Abstract

The enhancement of phosphorus (P) acquisition through deep P application has been documented in crops with fibrous root systems, but little is known about this effect on the morphology of a taproot system. A four-year field experiment with P application was conducted using Platycodon grandiflorum with a taproot system as the experimental material at two P rates of 40 and 60 kg ha⁻¹ with middle and deep P application patterns. The biomass and P accumulation of P. grandiflorum were greater with deep P application than with middle P application at the same P rate. Regardless of whether the root diameter being greater or less than 2 mm, the root length, volume and surface area of P. grandiflorum increased due to P application, and they were greater with deep P application than with middle P application at the same P rate. Four-year consecutive P application increased the concentrations of soil NaHCO₃-P, HCI-P, NaOH-P and residual-P, resulting in soil P accumulation, especially HCI-P. This is the first report that deep P application was more favorable to the growth of P. grandiflorum with a taproot system than middle P application. And this research provided evidence that deep phosphorus application is also suitable to crops with a taproot system.

摘要

已经在具有纤维根系统的作物中记录了通过深施磷来增强磷 (P) 的获取，但对这种对主根系统形态的影响知之甚少。使用具有主根系统的桔梗作为试验材料，以 40 和 60  kg ha ^-1两种磷肥施用量进行了为期四年的磷肥田间试验，并采用中深磷肥模式。相同施磷量下，深施磷的大花生物量和磷积累量大于中施磷。无论根径大于或小于 2  mm，大花的根长、体积和表面积由于施磷而增加，并且在相同的施磷率下，深施磷大于中施磷。连续4年施磷增加了土壤NaHCO ₃ -P、HCI-P、NaOH-P和残留P的浓度，导致土壤P积累，尤其是HCI-P。这是首次报道深施磷比中施磷更有利于主根系统桔梗的生长。而这项研究提供的证据表明，深施磷也适用于具有主根系统的作物。