摘 要

磷是植物生长所必须的大量元素之一，作为不可再生资源，由于长期的成土作用和采伐，磷素缺乏逐渐成为林木生长所面临的严重状况。在长期进化过程中，林木形成了适应低磷胁迫的适应机制来应对土壤有效磷缺乏的现象。通过观察测定杨树在缺磷条件下鲜重、株高、根长、茎粗及叶片数的变化，探究缺磷对杨树生长的影响，进而为林木响应缺磷胁迫的机制提供依据。通过缺磷、低磷和正常磷浓度处理杨树幼苗的实验可以看出缺磷对于杨树的地上地下部分形态变化和生物量分配都有一定的影响。缺磷对杨树株高的生长变化有明显的抑制；磷浓度的降低会影响杨树茎粗的生长；各磷浓度处理下的杨树均出现了叶片脱落的现象，缺磷条件下杨树叶片脱落现象最为严重；缺磷条件下杨树侧枝及侧枝叶片数增加明显；磷缺失造成根系的生长受抑制，缺磷条件下根冠比高于正常，在整株水平上，缺磷导致生物量积累远低于正常水平。

关键词：杨树；缺磷；形态变化；生长

Effects of phosphate deficiency in poplar seedlings

ABSTRACT

Phosphorus is one of the essential elements for plant growth. As a non-renewable resource, phosphorus deficiency has gradually become a serious condition for forest growth due to long-term soil-forming and logging.In the process of long-term evolution, forest trees have formed adaptive mechanisms to cope with the phenomenon of soil available phosphorus deficiency in response to low phosphorus stress.Through observing the change of fresh weight , plant height , root length , stem diameter and leaf number of poplar under the condition of phosphorus deficiency , the influence of phosphorus deficiency on the growth of poplar is explored , and the basis for the mechanism of forest wood to respond to phosphorus deficiency stress is provided .Through the experiments of phosphorus deficiency, low phosphorus concentration and normal phosphorus concentration, it can be seen that phosphorus deficiency has a certain effect on the aboveground and underground morphological changes and biomass allocation of poplar.Phosphorus deficiency significantly inhibited the growth of poplar plant height, but low phosphorus had no significant effect on poplar height.The decrease of phosphorus concentration will affect the growth of poplar stem diameter.The leaf shedding of poplar was observed under the condition of phosphorus deficiency, but the effect of low phosphorus on it was not obvious.Because of phosphorus deficiency, the growth of poplar was inhibited, the growth of root system was also inhibited, and the distribution of material in ground and underground was different. The ratio of root to shoot was higher than normal under phosphorus deficiency, but the growth of poplar was obviously poor. Biomass accumulation was much lower than low phosphorus and normal level, but low phosphorus had no obvious effect on poplar biomass accumulation, and its effect on poplar was mainly on aboveground and underground biomass allocation.

Key words：poplar；phosphorus deficiency；morphological change；grow

目 录

1 前言 1

1.1 研究背景 1

1.2 国内外研究现状 1

1.2.1 缺磷对植物形态的影响 1

1.2.2缺磷引起的生理变化 2

1.3 小结 2

2 材料与方法 4

2.1 实验材料 4

2.2 实验方法 4

2.2.1 苗木培养 4

2.2.2 实验材料处理 4

2.2.3 实验结果统计分析 5

3 结果与分析 6

3.1 缺磷对植物生长量的影响 6

3.2 缺磷对植物根系的影响 7

3.2.1 缺磷对杨树根长的影响 7

3.2.2 缺磷对杨树根冠比的影响 9

3.3 缺磷对植物地上部分的影响 10

3.3.1 缺磷对杨树株高的影响 11

3.3.2 缺磷对杨树茎粗的影响 13

3.3.3 缺磷对杨树叶片生长的影响 14

3.3.4 缺磷对杨树侧枝生长的影响 15

结 论 17

致 谢 18

参考文献 19

1 前言

1.1 研究背景

磷是植物生长发育过程中必需的矿质养分之一，是植物体中核酸、蛋白质、磷脂等大分子物质的重要组成成分，且在植物体内以多种途迳参与各种生理生化过程，参与膜结构、ATP、核酸等的构成，影响蛋白质的合成、新细胞的形成等。磷对植物生长发育十分重要。

土壤中的磷通常以无机磷和有机磷两种形式存在，植物只能够吸收利用无机磷，但植物可吸收利用的有效磷含量均较低（0.1～10.0μmol/L），由于长期的成土作用和采伐，磷素缺乏逐渐成为林木生长所面临的严重状况。磷为不可再生资源，因此，研究植物对磷的吸收和利用，挖掘植物自身潜力和土壤潜在的磷资源，有望从根本上提高植物应对磷胁迫的适应性，从而实现可持续发展。

1.2 国内外研究现状

1.2.1 缺磷对植物形态的影响

在低磷胁迫下，植物采取相应的适应机制作出反应，通过主动适应外界环境的改变，提高对磷的吸收。常冀原等的研究表明，不同的氮磷钾配比对于一年生江南油杉幼苗的生物量有显著影响^[1]。陈永亮等对落叶松的研究表明低磷胁迫下幼苗的平均单株干重净增量较磷充足的完全营养液中的显著降低，仅为其20.5%—26.3%^[2]。钱莲文等对常绿杨的研究表明，常绿杨三个无性系干物质的积累量随土壤磷素水平的提高而显著增加，说明磷是限制其生长的一个重要因素^[3]。

1.2.1.1 缺磷对植物根系形态的影响