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三种南方主要造林树种苗木生长响应模拟N沉降的种间差异

庞丽1,2,周志春1*,张一1,丰忠平3   

  1. 1中国林业科学研究院亚热带林业研究所 浙江省林木育种技术研究重点实验室 国家林业局马尾松工程技术研究中心, 浙江富阳 311400; 2安顺学院,贵州安顺 561000; 3浙江省淳安县姥山林场, 浙江淳安 311700)
  • 出版日期:2016-02-10 发布日期:2016-02-10

Interspecific differences in seedling growth of three main afforestation tree species in response to simulated N deposition.

PANG Li1,2, ZHOU Zhi-Chun1*, ZHANG Yi1, FENG Zhong-Ping3   

  1. (1Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Key Laboratory of Tree Breeding of Zhejiang Province, Engineering Research Center of Masson Pine of State Forestry Administration, Fuyang 311400, Zhejiang, China; 2 Anshun College, Anshun 561000, Guizhou, China; 3Laoshan Forest Farm of Chun’an County of Zhejiang Province, Chun’an 311700, Zhejiang, China)
  • Online:2016-02-10 Published:2016-02-10

摘要: 我国南方土壤缺P严重,加之近年来大气N沉降增加明显,导致森林土壤有效N含量增加和N/P发生改变,从而对林木的生长发育和生产力产生影响。本文选择马尾松、杉木和木荷等3种南方具有不同生长和生物学特性的主要针阔叶造林树种,设置低P胁迫下的模拟N沉降盆栽试验,研究N素增加下3种苗木生长发育及适应低P胁迫机制的种间差异。结果表明:1)模拟N沉降增加了马尾松和木荷生物量向地上部分的分配,增加了地上部分的生长量和生物量,但根系的生物量降低,2种幼苗的整株生物量变化均不显著。N素的增加严重抑制了杉木幼苗地上部分和根系的生长,整株生物量显著降低;2)模拟N沉降加剧了3种幼苗遭受低P胁迫的程度,其根系分泌性酸性磷酸酶(APase)活性及有机酸总量均增加。马尾松和木荷较杉木根系分泌物总量增加幅度大;3)模拟N沉降增加了3种幼苗叶N含量,降低了叶P含量,增加了叶N/P。杉木叶N/P增加幅度最大,马尾松叶最小。杉木叶N/P急剧增加,导致其叶P含量的相对匮缺,叶N、P素营养失衡,最终影响杉木叶光合作用。马尾松和木荷叶片N/P增加幅度较小,N素的增加促进了2种幼苗净光合速率的提高;4)N沉降下,马尾松、木荷表层土壤酸化程度较杉木大。杉木和马尾松土壤水解N含量增加幅度较木荷更大,这归因于木荷对土壤表层N的吸收和淋溶作用均较大,马尾松表层土壤N的淋溶作用较杉木强。3树种盆栽土壤有效P含量均降低,而表层土壤有效P含量均较底层高。

关键词: 干旱, α-萘乙酸, 开花期, 大豆, 碳代谢

Abstract: The enhanced atmospheric N deposition in recent years has brought the increases in N availability and N/P ratio in forest soils, which would impact the growth and productivity of plants. Pinus massoniana, Cunninghamia lanceolata and Schima superba are the main afforestation tree species with different growth and biological characteristics in southern China. Taking seedlings of the three tree species as test materials, a pot experiment was conducted to simulate low P soil conditions in combination with two N deposition levels, to study interspecific differences in growth and adaptation mechanism to low P stress under N addition. The results showed that: 1) The aboveground part growth of P. massoniana and S. superba was promoted by simulated N deposition, but their root growth and root biomass accumulation were inhibited. The whole plant biomass of P. massoniana and S. superba were not significantly changed under simulated N deposition. The aboveground part and root growth of C. lanceolata were severely inhibited by simulated N deposition, so its whole plant biomass was significantly decreased; 2) The degree of low P stress of the three tree species seedlings was increased by simulated N deposition, which led to the increase of root secreted APase activity and organic acids. The increased degrees of total amount of root secretion of P. massoniana and S. superba were greater than that of C. lanceolata; 3) Simulated N deposition increased leaf N contents of the three tree species, but decreased their leaf P contents, thus increased their leaf N/P ratios. The increased degree of leaf N/P of C. lanceolata was the maximum, and that of P. massoniana was the minimum. The rapid increase of leaf N/P ratio of C. lanceolata resulted in the relative scarcity of its leaf P content and imbalance of leaf N and P nutrients, finally influenced C. lanceolata leaf photosynthesis. The increased degree of leaf N/P ratios of P. massoniana and S. superba were relatively small. The increase of leaf N contents of P. massoniana and S. superba promoted their leaf net photosynthetic rates; 4) Under simulated N deposition, the acidification of surface soil of P. massoniana and S. superba was greater than that of C. lanceolata, while soil hydrolytic N contents of P. massoniana and C. lanceolata were increased as compared to S. superba due to greater N absorption and N leaching of surface soil of S. superba, and stronger surface soil N leaching of P. massoniana compared to C. lanceolata. In addition, soil available P contents of the three species were all decreased, and they were higher in the topsoil than in the subsoil under simulated N deposition.

Key words: flowering stage, drought stress, carbon metabolism., α-naphthaleneacetic acid (NAA), soybean