Effect Of Fertilization On Morphological Structure And Photosynthetic Capacity Of Phyllostachys Pubescens

Phyllostachys pubescens is one kind of bamboos,which with the widest distribution and largest covering area,gather with good economic,ecologic,and social benefits on it.In this paper,taking bamboo in different fertilizer application modes as the research object,some indices including leaf size, weight,chlorophyll content and photosynthetic rate are dynamically determined base on its growth rhythm,and its culm structure and biomass are also measured.The influence of fertilization to the Ph. pubescens leaf characteristic,distribution and photosynthetic character,its culm structure and productivity are studied,the interior law and mechanism are discussed,expecting to provide theory basis for the scientific fertilization of bamboo forest.The main results are as follows.1.Mature single-leaf area is 818-815mm²,and the thousand-leaf weight is 100-110 g, fertilization had no notable influence on single-leaf area,thousand-leaf weight and leaf distribution: Fertilization has promoted the differentiation of bud,significantly increased the total weight and size of a tree and the forest,all leaves weight in a bamboo tree is 4.620 kg in the mode of fertilization in leaf-expansion period(treatment 1),more than fertilization in August(treatment 2) by 14,8%,and more than no fertilizer treatment(CK) by 27.6%.Fertilization significantly increased leaf area index(LAI) of bamboo forest,LAI is stable untill July,when treatment 1 is 7.67,higher than treatment 2 by 14.5%, higher than CK by 23.9%,the increase of LAI was due to the increase of the number of leaves.Leaf distribution in its canopy fit Peal-Reed one dollar non-linear recession model,the weight of leaves in 14—17 branches is the heaviest,fertilization make the weight of the leaves in each branch increase.The comparison of each branch is treatment 1> treatment 2>CK,three treatments have significantly difference.2.Culm structure of bamboo shows that the height of the culm is between 12.45 m and 12.88 m, the weight is between 28.00 kg and 30.09 kg when its diameter at breast height(DBH) is 10.97 cm (covariance corrected).The distribution law of weight and wall thickness to height severally show logarithm curve mode and Morgan Mercer Florin mode,both of which were not affected by the fertilization.Fertilization had no influence on culm height and degree of sharpness,but notably reduce the weight of bamboo culm,clear bole height and node number.3.A mean value of SPAD of the treatment 1 in its growing season(between May and Dec) is 38.5,more than treatment 2 by 6.7%,than CK by 15.9%.4.Maximum photosynthetic rate(Pmax) of bamboo is between 9.05-12.97μmolm^-2s^-,and the light saturation point(LSP) is between 1320-1470μmolm^-2s^-1 in summer and autumn.Pmax and LSP in summer were significantly greater than that in autum though each fertilization mode has no significant difference.Daily mean water use efficiency(WUE) of treatment I in summer is 2.01 mmol-mol^-1.higher than treatment 2 by 11.91%,higher than CK by 22.7%.Daily mean WUE of treatment 1 in autum is 5.42 mmol-mol^-1,higher than treatment 2 by 7.1%,and higher than CK by 21.9%.The seasonal changing rhythm of photosynthetic rate in small year showes the double-peak curve,the average photosynthetic rate of treatment 1 is 7.35μmolm^-2s^-1,higher than 2 by 8.4%,higher than CK by 24.2%.5.Fertilization effectively increased the utilization of nutrients and forest productivity,it's better to fertilize in leaf-expansion period than that in August.In 2009,the number of new bamboo of treatment 1 is 70 per 600m²,more than treatment 2 by 19.2%,and more than CK by 44.2%:the average DBH of new bamboo of treatment 1 is 11.5 cm,larger than treatment 2 by 2.37%.and than CK by 4.59%.