Developing agricultural solutions with smallholder farmers - How to get started with participatory approaches

Farm Management,

A generalized approach for the calculation and automation of potentiometric titrations Part 2. Redox Titrations

The very fast calculation procedure described earlier is applied to calculate the titration curves of complicated redox systems. The theory is extended slightly to cover inhomogeneous redox systems. Titrations of iodine or 2,6-dichloroindophenol with ascorbic acid are described. It is shown that correspondence between theory and practice is good as long as the relevant stability constants and redox potentials are known with sufficient accuracy

A generalized approach for the calculation and automation of potentiometric titrations Part 1. Acid-Base Titrations

Fast and accurate calculation procedures for pH and redox potentials are required for optimum control of automatic titrations. The procedure suggested is based on a three-dimensional titration curve V = f(pH, redox potential). All possible interactions between species in the solution, e.g., changes in activity coefficients and influences of redox potential on pH variations, are taken into account. The number of titrant additions can be reduced considerably without loss of precision, by using the fact that the pH of a protolyte or mixture of protolytes at some fraction titrated does not depend strongly on the actual concentration

Psyllid Resistance in the Leucaena Genus

Leucaena species varied from highly susceptible to highly resistant in their response to the psyllid insect (Heteropsylla cubana) at 2 sites, a high psyllid environment at Brisbane, Australia and a moderate psyllid environment at Los Baños, Philippines. L. leucocephala was the most susceptible species. There was considerable intraspecific variation in psyllid resistance within L. collinsii, L. diversifolia and L. pallida. Plant reponse to psyllid challenge between environments was highly correlated but not linear. The higher psyllid challenge environment at Brisbane permitted greater discrimination between species and fewer Leucaena species were ranked as psyllid resistant

The Arthropod Fauna of Oak (Quercus spp., Fagaceae) Canopies in Norway

(1) We document the invertebrate fauna collected from 24 oak canopies in east and west Norway as a contribution to the Norwegian Biodiversity Information Centre’s ‘The Norwegian Taxonomy Initiative’. (2) A snap-shot inventory of the canopies was recorded by means of emitting a mist of natural pyrethrum into the canopies at night using a petrol-driven fogger and collecting the specimens in butterfly nets spread on the ground under the canopy. (3) Almost the entire catch of more than 6800 specimens was identified to 722 species. Out of 92 species new to the Norwegian fauna, 21 were new to science and, additionally, 15 were new to the Nordic fauna. Diptera alone constituted nearly half of the species represented, with 61 new records (18 new species). Additionally, 24 Hymenoptera (one new species), six oribatid mites (two new species) and one Thysanoptera were new to the Norwegian fauna. (4) Our study emphasizes the importance of the oak tree as a habitat both for a specific fauna and occasional visitors, and it demonstrates that the canopy fogging technique is an efficient way to find the ‘hidden fauna’ of Norwegian forests. The low number of red listed species found reflects how poor the Norwegian insect fauna is still studied. Moreover, the implication of the IUCN red list criteria for newly described or newly observed species is discussed.</jats:p

On the influence of the soil on the distribution of plants. Communicated by Count Marschall

Volume: 17Start Page: 520End Page: 52