土壤石砾含量对掌叶木幼苗生长和根系特征的影响

Influence of gravel content of soil on growth and root characteristics of Handeliodendron bodinieri seedlings

为探讨土壤石砾含量对珍稀濒危植物掌叶木幼苗生长和根系的影响,该研究以1个月生掌叶木幼苗为试验材料,进行5种不同土壤石砾含量[0(CK),20%,40%,60%和80%]盆栽试验,筛选最适宜掌叶木幼苗生长的土壤石砾含量。结果表明:(1)土壤石砾含量对掌叶木幼苗生长有极显著影响,其中幼苗苗高和地径相对增长率、叶面积、苗木质量指数、生物量(根、叶和全株)和根冠比均在土壤石砾含量为40%时最大。(2)土壤石砾含量对掌叶木幼苗根系形态具有极显著影响,总根长和根表面积在土壤石砾含量为40%时最大;而根系平均直径随石砾含量增加逐渐减小,当土壤石砾含量高达80%时,根系平均直径最小。(3)土壤石砾含量对掌叶木幼苗根系拓扑结构和分形特征无显著影响,而对根系平均连接长度和分叉数有极显著影响,其中各处理根系拓扑指数(TI)、修正拓扑指数(q_(a)和q_(b))均趋近于1,即掌叶木幼苗根系在不同土壤石砾含量中分支模式更趋近于鱼尾形分支;根系平均连接长度随石砾含量增加先增大后减小,在土壤石砾含量40%时最大;根系分叉数随石砾含量增加逐渐减小。(4)综合评价幼苗生长和根系形态与构型指标表明,掌叶木幼苗在40%土壤石砾含量中地下根系和地上茎叶生长状况最好。因此,土壤添加适量石砾能促进掌叶木幼苗生长,当石砾含量为40%时幼苗生长效果最好,苗木质量指数最高,最适宜掌叶木幼苗生长。

In order to explore the influence of gravel content of soil on the growth and root of the rare and endangered plant Handeliodendron bodinieri seedlings,one month age of H.bodinieri seedlings were used as materials and five pot experiments with different soil gravel contents[0(CK),20%,40%,60%and 80%]were carried out and the most suitable soil gravel content for the growth of H.bodinieri seedlings were selected.The results were as follows:(1)The gravel content of soil had a highly significant influence on the growth of H.bodinieri seedlings.Seedling height and ground diameter of relative growth rate,leaf area,seedling quality index,biomass(root,leaf and whole plant)and root-shoot ratio were all maximum when gravel content was 40%.(2)The gravel content of soil had a very significant influence on root morphology of H.bodinieri seedlings.The total root length and root surface area all reached the maximum when gravel content was 40%.However,the root average diameter decreased with the increase of the gravel content,and reached the minimum when the gravel content of soil was 80%.(3)The gravel content of soil had no obvious influence on root topological architecture and fractal characteristic of H.bodinieri seedlings,but had very significant influence on root average link length and root forks numbers.Root topological index(TI),modified topological index(q_(a),q_(b))all tended to be one in every treatment,so the branching pattern of the roots of H.bodinieri seedlings was close to fishtail branching in different gravel contents of soil.The root average link length increased first and then decreased with the increase of gravel content,and reached the maximum at 40%gravel content.The root forks number of H.bodinieri seedlings showed a gradually decreasing growth trend with the increase of gravel content.(4)According to the results of comprehensive evaluation of the seedlings growth,root morphology and architecture,H.bodinieri seedlings had the best growth status when the gravel content of soil was 40%.Therefore,adding a suitable amount of gravel in the soil can promote the growth of H.bodinieri seedlings.The seedling growth status and seedings quality index were the best under the treatment of gravel content of 40%.