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Scientia Silvae Sinicae ›› 2016, Vol. 52 ›› Issue (11): 29-38.doi: 10.11707/j.1001-7488.20161104

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Reasonable Canopy Light Intensity and High Light Efficiency Regulation of Sapindus mukorossi

Gao Yuan1, Jia Liming1,2, Gao Shilun1, Su Shuchai1, Duan Jie2, Weng Zhen3   

  1. 1. Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University Beijing 100083;
    2. National Energy R&D Center for Non-Food Biomass, Beijing Forestry University Beijing 100083;
    3. Yuanhua Forestry Biotechnology Co., Ltd Sanming 354500
  • Received:2016-05-29 Revised:2016-09-14 Online:2016-11-25 Published:2016-12-16

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Abstract:

[Objective] In this study, the tree control technology was applied in order to solve low yield of Sapindus mukorossi biodiesel feedstock forest. This paper is focus on revealing tree canopy with improper light intensity, and hence provides the theoretical and technical support.[Method] The light illumination in different parts of naturally growing trees was measured for 2 years. The number of flowers and fruit yield index, controlling opening angle and number of backbone branches, thinning out of fruiting-shoot were measured and two-factor interaction validation was conducted in this research.[Rusult] 1) The light intensity of naturally growing trees were unreasonable—the interior canopy light intensity was only 10% to 15% of the space's. A model was established between light intensity and yield after regulating the canopy structure, y=-0.011 9x2+5.926 3x-565.37(R2=0.738 38) and the best light intensity could range from (200-270)×100 lx. 2) The main phenological phases could also be inferred according to double peaks of light intensity of the naturally growing trees' canopy. In May, at the reproductive growth prophase, trees badly need nutrition, and form the first peak of light intensity. In June, in the turning process from the leaves-sprout stage to the fruit-set stage, the light intensity becomes to a lower level. In August, with leaves falling gradually, light intensity increases to the second peak and then enters into a relatively stable phase. 3) Trimming and pruning operations could be determined by different light distribution proportion. Generally speaking, compared with the space's light intensity, exterior canopy's is 40%-54%, central canopy's is 32%-35%, and interior canopy's is 27%-31% after pruning, which may increase the yield by two or three times and make use of light effectively. 4)The experiment was conducted by setting up different backbone branches numbers (3, 4, 5), opening angles (30°,45°,60°,90°) and leaving fruiting branches (8-20). The experimental results showed that the radial distribution of three backbone branches and five backbone branches was able to effectively improve the light by two or three times compared to control. The yield and light intensity of four backbone branches were lowest. The yield of five backbone branches declined at a rate of 25% year by year. However the yield of three backbone branches showed a steady-state trend for several years. As for opening angles, the yield of the 90° treatment was highest in 2013 but decreased in a rate of 50% after first year, suggesting a premature aging phenomenon. With the treatment of 45° opening angle for three years, the annual yield was lowest. The 60° opening angle treatment had stable yield and light intensity and was the best among the all treatments. As for the fruiting branches, the treatment of 16-18 fruiting branches contributed to the highest yield of 347 g[DK]·m-2.[Conclusion] In general,three backbone branches, 60° opening angle and leaving 16-18 fruiting branches per m2 crown projection area could most effectively improve light intensity and the yield by one or two times, which is consistent with the results of two-factor interaction validation. The findings suggest that standardizing, gardening, intensive cultivation techniques system should be all combined with selecting excellent-genetic S.mukorossi and highly efficient and intensive techniques, so as to form an integrate tree management technology to enhance feedstock forest's production.

Key words: Sapindus mukorossi, biomass feedstock forest, canopy light intensity, training and pruning, tree management

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