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Effect of patchy distribution of soil nutrients on root morphology and biomass allocation of selected grassland species: experimental approach

Zaller J.

Polish Journal of Ecology

2007

Vol. 55, nr 4

731-746

Nutrient distribution in natural habitats is usually patch in space and time, however most knowledge about plant growth and behaviour is based on experiments conducted under spatially homogenous conditions. Evidence has accumulated that the growth and competitive interaction of plant species are strongly affected by heterogeneous resource distribution, even when the total resource supply remains similar. For this study it is hypothesized that infestations of grasslands with the nitrophilous weed Rumex obtusifolius L. (broadleaved dock) are partially the consequence of its ability to exploit spatial nutrient heterogeneity. This was tested in a full-factorial pot experiment with homogeneously or heterogeneously distributed nitrogen and/or potassium at either normal or increased soil moisture where R. obtusifolius was grown together with three other grassland species (grass: Arrhenatherum elatius L., non-leguminous herb: Taraxacum officinale Weber, leguminous herb: Trifolium repens L.). The species differed significantly in their root morphology (root length and diameter, specific root length, number of root tips) and biomass allocation response to nutrient distribution, as well as to the nutrient type used to create patches and to soil moisture (e.g., significant species x treatment interactions). Generally, the root system of A. elatius showed the highest plasticity to imposed treatments, followed by T. officinale, R. obtusifolius and T. repens. Unexpectedly, root morphology of R. obtusifolius was unresponsive to soil heterogeneity and less responsive to nutrient type and irrigation than that of the other species. Nutrient type used to create patches influenced the biomass allocation to the root system of R. obtusifolius while nutrient distribution and irrigation showed no effect on biomass allocation. Exploitation of soil nitrate-nitrogen and potassium was similar among species but exploitation was individually affected by nutrient type, nutrient distribution and irrigation suggesting that species-specific differences in nutrient storage capacities in roots or adjustments regarding root nutrient uptake kinetics may play an important role. Results from this study show that R. obtusifolius does not seem to have superior traits to utilize soil nutrient heterogeneity, certain nutrient types or higher soil moisture that differentiates it from the other grassland species tested. The observed effects might have consequences for the long-term competitive relationships between species in the grassland community suggesting that cultural and biological management measures oriented towards the improvement of the competitive ability of co-occurring grassland species might also be important in heterogeneous soils.

Influence of organic fertilizers on heavy met al content in tall oat grass

Jasiewicz C., Antonkiewicz J., Baran A.

Chemia i Inżynieria Ekologiczna

2006

Vol. 13, nr 9

914-923

The studies on heavy metal content in tan oat grass were conducted in 2005 as a pot experiment. The experiment comprised the following treatments: mineral fertilization, farmyard manure, compost, mu-nicipal sludge and industrial sludge. Two levels of NPK fertilization were considered: 1 - 0.30 g N, 0.11 g P and 0.26 g K . pot-1, 2 - 0.60 g N, 0.22 g P and 0.52 g K . pot-1. The doses of farmyard manure, compost, municipal and industrial sludge were determined on the basis of nitrogen fertilization level and were applied in the first year of the experiment under maize. The results of study evidence that the content of heavy metals in tall oat grass depended on the amount of metal supplied with organic materials (doses and kind of organic fertilizers), dale of harvest and the plant part. High concentrations of heavy metals were observed in I cut from object fertilized with: industrial sludge (Zn, Cu, Ni), compost and industrial sludge (Pb), with farmyard manure2 and municipal sludge2 (Cd). High concentrations of Cu were registered in II cut fertilized with farmyard manure2, municipal sludge2, industrial sludge2 and and those of Ni with industrial sludge2. The contents of examined metal in particular parts of grass looked as follows: roots > I cut > II cut for Zn, Pb, Cu and roots > II cut > I cut for Cd and Ni. Bioaccumulation coefficient (BC) showed that tan oat grass was taking up more Zn, Ni and Cd than Pb or Cu. Translocation coefficient (Te) revealed that roots absorbed the largest amounts of Pb and Cd. Summary quantity of absorbed Zn, Cu Ni and Pb was the highest on object with industrial sludge2 application, whereas Cd on municipal sludge2.

Badania nad wpływem nawożenia organicznego na zawartość Zn, Cu, Ni, Pb i Cd w rajgrasie wynio-słym prowadzono w 2005 r. w warunkach doświadczenia wazonowego. W doświadczeniu wykorzystano; sole mineralne, obornik, kompost, osad miejski i osad przemysłowy w dwóch poziomach nawożenia. Dawka dla I poziomu wyniosła: 0,30 g N, 0,11 g P, 0,26 g K . wazon-I, a dla II poziomu: 0,60 g N, 0,22 g P, 0,52 g K . wazon-I. Zawartość metali ciężkich w rajgrasie zależała od dawki i rodzaju nawozu orga-nicznego, terminu zbioru oraz części rośliny. Wysoką zawartość w I pokosie: Zn, Cu, Ni spowodowało działanie nawozowe osadu przemysłowego2, Pb - nawożenie NPK, kompostem i osadem przemysłowym, a Cd - działanie obornika2 i osadu miejskiego1. Zwiększenie zawartości Cu w II pokosie wywołało działanie nawozowe podwójnej dawki obornika, osadu miejskiego i osadu przemysłowego, a Ni - osadu przemysłowgo. W przypadku pozostałych metali ich zawartości były niższe niż w roślinach z obiektu kontrolnego. Rozmieszczanie metali w rajgrasie w obiektach nawożonych materiałem organicznym kształtowało się następująco: dla Zn, Pb i Cu: korzenie> I pokos> II pokos oraz dla Ni i Cd: korzenie> II pokos >1 pokos. Obliczone wartości wskaźników bioakumulacji (BC) dla metali wskazują, że rajgras łatwiej pobierał Zn, Ni i Cd niż Pb i Cu. Analizując wartości współczynnika translokacji (TC), stwierdzono, że korzenie rajgrasu absorbowały największe ilości Pb i Cd. Rośliny z obiektu z podwójną dawką osadu przemysłowego pobrały największą sumaryczną ilość Zn, Cu, Ni i Pb, natomiast z obiektu z podwójna dawką osadu miejskiego pobrały najwięcej Cd.