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Correlative Bud Inhibition and Abscisic Acid in Acer pseudoplatanus and Syringa vulgaris (1976)

DORFFLING, KARL

Oxford, UK : Blackwell Publishing Ltd

Physiologia plantarum 38 (1976), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Growing shoots of Acer pseudoplatanus and Syringa vulgairs were decapitated and defoliated (“treated”) in June 1972–1975. During the 2–3 weeks after treatment the contents of abscisic acid (ABA) in the out-growing lateral buds at the upper-most node as well as in the petiole stumps and nodes were determined by means of gas-liquid chromatography. The concentration of ABA in lateral buds of intact shoots, calculated on a fresh weight basis, varied greatly from year but was consistently several times higher than in petioles and nodes. Defoliation and decapitation caused out-growth of the lateral buds. This was accompanied by a sharp decrease in the ABA concentration, which finally reached the level of petiole tissue. The concentration of ABA in controls (“untreated”) decreased also, but to a smaller extent, and remained higher than in petioles. In petioles and nodes of treated as well as of untreated shoots, the ABA concentration did not change. The absolute amount of ABA in the buds of treated shoots after 2–3 weeks varied greatly, but was apparently not different from the amount in buds of untreated controls or in buds at the beginning of the experiment. Therefore, the decrease of the ABA concentration was mainly due to fresh weight increase. The results are discussed in relation to a possible role of ABA in correlative bud inhibition.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1399-3054.1976.tb04012.x

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Salinity increases CO2 assimilation but reduces growth in field-grown, irrigated rice (2000)

Asch, Folkard ; Dingkuhn, Michael ; Dorffling, Karl

Springer

Plant and soil 218 (2000), S. 1-10

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ISSN: 1573-5036

Keywords: dry matter reduction ; leaf chlorophyll content ; leaf sodium uptake ; Oryza sativa ; photosynthesis ; salinity ; season effects

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Salinity is a major yield-reducing factor in coastal and arid, irrigated rice production systems. Salt tolerance is a major breeding objective. Three rice cultivars with different levels of salt tolerance were studied in the field for growth, sodium uptake, leaf chlorophyll content, specific leaf area (SLA), sodium concentration and leaf CO2 exchange rates (CER) at photosynthetic active radiation (PAR)-saturation. Plants were grown in Ndiaye, Senegal, at a research station of the West Africa Rice Development Association (WARDA), during the hot dry season (HDS) and the wet season (WS) 1994 under irrigation with fresh or saline water (flood water electrical conductivity = 3.5 mS cm-1). Relative leaf chlorophyll content (SPAD method) and root, stem, leaf blade and panicle dry weight were measured at weekly intervals throughout both seasons. Specific leaf area was measured on eight dates, and CER and leaf sodium content were measured at mid-season on the first (topmost) and second leaf. Salinity reduced yields to nearly zero and dry-matter accumulation by 90% for the susceptible cultivar in the HDS, but increased leaf chlorophyll content and CER at PAR- saturation. The increase in CER, which was also observed in the other cultivars and seasons, was explained by a combination of two hypotheses: leaf chlorophyll content was limited by the available N resources in controls, but not in salt-stressed plants; and the sodium concentrations were not high enough to cause early leaf senescence and chlorophyll degradation. The growth reductions were attributed to loss of assimilates (mechanisms unknown) that must have occurred after export from the sites of assimilation. The apparent, recurrent losses of assimilates, which were between 8% and 49% according to simulation with the crop model for potential yields in irrigated rice, ORYZA S, might be partly due to root decomposition and exudation. Possibly more importantly, energy-consuming processes, such as osmoregulation, interception of sodium and potassium from the transpiration stream in leaf sheaths and their subsequent storage, drained the assimilate supply.