Soil Health: Integrating Plant Roots–Plant Nutrition–Soil Microbiota Interactions

Rock zones have an important influence on the yield and quality of Wuyi rock tea. In this study, OPLS-DA combined with machine learning was used to analyze the effects of different rock zones and tea tree varieties on the physicochemical properties of rhizosphere soil, the growth of the tea tree and the quality of the tea leaves using tea trees in different rock zones. The results showed that rock zones had significant effects on rhizosphere soil physicochemical indexes, soil enzyme activities, tea tree growth and tea quality indexes, while there was little difference between different tea tree varieties. The interaction analysis showed that the physicochemical indexes of rhizosphere soil in different rock zones significantly affected tea quality, while also affecting growth indexes. The main indexes affecting tea yield and caffeine content were soil pH, available nitrogen, total phosphorus, total nitrogen and available phosphorus, while the main indexes affecting tea quality were available potassium, organic matter, total potassium, protease, polyphenol oxidase and urease. Analyses of PCA, OPLS-DA models and KNN and ANN machine learning showed that different rock zones could be effectively distinguished from each other with 100% accuracy, while different tea varieties had little difference and could not be distinguished. TOPSIS analysis found that the physicochemical indexes most affected by rock zone were available nitrogen, available potassium and sucrose, and the quality indexes most affected by rock zone were tea polyphenols and theanine. The growth index most affected by rock zone was tea yield. It was evident that the key difference between tea trees in different rock zones was yield and quality, with high yields in continent zones, and good quality in semi-rock zones and rock zones. This study provides a crucial foundation for tea-plantation management, the artificial regulation of tea yield and the quality of different rock zones of Wuyi rock tea. Full article

Radix pseudostellariae is one of the well-known genuine medicinal herbs in Fujian province, China. However, the continuous cropping obstacles with respect to R. pseudostellariae have seriously affected the sustainable utilization of medicinal resources and the development of related industrial systems. The occurrence of continuous cropping obstacles is a comprehensive effect of multiple deteriorating biological and abiotic factors in the rhizosphere soil. Therefore, intensive ecological methods have been the key to abating such obstacles. In this study, four treatments were set up, i.e., fallow (RP-F), fallow + bacterial fertilizer (RP-F-BF), rice-paddy-upland rotation (RP-R), and rice-paddy-upland rotation + bacterial fertilizer (RP-R-BF), during the interval between two plantings of R. pseudostellariae, with a newly planted (NP) treatment as the control. The results show that the yield of R. pseudostellariae under the RP-F treatment decreased by 46.25% compared to the NP treatment. Compared with the RP-F treatment, the yields of the RP-F-BF, RP-R, and RP-R-BF treatments significantly increased by 14.11%, 27.79%, and 62.51%, respectively. The medicinal quality of R. pseudostellariae treated with RP-R-BF was superior to that achieved with the other treatments, with the total saponin and polysaccharide contents increasing by 8.54% and 27.23%, respectively, compared to the RP-F treatment. The ecological intensive treatment of RP-R-BF significantly increased the soil pH, content of organic matter, abundance of beneficial microbial populations, and soil enzyme activity, thus remediating the deteriorating environment of continuous cropping soil. On this basis, the ecological intensive treatment RP-R-BF significantly increased the activity of protective enzymes and the expression levels of genes related to disease and stress resistance in leaves and root tubers. Redundancy and Pearson correlation analyses indicated that rice-paddy-upland rotation improved the soil structure, promoted the growth of eutrophic r-strategy bacterial communities, enhanced compound oxidation and reduction, broke the relationship between the deteriorating environment and harmful biological factors, and eventually weakened the intensity of harmful factors. The subsequent application of bacterial fertilizer improved the beneficial biological and abiotic factors, activated various ecological functions of the soil, enhanced the ecological relationship between various biological and abiotic factors, and reduced the stress intensity of R. pseudostellariae, thereby improving its disease and stress resistance, and ultimately reflecting the recovery of yield and quality. The results indirectly prove that the intensive ecological amelioration of the soil environment was the main factor for the yield recovery of R. pseudostellariae under continuous cropping. Full article

This study explores the interaction between pear fruit quality and the soil environment over four different planting years (5, 20, 30, and 40 years), focusing on the fruit’s chemical properties, rhizosphere soil properties, microbial communities, and both microbiomass and functional diversity. The results found that reducing sugar, sucrose, and vitamin C contents in pears initially increased with planting years before declining, while total acidity showed an inverse trend. Analysis of the soil physicochemical index revealed that rhizosphere soil physicochemical indexes were significantly different between different planting years, but there was no obvious regularity. Correlation analysis found that total phosphorus, total potassium, organic matter, and available nitrogen were significantly and positively correlated with pear quality indexes. Soil microbiomass carbon decreased before increasing with increasing planting year, while soil microbial nitrogen was irregular. Results of functional diversity of rhizosphere soil bacterial communities showed that the relationship of carbon source utilization among the six groups was 20 years > 5 years > 30 years > 40 years. Interestingly, the 20-year group had the most core differences in microbial communities. The study suggests that as pear trees age, adequate plant nutrition during peak fruiting periods can improve soil fertility, microbial functional diversity, and ultimately enhance fruit quality. Full article

Pruning is an agronomic practice that contributes to tea tree yield during cultivation, but little is known about how pruning improves yield through shifting bacterial communities in rhizosphere soil. Therefore, Meizhan tea (Camellia sinensis) was used as the research object to analyze the effect of unpruning and pruning on the growth and rhizosphere soil physicochemical indexes of the tea tree, and sequencing technology was used to obtain the diversity of soil bacterial communities. The results showed that leaf area, hundred bud weight and yield of pruned tea trees increased by 1.32, 1.40, and 1.84 times, respectively, and pH and available N, available P, and available K contents increased by 1.10, 1.07, 1.30, and 1.07 times, respectively, compared with unpruned treatment, while total N, total P, and total K contents decreased by 1.20, 1.37, and 1.13 times, respectively. Analysis of the bacterial community structure showed that the key differential bacteria between pruned and unpruned tea trees were Candidatus Solibacter, Acidibacter, Rhizomicrobium, Bryobacter, Solanum torvum, Mizugakiibacter, Nitrospira, Sphingomonas, and Granulicella. Among them, the bacterial abundance of Candidatus Solibacter, Bryobacter, and Nitrospira showed an upward trend and the rest showed a downward trend after pruned treatment. Interaction network analysis showed that the correlation between the total key genera of microorganisms and organic matter, total N, total K, and total P content in rhizosphere soil did not reach a significant level, whereas the correlation with soil available N, available K, available P, pH, and tea tree growth indexes were all positively and significantly correlated. It can be seen that pruning changed the structure of the rhizosphere soil microbial community of tea trees, promoted soil nutrient transformation, increased the content of soil available nutrients, and promoted the growth of tea tree. Full article

In order to fully comprehend the impact of soil acidification on the quality of tea, further analyses are essential and are of the utmost importance to the cultivation of tea trees and the simultaneous enhancement of tea quality. In May 2022, Tieguanyin tea trees planted in soils with different pH levels were selected as the research object of this study to analyze the effect of soil pH on the soil chemical index, soil fertility and the aroma quality of tea leaves. The results showed that the organic matter content, cation exchange capacity and the available nitrogen, available phosphorus and available potassium contents in the rhizosphere soil of the tea trees decreased significantly with decreasing soil pH levels (5.32–3.29), while the total nitrogen, total phosphorus and total potassium contents did not change significantly. The results of an aroma quality analysis showed that the aroma of the Tieguanyin tea was mainly floral, and the formation of floral odor characteristics was mainly derived from geraniol. The results of an interaction network analysis showed that the soil chemical indexes were significantly positively correlated with geraniol and floral aromas except for the total phosphorus and total potassium contents. In conclusion, with a decrease in the pH of soil, the soil’s cation exchange capacity, organic matter content and available nutrient content showed decreasing trends which, in turn, hindered the synthesis of geraniol and reduced the floral odor characteristics of tea leaves. Full article