Changes in land use may lead to increased soil nutrient levels in many ecosystems (e.g. due to intensification of agricultural fertilizer use). Plant species differ widely in their response to differences in soil nutrients, and for savannas it is uncertain how this nutrient enrichment will affect plant community dynamics. We set up a large controlled short-term experiment in a semi-arid savanna...

Most previous studies have ascribed variations in the resorption of a certain plant nutrient to its corresponding environmental availability or level in tissues, regardless of the other nutrients' status. However, given that plant growth relies on both sufficient and balanced nutrient supply, the nutrient resorption process should not only be related to the absolute nutrient status, but also be...

Internal differences between plant organs are caused by the functional differentiation of plant tissue, whereas external supply rates of elements constrain nutrient uptake. Previous studies have concentrated on foliar or whole-plant stoichiometric response to the environment, whereas investigation of organ-specific comparisons is still pending. We explore C:N:P ratios of stems, leaves, diaspore...

Maximum potato (Solanum tuberosum L.) tuber yields occur when an active plant canopy is maintained until normal plant maturation. Plaid nutrient concentrations and uptake rates play a major role in maintaining an active plant top. The objectives of this study were to relate the plant P concentrations to the P and dry matter balance between tuber and total plant growth needs. Growth analysis dat...

1. General theories of plant defence often fail to account for complex interactions between the resources required for defence expression. For example, the carbon that is used for carbon-based defence is acquired using nutrient-rich photosynthetic pigments, while nutrient gain itself requires substantial carbon allocation belowground. We should therefore expect the expression of plant defence t...

two laboratory and greenhouse experiments were carried out to compare and evaluate the nutrition of phaseolus vulgaris l. plant with foliar spray and root media. in laboratory, effect of four treatments; n- nutrition solution; urban solid waste leachate (uswl); vermi-compost extract and control (distilled water) on germination and seeding growth of phaseolus vulgaris l. was examined for 10 days...

Plants can remove or immobilize various environmental contaminants; however, little is known about the physiological mechanisms underlying responses to soil amendment with biosolids contaminated with heavy metals. We investigated the responses of cuttings of hybrid poplar clones Eridano and I-214 grown for a season in soil amended with nutrient-rich organic material from tanneries, which contai...

Optimal defense theories suggest that a trade-off between defense costs and benefits maintains genetic variation within plant populations. This study assessed the independent and interactive effects of genetic- and environment-based variation in aspen leaf chemistry on insect performance, preference, and defoliation. Gypsy moth larvae were released into screenhouses containing eight aspen genot...

Knecht Billberger, M. F. Plant growth – stoichiometry and competition. Doctor’s dissertation. ISSN 1652-6880, ISBN 91-576-7073-0. In four different studies, this thesis addresses issues concerning plant nutrition and growth from a theoretical perspective. Terrestrial plants require nutrients, water, light and space for their existence. All of these resources may be limiting for growth, however ...

Anthropogenic activities have increased phosphorus (P) inputs to most aquatic and terrestrial ecosystems. However, the relationship between plant nutrient resorption and P availability is still unclear, and much less is known about the underlying mechanisms. Here, we used a multi-level P addition experiment (0, 1.2, 4.8, and 9.6 g P m(-2) year(-1)) to assess the effect of P enrichment on nutrie...