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Magnesium levels in relation to rates of preterm birth: a systematic review and meta-analysis of ecological, observational, and interventional studies.
Zhang, Y, Xun, P, Chen, C, Lu, L, Shechter, M, Rosanoff, A, He, K
Nutrition reviews. 2021;(2):188-199
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Abstract
CONTEXT Experimental studies suggest that magnesium levels in pregnant women may affect the length of gestation, as magnesium affects the activity of smooth muscle in the uterus. Little is known about the association between magnesium levels or supplementation and the rate of preterm birth. OBJECTIVE The aim of this systematic review was to summarize the data on magnesium soil levels and preterm birth rates from ecological, observational, and interventional studies. DATA SOURCES Soil magnesium levels were obtained from US Geological Survey data, and preterm birth rates were acquired from the March of Dimes Foundation. Relevant epidemiological and clinical studies published until April 2019 in peer-reviewed journals were retrieved from PubMed, Google Scholar, and related reference lists. STUDY SELECTION Original studies published in English, conducted in humans, and in which magnesium (dietary/supplemental intake or biomarkers) was an exposure and preterm birth was an outcome were included. DATA EXTRACTION Eleven studies were included in the systematic review. Meta-analysis was performed on 6 studies. Overall relative risk (RR) and corresponding 95%CIs for risk of preterm birth in relation to magnesium supplementation were estimated by a random-effects model. RESULTS The ecological study revealed an inverse correlation between magnesium content in soil and rates of preterm birth across the United States (r = -0.68; P < 0.001). Findings from 11 observational studies generally support an inverse association between serum magnesium levels and rates of preterm birth. Of the 6 eligible randomized controlled trials, which included 3068 pregnant women aged 20 to 35 years and 352 preterm infants, the pooled RR was 0.58 (95%CI, 0.35-0.96) for women in the magnesium supplementation group compared with women in the control group. CONCLUSIONS Accumulated evidence from ecological, observational, and interventional studies consistently indicates that adequate magnesium intake during pregnancy may help reduce the incidence of preterm birth.
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Clonal integration enhances the performance of a clonal plant species under soil alkalinity stress.
Zhang, W, Yang, G, Sun, J, Chen, J, Zhang, Y
PloS one. 2015;(3):e0119942
Abstract
Clonal plants have been shown to successfully survive in stressful environments, including salinity stress, drought and depleted nutrients through clonal integration between original and subsequent ramets. However, relatively little is known about whether clonal integration can enhance the performance of clonal plants under alkalinity stress. We investigated the effect of clonal integration on the performance of a typical rhizomatous clonal plant, Leymus chinensis, using a factorial experimental design with four levels of alkalinity and two levels of rhizome connection treatments, connected (allowing integration) and severed (preventing integration). Clonal integration was estimated by comparing physiological and biomass features between the rhizome-connected and rhizome-severed treatments. We found that rhizome-connected treatment increased the biomass, height and leaf water potential of subsequent ramets at highly alkalinity treatments but did not affect them at low alkalinity treatments. However, rhizome-connected treatment decreased the root biomass of subsequent ramets and did not influence the photosynthetic rates of subsequent ramets. The biomass of original ramets was reduced by rhizome-connected treatment at the highest alkalinity level. These results suggest that clonal integration can increase the performance of clonal plants under alkalinity stress. Rhizome-connected plants showed dramatically increased survival of buds with negative effects on root weight, indicating that clonal integration influenced the resource allocation pattern of clonal plants. A cost-benefit analysis based on biomass measures showed that original and subsequent ramets significantly benefited from clonal integration in highly alkalinity stress, indicating that clonal integration is an important adaptive strategy by which clonal plants could survive in local alkalinity soil.
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Plant-plant-microbe mechanisms involved in soil-borne disease suppression on a maize and pepper intercropping system.
Yang, M, Zhang, Y, Qi, L, Mei, X, Liao, J, Ding, X, Deng, W, Fan, L, He, X, Vivanco, JM, et al
PloS one. 2014;(12):e115052
Abstract
BACKGROUND Intercropping systems could increase crop diversity and avoid vulnerability to biotic stresses. Most studies have shown that intercropping can provide relief to crops against wind-dispersed pathogens. However, there was limited data on how the practice of intercropping help crops against soil-borne Phytophthora disease. PRINCIPAL FINDINGS Compared to pepper monoculture, a large scale intercropping study of maize grown between pepper rows reduced disease levels of the soil-borne pepper Phytophthora blight. These reduced disease levels of Phytophthora in the intercropping system were correlated with the ability of maize plants to form a "root wall" that restricted the movement of Phytophthora capsici across rows. Experimentally, it was found that maize roots attracted the zoospores of P. capsici and then inhibited their growth. When maize plants were grown in close proximity to each other, the roots produced and secreted larger quantities of 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) and 6-methoxy-2-benzoxazolinone (MBOA). Furthermore, MBOA, benzothiazole (BZO), and 2-(methylthio)-benzothiazole (MBZO) were identified in root exudates of maize and showed antimicrobial activity against P. capsici. CONCLUSIONS Maize could form a "root wall" to restrict the spread of P. capsici across rows in maize and pepper intercropping systems. Antimicrobe compounds secreted by maize root were one of the factors that resulted in the inhibition of P. capsici. These results provide new insights into plant-plant-microbe mechanisms involved in intercropping systems.
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[Effects of soil root-growing space on root physiological characteristics and grain yield of sorghum].
Zhang, Y, Miao, G
Ying yong sheng tai xue bao = The journal of applied ecology. 2006;(4):635-9
Abstract
In this paper, soil culture was conducted on the Experimental Farm of Shanxi Agricultural University, with the sorghum planted in cylindrical nylon bags to confine the space of root growth but allow the pass-through of water and nutrients, aimed to study the effects of soil root-growing space on the root physiological characteristics and grain yield of sorghum. The results showed that the confinement of root growth space decreased the plant height, leaf area, SOD and POD activities in flag leaf, total root length, root absorbing area, dry weights of root and aboveground part, nutrient uptake and grain yield, but increased the activity of root and its active absorbing area. Fertilization stimulated the root growth under space stress, increased the activity of root and its absorbing area, promoted nutrient uptake, and thus, increased grain yield while decreased the detrimental effects derived from the confine of root growth space.
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[Spatial variability of farmland soil nutrients at Taihang piedmont].
Zhang, Y, Mao, R, Hu, C, Zhang, J, Zhu, A
Ying yong sheng tai xue bao = The journal of applied ecology. 2004;(11):2049-54
Abstract
By the method of geostatistics, this paper studied the spatial variability of soil nutrients in 30,490 hm2 crop field in Luancheng region and in 15 hm2 experimental field in Luancheng Ecological Agriculture Station of Chinese Academy of Sciences. The results showed that the variation of soil nutrient contents differed obviously, and the semivariograms could be simulated by Gaussian and spherical models with some nugget variances. The limit distance of spatial correlation was 4.2-15.6 km and 112-223 m in Luancheng region and in experimental field, respectively, and the spatial variability of soil organic matter, N, P and K was of semivariance structure. It revealed that there existed a spatial correlation in soil nutrient contents under relatively large-block scale, which made it possible to develop regionalized soil nutrient precision management.
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[Research advance in catalytic kinetics of soil hydrolase].
Zhang, Y, Chen, L, Liu, G, Wu, Z
Ying yong sheng tai xue bao = The journal of applied ecology. 2003;(12):2326-32
Abstract
Soil hydrolase is a group of soil enzymes that participated in many important biochemical reactions in soil and correlated with soil nutrient transformations. The catalytic kinetics of soil hydrolase can illuminate the characteristics of its catalytic processes, its substantial properties, and its response to environmental changes. This paper summarized the kinds of soil hydrolase and the main soil biochemical reactions they catalyzed, and summed up the research advances of their catalytic kinetics in soil. Some advices were proposed in understanding their action mechanism and in regulating their catalytic processes.