv.A-61/186). They have common feature, easy cutting propagation, high survival rate of plantation, growing fast, good timber material, straight-stem form, adapting to the subtropical environment conditions.Popularizing three ever-green poplar clones was important which will expand cultivated area of Poplar to south subtropical area in China and enrich South timber species resources, and change the situation of timber forest mainly dominated by the coniferous forest, and then deduce the pressure of a series of environmental problems brought about by a single species forest, and reduce the pressure on natural forest resources protection. But the related research on eco-physiology and environmental adaptability of three ever-green poplar clones was almost empty both at home and abroad. So it is an urgent need to study related things systematically to guide plantation.In this study, field experiment and two stress experiments including drought stress and low-phosphorus stress which were the main environmental factors for the growth of ever-green poplar clones in subtropical areas were done. Some eco-physiological and environmental adaptability characteristics were observed and analyzed by using a series of advanced testing equipments, such as photosynthesis system Li6400, chlorophyll fluorescence detector PAM2100, leaf area measurement Li3000C et al. We hope that the results can provide scientific and theoretical basis to popularization of three ever-green poplar clones.The cutting and transplanting experiments of three ever-green poplar clones displayed ever-green or semi-evergreen in the Fuzhou and Quanzhou, and there is no completely dormant, and the cutting survival rate was more than 90 %. There was a clear fast-growing period for height and ground diameter of yearly growth, height growth mainly in June, July, August and September. And ground diameter growth mainly in August, September and October. And the fast-growing period was far longer than that of the northern deciduous clones. Diurnal changes of photosynthetic, transpiration and water using efficiency were different in different month which resulted from clones and external environment factors. And the yearly changes of photosynthetic, Transpiration and water using efficiency indicated that high photosynthetic accompanied by high transpiration for three ever-green poplar clones. So, adequate water supplying were keys to ensure good growth of seedlings in the fast-growing period. Compared with one-year-old cutting seedlings, the growth vigor of two-year-old transplanting seedlings decreased obviously from the observational data of photosynthetic characteristics, growth and biomass. The reasons for this phenomenon may have two aspects, first, the transplanted seedlings could not grow as fast as one-year-old cutting seedlings. Second, transplanting methods and management measures were not appropriate.Different Phosphorus nutrition experiments of three ever-green poplar clones were made in this study. The results showed that, when phosphorus concentration was small, with the growing of phosphorus supply, three ever-green poplar clones growth increased continuously. But when the phosphorus concentration was up to a certain extent, the growth no longer increased with the increase of the concentration of phosphorus, and even declined individually. From the morphology and growth indexes under five gradient of phosphorus concentration, it could be see that when the phosphorus concentration was 0.2722 g / L which had been able to meet the growth of the basic needs of the phosphorus.In the perspective of selecting tolerance low-nutrition genotype plant, the eco-physiology of three ever-green poplar clones under the low-phosphorus stress was studied. The results showed that, lacking of phosphorus will significantly affect the growth when three ever-green poplar were in low phosphorus state , Their height, ground diameter, biomass and photosynthetic under low-phosphorus stress decreased significantly. Through change trend analysis of stoma conductance and intercellular CO2 concentration, it can be drawn that the reason of photosynthetic rate declining under low-phosphorus stress was non-stomatal constraint. In the same time, the chlorophyll fluorescence was affected and which was one of the factors of photosynthetic declining. The correlation of phosphorus absorption rate with growth of height, ground diameter growth, root-shoot ratio, biomass, leaf area, chlorophyll content and photosynthetic rates was significant; using principal component analysis, the phosphorus use efficiency was evaluated with seven physiology and morphology indicators. And the results showed that utilization of phosphorus from large to the order for: A-61/186, A-65/31 and A-65/27.The effects of drought stress and rehabilitation of water on the photosynthesis of three ever-green poplars were studied by gas exchange and chlorophyll fluorescence techniques. The results showed that, in the early phase of drought stress, the decrease of photosynthetic rate was mainly related to the decrease of stomata conductance. While in the late phase, the main limiting factor of photosynthetic rates was non-stomata. Synchronization of chlorophyll fluorescence results showed that the severe drought stress will damage PSII potential active, affecting the photosynthetic electron transfer, which was the main reason of the photosynthetic rate drop. And compared with normal water supply plants, growth and biomass of three ever-green poplar clones experienced drought stress and rehabilitation of water decreased significantly. So even if adequate water supply in the latter, the effects of water shortages on the growth of seedlings can not be resumed.Through comprehensive analysis of performance of three ever-green poplar clones in field conditions and two adversities circumstances, it can be drawn that the performance of A-61/186 was better than the other two under three conditions, was a first choice of planting species. The performance of A-65/27 and A-65/31 in all conditions was not consistent, and the differences of two clones were not obvious, so it was difficult to distinguish between pros and cons. However, this performance was only a preliminary findings of seedings of seedling stage. The clear merits of three clones were needed for further study.