ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Green revolution still too green (1999)

Sinclair, Thomas R. ; Cassman, Kenneth G.

[s.l.] : Macmillan Magazines Ltd.

Nature 398 (1999), S. 556-556

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ISSN: 1476-4687

Source: Nature Archives 1869 - 2009

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Notes: [Auszug] SirL. E. Drinkwater et al. report promising isolated studies on environmental quality and productivity in crop production. But these studies should not be used to discredit high-yield crop production technologies globally. We do not dispute David Tilman's call, in his News and ...

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1038/19182

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2

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Climate change, interannual weather differences and conflicting responses among crop characteristics: the case of forage quality (1995)

SELIGMAN, NO'AM G. ; SINCLAIR, THOMAS R.

Oxford, UK : Blackwell Publishing Ltd

Global change biology 1 (1995), S. 0

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ISSN: 1365-2486

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography

Notes: Yield and quality of cultivated forage crops are important determinants of animal production efficiency and both forage traits are sensitive to weather. Consequently, it can be presumed that these traits will respond to anticipated changes in the global environment associated with increases in [CO2] and temperature. Because of the large inter- and intra-annual weather variation that exists in most agricultural regions, it is not clear what the forage production response will be to predicted changes. This uncertainty in forage response to global environment change as compared to interannual weather variation was analysed using a mechanistic simulation model of plant development and growth. The results indicated that low soil-nutrient availability restricts forage production to such a degree that the global environment effects of higher [CO2] and temperature on quality are essentially irrelevant. When the nitrogen constraint was relaxed, higher [CO2] caused dry matter and digestibility to increase and protein concentration and leaf:stem ratio to decrease. Increased temperature had opposite effects. The combined effects of [CO2] and temperature were complex and annual weather variations were dominant, especially in rainfed situations. Limited reliability of predictions of crop response decades into the future indicates that it may be prudent to direct research effort to prepare for a wide range of climatic contingencies.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-2486.1995.tb00016.x

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3

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Soybean leaf growth and gas exchange response to drought under carbon dioxide enrichment (1999)

Serraj, Rachid ; Allen, L. Hartwell ; Sinclair, Thomas R.

Oxford, UK : Blackwell Science Ltd

Global change biology 5 (1999), S. 0

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ISSN: 1365-2486

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography

Notes: This study was conducted to determine the response in leaf growth and gas exchange of soybean (Glycine max Merr.) to the combined effects of water deficits and carbon dioxide (CO2) enrichment. Plants grown in pots were allowed to develop initially in a glasshouse under ambient CO2 and well-watered conditions. Four-week old plants were transferred into two different glasshouses with either ambient (360 μmol mol-1) or elevated (700 μmol mol-1) CO2. Following a 2-day acclimation period, the soil of the drought-stressed pots was allowed to dry slowly over a 2-week period. The stressed pots were watered daily so that the soil dried at an equivalent rate under the two CO2 levels. Elevated [CO2] decreased water loss rate and increased leaf area development and photosynthetic rate under both well-watered and drought-stressed conditions. There was, however, no significant effect of [CO2] in the response relative to soil water content of normalized leaf gas exchange and leaf area. The drought response based on soil water content for transpiration, leaf area, and photosynthesis provide an effective method for describing the responses of soybean physiological processes to the available soil water, independent of [CO2].

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2486.1999.00222.x

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4

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Accumulation of γ-aminobutyric acid in nodulated soybean in response to drought stress (1998)

Serraj, Rachid ; Shelp, Barry J. ; Sinclair, Thomas R.

Copenhagen : Munksgaard International Publishers

Physiologia plantarum 102 (1998), S. 0

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ISSN: 1399-3054

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Nitrogen fixation and nodule permeability to O2 diffusion are decreased by drought stress. Since γ-aminobutyric acid (GABA) synthesis is rapidly stimulated by a variety of stress conditions including hypoxia, it was hypothesized that decreased O2 availability in nodules stimulates glutamate decarboxylase (GAD) activity (EC 4.1.1.15), thereby resulting in GABA accumulation. First, the amino acid composition of xylem sap was determined in plants subjected to soil water deficits. While the xylem sap concentration of several amino acids increased when the plant was subjected to a water deficit, the greatest increase was in GABA. GABA accumulation was examined in response to stress induced by hypoxia or the addition of polyethylene glycol (PEG) to the nutrient solution. The exposure of soybean nodules to hypoxia for 6 h enhanced the GABA concentration by 6-fold, but there was no change in GABA concentration in response to the PEG treatment. No major changes in the in vitro GAD activity were measured in nodule cytosol or bacteroids. The present data do not support the hypothesis that decreased nodule O2 permeability and a resulting O2 deprivation inside nodules may stimulate in vitro GAD activity and thus GABA accumulation. However, the data could indicate a possible effect of hypoxia and drought stress on the in vivo activity of GAD.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1034/j.1399-3054.1998.1020111.x

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5

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Historical Change in Harvest Index and Crop Nitrogen Accumulation (1998)

Sinclair, Thomas R.

Springer

Crop science 38 (1998), S. 638-643

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ISSN: 1435-0653

Source: Springer Online Journal Archives 1860-2000

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

Type of Medium: Electronic Resource

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

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6

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Extractable Soil Water and Transpiration Rate of Soybean on Sandy Soils (1998)

Sinclair, Thomas R. ; Hammond, Luther C. ; Harrison, J.

Springer

Semigroup forum 90 (1998), S. 363-368

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ISSN: 1432-2137

Source: Springer Online Journal Archives 1860-2000

Topics: Mathematics

Notes: Substantial consistency has been obtained in describing plant response to drying soil by expressing plant performance as a function of the fraction of soil water that can be used by the plants. Generally, there is no decrease in plant activity until the soil water has been decreased to the level where only about 0.3 of the water that can be extracted by the plants remains in the soil. There is, however, ambiguity as to whether this relationship is appropriate for sandy soils. The objective of this research was to compare methods for describing extractable soil water by soybean [Glycine max (L.) Merr.] plants grown in pots with soils differing in sand content. The two methods tested were based on thermodynamic and physiological definitions of the upper and lower end-points of extractable soil water. While differences existed in the volumetric soil water content for the two definitions of the lower end-point of extractable soil water, these differences were small. In contrast, very large differences existed in defining the volumetric soil water of the upper end-point either thermodynamically (commonly assumed to be -10 kPa for sands) or physiologically (pot capacity). As a consequence, there were large differences in the response curves obtained based on the two expressions of extractable soil water. The threshold for transpiration expressed as an absolute volumetric soil water was of course independent of the determination of the end-points. Instead of relying on a relative transpiration response to extractable soil water, for sandy soils it may be necessary to use the volumetric soil water content determined under controlled conditions to interpret crop response under any particular field situation.

Type of Medium: Electronic Resource

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

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7

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Soil core and minirhizotron comparison for the determination of root length density (1994)

Samson, Benjamin K. ; Sinclair, Thomas R.

Springer

Plant and soil 161 (1994), S. 225-232

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ISSN: 1573-5036

Keywords: minirhizotron ; root-length density ; soil core ; Zea mays

Source: Springer Online Journal Archives 1860-2000

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

Notes: Abstract Detailed knowledge of the distribution of roots in the soil is important in understanding the extraction of water and nutrients from soil. Various techniques have been developed to monitor root-length density under field conditions. Excavation techniques, including soil cores, have long been considered to give reliable estimates of root-length density, but these techniques are laborious in sample collection and tedious in determination of root lengths. An attractive alternative for monitoring root-length density has been the minirhizotron whereby a periscope is inserted into a clear tube permanently installed in the soil for repeated and rapid measures of root development. The objective of this study was to compare the ability of the minirhizotron technique to measure root-length density as compared to the root-core technique. As in previous studies, substantial disagreement existed between the two techniques in the top 30-cm of the soil. The results from the minirhizotron consistently indicated a much lower root population than the root-core technique in the surface layer of soil. This is especially worrisome because more than 45% of the root-length density was found in this layer with the root-core technique. At deeper soil layers, the minirhizotron data proved to be no less variable than the root-core technique making the determination of statistically significant results difficult. Finally, the relationship between the minirhizotron and soil-core results varied with time even when the observations from the soil surface layer were ignored. Attempts to directly translate minirhizotron observations into a root-length density using a correlation approach would be suspect based on the results of this experiment.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00046393

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