The objectives of this experiment were (i) to determine the effect of water supply on the photosynthetic capacity of leaves, bracts, capsule walls, and stalks of cotton at different growth stages and (ii) to determine the contributions of these nonleaf organs to whole plant photosynthesis. Water deficit reduced the total surface area per plant but increased the proportion of nonleaf to total pl...

* Author for correspondence and reprint requests Z. Naturforsch. 54c, 698-703 (1999); received November 17, 1998/March 20. 1999 a-Tocopherol, Photosynthesis, Drought, Rosmarinus officinalis, Melissa officinalis Summer diurnal variations of photosynthesis and a-tocopherol content were measured in relation to natural drought in field-grown rosemary (Rosmarinus officinalis L.) and lemon balm (Meli...

The effect of different wavebands of artificial UV (UVB and UVA) and photosynthetically active radiation (PAR) was assessed in two species of the genus Ulva, U. olivascens and U. rotundata, from southern Spain in order to test for possible differences in acclimation of photosynthesis. Both species share similar morphology but are subject to different light environments: U. rotundata is an estua...

One of the purposes of consciousness is to acquire knowledge. The models of this task traditionally assume a division between the known and the knower, a division that leads into doubtful reasoning about some kind of (frequently disguised) homunculus. The current paper tries to avoid such fallacies by viewing the adaptation of the mind as an evolutionary process, a process distinct (but not ind...

to evaluate the effect of different levels of drought stress on some physiological parameters in strawberry, potted experiment involing strawberry cultivars  ‘marak٫ , ‘camarosa٫ and ‘gaviota٫ was conducted during summer 2009. the experiment consisted of three drought stress levels in three replications. the experimental arrangement was a factorial one, based upon a randomized complete block de...

Long-term, whole crop CO2 exchange measurements can be used to study factors affecting crop growth. These factors include daily carbon gain, cumulative carbon gain, and carbon use efficiency, which cannot be determined from short-term measurements. We describe a system that measures semicontinuously crop CO2 exchange in 10 chambers over a period of weeks or months. Exchange of CO2 in every cham...

Methane is oversaturated relative to the atmosphere in many rivers, yet its cycling and fate is poorly understood. While photosynthesis is the dominant source of autotrophic carbon to rivers, chemosynthesis and particularly methane oxidation could provide alternative sources of primary production where the riverbed is heavily shaded or at depth beneath the sediment surface. Here, we highlight g...