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Scientia Silvae Sinicae ›› 2015, Vol. 51 ›› Issue (9): 59-64.doi: 10.11707/j.1001-7488.20150908

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Mobilization of Insoluble Iron Bound Phosphate and Effective Factors by Root Cell Walls of Chinese Fir

Wang Pan1,2, Wu Pengfei1,2, Ma Xiangqing1,2, Chen Nailian1,2, Zhang Yunpeng1,2   

  1. 1. College of Forestry, Fujian Agriculture and Forestry University Fuzhou 350002;
    2. The State Forestry Administration Fir Engineering Technology Research Center Fuzhou 350002
  • Received:2014-08-22 Revised:2015-02-01 Online:2015-09-25 Published:2015-10-16

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Abstract:

[Objective] Aims: The insoluble iron bound phosphate in red soil of southern China was used to study the capacity of cell wall of Chinese fir roots in mobilizing insoluble iron bound phosphate and the impact factors, including forest age, root diameter and tissue structure of Chinese fir root cell wall. This study aims at providing a theoretical basis for fully using potentially available phosphorus content in the forest red soil of southern China. [Method] Methods: In Xinkou Forest Station of Sanming in Fujian, we chose 3 average trees from different aged forests, the 10-year-old as the young forest, 22-year-old as middle-aged forest and 34-year-old as old forest of Chinese fir plantations, and classified the roots into 6 classes according to the root diameter, less than 2 mm, 2-5 mm, 5-10 mm, 10-20 mm, 20-30 mm, and more than 30 mm. The cell wall was extracted from xylem and phloem of different root classes, respectively. The phosphorus content mobilized by cell-wall from insoluble iron bound phosphate was determined by using the molybdenum antimony colorimetric method, to analyze and compare the ability of cell wall of Chinese fir root in mobilization of insoluble iron bound phosphate, and the influence factors, such as root diameter, tissue structures and forest age. [Result] The mobilizing phosphorus content by Chinese fir root cell wall from insoluble iron bound phosphate was from 17.67 mg kg-1 to 497.50 mg kg-1. The xylem and phloem cell wall of less than 10 mm diameter roots had greater ability of activating insoluble iron bound phosphate than that of the more than 10 mm diameter roots. Compared with xylem in each forest age, the phloem cell wall of the same diameter root activated more insoluble iron bound phosphate. There was difference in activating ability of insoluble iron bound phosphate among the different forest ages with the same root diameter, and the ability of cell wall in activating insoluble iron bound phosphate was as follows: old forest > middle-aged forest > young forest. [Conclusion] The factors such as root diameter, tissue structures and forest age of Chinese fir had a significantly impact on the capacity for root cell wall to activate insoluble iron bound phosphate. The smaller diameter roots had greater ability activating insoluble iron bound phosphate than the bigger roots; the older forest had greater ability in activating insoluble iron bound phosphate than the younger, and the cell wall extracted from phloem had significantly greater activation ability than that from the xylem. This would be related to the inclusions accumulation of phosphorus dissolved of the cell wall and development pattern of spatial structure. The rapid growth of fine root would conducive to the formation and accumulation of active substances of cell wall. Phloem is a storage tissue of plants, and it has a higher chemical contents compared with the xylem. The forest age especially plays an important role in accumulation of the main contents like pectin in the cell wall. Thus, it is proposed that the genes and proteins involved in cell wall synthesis and restructuring should be studied and emphasized in the future, to understand the mechanism of cell wall in mobilizing insoluble iron bound phosphate through releasing specific active substances under stress condition.

Key words: Cunninghamia lanceolata, root cell wall, insoluble phosphate, xylem, phloem

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