The Physalis angulata L. species has attracted interest due to the production of compounds with pharmacological activity and its potential for fruiticulture. Given that it is a fast-growing and highly productive species, determining the most adequate nitrogen (N) doses could contribute to higher crop yields. This study aimed at assessing the influence of N concentrations, in a hydroponic system, on the growth and production of P. angulata, as well as determining the critical N level in leaves. The experiment was conducted in individual pots with nutrient solutions, applying a completely randomized design and twelve replications, using five N doses (0 mg L-1, 56 mg L-1, 112 mg L-1, 168 mg L-1 and 224 mg L-1). Growth and production indices, amount of total N on leaves and stems and critical N levels were assessed. The increase of N doses in the nutrient solution influenced plant growth and fruit production, as well as the accumulation of total N in the leaves and stems. Based on the maximum economic yield, a dose of 162 mg L-1 of N is recommended for hydroponics, which provided a fruit yield of 7.27 g m-2 and critical total N level in leaves of 51.98 g kg-1.

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The aim of this study was to compare different protocols for extraction and quantification of photosynthetic pigments, considering different solvents, extraction time and temperature, to determine the best methodology for Physalis angulata L. leaves. The efficiency of immersion of leaf discs in 95% ethanol, 80% acetone and dimethyl sulfoxide (DMSO) was evaluated for 24, 48 and 72 hours. The effect of temperature on extraction with DMSO was also evaluated, with the samples incubated at room temperature and in a water bath at 65 °C. These protocols were compared with the classical methods of plant tissue maceration in 80% acetone followed by filtration, which proved to be the most efficient for Physalis angulata plants and indicated for use in the laboratory. The use of high temperatures (65 °C) is not necessary for the chlorophyll extraction process with DMSO, the room temperature is most efficient in the extraction of carotenoids. Considering the total chlorophyll content, the leaf discs immersion technique in a solvent is acceptable, with 95% ethanol and 24 hours incubation and the most economically viable alternative.

RESUMO As principais fontes de absorção de N pelas plantas são os íons NH 4 + e NO 3-e a utilização de proporções desbalanceadas pode promover alteração no crescimento e desenvolvimento de diversas espécies. Dessa forma, objetivou-se com esse trabalho avaliar o efeito de proporções de NO 3-:NH 4 + em solução nutritiva na produção de massa seca de plantas de Physalis angulata L. O trabalho foi conduzido em casa de

It’s known that drought affects crop growth, however, little is known about the physiological responses developed under these conditions by underexploited species, such as Physalis angulata. This study aimed at assessing the physiological responses of Physalis angulata plants after 40 days under different water availability (100%, 80%, 60%, 40% and 20% of pot field capacity). In this research, the effects of the water deficit on the relative water content, water potential, gas exchange, sugars accumulation and activity of nitrate reductase were evaluated. Water relations were affected mainly in plants under severe water deficit, however, the variables remained stable when cultivated at sub-optimal levels of field capacity. Gas exchanges were also affected by water deficit, with reduction in carbon assimilation, internal carbon, stomatal conductance and transpiration, as well as increased leaf temperature and water use efficiency. Plants accumulated sugars as a mechanism of tolerance to severe water deficit, while nitrate reductase activity was reduced. P. angulata plants develop important strategies to tolerate water deficit, contributing to the establishment of crops under low water availability.

RESUMOangulata L., a naturally occurring species (Matos 2000), appears as an alternative for the region.P. angulata is a herbaceous plant of approximately 70 cm in height, popularly known in Brazil as mullaca, camapu and juá-de-capote (Freitas et al. 2006). Its fruit, a globose berry with numerous seeds, has a sweet and slightly acidic taste, with a high content of vitamins, phosphorus, iron, flavonoids and fibers (Velasquez et al. 2007, Rufato et al. 2008. Despite such a great potential, the species is not much explored, and little research is carried out on its cultivation, mainly regarding techniques to increase fruit quality and yield.

Nitrate reductase (NR) is the first enzyme in the nitrogen assimilation pathway. The determination of its activity requires modifications for each plant species. The goal of this work was to evaluate the variation of NR activity throughout the day and the optimization of assay conditions in foliar and radicular tissues of Physalis angulata. The analysis was done in plants cultivated in a hydroponic system at two months of age. The NR activity was based on the in vivo assay method. Enzyme activity was observed on leaf and root, indicating two sites of nitrate assimilation with a higher activity in the daylight in leaf. The NR activity in leaf was increased after 4h of luminosity. In the root, we observed a high activity during most of the day, especially in periods of higher solar radiation and temperature. To obtain the highest activity of NR in both tissues we suggest 1% n-propanol, 50mM of KNO3- in pH=7 phosphate buffer for 75 min incubation in water bath.