Os efeitos da liberação de aleloquímicos de uma espécie sobre outra podem resultar em danos ecológicos aos ecossistemas, como a facilitação de estabilização e povoamento de espécies invasoras. Com este trabalho, objetivou-se avaliar os efeitos alelopáticos de partes vegetais da algaroba, espécie invasora, sobre a emergência e o crescimento inicial de plântulas de jurema-preta, espécie nativa da Caatinga. Prepararam-se extratos aquosos de folhas, cascas e raízes da algaroba, usando 125 g de material vegetal para cada 500 mL de água destilada, nas concentrações 0, 25, 50, 75 e 100%. Foram utilizados tubetes de 55 cm³ preenchidos com solo. Distribuíram-se os tratamentos em delineamento inteiramente casualizado (DIC), com quatro repetições, cada uma com cinco tubetes. Avaliaram-se a porcentagem de emergência, altura, diâmetro do caule, número de folhas e peso seco de folhas, caule, raiz, parte aérea e total. A exceção do extrato de casca a 100% no peso seco total, todos os extratos causaram efeitos deletérios a emergência e plântulas de jurema-preta, sendo o extrato de raiz a 100%, o responsável pela maior redução na porcentagem de emergência, 33%, em compração com o tratamento controle. Palavra-chave: alelopatia, algaroba, invasão biológica, jurema-preta, semiárido. ALLELOPATHIC EFFECT OF AQUEOUS EXTRACTS OF Prosopis juliflora (SW.) DC IN THE EMERGENCE AND INITIAL GROWTH OF Mimosa tenuiflora (WILLD.) Poiret SEEDLINGS   ABSTRACT: The effects of allelochemicals release of one species over another may result in ecological damage to ecosystems, such as facilitating the stabilization and settlement of invasive species. The objective of this study was to evaluate the allelopathic potential of different plant parts of Prosopis juliflora, invasive species, emergence and early growth of Mimosa tenuiflora, native species of Caatinga. The aqueous extracts of leaves, barks and roots from the algaroba were prepared at a ratio of 125 g of plant material to 500 ml of distilled water, diluted at concentrations of 0, 25, 50, 75 and 100%. For emergence and early growth, tubes were used in 55 cm³, with application of the extracts every 15 days. The treatments were also distributed in DIC, with four replications and five tubes by repetition. We evaluated the percentage of emergence, plant height, stem diameter, number of leaves, dry weight of leaves, stem, root, aerial and total parts. With the exception of 100% bark extract on the total dry weight of all the extracts caused deleterious effects the emergence and seedling jurema-preta, being the extract of root to 100%, responsible for the greater reduction in the percentage of emergency, 33%, in purchase with the control treatment. Keywords: allelopathy, algaroba, biological invasion, jurema-preta, semiarid.   DOI:

The common climatic characteristics in semi-arid regions can cause abiotic stress and be a limiting factor for crops. Under these conditions, the use of beneficial elements such as selenium (Se) is an alternative to mitigate the harmful effects of abiotic stresses and increase yield. Therefore, this research aimed to evaluate the agronomic performance of onion grown in a semi-arid region under the application of Se. A field experiment was performed in a randomized block design, where five doses of Se (0, 15, 30, 45, and 60 g ha^-1), by foliar application, were tested on two onion hybrids (Andrômeda and Rio das Antas). Growth, nutritional and yield variables were analyzed. Se increased the height and accumulation of dry mass in onion plants, with a maximum at the 60 g ha^-1 dose of Se, the same dose at which the highest commercial (78.15 t ha^-1) and total (86.03 t ha^-1) bulb yields were obtained in Rio das Antas; however, for Andrômeda, there was no effect of Se on yield. Applied Se doses also increased the content of this element in the bulbs. Despite increasing bulb yields only in the Rio das Antas hybrid, 60 g ha^-1 of Se is recommended for onions due to its effects on plant growth and the biofortification of bulbs with Se.

Agronomic biofortification is a technique that helps reduce hidden hunger worldwide. Zinc (Zn) is important for human health and essential for plant development and growth. Thus, this research aimed to evaluate the effects of fertilization with Zn on agronomic performance and the agronomic biofortification of beet. Two experiments were conducted at the Rafael Fernandes Experimental Farm, belonging to the Federal Rural University of the Semi-arid, in Mossoró-RN. Each experiment was designed in complete randomized blocks, with five treatments and four replications. The treatments consisted of Zn doses (0, 1.5, 3.0, 4.5, and 6.0 kg ha⁻¹). Zn fertilization did not affect the total and non-commercial yield of beet; however, the dose of 6.0 kg ha⁻¹ of Zn promoted maximum commercial yield (20.34 t ha⁻¹). At the maximum dose, higher Zn content was also observed in the nutritional status diagnosis leaf and higher Zn accumulation was found in the leaf, tuberous root, and throughout the plant. There was also an effect on postharvest variables. There was only tuberous root biofortification in 2021. The recommended dose in beet cultivation is 6.0 kg ha⁻¹ of Zn.

The treatment with low temperatures, for a certain period, stimulates the accumulation of phytohormones in garlic seed cloves, which influence the growth and development of the plants. Thus, this work aimed to evaluate the effects of garlic seed cloves under negative temperatures for different periods on the development and productivity of noble garlic cultivated in the Brazilian semi-arid region. Two experiments were carried out and analyzed separately in the municipalities of Mossoró and São Miguel, RN, Brazil, in which three temperature ranges (−5 to −3 °C, −2 to 0 °C and 1 to 3 °C) and three periods (50, 55, and 60 days) were tested. Low-temperature conditioning of the garlic seed cloves was carried out in a temperature-controlled freezer. Relative humidity during treatment ranged from 60 to 70%. Seed cloves submitted to temperatures below zero provided the differentiation of cloves, even in unfavorable edaphoclimatic conditions for cultivating noble garlic. Seed cloves conditioned with negative temperatures increased the productivity of garlic grown in Mossoró, but with a lower average yield than garlic produced in São Miguel. Garlic seed cloves treated at negative temperatures in São Miguel provided garlic productivity equivalent to the yield of garlic grown in the states of the southern region. In addition, it produced class 6 and 7 bulbs, which have greater commercial value and acceptance by consumers. The results demonstrated the potential of garlic seed cloves treated with temperatures below zero to increase the production of noble garlic in the semi-arid region of the country.

Micronutrients structurally constitute several enzymes and act as a cofactor of essential proteins to maintain cell function, thereby contributing to crop growth and yield. The objective of this study was to evaluate the leaf content, growth, accumulation of micronutrients, classification and yield of onion as a function of fertilization with boron, cooper and zinc in two years of cultivation. The experiments were carried out from June to November in 2018 and 2019, in a soil classified as Ultisol, both at the Rafael Fernandes Experimental Farm, belonging to the Universidade Federal Rural do Semiárido, in the municipality of Mossoró, Rio Grande do Norte, Brazil. The experimental design was in randomized blocks with 15 treatments and four replicates. The treatments consisted of application of doses of B, Cu and Zn, in two experiments. Contents of B, Cu and Zn in the diagnostic leaf, growth, accumulation of B, Cu and Zn in the leaf, bulb and total, classification and commercial, non-commercial and total yields were evaluated. Application of B, Cu and Zn did not influence the number of leaves, relation of bulb shape, leaf, bulb, and total dry mass and yield of onion. Application of B, Cu and Zn, respectively at doses of 1-2-1 kg ha-1 favored a greater accumulation of B, Zn and Cu in the bulb. Higher number of leaves, leaf dry mass, bulb dry mass, total dry mass, class 1 bulbs and non-commercial yield were produced in Experiment 1.

Regions with semi-arid climates have environmental conditions that result in abiotic stress to plants. The largest melon (Cucumis melo L.) production area in Brazil, the state of Rio Grande do Norte, has these climatic characteristics. Use of biostimulants in these production systems can mitigate effects of abiotic stress and increase yield and fruit quality. The objective in this study was to evaluate the physiological and production characteristics of melon, under the application of biostimulants. The biostimulants Acadian^®, Folicist^® and Nov@^® were applied and compared to the control treatment (no biostimulants), in ‘Goldex’ and ‘McLaren’ melons. Nov@^® led to higher CO₂ assimilation, transpiration and stomatal conductance, as well as ascorbate peroxidase, in ‘Goldex’ and ‘McLaren’. Greater catalase was obtained with the application of Nov@^®, while the use of Folicist^® resulted in higher malondialdehyde content. The cultivar ‘McLaren’ exhibited the best physiological and biochemical performance, and ‘Goldex’ the best yield. Folicist^® promotes physiological adaptations to stress without impairing photosynthetic activity. The biostimulants increased yield and number of fruits per plant and promoted physiological adaptations to semi-arid conditions.