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close this bookAbstracts on Sustainable Agriculture (GTZ; 1992; 423 pages)
Open this folder and view contentsAbstracts On Traditional Land-Use Systems
Open this folder and view contentsAbstracts on farming systems research and development
Open this folder and view contentsAbstracts on integrated systems
Open this folder and view contentsAbstracts on cropping system
Open this folder and view contentsAbstracts on agroecology
Open this folder and view contentsAbstracts on agrometeorology
Open this folder and view contentsAbstracts on agroforestry
Open this folder and view contentsAbstracts on homegardens
Open this folder and view contentsAbstracts on seed production
Open this folder and view contentsAbstracts on plant protection
Open this folder and view contentsAbstracts on water management
close this folderAbstracts on soil fertility
View the documentAcknowledgements
View the document1. Soil constraints on sustainable plant production in the tropics.
View the document2. Impact of agricultural practices on soil pollution.
View the document3. The use of organic biostimulants to help low input sustainable agriculture.
View the document4. Nitrogen cycling in high-input versus reduced-input arable farming.
View the document5. Green manure in rice farming.
View the document6. Role of green manure in low-input farming in the humid tropics.
View the document7. Green manuring with vetch on acid soil in the highland region of Rwanda.
View the document8. Tropical lowland rice response to preceding crops, organic manures and nitrogen fertilizer.
View the document9. Pearl millet and cowpea yields in sole and intercrop systems, and their after-effects on soil and crop productivity.
View the document10. Influence of some characteristics of bean seed and seedlings on the tolerance to low phosphorus availability in the soil. (Infuencia de algunas caracteristicas de las semillas y plantulas de frijol Phaseolus vulgaris L. sobre la tolerancia a la baja disponibilidad de fósforo en el suelo )
View the document11. Evaluation of diverse effects of phosphate application on legumes of arid areas.
View the document12. Effect of n and p fertilizers on sustainability of pigeonpea and sorghum systems in sole and intercropping.
View the document13. Efficient fertilizer use in acid upland soils of the humid tropics.
View the document14. Vesicular-arbuscular mycorrhiza management.
View the document15. Impact of tropical va mycorrhizae on growth promotion of cajanus cajan as influenced by p sources and p levels.
View the document16. Benefit and cost analysis and phosphorus efficiency of va mycorrhizal fungi colonizations with sorghum (sorghum bicolor) genotypes grown at varied phosphorus levels.
Open this folder and view contentsAbstracts on erosion and desertification control
Open this folder and view contentsAbstracts on potential crops for marginal lands

15. Impact of tropical va mycorrhizae on growth promotion of cajanus cajan as influenced by p sources and p levels.

Publ. of the Institute of Agronomy in the Tropics, Univ. Göttingen, Germany. Presented at the Int. Symposium on Management of Mycorrhiza in Agric., Hortic. and Forestry, Perth, Australia, 1992

The aim of the present paper revolves around the following questions: Are there differences between various VA mycorrhizal fungi in improving P uptake from different P sources with varying solubility? Do different P fertilizers exert an effect on the interaction of VA mycorrhiza and rhizobium? Does pigeon pea take advantage of a dual symbiosis?

The contribution of legumes in tropical cropping systems to maintain/restore soil fertility is gaining increasing importance. The most important aspect of tropical legumes is their ability to fix P in association with rhizobium atmospheric dinitrogen which becomes available to subsequent crops in rotational cropping systems. This is true for pigeon pea (Cajanus cajan) which fits into many agronomic management systems because of its multipurpose use. However, unfavorable soil conditions in the tropics often impede development of pigeon pea and phosphorous is considered to be the most limiting factor. Studies indicate the need for application of between 20-100 kg/ha of phosphorus.

This, however, is a luxury most farmers in the tropics with very limited financial resources can ill-afford. Consequently, seeking other possibilities to overcome this problem deserves special attention. In this context, the management of effective VA mycorrhizal fungi could become a promising tool to increase the efficiency of applied P fertilizers and thus reducing financial expenses.

The present research work was conducted under greenhouse conditions using a non-sterilized P fixing soil. Three P sources were applied at the following rates (kg P/ha): single superphosphate 10, 30, 60; and two rock phosphated from Brazil; Patos de Minas (total P, 10.7%): 50, 150, 300; and Araxá (total P, 12.1%): 50, 150, 300. The soil contained 2 native species of Glomales: Glomus albidum and Glomus intraradix. The mycorrhizal inoculum consisted of an air-dried mixture of soil/roots/spores and was applied at the rate of 2g/pot. Four VAM species originating from the Cerrado Ecosystem of Brazil were tested:

Glomus clarum, Glomus pallidum, Entrophospora colombiana, Acaulospora rehmii and Glomus manihotis from CIAT/Colombia (C-1-1). Cajanus cajan plants were not fertilized with N but inoculated with a peat-based inoculum of effective strains of rhizobium also from the Cerrado region.

The present results clearly indicate a strong dependency of pigeonpea on VAM fungi under P stress and Glomus clarum proved to be the most effective fungus irrespective of the P source and P level. In general, mycorrhizal infection rate was not influenced by the P source. However, with the exception of Glomus clarum, infection rate tended to decrease with increasing P levels. P uptake of inoculated plants corresponded well with the plant development and a similar tendency was observed with N uptake. With inoculated plants a significant relationship between P uptake/nodule formation and nodule formation/shoot dry weight was found, in particular with rock phosphate (Araxás). This relationship decreased with increasing solubility of the P source. The present results bear evidence that the fertilizer efficiency of low grade rock phosphates is dependent on an effective VA mycorrhiza. With Cajanus cajan an additive interaction of effective VA mycorrhiza and rhizobium was observed resulting in: improved P and N uptake, increased nodule formation and, enhanced plant growth.

1252 92 - 12/78

Soil fertility

USA, study, greenhouse experiment, sorghum, genotypes, mycorrhiza, phosphorus efficiency, cost/benefit analysis

RAJU, P.S. et al.

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