Studies of the Rhizosphere of Strawberry Plants at the Research Institute of Pomology and Floriculture in Skierniewice,Poland

Abstract

Rhizosphere studies are particularly important because of the recently introduced fertigation systems in strawberry cultivation, both in the field and under cover. Because of the need for developing fruit production in a balanced environment, rhizosphere studies help in determining precise doses of mineral fertilizers necessary for proper growth and production of economically important strawberry cultivars with specific requirements. The present experiment was carried out using rhizoboxes and determined pH changes in the rhizosphere of strawberries depending on the dose and form of nitrogen applied. The method enables visualization of pH changes in the rhizosphere and the soil as they become visible due to color changes under the influence of root exudates. To achieve this, the exposed plant roots and the entire soil mass penetrated by the roots in the rhizobox were covered with a thin (0.5 cm) agar filter containing 1% agar and 1% pH indicator (bromocresol purple). The color of the agar filter covering the roots indicates pH levels in various zones of the root system and depends on the applied forms of nitrogen. The highest pH values in the rhizosphere were measured in the root tips, lower in the middle root zone, and the lowest at the root bases. Plants supplied with N-NH4+ had the lowest rhizosphere pH, which was associated with an intensive release of H+ ions to the rhizosphere and acidification in the root zone.     

Effect of Bean (Phaseolus vulgaris L.) Rhizosphere on Zinc-Release Kinetics

The primary factor that influences release of zinc (Zn) for plants is the rhizosphere. However, information about Zn-desorption characteristics in the rhizosphere is limited. A greenhouse experiment was performed to determine Zn-release characteristics in the bulk and the rhizosphere soils using a rhizobox. The kinetics of Zn release was determined by successive extraction with diethylenetriaminepentaacetic acid (DTPA)– triethanolamine (TEA) in a period of 1 to 504 h at 25 ± 1 °C in the bulk and the rhizosphere soils. Moreover, Zn extracted by using three extractants [DTPA-TEA, ammonium bicarbonate (AB)-DTPA, and Mehlich 3] in the bulk and the rhizosphere soils. The results showed that Zn extracted in the rhizosphere soils were significantly (P < 0.01) lower than the bulk soils. The mean of Zn release in the bulk and the rhizosphere soils were 5.31 and 4.91 mg kg^?1, respectively. Release kinetics of Zn conformed fairly well to power function, first order, parabolic diffusion, and simplified Elovich equations. The results of kinetics study indicated that release-rate coefficients decreased in the rhizosphere soils compare to the bulk soils. The correlation studies showed that Zn release after 504 h was significantly correlated (P < 0.05) with Zn extracted by using DTPA-TEA, AB-DTPA, and Mehlich 3 in the bulk and the rhizosphere soils. The results of this research showed that Zn-release characteristics in the bean rhizosphere soils were different from the bulk soils.     

一株在微生物燃料电池中可以利用喹啉发电的产电假单胞杆菌Q1的产电特性研究

A rhizobox experiment was conducted to compare iron (Fe) oxidation and changes of pH, redox potential (Eh) and fractions of zinc (Zn) and lead (Pb) in rhizosphere and non-rhizosphere soils of four emergent-rooted wetland plants (Echinodorus macrophyllus, Eleocharis geniculata, Hydrocotyle vulgaris and Veronica serpyllifolia) with different radial oxygen loss (ROL) from roots. The results indicated that all these wetland plants decreased pH and concentration of Fe(Ⅱ) but increased the Eh in the rhizosphere soils. Pb and Zn were transformed from unstable fractions to more stable fractions in the rhizosphere soils, so decreasing their potential metal mobility factors (MF). Among the four plants, E. macrophyllus, with the highest ROL and root biomass, possessed the greatest ability in formation of Fe plaque and in the reduction of heavy metal MFs in the rhizosphere soil. Wetland plants, with higher ROLs and root biomass, may thus be effective in decreasing potential long-term heavy metal bioavailabilities.     

刈割、AM真菌和施磷对根箱栽培中柑橘和柱花草生长的影响

利用根箱栽培模拟果园生草栽培,以柑橘Citrus sinensis(L)Osbeck．cv．Luogangcheng和柱花草Stylosanthes gracilis H．B．K．cv．Graham来研究生草刈割、AM真菌和施磷在减轻养分竞争上的作用．结果表明,3种措施在不同程度上减轻了柱花草对柑橘生长的抑制效应,增加了柑橘的株高、叶片数和干质量;柱花草刈割的作用最明显,导致柱花草的根冠比急剧降低,表明刈割可能是通过抑制根系生长来减轻养分竞争．     

Rhizosphere effects on Cu availability and fractionation in sewage sludge‐amended calcareous soils

Rhizosphere processes have a major impact on copper (Cu) availability and its fractions in soils. A greenhouse experiment with wheat was performed to investigate availability (using seven chemical procedures) and fractionation of Cu in the rhizosphere of ten agricultural soils (Typic Calcixerepts) amended with sewage sludge (1% w/w) using rhizoboxes. The results show that available Cu concentrations in rhizosphere soils were significantly (P < 1%) lower than in bulk soils. In comparison with the bulk soils, in the rhizosphere soils the concentration of Cu associated with organic matter and residual Cu increased by 24 and 4%, respectively, whereas exchangeable Cu, Cu associated with iron‐manganese oxides, and Cu associated with carbonate decreased by 20, 14, and 12%, respectively. Dissolved organic carbon (DOC) and Cu associated with iron‐manganese oxides and Cu associated with organic matter in the rhizosphere and bulk soils were significantly correlated (P < 5%). The results show that the differences between rhizosphere and bulk soils in chemical conditions such as DOC concentrations can change the proportion of soil Cu fractions and, therefore, Cu availability for wheat in calcareous soils amended with sewage sludge. The results show that the wheat root‐induced modifications of chemical and biological soil conditions do not only lead to Cu depletion in mobile soil Cu fractions, but also to modification in soil Cu fractions which are commonly considered as more stable.     

利用根箱法解析转双价（Bt + CpTI）基因棉花对土壤微生物数量及细菌多样性的影响

 利用根箱法对棉花根部土壤进行分区采集,并采用传统平板培养和DGGE克隆测序技术相结合的方法,对转双价基因棉和常规棉3个生长时期(播种后40 d、50 d和60 d)不同根区土壤细菌、放线菌和真菌数量及细菌多样性进行对比分析。平板培养结果表明,与常规棉相比,转双价基因棉S1根区土壤细菌、放线菌的数量显著降低,而S2根区土壤细菌、放线菌、真菌和S3根区土壤细菌、真菌的数量显著增加(P＜0.05);DGGE图谱分析表明,在棉花生长的3个时期内,转双价基因棉和常规棉根区土壤细菌多样性指数、均匀度和条带数均无显著差异(P＞0.05),2种棉花处理间有着很强的相似性,不受转双价基因棉种植的影响。转双价基因棉种植仅改变了根区土壤可培养微生物数量,对细菌多样性无显著影响。     

丛枝菌根真菌菌丝对土壤微生物群落结构及 多氯联苯降解的影响

以摩西球囊霉(Glomus mosseae)为供试菌种,在光照培养箱内利用分室根箱研究丛枝菌根真菌菌丝对多氯联苯(polychlorinated biphenyls,PCBs)污染土壤的修复效应及其机理。试验设置接种丛枝菌根真菌的处理以及不接种的对照,选用美国南瓜(Cucurbita pepo L.)为供试植物,在南瓜生长40天后将接种菌根真菌处理的菌丝室土壤从尼龙网向外水平分为4层取样,测定PCBs及磷脂脂肪酸含量。结果表明:菌丝可以穿越尼龙网影响菌丝室土壤,且距离尼龙网越远菌丝量越低;菌丝显著促进了土壤微生物量(P0.05),并改变了不同土层土壤微生物群落结构;接种菌根真菌处理各土层PCBs降解率为35.67%~57.39%,均显著高于对照的17.31%,相关分析结果表明土壤三氯、四氯联苯以及PCBs总量与菌丝量呈极显著负相关(P0.01);菌丝际土壤微生物量,特别是细菌生物量与土壤三氯联苯含量呈显著负相关(P0.05)。可见,菌丝通过影响菌丝际土壤微生物群落结构及生物量,促进三氯及四氯联苯降解,从而提高土壤PCBs修复效率。     

Novel micro–suction‐cup design for sampling soil solution at defined distances from roots

Micro–suction cups made of nylon membranes and polyacrylic tubes with planar geometry of the membrane were designed for repeated sampling of rhizosphere solution at defined distances from a root monolayer. Adsorption tests revealed that the materials used (nylon membrane, polyacrylic tube) have little influence on the concentration of heavy metals in the sample solution, whereas some organic acids are partly retained by the suction cup. A sampling protocol was developed for collecting extremely small solution volumes (i.e., droplets of 28.3±2.46 μl) for subsequent measurements of trace elements using ICP‐SFMS. A homogeneity test showed that soil‐solution concentrations of Ca, K, Mg, and Ni could be reproduced independent of the suction‐cup position in a rhizobox experiment without plants. In a similar experiment, the rhizobox was planted with the Ni hyperaccumulator Thlaspi goesingense. Compared to more distant soil layers, an increase of Ni and a concurrent decrease of Ca, K, and Mg at 1 mm distance from the root plane was found. These changes can be related to plant uptake and mobilization processes. Our results show that the novel micro–suction cups are a valuable tool for elucidating rhizosphere processes.     

转Bt基因玉米对土壤微生物量碳氮的影响

利用三室根箱装置获得玉米生长室(S1)、根际土(S2)、非根际土(S3)3个不同根区土壤,研究了转基因玉米Bt11及其非转基因亲本玉米播种后40,50和60 d各根区土壤微生物量碳、氮的变化.结果表明,转Bt基因玉米播种后40 d各根区土壤微生物量碳与非转基因亲本玉米相比无显著差异,土壤微生物量氮显著升高;播种后50 ...     

土壤栽培条件下根系生长非扰动观测根箱及其应用

原位观察土壤中根系的生长情况是一个难题。该文提出了一种土壤栽培条件下根系生长非扰动观测根箱,并以栽种烟草为例说明其应用。该装置由生长室、水肥供应系统、图像捕获与分析系统构成。烟草根系在生长室中生长,水肥供应系统独立调节各分室的水肥供应。利用数码相机定期捕获观察面的根系图像,再用ImageJ软件分析数据,即可实现根系的定量观测。结果表明,烟草根系伸长速率在移栽后第35天和第46天出现2个增长高峰,其峰值分别为54.58和185.69cm/d。根系深度与宽度的比值随生长时间呈现"V"形曲线。根系的快速生长区域具有下移的趋势。比较生长室观察面所得数据和挖掘根箱获得的数据,结果表明,>20～40cm土层根系最多,2种方法所得到的根长在各土层的分布趋势基本一致、相关性显著,表明本装置可应用于土壤栽培条件下根系生长的非扰动观测。