Dependence of tumor on essential nutrients is known to be crucial for its evolution and became one of the targets for medical therapies. Based on this fact a reaction–diffusion system with chemotaxis term and nutrient–based growth of tumors is presented. The formulation of the model considers also an influence of tumor and pharmacological factors on nutrient concentration. In the paper converge...

A system was evaluated for growing plants at reproducible levels of water stress. Beans (Phaseolus vulgaris L.) were grown in vermiculite, transferred to a semipermeable membrane system that encased the root-vermiculite mass, and then placed into nutrient solutions to which various amounts of polyethylene glycol (PEG) 20M were added to control solution water potential. The membrane (Spectrapor ...

The paper considers a simple model of radially symmetric cell which undergoes growth due to a continuous supply of nutrient, and disintegration as a result from the various tasks the cell performs. The boundary of the cell is a \free boundary", unknown in advance, which evolves by responding to both the growth and disintegration processes. If the nutrient concentration (at in nity) exceeds a ce...

Suboptimal N or P availability and cool temperatures all decrease apparent hydraulic conductance (L) of cotton (Gossypium hirsutum L.) roots. The interaction between nutrient status and root temperature was tested in seedlings grown in nutrient solutions. The depression of L (calculated as the ratio of transpiration rate to absolute value of leaf water potential [Psi(w)]) by nutrient stress dep...

Basil is a very important medicinal plant and culinary spice, and is marketed fresh, dried or frozen. In crop nutrition, nitrogen is essential for plant growth and as a macro-element, is part of the proteins’ structure and participates in the metabolic processes involved in the synthesis and energy transfer. It has been shown that a balance between ammonium and nitrate favors plant growth and t...

In this paper we present and analyze a nutrient-oxygen-phytoplankton-zooplankton mathematical model simulating lagoon ecological interactions. We obtain sufficient conditions, based on principal eigenvalue criteria -- for the existence of periodic solutions. A decoupled model which arises in the high nutrient regime is then considered in further detail for gathering some explicit conditions on ...

Water and osmotic potential energies were measured with thermocouple psychrometers, at intervals during a 4-week period, in growing leaves of bean (Phaseolus vulgaris, var. Blue Lake) and barley (Hordeum vulgare, var. Liberty) plants having roots equally split between 2 differentially salinized nutrient solutions. The osmotic potentials of plants with half their roots in saline solutions were a...

The interactive effects of N (6, 9, 12 and 15 mmol L-1) and K (3, 5, 7, and 9 mmol L-1) concentrations in nutrient solutions were evaluated on bell pepper grown in a coconut-coir substrate and fertilized without drainage. An additional treatment with drainage was evaluated using N and K concentrations of 12 and 7 mmol L-1, respectively. The hybrid Eppo cultivar of yellow bell pepper was cultiva...

A multi-objective chance-constrained programming integrated with Genetic Algorithm and robustness evaluation methods was proposed to weigh the conflict between system investment against risk for watershed load reduction, which was firstly applied to nutrient load reduction in the Lake Qilu watershed of the Yunnan Plateau, China. Eight sets of Pareto solutions were acceptable for both system inv...

Symptoms of nutrient deficiency in carambola {Aver rhoa carambola L.), lychee (Litchi chinensis Sonn.) and papaya (Carica papaya L.) trees have been observed periodically in south Florida, but have not been experimentally verified. Young 'Arkin' carambola, 'Mauritius' and 'Brewster' lychee and 'Cariflora' papaya were grown in 26-liter containers filled with coarse silica sand, irrigated with de...