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Abstract: In Theobroma grandiflorum (cupuassu) orchards, efficient nutrient management is essential to achieve high yields and fruit quality. Thus, fertilization programs should be guided by the concentration of nutrients exported by fruits, as observed with other fruit species. The aim of this study was to quantify the export of macro and micronutrients by fruits of cupuassu genotypes, in order to guide nutrient replacement recommendations replacement. Six cupuassu genotypes (‘BRS Careca’, ‘BRS Fartura’, ‘BRS Duquesa’, ‘BRS Curinga’, ‘BRS Golias’ and ‘genotype 63’) were used, and 40 fruits per genotype were sampled, totaling 240 fruits, in the municipality of Tomé-Açu (Pará/Brazil). Fruits were broken and manually pulped and then separated into peel, seed and pulp. In each fruit part, the contents of macro and micronutrients were analyzed, and later extrapolated to ton of fresh fruits. Potassium was the macronutrient most exported by cupuassu fruits, and ‘genotype 63’ accounted for the largest exports per ton of fresh fruits of this nutrient. The export of nutrients per ton of fresh fruits followed this order for macronutrients (kg ton-1): K (4.34), N (2.73), P (0.54), Mg (0.40), S (0.29), Ca (0.26) and for micronutrients (g ton-1): Zn (6.24), Fe (4.97), Mn (3.49), Cu (2.45), Ni (0.18) and Mo (0.11). The average replacement per plant and per year, during the productive phase, for the five Cupuassu genotypes is 471 g of K2O, 326 g of N, 245 g of P2O5, 27 g of CaO, 56 g of MgO, 63 g of SO4-2 and 15 g of Fritted Trace Elements (FTE).

Jambu, a plant native to the Amazon, is rich in essential oils, particularly spilanthols and phytols. Although hydroponic cultivation of this vegetable is practiced, the process remains relatively understudied. In this context, this study aimed to assess the influence of electrical conductivity of nutrient solutions on jambu production. Greenhouse experiments were conducted at Universidade Estadual do Norte Fluminense (UENF), Brazil, employing a randomized block design encompassing six blocks comprising six Hoagland and Arnon nutrient solutions with electrical conductivities of 0.5, 1.0, 2.0, 2.5, 3.0, and 4.0 mS cm−1. Harvesting occurred 72 d after sowing, and the plants exhibited improved growth at electrical conductivity close to 3.5 mS cm−1. The levels of N, P, K, B, Zn, Mn, and essential oils of jambu plants increased linearly with increasing electrical conductivity. Twenty-three compounds were detected among the investigated essential oils, with spilanthol, phytol, and acmellonate present in the highest amounts. Increase in electrical conductivity led to increases in the percentage areas of several compounds, such as (Z,Z)-1,8,11-heptadecatriene, caryophyllene, 6-pentadecen-1-ol, 1-pentadecene, spilanthol isomer 1, (E)-β-ionone, kessane, and caryophyllene oxide. Furthermore, higher electrical conductivity resulted in decreasing percentages of compounds such as spilanthol, phytol, and Compound 2. Notably, a 609.74 % increase in caryophyllene and a 25.65 % reduction in spilanthol were observed with increasing electrical conductivity. These results suggest that the productivity of jambu plants is improved, including the production of essential oils, with cultivation in solutions with electrical conductivities above 2.5 mS cm−1. However, this condition may negatively affect most cultivated vegetables. The mechanisms underlying the increased tolerance of jambu to higher electrical conductivities require further investigation.