Vegetos
(An International Journal of Plant Research & Biotechnology)
(eISSN: 2229-4473)
Growth, biochemical, and physiological responses of cacao seedlings to anaerobic digestate, diabase rock powder, and reduced NPK fertilization
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Research Articles | Published: 26 September, 2026
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Keywords: Anaerobic digestate, Cacao seedlings, Diabase rock powder, Integrated fertilization, Reduced NPK fertilization
Abstract
The use of alternative nutrient sources for seedling production may reduce dependence on mineral fertilizers. This study evaluated the effects of anaerobic digestate and diabase rock powder combined with reduced NPK fertilization on growth, biochemical traits, gas exchange, and chlorophyll fluorescence of cacao (Theobroma cacao L.) seedlings under greenhouse conditions. The experiment was conducted in a randomized block design with nine treatments: control, full NPK, reduced NPK (NPKR), rock powder (RP), anaerobic digestate (DIG), RP + DIG, RP + NPKR, DIG + NPKR, and RP + DIG + NPKR. After six months, growth, biomass, biochemical, gas exchange, and chlorophyll fluorescence parameters were evaluated. DIG + NPKR promoted greater leaf area and total dry biomass than full NPK, together with higher total soluble protein concentration. Differences in soluble carbohydrate concentrations were also detected among fertilization treatments. No significant treatment effects were detected for gas exchange or chlorophyll fluorescence. Overall, anaerobic digestate combined with a 50% reduction in mineral NPK dose is a promising strategy for cacao seedling production under greenhouse conditions, although total nutrient inputs were not equivalent among fertilization strategies.
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Author Information
Doctoral Program in Agronomy, Federal Rural University of Amazonia (UFRA), Institute of Agrarian Sciences, Belém, Brazil