ZfN: Search Results

1	Author	L. A. Buscarlet, A. Ferran, M. Larroque	Requires cookie*
	Title	Water Budget in Larvae of Semiadalia undecimnotata Schn. Studied with Tritiated Water
	Abstract	The rates of water vapor entry, body water clearance and the net loss of water in larvae o f Semi adalia undecimnotata (3rd and 4th stage) of different weights were determ ined from observed changes in the mass of body water and its tritium content for each of several relative hum idities (RH) in am bient air. The water clearance and vapor entry rates as a function o f weight increases from emergence to the middle of the stage and then rem ains constant. The vapor entry rate increases with RH while the clearance rate is independant o f RH. The perm eability of the cuticle has not the same value in the inward and in the outward direction. The perm eability to body water escape is not affected by RH and reaches a m axim um at the m iddle of the stage. The inward perm eability does not depend on weight and increases appreciably as RH reaches saturation. One day of starvation affected these movements o f water most in larvae at the m iddle o f their stage. These results are discussed in relation to some physiological data concerning the cuticular struc ture and its evolution with age.
	Reference	Z. Naturforsch. 35c, 319—325 (1980); received N ovem ber 1 1979
	Published	1980
	Keywords	Semiadalia undecimnotata, Tritiated Water, Transpiration, Water Absorption, Cuticle Permeability
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	TEI-XML for	default:Reihe_C/35/ZNC-1980-35c-0319.pdf
	Identifier	ZNC-1980-35c-0319
	Volume	35

2	Author	Aloysius Wild, Peter Sabel, Lucia Wild-Peters, Ursula Schmieden	Requires cookie*
	Title	Photosynthesis and Transpiration in Damaged and Undamaged Spruce Trees
	Abstract	The investigations presented here focus on the C 0 2/H 20 gas exchange in damaged and undamaged spruce trees while using open-air measurements as well as measurements under defined conditions in the laboratory. The studies were performed at two different sites in the Hunsrück and the Westerwald mountains. In the laboratory the C 0 2/H 20 gas exchange was measured on detached branches under controlled conditions in the course of two years. C 0 2 saturation curves were also generated. In addition C 0 2 compensation points were deter mined employing a closed system. In the natural habitat diurnal course measurements of photosynthesis and transpiration as well as light-saturation curves for photosynthesis were performed. In parallel with the photosynthesis and transpiration measurements, measure ments of the water potential were taken at both locations. The photosynthetic capacity and transpiration rate show a typical annual course with pro nounced maxima in spring and late summer and minima in summer and winter. The needles of the damaged trees exhibit higher transpiration rates and a distinct reduction in photosyn thesis than the needles of the undamaged trees during two seasons. The diurnal course mea surements of net photosynthesis and transpiration show a maximum in photosynthesis and transpiration in the afternoon in May and September, but a characteristic midday depression in July. Photosynthesis was markedly lower and transpiration higher in the needles of the damaged trees. The damaged trees show a lower increase in the light and C 0 2 saturation curves and higher C 0 2 compensation points as compared to the undamaged trees. The water potential reaches much lower values during the course of the day in needles of the dam aged trees. The reduction of the photosynthetic rate on one hand and the increase in transpiration on the other hand result in an extrem e lowering of the water use efficiency in photosynthesis. The damage to the thylakoid membranes and to the guard cells obviously results in a pro found disturbance of the physiological hom eostasis o f the needles and could thus lead to premature needle loss.
	Reference	Z. Naturforsch. 51c, 200 (1996); received Decem ber 27 1995/January 29 1996 D edicated to
	Published	1996
	Keywords	birthday C 0 2/H 20 Gas Exchange C 0 2 Compensation Point, Photosynthesis, Picea abies, Transpiration, Water Potential, Forest D isease
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	TEI-XML for	default:Reihe_C/51/ZNC-1996-51c-0200.pdf
	Identifier	ZNC-1996-51c-0200
	Volume	51