Abstracts on sustainable agriculture 1992 Gate- GTZ: Abstracts on soil fertility: 16. Benefit and cost analysis and phosphorus efficiency of va mycorrhizal fungi colonizations with sorghum (sorghum bicolor) genotypes grown at varied phosphorus levels.

Abstracts on sustainable agriculture 1992 Gate- GTZ

Abstracts on soil fertility

		Acknowledgements
		1. Soil constraints on sustainable plant production in the tropics.
		2. Impact of agricultural practices on soil pollution.
		3. The use of organic biostimulants to help low input sustainable agriculture.
		4. Nitrogen cycling in high-input versus reduced-input arable farming.
		5. Green manure in rice farming.
		6. Role of green manure in low-input farming in the humid tropics.
		7. Green manuring with vetch on acid soil in the highland region of Rwanda.
		8. Tropical lowland rice response to preceding crops, organic manures and nitrogen fertilizer.
		9. Pearl millet and cowpea yields in sole and intercrop systems, and their after-effects on soil and crop productivity.
		10. 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 )
		11. Evaluation of diverse effects of phosphate application on legumes of arid areas.
		12. Effect of n and p fertilizers on sustainability of pigeonpea and sorghum systems in sole and intercropping.
		13. Efficient fertilizer use in acid upland soils of the humid tropics.
		14. Vesicular-arbuscular mycorrhiza management.
		15. Impact of tropical va mycorrhizae on growth promotion of cajanus cajan as influenced by p sources and p levels.
		16. Benefit and cost analysis and phosphorus efficiency of va mycorrhizal fungi colonizations with sorghum (sorghum bicolor) genotypes grown at varied phosphorus levels.

16. Benefit and cost analysis and phosphorus efficiency of va mycorrhizal fungi colonizations with sorghum (sorghum bicolor) genotypes grown at varied phosphorus levels.

Plant and Soil, 124, 1990, pp. 199-204

This study was conducted to determine benefit and cost analysis and P efficiency (dry matter produced/unit P absorbed) of Glomus fasciculatum colonization with sorghum roots when genotypes were grown at different soil P levels.

Sorghum [Sorghum bicolor (L.) Moench] was grown in a greenhouse in a low P (3.6 mgkg-1) soil inoculated with the vesicular-arbuscular mycorrhizal fungi (VMAF) Glomus fasciculatum and P added at 0, 12.5, 25.0, and 37.5 mgkg-1 soil to determine the effects of VAMF-root associations on plant growth, and P efficiency (dry matter produced/unit P absorbed).

Root associations with vesicular-arbuscular mycorrhizal fungi (VAMF) normally benefit plant growth, particularly through enhanced P uptake.

Host plants must provide carbohydrates to VAMF for development and growth.

In this study root colonization with VAMF and shoot growth enhancements decreased with increased soil P applications. Mycorrhizal plants were less P efficient than nonmycorrhizal plants. Shoot dry matter differences between mycorrhizal and nonmycorrhizal plants were considered the benefit derived by plants from VAMF-root associations.

Shoot dry matter differences between mycorrhizal and nonmycorrhizal plants with similar P concentrations were considered the costs paid by plants for VAMF-root associations. Values of benefit and cost analysis for VAMF-root associations were highest when soil P was lowest and decreased with increasing P applications. Genotypic differences for calculated costs were pronounced, but not benefits. Benefit and cost analysis may be helpful to evaluate host plant genotypes and VAMF species to optimize efficiencies of VAMF symbiosis in different soil environments.

VAMF associations with plant roots not only benefit growth and mineral element uptake, but VAMF infected plants can give greater tolerance to root pathogens, drought, low soil temperatures, adverse soil pH, and transplant shock. VAMF-root associations have great potential in land reclamation and agriculture practices on arid and acid lands, where drought, low soil fertility (especially P deficiency), and high soil salinity and/or toxicity elements can be major constraints to crop production.