供磷水平及方式对杉木幼苗根系生长和磷利用效率的影响

为研究杉木幼苗根系生长、形态学指标及养分利用效率对土壤磷素异质分布的响应规律,选择杉木种子园单株采种培育的半同胞家系实生幼苗为研究对象,采用室内沙培控磷盆栽试验,设计低浓度供磷(8 mg/kg KH₂PO₄)、正常供磷(16 mg/kg KH₂PO₄)和高浓度供磷(32 mg/kg KH₂PO₄)3个供磷水平,每个供磷水平分别采用2种供磷方式(局部供磷和均匀供磷)进行根部施磷。结果表明:(1)从供磷水平来看,低浓度供磷下的杉木根长、根系生物量、根冠比、根系及全株的磷素利用效率均显著大于正常供磷和高浓度供磷,而根平均直径相反;随着供磷水平的提高,杉木苗高和地上部生物量无显著差异,而比根长表现出逐渐降低的趋势。(2)从供磷方式来看,局部供磷处理的杉木苗高、根长、根系表面积、比根长、地上部生物量、根系及全株的磷素利用效率均显著大于均匀供磷处理,而根平均直径和根冠比则相反。总体上,低浓度局部供磷处理下杉木可明显增强其根系的形态可塑性,从而优化根系在养分异质土壤里的...

Effects of phosphorus supply levels and methods on root growth and phosphorus use efficiency of Chinese fir seedling

The objective of this study was to examine the response of root traits, morphological indexes, and nutrient use efficiency of Chinese fir seedlings to heterogeneous distribution of available phosphorus (P) in soil. Seedlings of half-sib family cultivated in single seed plantation of Chinese fir seed orchard were selected as research material, and indoor pot experiments were conducted. The pot experiments involved three P supply levels including low (8 mg/kg), normal (16 mg/kg), and high P treatment (32 mg/kg). Two kinds of P supply methods (heterogeneous and homogeneous P supply) of each P supply level were used to apply P to roots of single plants. The results showed that:1) root length, root biomass, root-shoot ratio, root and whole plant P use efficiency of Chinese fir under low P supply were significantly higher than those under the normal or high P supply, while average root diameter was the opposite. With the increase of P supply level, there was no significant difference in seedling height and aboveground biomass of Chinese fir, but the specific root length showed a decreasing trend. 2) The seedling height, root length, root surface area, specific root length, aboveground biomass, and whole plant P use efficiency were significantly higher in the heterogeneous P supply treatment than those in the homogeneous P supply treatment, while the average root diameter and root-shoot ratio were the opposite. In conclusion, the morphological plasticity of Chinese fir roots could be significantly enhanced under low concentration and heterogeneous P supply, thus optimizing the spatial distribution of roots in nutrient-heterogeneous soils, and maintaining the normal growth of shoots by improving the P use efficiency of roots.