Nitrogen fixed in 13 provenances of Acacia albida and 11 isolines of Leucaena leucocephala inoculated with effective Rhizobium strains was measured by 15N techniques and the total N difference method. In the test soil, on the average, L. leucocephala derived about 65% of its total N from atmospheric N2 fixation compared to about 20% by A. albida. Significant differences in the percentage of N derived from atmospheric N2 (% Ndfa) occurred, between provenances or isolines within species. The % Ndfa ...

Differences in the nitrogen-fixing abilities of provenances of Casuarina equisetifolia and C. cunninghamiana were assessed in pot experiments. Three methods, the 15N isotope dilution, the A value and total N difference were used to measure N2 fixed. There was a good agreement between the A value and isotope dilution methods for measuring N2 fixed. The total N difference method gave unreliable values, with large coefficients of variation. There were significant differences in the proportions and ...

We studied the effect of three successive cuttings on N uptake and fixation and N distribution in Leucaena leucocephala. Two isolines, uninoculated or inoculated with three different Rhizobium strains, were grown for 36 weeks and cut every 12 weeks. The soil was labelled with 50 ppm KNO 3 enriched with 10 atom % 15N excess soon after the first cutting. Except for the atom % 15N excess in branches of K28 at the second cutting, both the L. leucocephala isolines showed similar patterns of total N, ...

The cereal cyst nematode,Heterodera avenue Wollenweber, is a serious pest of cereals in many countries. A high level of resistance to the unique Australian pathotype of the nematode has been demonstrated in a triticale line (T701-4-6), which was originally obtained from CIMMYT. The level of resistance is similar to that in rye cultivar, South Australian, but higher than that in the wheat line (AUS 10894), hitherto reported to have useful resistance to the Australian pathotype. The gene for resistance ...

Our aim in this study was to identify the economically optimal level of use of resources for a grazing system in tropical Australia and to compare it with the biological optimum. Grazing management trials were conducted in the Ord River irrigation area of north-western Australia. Biologists at the Commonwealth Scientific and Industrial Research Organization provided the biological data. The liveweight gains of Kimberley shorthorn steers were recorded, after a 1-year fattening period, for different ...

Cassava is the major root crop in eastern and southern Africa. It is an important source of calories for the inhabitants of such countries as Uganda, Malawi, and Mozambique. It may also be the best alternative for overcoming the food scarcities caused by frequent droughts in the region.

Shoot-tips 15cm long from 15 soybean cultivars and breeding lines were individually immersed in Hoagland's solution in 1 × 14 cm test tubes, and supported by cotton plugs. All leaves were removed leaving about 1 cm of each petiole on the shoot. A 4 mm mycelial plug of Sclerotium rolfsii Sacc., taken from the periphery of a 3-day-old culture grown on acidified potato dextrose agar (PDA) media was placed between the stem and a petiole in the middle of the shoot. Tubes with shoots were then placed ...

En Ikom, Nigeria del Sudeste, se realizó en el año de 1981/82 un análisis en campo de sistemas de cultivo orientados al cacao en suelos basálticos. El objetivo fue elaborar las principales características del sistema de producción y sus limitaciones. El sistema se realiza en dos grupos de productores: Los productores que tienen un bajo estado social y los que tienen un alto estado social. Ambos grupos se caracterizan por grandes contrastes socio-económicos. El tradicional sistema de arrendamiento ...