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United States Department of Agriculture

Agricultural Research Service

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Research Project: CACAO GENOTYPIC RESPONSE TO ABIOTIC STRESSES, MANAGEMENT AND SOIL QUALITY AND THE ACQUISITION AND CHARACTERIZATION OF CACAO GERMPLASM

Location: Sustainable Perennial Crops

2013 Annual Report


1a.Objectives (from AD-416):
1. To assess the genotypic differences of cacao and legume cover crops to abiotic stresses such as nutrient deficiency/elemental toxicities, moisture stresses, and shade.

2. Cacao management systems such as agroforestry and cover crops systems and their impact on the soil quality factors will be evaluated.


1b.Approach (from AD-416):
Fundação Pau Brasil actively promotes sustainable cacao production through collaborations with cacao research institutions. This specific cooperative agreement (SCA) will emphasize the coordination of research approaches of the USDA/ARS and all collaborating institution mentioned here and will promote sustainable cacao production research and identification of abiotic stress tolerant cacao germplasms. The agreement promotes international partnerships and cooperation with the USDA-ARS.


3.Progress Report:

Specific research activities conducted under this agreement include the assessment of cacao genotypes to abiotic stresses such as nutrient deficiencies/toxicities, drought/water logging, and light intensities. Additionally, cacao management systems are being evaluated for their impact on soil quality and bean quality. This collaborative research project is being conducted with a multidisciplinary team of researchers from CEPLAC/CEPEC (Comissao Executiva do Plano da Lavoura Cacaueira/Centro de Pesquisas de Cacau) in Itabuna, Bahia, UESC (Universidade Estadual Santa Cruz) in Ilheus, Bahia, Institute of Cabruca, Ilheus, Bahia, the UENF (Universidade Estadual de North Fluminense) Campose, RJ and National Rice and Bean Research Center of EMBRAPA (Empresa Brasileira de Pesquisa Agropecuária) Santo de Antonio, Goias GO. For 2013, the first set of experiments to evaluate cacao responses to drought and toxic/deficient levels of soil Zn, Cu and cover crop responses to various levels of soil Zn have been completed. Soil quality evaluations for 15 cacao management experiments have been completed. Bean quality evaluations for these various cacao management experiments are in progress. Flooding decreases a number of key cacao growth factors in both flood tolerant and intolerant cacao genotypes. Flood susceptible genotypes showed changes in fluorescence emission, reduction in chlorophyll content and increased activity of stress enzymes. Flooding also caused changes in macro and micronutrient levels, in the total amount of soluble sugars and in the starch concentrations. Stable plant traits were identified that respond to flooding. This will be useful in the identification of cacao genotypes that have tolerance to short periods of flooding. Increasing Al concentrations in the growth medium decreased the growth, the rate of photosynthesis and mineral contents. Genotypic differences for tolerance to Al were observed among the tested cacao varieties. Research was undertaken in cacao growing regions of Bahia, Brazil to characterize the tree species diversity in the cabruca type of cacao management system. This system plants cacao under native rainforest trees. The composition of dominant trees in the cabruca system was strongly influenced by preferences of farmers, particularly for their use as food and wood. Also under the cabruca agroforestry system, the level of organic Phosphorus (P) in soil was negatively correlated with organic biomass or organic C in the soil. The experiments established in Bahia, Brazil are also serving as a training ground for graduate students in cacao stress physiology and in the development of management practices for sustainable cacao production. This is the final report for this agreement.


Last Modified: 8/27/2014
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