常绿-半常绿杨树对磷素的利用特性

缺磷是限制农林业产量的一个重要因子,传统的农林业生产主要通过施肥和土壤改良来满足植物对磷的需求,近年来人们开始发掘磷高效利用植物来替代传统方法提高磷的利用效率.A-65/27、A-65/31及A-61/186是目前世界上仅有的3个常绿杨树无性系,共同特点是容易扦插繁殖,造林成活率高,生长快,材质好.3个无性系的推广将极大地丰富南方用材林树种资源.为揭示磷素胁迫条件下常绿杨无性系对土壤中磷素的利用特性,通过沙培试验,设计5个磷素处理水平(磷的质量浓度依次是0.00、0.0310、0.0619、0.1239、0.1858 g·L~(-1)),进行不同磷素处理水平下常绿杨生长及生理生态特性的研究.结果表明:当磷的质量浓度为0.0619 g·L~(-1)时已经能满足常绿杨生长对磷的基本需求;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;低磷胁迫下光合速率也明显下降,通过对气孔导度及胞间二氧化碳浓度的变化趋势分析,导致光合速率下降的主要原因是非气孔限制因素,同步叶绿素荧光的测定表明光系统Ⅱ受到了一定的影响,这是非气孔限制因素之一.

Study on phosphorus nutrition characteristics of three evergreen poplar clones

Phosphorus (P) deficiency is one of the main factors that influences productivity in agricultural and forestry systems. Fertilization and soil improvement are the primary measures to meet the P demands in traditional agri-forestry production. Recently, plants with high phosphorus use efficiency have been discovered and used to replace traditional measures for improving phosphorus use efficiency of crops. A-65/27, A-65/31 and A-61/186 are only there evergreen poplar clones in the world. Their common features are easily cutting propagation, higher afforestation survival rate and fast-growing evergreen poplar clones with high yield and excellent wood quality. Tree species resources of south timber forests would be abounded significantly through extensively planting these poplar clones. In order to understand the P demands of evergreen poplar clones. The sand potted evergreen poplar clones were sub-jected to five P supply levels: 0.00, 0.031 0, 0.061 9, 0.123 9, 0.185 8 g·L~(-1). The results showed that the phosphorus concentration of 0.061 9 g·L~(-1) would he able to meet the basic needs of the phosphorus for the growth of evergreen poplar clones. Lacking of phos-phorus would significantly affect the growth of height, ground diameter and biomass. And photosynthetic rate under low-phosphorus stress decreased significantly. Through analysis of changing trends of stoma conductance and intercellular CO_2 concentration, it would be known that main reasons of photosynthetic rate declining were non-stomatal constraint. The chlorophyll fluorescence measured synchronously was affected also, and this was one of the factors of non-stomatal constraint.