ABSTRACT
To investigate the interaction between Pinus tabuliformis and root microorganisms and its effects on the stability of P. tabuliformis forests, we collected rhizosphere and non-rhizosphere soil from natural and planted P. tabuliformis forests in Huanglong County of Shaanxi Province. The non-rhizosphere soil was used to analyze chemical properties, while the rhizosphere soil was used to isolate and purify phosphorus-solubilizing (organic and inorganic phosphorus) bacteria. We mea-sured the phosphate-solubilizing ability and identified those bacteria using DNA genes sequencing. The results showed that soil total carbon concentration (TC), total nitrogen concentration (TN), carbon:nitrogen (C/N), and nitrogen:phosphorus (N/P) were significantly higher in natural forest than those in the plantation. A total of 20 genera and 65 species of phosphate-solubilizing bacteria were identified in those two forests, with Bacillus, Streptomyces and Pseudomonas as the dominant group. The diversity, richness, and evenness of phosphate-solubilizing bacteria in the natural forest were higher than that in the planted forest, but dominance was lower. Streptomyces was positively correlated with soil TC, TN, C/N and N/P ratios, while Bacillus and Pseudomonas were positively correlated with soil nitrate (NO3-), ammonium (NH4+), available phosphorus (AP), and total phosphorus (TP). The solubilizing ability of phosphate-solubilizing bacteria was different between two forest types, indicating that Pseudomonas sp.34-5 shared in two forests had the strongest phosphate-solubilizing ability for calcium phosphate with 11.40 µg·mL-1 and Bacillus mycoides BF1-5 exclusive to natural forest had the strongest phosphate-solubilizing ability for lecithin with 4.58 µg·mL-1. The composition and structure of phosphorus-solubilizing bacterial community were different in two forest types, with higher diversity, richness and phosphate-solubilizing ability in natural forest than that in plantation.
Subject(s)
Pinus , Rhizosphere , Bacillus , Bacteria/genetics , China , Forests , Phosphates , Soil , Soil MicrobiologyABSTRACT
The continuous cropping obstacles caused by the increase of kiwifruit planting period resulted in imbalance of soil microbial community structure, and decrease of soil enzyme activity and physicochemical indicators, which substantially reduced both the quality and yield of kiwifruit. Under the field conditions, the traditional fertilization of fruit farmers was used as a control (CK) to study the effects of two different microbial fertilizers, JF and KF, which had been verified the growth promotion of kiwifruit aseptic seedlings test, on soil microbial community structure, soil enzyme activities, soil physicochemical characters during different growth periods of kiwifruit (germination period, florescence period, fruit enlargement period, fruit ripening period and next year germination period), as well as fruit quality. The results showed that both fertilizers significantly increased the ratio of bacteria with fungi and the ratio of actinomycetes with fungi in the kiwifruit orchard soil, indicating that they could improve and balance the soil microbial community structure. The enzymes activity in kiwifruit orchard soil with the addition of both fertilizers were significantly higher than that in CK, and among which sucrose, urease, phosphatase and polyphenol oxidase were increased by 17.9%-83.5%, 7.9%-83.0%, 7.3%-45.4% and 8.1%-140.3%, respectively. JF and KF increased soil fertility (the concentrations of available nitrogen, phosphorus, potassium, total nitrogen, total phosphorus, total potassium, and organic matter content significantly increased) and decreased soil pH (a decrease of 0.29 to 0.34). After application of microbial ferti-lizer, the content of vitamin C, soluble sugar, soluble protein and other contents of kiwifruit increased, and the titratable acid content decreased. Therefore, the application of both fertilizers could balance soil microbial community structure, enhance soil fertility, and improve the fruit quality of kiwifruit. Our results provide robust theoretical basis for the application of microbial fertilizers in the old-aged kiwifruit orchards.
