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To analyze the effects of soil acidity on tea quality and the ability of soil nitrogen transformation, the tea leaves and tea tree rhizosphere soils were collected from 26-tea plantations and determined their contents of theanine and amino acids in tea leaves, the number of soil nitrogen transforming microorganisms and soil biochemical intensity. The results showed that the content of theanine and amino acid in tea leaves, the number of aerobic nitrogen-fixing bacteria and ammonifying bacteria in the soil and the nitrogen fixation intensity and ammonification intensity of the soil increased with the increase of pH value of tea tree rhizosphere soil. However, the number of soil nitrifying bacteria and denitrifying bacteria and soil nitrification intensity and denitrification intensity showed a downward trend. The results of principal component analysis showed that the contribution rate of principal component 1 and principal component 2 was 84.97 % and 7.57 %, respectively. In the soil with different acidity, the main contribution to differentiate the amino acid and theanine content in tea leaves came from the ability of soil for nitrogen fixation and ammonification as well as the ability of soil nitrification and denitrification. The results of correlation analysis showed that soil pH value was significantly positively correlated with theanine, amino acid, aerobic nitrogen-fixing bacteria, ammonifying bacteria, nitrogen fixation intensity and ammoniating intensity, while significantly negatively correlated with nitrifying bacteria, denitrifying bacteria, nitrification intensity and denitrification intensity. The intensification of soil acidity decreased the nitrogen fixation and ammonification activities and boosted nitrification and denitrification activities and decreased the quality of tea leaves. [ABSTRACT FROM AUTHOR]

We studied the effects of soil pH (3.29, 4.74 and 5.32) on nitrogen uptake and its use efficiency by tea bush. The results showed that with the increase of soil pH value (3.29 ~ 5.32), the nitrogen utilization efficiency of tea bushes increased from 94.28 % to 461.14 %, the nitrogen absorption efficiency increased from 1.05 % to 3.95 % and the nitrogen physiological utilization efficiency increased from 89.79 % to 116.74 %. Besides with the increase of soil pH, the activity of spoil enzymes (Urease, protease, asparaginase, N-acetamide glucose ribosidase) in tea rhizosphere soil was significantly increased, while, that of nitrate reductase and nitrite reductase was decreased significantly. With the increase of soil pH, the expression of nifH gene in tea rhizosphere soil increase significantly, while expression of amoA-AOA, amoA-AOB, nirK, nirS, narG and nosZ gene was decreased. Correlation analysis showed that pH value in tea rhizosphere soil was significantly and positively correlated with nitrogen utilization efficiency, nitrogen uptake efficiency, nitrogen physiological utilization efficiency, urease activity, protease activity, asparaginase activity, N-acetamide glucose ribosidase activity and the expression of nifH gene. Correlation analysis was negatively correlated with nitrate reductase activity, nitrite reductase activity and the expression of amoA-AOA, amoA-AOB, nirK, nirS, narG and nosZ gene. The results indicated that soil acidity significantly affected the ability of soil nitrogen conversion and nitrogen absorption and utilization ability of tea bushes. [ABSTRACT FROM AUTHOR]

We screened the fermentation broth of fungi from the rhizosphere soil of passion fruit (Passiflora edulis Sims.) for their herbicidal potential in bioassays and Pot culture. The potent herbicidal compounds of the fungi fermentation broth were evaluated by bioassay and pot test. The candidate substances in the fungi fermentation broth were analysed and identified. Nine fungi (No. 1, 2, 3, 4, 5, 6, 7, 8 and 9) were isolated from the rhizosphere soil of passion fruit using the plate dilution coating method. In Petriplate Bioassay, the fermentation broth of newly identified fungus Aspergillus sydowi 'FJFAFU01' drastically inhibited the growth of lettuce (Lactuca sativa) and barnyard grass (Echinochloa crus-galli). In Pot Culture, 50-times diluted fermentation broth inhibited the barnyard grass height by 42.73%. The HPLC and GC-MS analysis showed that the fermentation broth contained higher contents of nitrogenous compounds and oxygen compounds, including phenolic acids, terpenoids, flavonoids and alkaloids. The Aspergillus sydowi FJFAFU01 screened from the rhizosphere soil of passion fruit contained phenolic acids, terpenoids, flavonoids and alkaloids, these inhibited the growth of barnyard grass. Thus Aspergillus sydowi 'FJFAFU01' may be developed as potential mycoherbicide. [ABSTRACT FROM AUTHOR]

We studied the effects of soil nitrogen and pH in tea plantation soil on tea tree yield and quality in 90-tea plantations in Anxi county, Fujian province, China. The tea tree rhizosphere soil samples were collected for soil pH, ammonium nitrogen and nitrate nitrogen content from 90-tea plantations. The yield of tea tree and the contents of tea polyphenols, theanine and caffeine in tea leaves increased with the increase in soil pH. Secondly, as the soil pH increased, the content of ammonium nitrogen and the ratio of ammonium nitrogen to nitrate nitrogen in tea tree rhizosphere soil also increased, but the content of nitrate nitrogen decreased. Further the yield of tea tree and the contents of tea polyphenols, theanine and caffeine increased, with the increase in ratio of ammonium nitrogen to nitrate nitrogen in the soil. The pH of tea plantation soil was significantly positively correlated with the tea tree yield and quality, and the content of soil ammonium nitrogen, but negatively correlated with nitrate content in soil. This study provides basis for the scientific and rational use of nitrogenous fertilizers in tea plantations. [ABSTRACT FROM AUTHOR]