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Seed germination and emergence of Eragrostis tenuifolia (A. Rich.) Hochst. ex Steud. in response to environmental factors

100%

Bittencourt H. H., da Silva Bonome L. T., de Bortoli Pagnoncelli,Jr F., Lana M. A., Muzell Trezzi M.

Journal of Plant Protection Research

2016

tom 56

nr 1

Eragrostis tenuifolia is a weed species that is gaining ground in Brazil. This weed occurs in pastures, grasslands, crop fields, and roadsides. The objective of this study was to examine the effects of different environmental factors on E. tenuifolia seed germination and seedling emergence. The optimum constant temperature for germination was around 35–30°C. It was also found that 85% of seeds germinated under a 30/20°C alternate temperature regime. Light appears to have a positive effect on seed germination. No seedlings emerged when seeds were buried 3 cm or deeper. The results suggested that E. tenuifolia has the potential to spread into pastures and in no-tillage crop systems in Brazil. Measures such as the use of cover crops and/or soil cultivation can be used to limit germination and seedling emergence, respectively.

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

100%

Zaller J. G.

Polish Journal of Ecology

2007

tom 55

nr 4

Nutrient distribution in natural habitats is usually patchy 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 rather than homogeneous 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 × 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.

Ograniczanie wyników

1 Journal of Plant Protection Research

1 Polish Journal of Ecology

1 Bittencourt H. H.

1 Lana M. A.

1 Muzell Trezzi M.

1 Zaller J. G.

1 da Silva Bonome L. T.

1 de Bortoli Pagnoncelli,Jr F.

1 2016

1 2007

Wyniki wyszukiwania

Seed germination and emergence of Eragrostis tenuifolia (A. Rich.) Hochst. ex Steud. in response to environmental factors

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