Calcium nutrition of higher plants.

Despite low intra-cellular requirements for Ca in the higher plants, Ca deficiency has been recorded in agricultural and horticultural plants during recent years. Because of insufficient selective and active uptake of Ca and its slow translocation, a high Ca concentration at the root surfaces is essential. The Ca requirement also increases when the supply of other nutrients, particularly cations increases. The use of inorganic fertilizers containing Ca should therefore receive more consideration. 56 references. (Abstract retrieved from CAB Abstracts by CABI’s permission

Effect of residue mixtures on response of cumulative respiration to salinity

The study aimed to investigate the response of soil respiration to salinity when amended with mixtures of rapidly and slowly decomposable residues. Two incubation experiments were carried out with loam soils having EC1:50.1, 1.0, 2.5 and 3.3 dS m-1. In experiment one, the four soils were amended with 20 g kg-1 soil as sawdust (C/N 114) or kikuyu (C/N 19) alone or mixed at different ratios. In all mixtures, the decrease in cumulative respiration at 1 dS m-1compared to non-saline soil was smaller than with sawdust alone. In experiment two, three soils (EC1:50.1, 1.0 and 2.5 dS m-1) were amended once or three times to a total addition rate of 10 g C kg-l soil either with sawdust alone, kikuyu alone or mixtures. In the treatments with mixtures, the decrease in cumulative respiration from non-saline to EC 1 dS m-1 was smallest in the treatments with three residue additions where 25% kikuyu was added on day 0 or on day 14 after addition of 50% sawdust on day 0. We conclude that even a relatively small proportion of rapidly decomposable residue in a mixture is sufficient to alleviate the negative impact of salinity on soil respiration.H. Hasbullah, P. Marschne

Relations between replant disease, growth parameters and mineral nutrition status of grapevines (Vitis sp.)

Grapevine cultivars Riesling (Vitis vinifera L.), 5 C (V. berlandieri PLANCH. x V. riparia MICHX.), Riesling grafted on rootstock cultivar 5 C (Riesling/5 C) and maize (Zea may L.) were grown in pots on a soil from a grapevine nursery affected with replant disease and on a soil that had not been planted with grapevines before. On replant soil the grapevines, in particular 5 C and Riesling/5 C, were severely inhibited in shoot and root growth, while ungrafted Riesling was less affected. In contrast, maize produced similar dry weights on both soils. There was no causal relationship between the incidence of replant disease in grapevines and their nutritional status, regarding macro- and micronutrients. However, compared to non-replant soil, on replant soil the manganese concentrations in shoots of all grapevine types were significantly lower, indicating an alteration of microbial activity and/or microbial composition in the rhizosphere of grapevines. Grapevine replant disease could not be induced in a soil by incubating the tenfold amount of grapevine roots, that seasonally remain in the nursery soil. Thus, the growth inhibition of grapevines cannot be attributed to substances released from dead grapevine roots of the degradation products. Obviously, factors associated with living roots (rhizosphere) are an essential prerequisite for the development of replant disease. The elimination of replant disease by steam sterilization of replant soil supports the assumption, that rhizosphere microorganisms are involved with grapevine replant disease

Development of a Radioimmunoassay for Pig Pancreatic Kallikrein

Peer Reviewe

Beziehung zwischen der Eisenversorgung von Weinreben und dem pH-Verlauf in der Nährlösung

 Relation between iron supply to grapevine and pH pattern in the nutrient solutionIn water culture experiments the effects of iron deficiency (-Fe) and iron supply as FeEDTA (control) or Fe(OH)3 on the pH pattern in the nutrient solution in the harvest composition, the wine pH and the level of free SO2 are also signifiner" have been studied.With sufficient iron (FeEDTA), the pH of the nutrient solution increased from 6 to approximately 7 during the experiment. However, the pH decreased under iron stress (-Fe or Fe(OH)3) to as low as 4. Simultaneously with this decrease in pH, chlorosis occured on the young leaves; with Fe(OH)3-supply, however, the pH rose again after some days, accompanied by regreening of the leaves. At harvest, the young leaves of the Fe(OH)3 treatment contained more iron and the chlorophyll content was at least as high as in the control (FeEDTA). Nevcrtheless, with Fe(OH)3 the shoot growth was clepressed as much as in plants without iron supply (-Fe).The results indicate that like other dicotyledonous plant species, grapevine is also able to lower the pH of the growth medium under iron stress and utilize inorganic Fe-III compounds even in well aeiated systems. This regulation mechanism is probably of considerable im~)ortance for the iron uptake from soils low in iron availability