A model for nutrient-phytoplankton dynamics is constructed and analyzed. A theoretical analysis shows that changes in the nutrient input can significantly change the qualitative behavior of the phytoplankton dynamics. In particular, the behavior can change from asymptotically stable to periodic. Numerical solutions of the model are carried out for seasonal nutrient inputs of a range of differen...

abstract the association between neotyphodium spp. endophytes and cool-season grasses, particularly tall fescue (festuca arundinacea, schreb), represents a widespread type of mutualism in nature. numerous researches were performed about positive effect of symbiosis on plant resistance to different stresses but the role of symbiosis on nutrients uptake particularly potassium uptake and k-bearing...

in vascular plants, the soil solution is transported from the roots to the leaves through smalldiameter vessels found in the xylem; this transport not only allows the nutrient uptake but also the accumulation of heavy metals in their shoots. by analogy to this phenomenon, the present study aimed at the evaluation of heavy metals transport (pb, cr, as, cd, zn, ni and al) in ph 4 and ph 8 solutio...

in vascular plants, the soil solution is transported from the roots to the leaves through smalldiameter vessels found in the xylem; this transport not only allows the nutrient uptake but also the accumulation of heavy metals in their shoots. by analogy to this phenomenon, the present study aimed at the evaluation of heavy metals transport (pb, cr, as, cd, zn, ni and al) in ph 4 and ph 8 solutio...

rapeseed (brassica napus l.) is a crop relatively tolerant to salt. the effect of different ratios of nacl/kcl was studied in two cultivars (hyola308 and kristina) of rapeseed in 2002. canola seedlings were grown in hoagland’s solutions, which were salinized by different ratios of nacl/kcl. the treatments or kcl:nacl ratios were 0:0 (control);10:10; 20:0 (total added salt or tas=20 mol.m-3), 0:...

A chemostat model of a single species feeding on a limiting nutrient supplied at a constant rate is proposed. The model incorporates a general nutrient uptake function and a distributed delay. The delay indicates that the growth of the species depends on the past concentration of nutrient. Using the average time delay as a bifurcation parameter, it is proven that the model undergoes a sequence ...