Journal of Plant Nutrition and Soil Science 

About: Journal of Plant Nutrition and Soil Science is an academic journal published by Wiley. The journal publishes majorly in the area(s): Soil water & Soil organic matter. It has an ISSN identifier of 1436-8730. Over the lifetime, 7987 publications have been published receiving 133440 citations. The journal is also known as: Zeitschrift für Pflanzenernährung und Bodenkunde (1999) & Zeitschrift für Pflanzenernährung und Bodenkunde (Internet).

Pharmaceutical antibiotic compounds in soils – a review

Abstract: Antibiotics are highly effective, bioactive substances. As a result of their consumption, excretion, and persistence, they are disseminated mostly via excrements and enter the soils and other environmental compartments. Resulting residual concentrations in soils range from a few μg upto g kg–1 and correspond to those found for pesticides. Numerous antibiotic molecules comprise of a non-polar core combined with polar functional moieties. Many antibiotics are amphiphilic or amphoteric and ionize. However, physicochemical properties vary widely among compounds from the various structural classes. Existing analytical methods for environmental samples often combine an extraction with acidic buffered solvents and the use of LC-MS for determination. In soils, adsorption of antibiotics to the organic and mineral exchange sites is mostly due to charge transfer and ion interactions and not to hydrophobic partitioning. Sorption is strongly influenced by the pH of the medium and governs the mobility and transport of the antibiotics. In particular for the strongly adsorbed antibiotics, fast leaching through soils by macropore or preferential transport facilitated by dissolved soil colloids seems to be the major transport process. Antibiotics of numerous classes are photodegraded. However, on soil surfaces this process if of minor influence. Compared to this, biotransformation yields a more effective degradation and inactivation of antibiotics. However, some metabolites still comprise of an antibiotic potency. Degradation of antibiotics is hampered by fixation to the soil matrix; persisting antibiotics were already determined in soils. Effects on soil organisms are very diverse, although all antibiotics are highly bioactive. The absence of effects might in parts be due to a lack of suitable test methods. However, dose and persistence time related effects especially on soil microorganisms are often observed that might cause shifts of the microbial community. Significant effects on soil fauna were only determined for anthelmintics. Due to the antibiotic effect, resistance in soil microorganisms can be provoked by antibiotics. Additionally, the administration of antibiotics mostly causes the formation of resistant microorganisms within the treated body. Hence, resistant microorganisms reach directly the soils with contaminated excrements. When pathogens are resistant or acquire resistance from commensal microorganisms via gene transfer, humans and animals are endangered to suffer from infections that cannot be treated with pharmacotherapy. The uptake into plants even of mobile antibiotics is small. However, effects on plant growth were determined for some species and antibiotics.

The role of potassium in alleviating detrimental effects of abiotic stresses in plants

Abstract: Plants exposed to environmental stress factors, such as drought, chilling, high light intensity, heat, and nutrient limitations, suffer from oxidative damage catalyzed by reactive oxygen species (ROS), e.g., superoxide radical (O2 -), hydrogen peroxide (H2O2) and hydroxyl radical (OH ). Reactive O2 species are known to be primarily responsible for impairment of cellular function and growth depression under stress conditions. In plants, ROS are predominantly produced during the photosynthetic electron transport and activation of membrane-bound NAD(P)H oxidases. Increasing evidence suggests that improvement of potassium (K)-nutritional status of plants can greatly lower the ROS production by reducing activity of NAD(P)H oxidases and maintaining photosynthetic electron transport. Potassium deficiency causes severe reduction in photosynthetic CO2 fixation and impairment in partitioning and utilization of photosynthates. Such disturbances result in excess of photosynthetically produced electrons and thus stimulation of ROS production by intensified transfer of electrons to O2. Recently, it was shown that there is an impressive increase in capacity of bean root cells to oxidize NADPH when exposed to K deficiency. An increase in NADPH oxidation was up to 8-fold higher in plants with low K supply than in K-sufficient plants. Accordingly, K deficiency also caused an increase in NADPH-dependent O2 - generation in root cells. The results indicate that increases in ROS production during both photosynthetic electron transport and NADPH-oxidizing enzyme reactions may be involved in membrane damage and chlorophyll degradation in K-deficient plants. In good agreement with this suggestion, increases in severity of K deficiency were associated with enhanced activity of enzymes involved in detoxification of H2O2 (ascorbate peroxidase) and utilization of H2O2 in oxidative processes (guaiacol peroxidase). Moreover, K-deficient plants are highly light-sensitive and very rapidly become chlorotic and necrotic when exposed to high light intensity. In view of the fact that ROS production by photosynthetic electron transport and NADPH oxidases is especially high when plants are exposed to environmental stress conditions, it seems reasonable to suggest that the improvement of K-nutritional status of plants might be of great importance for the survival of crop plants under environmental stress conditions, such as drought, chilling, and high light intensity. Several examples are presented here emphasizing the roles of K in alleviating adverse effects of different abiotic stress factors on crop production.

Carbon input by plants into the soil. Review.

Abstract: The methods used for estimating below-ground carbon (C) translocation by plants, and the results obtained for different plant species are reviewed. Three tracer techniques using C isotopes to quantify root-derived C are discussed: pulse labeling, continuous labeling, and a method based on the difference in 13 C natural abundance in C3 and C4 plants. It is shown, that only the tracer methods provided adequate results for the whole below-ground C translocation. This included roots, exudates and other organic substances, quickly decomposable by soil microorganisms, and CO 2 produced by root respiration. Advantages due to coupling of two different tracer techniques are shown. The differences in the below-ground C translocation pattern between plant species (cereals, grasses, and trees) are discussed. Cereals (wheat and barley) transfer 20%-30% of total assimilated C into the soil. Half of this amount is subsequently found in the roots and about one-third in CO2 evolved from the soil by root respiration and microbial utilization of rootborne organic substances. The remaining part of below-ground translocated C is incorporated into the soil microorganisms and soil organic matter. The portion of assimilated C allocated below the ground by cereals decreases during growth and by increasing N fertilization. Pasture plants translocated about 30%-50% of assimilates below-ground, and their translocation patterns were similar to those of crop plants. On average, the total C amounts translocated into the soil by cereals and pasture plants are approximately the same (1500 kg C ha -1 ), when the same growth period is considered. However, during one vegetation period the cereals and grasses allocated beneath the ground about 1500 and 2200kg C ha -1 , respectively. Finally, a simple approach is suggested for a rough calculation of C input into the soil and for root-derived CO 2 efflux from the soil.