不同树形油茶无性系发枝及光合特性研究

Research on Branching and Photosynthetic Utilization of Oil-tea Camellia with Different Tree Shapes

研究了不同树形油茶无性系的发枝和光合特性及对修剪处理的响应。结果表明:供试油茶无性系的树形指数介于0.72 1.33之间,树形指数大小顺序为长林175号>长林40号>长林53号>长林4号>长林46号,长林175号、长林40号无性系树形直立,长林4号和长林46号无性系树形开张,长林53号无性系居中。与树冠下层和内层相比,树冠上层的新梢发枝量、新梢长度、新叶比、叶片净光合速率(Pn)和叶片水分利用效率(WUE)较高,且随着树形指数增大,新梢长度、新叶比、叶片净光合速率(Pn)和叶片水分利用效率(WUE)总体上表现出先升高后下降的趋势,树冠不同部位的新梢发枝量、新叶比差异逐渐变大,新梢长度的差异减小,树形指数居中的长林53号无性系新梢长度、新叶比和叶片净光合速率(Pn)最高。油茶无性系冠层反射率(Re)的日变化表现出先下降后上升的趋势,冠层截获率(In)则表现出先升高后下降趋势,树形直立的长林175号无性系冠层反射率(Re)最高,冠层截获率(In)较低,树形开张的长林4号无性系冠层反射率(Re)较低,冠层截获率(In)较高。修剪处理显著降低了树形直立的油茶无性系新梢发枝量,并提高了树形开张的无性系新梢发枝量和树冠内层新梢长度;修剪处理还降低了冠层截获率(In),显著提高了冠层内部叶片的净光合速率(Pn)和水分利用效率(WUE)。研究结果为油茶栽培、修剪管理以及优良油茶资源的发掘利用提供了技术依据。

The branching, photosynthetic utilization and the response to pruning of oil-tea camellia （ Camellia oleif- era Abel. ） with different tree shapes were studied. The results showed that the tree shape index of selected oil - tea camellia clones was between 0.72 and 1.33 in the sequence of ＇ changlin175＇ 〉 ＇ changlin40＇ 〉 ＇ changlin53＇ 〉 ＇ changlin4＇ 〉 ＇ changlin46＇. The tree shape of ＇ changlin175＇ and ＇ changlin40＇ belonged to upright type due to their higher tree shape index and the ＇ changlin4＇ and＇ changlin46＇ were open type. ＂changlin53＂ was moderate. The branching number, length of shoot, new leaves ratio, net photosynthetic rate and water use efficiency （WUE） were higher in the upper layer of canopy than that in lower and inner layer of canopy. With the increase of tree shape index, the length of shoot, new leaves ratio, net photosynthetic rate and WUE increased at initial stage and then decreased, and the difference of branching number, new leaves ratio among different parts of canopy became bigger, while the difference of shoot length became smaller. The length of shoot, new leaves ratio, net photosynthetic rate were the highest in ＇ changlin53＇ whose tree shape index was moderate. The diurnal variation of PAR reflectivity in oil-tea camellia showed an upward trend after the first drop and the diurnal variation of PAR interception rate was opposite. The upright type ＇ changlin175＇ showed higher PAR reflectivity and lower PAR interception rate than that of open type ＇ changlin4＇. The branching number of upright type oil-tea camellia clones decreased significantly, while the branching number and shoot length of inner layer canopy of open type oil-tea camellia clones increased significantly after the treatment of pruning. The PAR interception rate decreased and the net photosynthetic rate and WUE of inner layer canopy increased apparently after pruning treatment.