Cherry tomato cultivation in the semi-arid region of northeastern Brazil is limited by water scarcity, so it is common to use water sources with high concentrations of salts in this region, which have a deleterious effect on plants, which can be alleviated through management strategies, and fertilization with nitrogen stands out. This study aimed to evaluate the growth, gas exchange and production of cherry tomato under irrigation with saline water and nitrogen fertilization. The experiment was carried out in a screened environment at the CCTA/UFCG in Pombal - PB from October 2020 to February 2021, using a randomized block design, in a 5 × 5 factorial scheme, with five levels of electrical conductivities of water - ECw (0.3; 1.3; 2.3; 3.3 and 4.3 dS m−1) and five nitrogen doses - ND (50; 75; 100; 125 and 150% of the recommended dose for the crop), with three replicates. Irrigation water salinity from 0.3 dS m−1 reduced stomatal conductance, transpiration, CO2 assimilation rate and production components of cherry tomato. Nitrogen fertilization from 50% of the recommendation reduced stomatal conductance, transpiration and CO2 assimilation rate of cherry tomato. Irrigation with water of electrical conductivity from 0.3 dS m−1 associated with nitrogen dose of 150% of the recommendation intensified the effect of salt stress on dry biomass accumulation in cherry tomato.

Saline water has been used in irrigation due to the limited availability of fresh water, especially in arid and semi-arid regions. However, the use of this type of water can affect crop growth and development. Studies have tested the use of chemical conditioners to minimize the negative effects of salinity on plants. In this scenario, the present study examined the role of hydrogen peroxide in mitigating the negative effects of salt stress on zucchini plants grown in a hydroponic system. The study was carried out in a greenhouse in Pombal - PB, Brazil. The NFT (nutrient film technique) hydroponic system was employed. A randomized complete experimental design was set up with a 4 × 4 factorial arrangement consisting of four levels of electrical conductivity in the nutrient solution (ECns: 2.1 [control], 3.6, 5.1, and 6.6 dS m-1) and four concentrations of hydrogen peroxide (H2O2: 0, 20, 40, and 60 μM), in three replicates. Foliar spraying with H2O2 at 60 and 40 μM associated with the nutrient solution of 2.1 dS m-1 increased stem diameter and root length, respectively, at 47 days after transplanting. However, at ECns higher than 2.1 dS m-1, the application of H2O2 at the concentrations of 60 and 40 μM intensified salt stress, reducing stem diameter and root length. Nutrient solution salinity levels above 2.1 dS m-1 reduce photosynthetic pigments; the number of leaves; leaf area; the length of the main branch; and the dry biomass of stems, leaves, and roots of zucchini plants. Chlorophyll b and carotenoid contents are the variables most sensitive to changes in salinity levels.

A má distribuição das chuvas pode limitar as trocas gasosas na cultura da cana-de-açúcar, podendo a irrigação mitigar esse efeito. Objetivou-se com este trabalho avaliar o efeito do uso de lâminas de irrigação aplicadas por gotejamentos subsuperficial pulsada e continua nas trocas gasosas da cana-de-açúcar. O experimento foi conduzido em campo na Estação Experimental de Cana-de-Açúcar de Carpina, no período de dezembro 2019 a dezembro de 2020. O delineamento experimental utilizado foi o casualizado em blocos, em arranjo fatorial 2 x 5, sendo estes dois tipos de aplicação da irrigação (irrigação pulsada e contínua) e cinco lâminas de reposição da evapotranspiração da cultura (40, 60, 80, 100 e 120% da ETc), com 4 repetições. A cultivar de cana-de- açúcar avaliada foi a RB 041443. A aplicação dos tratamentos foi realizada nos meses de agosto, setembro e outubro períodos esses de menores índices pluviométricos, por meio de um sistema de irrigação por gotejamento de subsuperfície. Foram analisados, aos 330 dias após o plantio, no horário entre 11 e 13 h com Analisador de Gás Infravermelho (IRGA LI-6400), as seguintes variáveis: temperatura foliar (Tleaf), concentração interna de CO2, (Ci), condutância estomática (gs), transpiração (E), fotossíntese líquida (A), eficiência instantânea de uso da água (A/E), eficiência intrínseca do uso da água (A/gs), e a eficiência instantânea de carboxilação (A/Ci). As melhores respostas fisiológicas para a fotossíntese líquida, condutância estomática e transpiração foram obtidas com a aplicação das lâminas de 85,1; 80,0 e 80,5% da ETc, respectivamente. Os maiores valores para as eficiências intrínseca e instantânea do uso da água foram obtidos com a aplicação da irrigação de forma pulsada.

O mandacaru (Cereus jamacaru DC) é uma espécie endêmica da caatinga que se encontra em extinção devido a ação antrópica por meio da pratica da agropecuária extrativista, desmatamento, queimadas entre outras.A pesquisa objetivou avaliar as taxas de sobrevivência e de desenvolvimento de Cereusjamacaru DC. Introduzido por propagação vegetativa em áreas de clareira no semiárido paraibano.Foi realizado o plantio de223 cladódios em três clareiras no Espaço Experimental Reservado para Estudos de Ecologia e Dinâmica da Caatinga - Área II, dispostos em linhas no espaçamento de 1m entre plantas e 2m entre linhas. Realizou-se a medição detamanho e diâmetro dos cladódiose o monitoramento mensal da sobrevivência e das fenofases reprodutivas, correlacionado com os dados de precipitação para o período de janeiro a julho de 2017. Não ocorreu mortalidade nos primeiros meses seguintes ao plantio, mas somente a partir do mês de maio, quando foi registrado o pico com 33 indivíduos, sendo observada mortalidade ainda no mês de julho, quando se registrou a morte de nove indivíduos, perfazendo um percentual de 18,8% do total de cladódios implantados. De modo geral, C. jamacaru apresentou-se viável para plantio em área de clareira, podendo se tornar uma alternativa de cultivo para os agricultores em suas propriedades, servindo na recuperação de áreas degradadas.

The objective of this work was to determine nutrient extraction and export in sugarcane under pulsed and continuous irrigation at five levels of replacement of crop evapotranspiration. The experiment was conducted from 12/12/2019 to 12/22/2020 under field conditions in the municipality of Carpina, in the state of Pernambuco, Brazil. The used experimental design was randomized complete blocks, in a 2x5 factorial arrangement, with two types of irrigation application (pulsed and continuous irrigation) and five levels of replacement of crop evapotranspiration (40, 60, 80, 100 and 120%), with four replicates, totaling 40 experimental units. For pulsed irrigation, five irrigation pulses were defined, with an interval of 40 min between each of them. For the analyses of nutrient extraction and export, plants were collected in the usable area of each experimental plot, at the time of harvest. The isolated factor type of fertigation application significantly influenced the extraction and export of iron, manganese, and zinc, as well as the export of sulfur. Under pulsed irrigation, the descending order of nutrient extraction and export is: K>N>Ca>S>Mg>P>Fe>Zn>Mn>Cu and N>K>Ca>Mg>S>P>Fe>Zn>Mn>Cu, respectively. Under continuous irrigation, the order of extraction and export is: K>N>S>Ca>Mg>P>Fe>Zn>Mn>Cu and N>K>Mg>Ca>S>P>Fe>Zn>Cu>Mn, respectively.

Saline water is an alternative to the low availability of high-quality water in semi-arid regions. However, although these water sources negatively affect most crops, their use allied to management practices aiming to mitigate the effects of salts has been increasingly studied, including nitrogen fertilization. From this perspective, this study aimed to evaluate the growth and physicochemical characterization of cherry tomato plants irrigated with saline water and nitrogen fertilization. The experiment was conducted under field conditions at the Center of Sciences and Agrifood Technology of the Federal University of Campina Grande in Pombal – PB, using a randomized block design arranged as a 5 × 5 factorial referring to five electrical conductivity levels of irrigation water - ECw (0.3, 1.3, 2.3, 3.3, and 4.3 dS m-1) and five nitrogen doses - ND (50, 75, 100, 125, and 150% of the N recommendation), with three replications. The nitrogen doses did not mitigate the effects of salt stress on plant height and stem diameter of cherry tomato. However, irrigation with the electrical conductivity of 3.3 dS m^-1 increased the soluble solids of cherry tomato fruits.