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Digitale Medien

Effect of phosphorus supply on the formation and function of proteoid roots of white lupin (Lupinus albus L.) (1998)

Keerthisinghe, G. ; Hocking, P. J. ; Ryan, P. R. ; [weitere]

Oxford, UK : Blackwell Science Ltd, UK

Plant, cell & environment 21 (1998), S. 0

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ISSN: 1365-3040

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: We investigated (1) the effect of constant and altered inorganic phosphate (Pi) supply (1–100 mmol m–3) on proteoid root production by white lupin (Lupinus albus L.); and (2) the variation in citrate efflux, enzyme activity and phosphate uptake along the proteoid root axis in solution culture. Proteoid root formation was greatest at Pi solution concentrations of 1–10 mmol m–3 and was suppressed at 25 mmol m–3 Pi and higher. Except at 1 mmol m–3 Pi, the formation of proteoid roots did not affect plant dry matter yields or shoot to root dry matter ratios, indicating that proteoid roots can form under conditions of adequate P supply and not at the expense of dry matter production. Plants with over 50% of the root system as proteoid roots had tissue P concentrations considered adequate for maximum growth, providing additional evidence that proteoid roots can form on P-sufficient plants. There was an inverse relationship between the Pi concentration in the youngest mature leaf and proteoid root formation. Citrate efflux and the activities of enzymes associated with citric acid synthesis (phosphoenolpyruvate carboxylase and malate dehydrogenase) varied along the proteoid root axis, being greatest in young proteoid rootlets of the 1–3 cm region from the root tip. Citrate release from the 0–1 and 5–9 cm regions of the proteoid root was only 7% (per unit root length) of that from the 1–3 cm segment. Electrical potential and 32Pi uptake measurements showed that Pi uptake was more uniform along the proteoid root than citrate efflux.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1046/j.1365-3040.1998.00300.x

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Digitale Medien

Effect of Leucaena leucocephala (Lam) de Wit. as a green manure on nitrogen uptake and yield of rice (1990)

Zoysa, A. K. N. ; Keerthisinghe, G. ; Upasena, S. H.

Springer

Biology and fertility of soils 9 (1990), S. 68-70

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ISSN: 1432-0789

Schlagwort(e): Leucaena leucocephala ; Green manure ; N Uptake ; Yield ; Wetland rice ; Oryza sativa

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Geologie und Paläontologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Summary Field studies were conducted over two seasons to examine the effect of Leucaena leucocephala as a green manure on the N uptake and yield of rice grown under lowland conditions. The treatments were 0, 4, 8, and 12t Leucaena ha-1 with 0,44, and 88 kg N ha-1 as urea in a factorial combination. N uptake was evaluated at maximum tillering, panicle initiation, and harvest. The incorporation of Leucaena increased N uptake throughout the vegetative period in both seasons, irrespective of the mineral-N level. At all levels of N, the grain yield increased significantly following the incorporation of Leucaena, and in both seasons the Leucaena treatment of 8 t ha-1 was almost as effective as the highest mineral-N application.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00335864

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Digitale Medien

6. Ammonium dynamics of puddled soils in relation to growth and yield of lowland rice (1986)

Mengel, K ; Schon, HG ; Keerthisinghe, G ; [weitere]

Springer

Nutrient cycling in agroecosystems 9 (1986), S. 117-130

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ISSN: 1573-0867

Schlagwort(e): exchangeable NH 4 + ; nonexchangeable NH 4 + ; 15N tracer technique ; NH 4 + fixation ; vermiculite

Quelle: Springer Online Journal Archives 1860-2000

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Abstract The release of non-exchangeable (fixed) NH 4 + and the importance of exchangeable NH 4 + at transplanting (initial exchangeable NH 4 + ) for rice (Oryza sativa L.) growth was studied in representative lowland rice soils of the Philippines. The experiments showed that initial exchangeable ammonium behaved like fertilizer N and thus may serve as a valuable guideline for nitrogen fertilizer application rates when calculated on a hectare basis. By using the15N tracer technique it was found that nonexchangeable ammonium in soil may contribute to the nitrogen supplying capacity of lowland rice soils. Fixation and release of NH 4 + seem to be more dependent on the form of clay minerals than on clay content. In soils rich in vermiculite non-exchangeable ammonium should be considered together with other available N sources such as exchangeable ammonium for N fertilizer recommendations for lowland rice.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01048698

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Digitale Medien

Effect of fluoride supply on fluoride concentrations in five pasture species: Levels required to reach phytotoxic or potentially zootoxic concentrations in plant tissue (2000)

Stevens, D. P. ; McLaughlin, M. J. ; Randall, P. J. ; [weitere]

Springer

Plant and soil 227 (2000), S. 223-233

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ISSN: 1573-5036

Schlagwort(e): fluoride ; plant uptake ; pasture

Quelle: Springer Online Journal Archives 1860-2000

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Abstract Recent findings have highlighted the possibility of increased fluoride (F) concentrations in herbage through F taken up from soil via the plant root. This paper aimed to assess the risk of F concentrations reaching phytotoxic or zootoxic concentrations in pasture plants. Five plant species commonly found in improved pastures in Australia, the sown species subterranean clover (Trifolium subterranean) and cocksfoot (Dactylis glomerata), and weeds barley grass (Hordeum leporinum), scotch thistle (Onopordum acanthium) and sorrel (Rumex acetosella) were grown in complete nutrient solutions with graded levels of added F to determine the effects of F− activity in solution on phytotoxicity and uptake of F by their roots. A model was developed using data from these solution culture experiments and data from the literature. The model assessed uptake of F by plants grown over a range of soil pH values and determined the risk of F taken up through the plant roots reaching phytotoxic concentrations, or concentrations potentially injurious to grazing animals, in the plant shoots. Modelling data suggested that the plants studied would not accumulate phytotoxic concentrations of F in shoots or concentrations of F deleterious to grazing animals through root uptake in neutral pH agricultural soils. The risks from F addition to soils in phosphatic fertilisers leading to reduction in pasture growth or animal health are therefore low. However, in highly F-polluted soil, as the soil becomes more acidic or alkaline, the risk of zootoxic concentrations of F in shoots of plants would increase.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1023/A:1026523031815

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