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Title: SOIL ALUMINUM INFLUENCE ON GROWTH AND UPTAKE OF MICRONUTRIENTS BY CACAO

Author
item Baligar, Virupax
item FAGERIA, N - EMBRAPA,BRAZIL

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/25/2005
Publication Date: 9/14/2005
Citation: Baligar, V.C., Fageria, N.K. 2005. Soil aluminum influence on growth and uptake of micronutrients by cacao. Meeting Abstract.

Interpretive Summary:

Technical Abstract: In tropical soils, Al toxicity and inadequate supply of essential nutrients are the major factors affecting productivity of plantation crops such as cacao (Theobroma cacao L). Information on micronutrient requirements of cacao grown on infertile acidic soil are scarce. A growth chamber experiment was conducted to evaluate influence of three soil Al saturations i. e. 0.2, 19 and 26% on root and shoot growth and uptake of micronutrients. Root and shoot growth were significantly reduced with higher soil Al saturations, however, root growth was more sensitive to Al toxicity than shoot growth. Critical Al saturation is defined as 90% relative yield production as a function of soil Al saturation. The critical soil Al saturation for root and shoot growth were 2 and 15% soil Al saturation, respectively. Uptake of Cu, Fe, Mn and Zn quadratically decreased with increasing soil Al saturation in the range of 0.2 to 26% but uptake for B increased with increasing soil Al saturation. Among the micronutrients, maximum uptake was of Mn and minimum uptake was of Cu. The nutrient efficiency ratio for B, Mn and Zn quadratically increased with increasing soil Al saturation and the relations were significant. Micronutrient efficiency ratios were in the order of Cu > Zn > Fe > Mn. Results of this study suggest that uptake of all the micronutrients by cacao significantly decreased in the presence of toxic levels of Al in the growth medium, except B. Adequate supply of micronutrients in highly weathered tropical soils is essential factor to improve yield potential of cacao.