ABSTRACT Jambu is a leafy vegetable from the northern region of Brazil and its cultivation in the soil has considerably reduced its production, due to pests and diseases. Based on this, the objective ...of this work was to evaluate the growth, yield and postharvest quality of hydroponic jambu plants in response to the variation of nitrogen (N) concentration in the nutrient solution. The design used was completely randomized with eight replicates and six treatments, consisting of N concentrations in the nutrient solution (11, 13, 15, 17, 19 and 21 mmol L-1). Main stem length (MSL), diameter (D), leaf area (LA), number of inflorescences (NI), shoot fresh mass (SFM), shoot dry mass (SDM), root fresh mass (RFM), root dry mass (RDM), inflorescence fresh mass (IFM), inflorescence dry mass (IDM), N content, total soluble solids (TSS), pH, titratable acidity (TA) and TSS/TA ratio were evaluated. Both growth and yield were explained by positive linear models, and the best results were obtained at the N concentration of 21 mmol L-1. As for the quality variables TSS and TSS/TA, these were also explained by increasing linear models with maximum responses at the N concentration of 21 mmol L-1. As the N concentration increased, there were reductions in TA. Based on the results, the N concentration of 21 mmol L-1 in the nutrient solution enables better response in terms of growth, production and postharvest quality in jambu.
Acmella oleracea is a herbaceous plant native to the Amazon region that is currently arousing industrial interest due to its potential gastronomic, cosmetic and pharmaceutical uses. Accordingly, the ...objective of the current study was to test the influence of temperatures on A. oleracea seed germination and seedling vigor. A completely randomized design (CRD) with five treatments and five replicates was used. Treatments consisted of temperatures: 23, 26, 29, 32 and 35 ºC. The study was conducted in BODtype climate chambers with relative humidity above 90% and a 12 h photoperiod. Germination, germination speed index (GSI), average germination time, root length and number of normal and abnormal seedlings were recorded. Temperature influenced all analyzed variables, except average germination time and number of normal/abnormal seedlings. A quadratic model best described the relationship between dependent and independent variables. In general, maximum germination values, and GSI and root lengths were obtained at temperatures close to 29 °C, while the lowest observed values for these variables occurred at extreme temperatures (23 and 35 °C). The highest percentage of germinated seeds occurred on the second day. Temperatures above 29 ºC induced a significant reduction in the A. oleracea seedling root lengths.
Jambu is considered a leafy vegetable with expressive relevance in the regions that compose the Brazilian Amazon. However, there are challenges regarding its cultivation, particularly for the ...nutritional management, since there is little technical information that allows an increase in the efficiency of its production. In this sense, nitrogen (N) gains prominence, since it is related to the increased yield and quality of leafy vegetables, therefore its monitoring of N content in plants is necessary. The objective of this study was to evaluate the efficiency of using the SPAD index to estimate the N content of jambu leaves, total chlorophyll concentration, as well as its relationship with dry mass accumulation due to the increase of nitrogen concentration in the nutrient solution. The design used was completely randomized with eight replications. The treatments were six nitrogen concentrations in the nutrient solution (11, 13, 15, 17, 19 and 21 mmol L-¹). After 21 days of transplantation, the SPAD index was measured. Then, these plants were collected to quantify the total chlorophyll, dry mass and nitrogen content. In general, the variables were explained by increasing linear models. There was a positive correlation between the SPAD index and the other characteristics evaluated. Based on the results, the best response at the concentration of 21 mmol L-¹ in the nutrient solution stands out. In addition, the SPAD index has potential to be used in the diagnosis of nitrogen status in jambu leaves.
Jambu is a vegetable, widely consumed in the Brazilian North Region, both in typical foods and medicinal herb. Despite its versatility, there are uncountable challenges in relation to its ...cultivation, especially with regard to the availability of information on nutritional management, such as the lack of data on the effect of liming associated with the supply of nitrogen (N) on the production performance of the crop. Thus, the effect of nitrogen fertilization and liming on growth, production, physiological responses and post-harvest quality of the yellow-flowered variety jambu was evaluated. The experimental design was randomized in factorial blocks (6 x 2), with five repetitions. The treatments consisted in the combination of six doses of N (0; 60; 90; 120; 150 and 180 kg ha-1) with and without liming application (0 and 70% V). The variables of growth, production, gas exchange and post-harvest quality of jambu were evaluated. Standardly, there was interaction between N-dose and liming factors for most of the analyzed variables, except for titratable acidity and total soluble solids and titratable acidity ratio. In general, the increasing of N doses combined with liming positively affected growth, production, physiological responses and post-harvest quality, and it was observed that in the 170 kg ha-1 dose of N higher response was obtained in the biomass accumulation of the aerial part and in the 180 kg ha-1 dose of N maximum production of inflorescences. Therefore, the use of correctives associated with nitrogen fertilization is recommended to obtain more significant production and quality of jambu.
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