|Fageria, Nand - EMBRAPA-CNPAF BRAZIL|
Submitted to: Soil Science and Plant Nutrition (SSPN)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 29, 2004
Publication Date: July 7, 2012
Citation: Baligar, V.C., Fageria, N.K. 2012. Soil aluminum effects on growth and nutrition of cacao. Soil Science and Plant Nutrition (SSPN). 51:709-713. Interpretive Summary: In cacao growing regions, acidity is a major soil degradation factor. Soils under cacao have become infertile and acidic due to lack of proper fertilizer and liming practices, long-term cultivation, and poor management. Cacao production in these acidic infertile soils is limited by the presence of toxic levels of Al and inadequate availability of essential nutrients. Soil acidity constraints, especially high levels of exchangeable Al, on growth and mineral nutrition of cacao are not very well understood. This study compared the effects of three levels of soil Al saturation on growth, relative growth rate, net assimilation rate, and nutrition uptake of cacao. Overall, increasing soil Al saturation reduced shoot and root growth, relative growth rate, and net assimilation rate in cacao. Increasing soil Al saturation increased nutrient use efficiency ratio (ER) for calcium and magnesium and decreased ER for other essential macro nutrients. Reduction of soil acidity constraints with addition of lime, and maintenance of adequate levels of essential nutrients appear to be key factors in improving cacao yields in infertile, acidic tropical soils.
Technical Abstract: In acid soils Al toxicity and deficiencies of nutrients are responsible for low yields of cacao (Theobroma cacao L). Research was undertaken in a growth room to evaluate the effects of three levels (0.2, 19, and 26%) of soil Al saturations on growth and nutrient uptake parameters of cacao. Overall, increasing soil Al saturation decreased shoot and root dry weight, stem height, root length, leaf mass/unit leaf area, relative growth rate, and net assimilation rate. However, increasing soil Al saturation increased leaf area, specific leaf area, and leaf area ratio. Overall increasing soil Al saturation increased uptake of Na and decreased uptake of other elements. Nutrient influx (IN) and transport (TR) for K, Ca and Mg decreased, and for S and P, increased due to increasing soil Al saturation. Increasing soil Al saturation increased nutrient use efficiency ratio (ER) for Ca and Mg, and decreased ER for other elements.