Zur Einstäubung von Getreide mit Kontaktinsektiziden

Ohne Zusammenfassung     

Rate of stomatal opening, shoot hydraulic conductance and photosynthetic characteristics in relation to leaf abscisic acid concentration in six temperate deciduous trees

Correlations between leaf abscisic acid concentration ([ABA]), stomatal conductance (gs), rate of stomatal opening in response to an increase in leaf water potential (si), shoot hydraulic conductance (L) and photosynthetic characteristics were examined in saplings of six temperate deciduous tree species: Acer platanoides L., Padus avium Mill., Populus tremula L., Quercus robur L., Salix caprea L. and Tilia cordata Mill. Species-specific values of foliar [ABA] were negatively related to the mean values of gs, si, L and light- and CO2- saturated net photosynthesis (P(max)), thus providing strong correlative evidence of a scaling of foliar gas exchange and hydraulic characteristics with leaf endogenous [ABA]. In addition, we suggest that mean gs, si, L and Pmax for mature leaves may partly be determined by the species-specific [ABA] during leaf growth. The most drought-intolerant species had the lowest [ABA] and the highest gs, suggesting that interspecific differences in [ABA] may be linked to differences in species-specific water-use efficiency. Application of high concentrations of exogenous ABA led to large decreases in gs, si and P(max), further underscoring the direct role of ABA in regulating stomatal opening and photosynthetic rate. Exogenous ABA also decreased L, but the decreases were considerably smaller than the decreases in gs, si and Pmax. Thus, exogenous ABA predominantly affected the stomata directly, but modification of L by ABA may also be an important mechanism of ABA action. We conclude that interspecific variability in endogenous [ABA] during foliage growth and in mature leaves provides an important factor explaining observed differences in L, gs, si and Pmax among temperate deciduous tree species.     

Nutritional management of hyperlipaemia

Hyperlipaemia is a disease resulting from excessive mobilisation of triglyceride stores such that plasma clearance processes become overwhelmed. Consequently increased plasma triglyceride concentrations (>5.6 mmol/l), visibly cloudy plasma and a sick, anorexic or hypophagic subject follow. Epidemiological studies have identified many predisposing and triggering factors and the attentive carer or veterinary surgeon should be alert to such risk factors so that the disease can be prevented, or at least identified and treated at an early stage. Hyperlipaemic subjects are invariably in a negative energy balance, and nutritional management therefore plays a central role in both the prevention and resolution of the disease.     

Climate trends and global crop production since 1980

Efforts to anticipate how climate change will affect future food availability can benefit from understanding the impacts of changes to date. We found that in the cropping regions and growing seasons of most countries, with the important exception of the United States, temperature trends from 1980 to 2008 exceeded one standard deviation of historic year-to-year variability. Models that link yields of the four largest commodity crops to weather indicate that global maize and wheat production declined by 3.8 and 5.5%, respectively, relative to a counterfactual without climate trends. For soybeans and rice, winners and losers largely balanced out. Climate trends were large enough in some countries to offset a significant portion of the increases in average yields that arose from technology, carbon dioxide fertilization, and other factors.     

Effect of VA Mycorrhiza on Dry Weight and Phosphorus Content in Shoots of Cereal Crops Fertilized with Rock Phosphates at Different Soil pH and Temperature Levels

The influence of the VAM fungi Glomus macrocarpum and G. manihotis on shoot dry weight and P contents in the shoots of various graminaceous species was studied in pot culture experiments. The treatments included fertilization with different rock phosphates, four soil pH levels (pH 4.5, 5.5, 6.5, 7.5) and four soil temperatures (20, 25, 30, 35°C). The rock phosphate treatments were compared with soluble phosphate (mono calcium phosphate, MCP) and with a check (no P fertilizer, OP). Increases of shoot dry weight up to 143% could be found with mycorrhizal Triticum aestivum using Kodjari rock phosphate as P source. In the presence of VAM, Sorghum bicolor and T. aestivum fertilized with any of the rock phosphates, except Kola, produced yields comparable with those of plants fertilized with MCP, at soil pH 5.5 to 7.5 and at 25°C soil temperature. As the soil pH increased from 5.5 to 7.5 dry weight declined. Likewise, yields decreased with increasing soil temperature and at 35°C VAM showed no effect in all treatments.