Fusariosis is a disease that causes economic damage to black pepper (Piper nigrum L.) producers. Despite being a major disease, there is no record of efficient chemical control. Thus, the objective was to evaluate the antifungal activity of copper, zinc and potassium compounds in mycelial growth and conidial germination of Fusarium solani f. sp. piperis in vitro. For inoculation in PDA (Potato Dextrose Agar) medium, 7 mm discs from the pure culture were transferred to Petri dishes. The plates were incubated at 25ºC in a biochemical oxygen demand (BOD) chamber, with photoperiod of 12 h, for 15 days. Micronutrients were supplied as sulfates, CuSO4 (copper sulfate) and ZnSO4 (zinc sulfate), at concentrations of 1, 5, 10, 15 and 20 mmol/L. Potassium macronutrient (K) was supplied as KCl (potassium chloride) at concentrations of 30, 60, 90,120 and 150 mmol/L. The experiment was performed using a completely randomized design with 6 treatments and ten replications. CuSO4 showed fungicidal effect at concentrations of 10, 15 and 20 mmol/L. For ZnSO4 mycelial growth was completely inhibited at concentrations of 15 and 20 mmol/L. There was no inhibition or reduction of fungal growth in the presence of K. Copper and zinc at minimal concentrations were efficient in controlling mycelial growth and inhibition of spore germination of F. solani f. sp. piperis. In contrast, potassium did not exert fungicidal or fungistatic effect on the fungus.

This study evaluated the effect of silicon (Si)-supplementation in controlling the fusariosis in two Piper nigrum cultivars (Bragantina and Kottanadan). We hypothesized that susceptible cultivar improves the photosynthetic performance with Si-supplementation. Under greenhouse conditions, six-month-old plants were treated with silicon 30 and 15 d before inoculation with Fusarium solani f. sp. piperis and compared with untreated plants and with healthy control plants. All samples remained photosynthetically active after infection. Chlorophyll content, chlorophyll a fluorescence, and leaf gas-exchange parameters were less affected in Si-supplemented plants as well as healthy control plants. The net carbon assimilation, stomatal conductance, associated with higher internal carbon values suggest that the lower CO2 influx in inoculated plants of Bragantina cultivar was caused by photochemical and biochemical limitations. Si-supplementation reduced the disease severity improving protection, apparently associated with the preservation of photosynthetic performance, especially for Bragantina cultivar.

The black pepper (Piper nigrum L.) is one of the most popular peppers in the world. Nonetheless, there are several limitations on cultivation, resulting in reduced production or a complete loss of the crop. The major disease affecting this crop is fusarium root rot caused by Fusarium solani f. sp. piperis, which is responsible for decimating whole crops in Brazil, with losses reaching millions of dollars per year. So far, there is no effective control measure against this fungus and no cultivars resistant to it. In this study, in vitro effects of different products on colony growth was evaluated. Carbendazim, chitosan, silicon, and phosphate were tested against F.solani f. sp. piperis isolates CML-2466, CML-2353, E-637, and E-596. Chitosan and silicon did not inhibit mycelial growth of any of the isolates, while phosphite inhibited mycelial growth by 100%. Carbendazim was found to be fungitoxic for isolates CML-2353 and E-596 and fungistatic for CML-2466 and E-637, inhibiting the mycelial growth of these isolates by 60 and 80%, respectively. There were no dose effects of the products tested.

The barks of fruits are usually discarded as organic waste; a valuable source of nutrients is obtained are used as a starting source in the preparation of functional foods. In this work, the physicochemical properties (pH, titrable acidity and soluble solids), mineral and bromatological analysis of nine Amazonian fruits were studied: abiu, acerola, araçá, bacupari, biribá, camu-camu, fruta-do-conde, araçá and taperebá. The most acidic values stand out for the different fruits, with the exception of the abiu bark (pH = 4.7). As for its nutritional contribution, it was the araçá barks that presented the highest energy value of 276.29 Kcal 100 g-1. Among the macrominerals, the potassium concentration stands out, being the highest concentration for the graviola bark, 521.04 mg 100 g-1 followed by magnesium, where the concentration in the biribá was 64.21 mg 100 g-1. On the other hand, the husks are rich in micronutrients, highlighting the concentration of zinc in the bark of araçá, 12.23 mg 100 g-1 and manganese in the bark of abiu, 6.84 mg 100 g-1. The Pearson correlation coefficient presented a highly significant correlation for Fe-Al (0.96), P-Fe (0.94) and Fe-Zn (0.89). O bligpot of principal components (PCA) explains 56% of the cases, being the minerals Mg, Na, Co, K, S and Ca highly associated for the graviola and bacuparí.