Effects of different application modes of phosphorus-solubilizing bacterial fertilizer on seedling root growth and phosphorus nutrition of Pinus massoniana families

Abstract

In order to study the effect of different application modes of phosphorus-solubilizing bacterial fertilizer (PSB fertilizer) on seedling phosphorus nutrition of Pinus massoniana, a pot inoculation experiment with local and evenly application of PSB fertilizer was set up. We studied the responses of P uptake and root growth of different P. massoniana families under different PSB fertilizer treatments through using WinRHIZO Pro STD1600+ root image analysis software and Molybdenum antimony colorimetric method. The results were as follows: (1)Inoculating PSB fertilizer had a significant effect on growth of P. massoniana seedlings. The main growth indexes, such as seedling height, ground diameter, root dry matter weight, root/shoot and whole plant dry matter weight, significantly increased under local treatment. (2)Local treatment significantly increased the root length, root surface area, root volume and root tip number of seedlings. The root length of 0<root diameter (D)≤0.5 mm fine roots under local treatment was nearly three times of that under evenly treatment. Differences of root growth were related to the heterogeneous distribution of soil P caused by localized application of PSB fertilizer under the two treatments. (3) Inoculating PSB fertilizer significantly increased the P uptake of root, stem, leave and whole plant, and the local treatment was significantly higher than evenly treatment. Correlation analysis showed that P uptake of seedlings was significantly positively correlated with root morphological parameters and root length of D≤1.0 mm. This indicated that local treatment promoted P uptake by inducing root growth. (4)Due to the genetic background, the families of P. massoniana showed different performance under application of PSB fertilizer. The low phophorus tolerance provenance No. 22 was a much sensitive family, and all growth indexes were significantly higher than those of No. 10 and No. 50 families. In conclusion, local application of PSB fertilizer significantly promoted the growth and P uptake of P. massoniana families under low P environment, and this study provides guidances for the management of P. massoniana plantation under P poor sites.

Keywords

• psb fertilizer
• pinus massoniana family
• low p environment
• root growth
• p uptake