Subjects: Biology >> Botany >> Applied botany submitted time 2022-03-18 Cooperative journals: 《广西植物》
Abstract： In order to explore the relationship between the growth of Paris polyphylla var. chinensis and the microbial community structure changes of the rhizosphere soil, the Illumina high-throughput sequencing technique was used to sequence the 16S rRNA gene of bacteria and 18S sequences of fungal at four different growth years, including 3 years, 5 years, 7 years and 9 years. The results were as follows: (1) Proteobacteria, Acidobacteria, Actinobacteria and Chloroflexi were dominant bacteria in the rhizosphere soil of P. polyphylla in different growth years. The dominant fungi phylas were Ascomycota, Basidiomycota and Mucoromycota. (2) The bacterial species in the rhizosphere of Paris polyphylla in different growth years were more abundant than fungi, and the degree of diversification was higher. The lowest point of bacterial diversity, which decreased, increased, and then decreased again with the increase of growth years showed a pattern of “И”, was at the 5th year and the highest point was at the 7th year. The fungal diversity showed a pattern of “ Λ ” that first increased and then decreased with the increase of growth years, and the highest point was at the 7th year. The abundance of bacterial communities also showed a pattern of “Λ” that first increased and then decreased with the increase of growth years, and the highest point was also at the 7th year. The abundance of fungi did not change much as the year growing. (3) The UPGMA cluster analysis showed that the microbial community structure of the rhizosphere soil had evolved significantly. The period when the bacterial community evolved more drastically was in the 7th year after planting, and the fungal community was in the 5th. (4) Spearman correlation analysis found that total nitrogen and available potassium were the main factors affecting the composition of rhizosphere soil bacteria, and Total potassium was the main factor affecting the composition of fungi. All the above results indicate that the composition and structure of the soil microbial community in the rhizosphere of wild P. polyphylla at different growth and development stages are different, and the 5-7th year is a critical period for significant changes in the diverdity of the soil microbial community.
Subjects: Biology >> Botany >> Applied botany submitted time 2021-12-19 Cooperative journals: 《广西植物》
Abstract： Leaf chlorophyll content is central to carbon, water and energy exchange between the biosphere and the atmosphere, also to the terrestrial ecosystem function. Quantitative estimates of leaf chlorophyll content with hyperspectral imagery can provide scientific insight for assessing plant’s growth and stress as affected by abiotic and biotic factors. However, few studies have been conducted the application of spectral indices in estimation of leaf chlorophyll contents of plants in karst areas, especially in South China. After a review of the application of common spectral indices in estimation of leaf biochemistry parameters, we found that most of the common spectral indices were developed based on the difference, simple ratios, normalized difference and inverse difference formulation of leaf spectral reflectance. Therefore, we firstly measured the raw reflectance spectra of leaves from four typical karst species, namely Vitex negundo, Rhus chinensis, Celtis sinensis and Alchornea trewioides with a ASD Field Spec 4 (Analytical Spectral Devices, Inc., Boulder, Colorado, US) spectrometers. We then used the above-mentioned four formulations to process the raw reflectance spectra and their first-order derivative spectra. Finally, we analyzed the relation between leaf chlorophyll contents and relative leaf raw reflectance spectra and their first-order derivative spectra, and tried to propose the best spectral index for estimation leaf chlorophyll content of the plants of karst areas in South China. The results were as follows: (1) Among the common spectral indices, the modified normalized difference vegetation index (mND705) performed well in estimation leaf chlorophyll contents of four typical karst species in term of the determination coefficient (R2 was equal to 0.45) and root mean squared error (RMSE was equal to 0.26 mg•g-1). (2) However, most of the common spectral indices were not suitable for estimation leaf chlorophyll content of the plants in karst areas. Thought the prediction capability of fluorescence ratio index (FRI1) and chlorophyll absorption area index (CAAI) were almost the same in estimation of leaf chlorophyll content of plants in karst and non-karst areas, their accuracy of prediction was relative low according to the determination coefficient. (3) The spectral indices proposed in this study performed well in estimation leaf chlorophyll content of the plants in karst areas either based on the raw reflectance spectra or their first-order derivative spectra compared against others common spectral indices, especially for the difference spectral index based on the first-order derivative spectra (dD(760, 769)). Its determination coefficient was 0.71 and the root mean squared error was 0.19 mg•g-1. We, therefore proposed that the difference spectral index based on the first-order derivative spectra (dD(760, 769)) can be used for estimation leaf chlorophyll content of the plants in karst areas. Our results concluded that leaf chlorophyll content of plants in karst areas can be quickly and quantitatively estimated using spectral index combined with hyperspectral remote sensing data. These results can also provide scientific insights for estimating plants’ growth and their adaptation to environmental stress.
Subjects: Biology >> Botany >> Applied botany submitted time 2021-04-02 Cooperative journals: 《广西植物》
Abstract：叶片水分状况是反映植被生理状况的重要指标，构建高普适性的植物叶片含水率高光谱反演模型对准确评价岩溶和非岩溶植被生态功能具有重要意义。以我国西南典型区域内岩溶区与非岩溶区共 17 种植物 694 个样品为研究对象，同步测量叶片含水率和反射光谱，采用单波段、差值型、比值型、归一化型等四类光谱指数模型，对反射光谱及一阶导数光谱进行全波段搜索分析。结果表明：光谱指数 D 2048 -D 1733 的建模与验证结果均最好，为岩溶植物叶 片 含 水 率 的 最 佳 估 计 光 谱 指 数 ； 对 于 非 岩 溶 植 物 ， 光 谱 指 数 D 2356 /D 1885 和(D 2356 -D 1885 )/(D 2356 +D 1885 )建模与验证结果均相差很小，均可作为叶片含水率最佳估计模型；该研究结果还表明叶片绒毛对岩溶植物叶片含水率反演光谱指数构建影响不大。总体上，新构建的最优光谱指数对岩溶区与非岩溶区植物叶片含水率的拟合效果优于传统指数，具有较好的普适性，可为精准评估桂北地区植被水分状态提供科学依据。
Subjects: Biology >> Botany >> Applied botany submitted time 2019-08-27 Cooperative journals: 《广西植物》
Abstract：为探讨桉树不同林龄土壤微生物活性的响应特征，采用时空互代法，选择广西北部低山丘陵地区1~5 a生桉树人工林为研究对象，分析了土壤微生物、酶活性在不同土层和季节的变化规律。结果表明：(1)土壤微生物和酶活性在土层中有明显的垂直分布特征，均随土层加深而趋于降低，且各土层间差异显著。(2)细菌、放线菌数量随季节的大小顺序为秋季>夏季>春季>冬季，真菌的变化规律为春季>夏季>秋季>冬季，而酶活性随季节变化表现为夏、秋季活性较高，春、冬季活性较低。(3)细菌、真菌、脲酶、过氧化氢酶随林龄增大表现出先减小后增大的趋势，放线菌则呈现先减小后增大再减小的趋势，而蔗糖酶、酸性磷酸酶随林龄的增大趋于增大。(4)林地土壤中三大类群微生物与四种土壤酶之间存在极显著正相关关系，说明土壤微生物与土壤酶活性相互影响，两者之间关系密切，共同影响土壤的质量。不同土层土壤微生物和酶活性的季节响应特征差异较大，总体在冬季最低，主要与气温、水分条件、凋落物养分的归还等影响有关。不同季节、土层、林龄之间的交互作用对土壤微生物和酶活性有显著影响。
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