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.

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.

Elephant grass (Cenchrus purpureus syn. Pennisetum purpureum) stands out for its high dry matter production per unit area and good nutritional value and is cultivated throughout Brazil. This study aimed to evaluate the performance of elephant grass cultivar ‘Cameroon’ fertilized with nitrogen (N) and phosphorus (P) at different rates. The experimental design was in randomized blocks with 10 treatments and 4 replicates. The treatments consisted of 5 doses of N (0, 200, 400, 600 and 800 kg N/ha) all with 66 kg P/ha and 5 doses of P (0, 22, 44, 66 and 88 kg P/ha) all with 600 kg N/ha. The variables evaluated during 3 harvests were: shoot dry matter (DM) yield, N and P concentrations in shoots, and uptakes of N and P in forage. Results showed that, in the arenosol of the experimental area, high doses of N and P could produce high yields of the grass (40‒41 t DM/ha) over 260 days. The grass extracted large amounts of N (on average, 800 kg N/ha over 260 days) and P concentrations were significantly affected by P fertilization only in the last harvest, where it increased from 0.27 to 0.78 g P/kg DM. However, application of only 200 kg N/ha will produce more than 60% of the DM yield response achieved with 800 kg N/ha. Similarly, there seems little merit in applying more than 22 kg P/ha with the N. Longer-term studies are needed to test these hypotheses along with economic assessments to determine the financial soundness of such decisions.

There is a worldwide concern regarding the management of agroindustrial residues, involving sustainable practices that contribute to taking advantage of the residues as inputs in productive processes, allowing greater efficiency in the integration of agricultural activities and mitigating their adverse effects on the soil. Therefore, the objective of this study was to assess the effects of application of cassava wastewater on the chemical attributes of the soil cultivated with Brachiaria brizantha cv. Marandu. The experimental design was in randomized blocks with five treatments (0, 15, 30, 60 and 120 m³ ha-1 of cassava wastewater) and four repetitions. To characterize soil chemical attributes soil samples were collected at depths 0 to 10 and 10 to 20 cm, for determination of the concentrations of soil organic matter, available phosphorus, exchangeable potassium, sodium, calcium and magnesium before and after cassava wastewater application were determined. The application of cassava wastewater increases available phosphorus and exchangeable potassium concentrations, decreases exchangeable calcium, magnesium and organic matter contents of the soil cultivated with Marandu grass. Cassava wastewater can be used as organic fertilizer for pastures of Marandu grass with doses of up to 120 m³ ha-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.