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Semi-arid regions present the inherent problem of accumulation of salts in the soil due to the use of brackish water for irrigation, and water deficit compromises the growth and physiological indices of crops. This study evaluated the effect of salt and water stress on growth and gas exchange in the zucchini cv. Caserta crop. The study was conducted at the University of International Integration of Afro-Brazilian Lusophony, Redenção, Ceará State, Brazil. The experimental design was completely randomized, in a 5 × 2 factorial scheme with five levels of electrical conductivity of the irrigation water - ECw (0.5, 1.0, 1.5, 2.0, and 2.5 dS m-1) and two water regimes (50 and 100% of the potential crop evapotranspiration - ETc), with five replicates. At 36 days after sowing, the following traits were evaluated: CO2 assimilation rate, transpiration, stomatal conductance, internal carbon concentration, leaf temperature, relative chlorophyll index, and water use efficiency. At 45 days after sowing, the plant height, stem diameter, number of leaves, and leaf area were also evaluated. The use of brackish water (1 to 2.5 dS m-1) reduced the growth parameters of zucchini cv. Caserta. The increase in ECw caused a decline in the physiological traits. Under 100% ETc, higher values of CO2 assimilation rate, transpiration, and instantaneous water use efficiency were recorded, and there was 50% ETc for internal carbon concentration, even with the increase in ECw.

The demands of high-quality zucchini fruits by the consumer market make studies regarding the improvement of cultivation systems, such as plant nutrition and salinity tolerance. Considering the demands of the consumer market for the high quality of zucchini fruits, it is necessary studies regarding the improvement of production systems for this improvement, such as nutrition and salinity tolerance to plant. Thus, this study aimed to evaluate the zucchini fruits quality characteristics, grown in soilless, under N:K ratios, and levels of electrical conductivity of the nutrient solution. The experiment was conducted in a protected environment in pots with 8.2 dm3 of volumetric capacity filled with commercial substrate. The trial design adopted was randomized blocks, with three replicates, in a 5x3 factorial scheme, with five levels of electrical conductivity (1.0; 2.0; 3.0; 4.0; and 5.0 dS m-1) and three N:K ratios (2:1; 1:1; and 1:2), both in the nutrient solution. The application of the nutrient solution was by fertigation through drip irrigation. Throughout the experiment, variables related to fruit quality and total plant biomass production were analyzed. The increase of the electrical conductivity in the nutrient solution provided an increase in the values of fruits organoleptic properties. Regarding the nutrient solution N:K ratios, the 1:2 ratio provided larger fruits and a higher percentage of water.

Although there are fertilization recommendations for the cultivation of zucchini, there are just few researches about the effects of nutrients in seed production. Calcium and boron have a low mobility in plants, and some researches recommend foliar application for these nutrients. Thus, the objective of this research was to evaluate the foliar application of calcium and boron in the production and quality of zucchini seeds. The experimental design was randomized blocks with seven replications. Four treatments were evaluated: only calcium (0.2%) application, only boron (0.1%) application, combined application of calcium (0.2%) and boron (0.1%) and the control (without calcium and boron.) The following characteristics were evaluated: number of pollen grains per flower, hundred seeds weight; seed number and weight per fruit and seed physiological quality (germination; first germination count and speed of germination index - SGI). Only boron application reduced the number of seeds produced per fruit. The combined foliar application of calcium and boron, in addition to reducing the number of seeds, also reduced SGI. The calcium only application increased the amount of pollen per flower (superior to all other treatments) and also the number of seeds per fruit (compared to the combined application of calcium + boron), without affecting the quality of the zucchini seeds. So, it can be recomended the aplication of Ca during zucchini flowering for seed production.

The objective of this research was to evaluate the agronomic performance of Italian zucchini as a function of phosphate fertilization. The experiments were carried at the Rafael Fernandes Experimental Farm, Federal Rural University of the Semi-Arid Region, Mossoró, RN, Brazil, from August to November 2015 and from July to September 2016. The experimental design was randomized blocks in 2 x 5 factorial scheme, with four replicates. The treatments consisted of the combination of two cultivars (Caserta and Alícia) and five doses of phosphorus (0, 40, 78, 120 and 150 kg ha-1 of P2O5). Phosphorus doses associated with the maximum marketable yields estimated were smaller for Alícia than for Caserta in the period from August to November 2015. In the period from July to September 2016, these estimated doses were higher for Alícia compared with Caserta. Alícia, regardless of crop season, was superior to Caserta. Zucchini cultivation from July to September of 2016 resulted in higher fruit yield in comparison to the period from August to November 2015. RESUMO Esta pesquisa foi realizada com o objetivo de avaliar o desempenho agronômico da abobrinha italiana em função da adubação fosfatada. Os experimentos foram realizados na Fazenda Experimental Rafael Fernandes, da Universidade Federal Rural do Semi-Árido, Mossoró, RN, Brasil, nos períodos de agosto a novembro de 2015 e de julho a setembro de 2016. O delineamento utilizado foi em blocos casualizados, em esquema fatorial 2 x 5, com quatro repetições. Os tratamentos consistiram da combinação de duas cultivares (Caserta e Alícia) e cinco doses de fósforo (0, 40, 78, 120 e 150 kg ha-1 P2O5). As doses de fósforo associadas às máximas produtividades comerciais estimadas foram menores para Alícia em relação à Caserta no período de agosto a novembro de 2015. De julho a setembro de 2016, essas doses estimadas foram maiores para Alícia comparado à Caserta. A ‘Alícia’, independente da época de cultivo foi superior a ‘Caserta’. O cultivo de abobrinha no período de julho a setembro de 2016 proporcionou maior produção de frutos em relação ao período de agosto a novembro de 2015.

O experimento foi realizado em Piracicaba, SP, com o objetivo de avaliar os efeitos de doses de CO2 aplicadas via água de irrigação associadas ou não a cobertura plástica do solo na produção da abobrinha cultivada em campo aberto. O delineamento foi em blocos completos ao acaso, em esquema de parcelas subdivididas, com o fator CO2 na parcela e o fator cobertura nas subparcelas. Os tratamentos foram constituídos das seguintes doses de CO2 aplicados via água de irrigação: 0; 59; 148 e 274 kg ha-1 de CO2. O sistema de irrigação foi por gotejamento com reposição diária de água, baseada no tanque classe A. As variáveis analisadas foram: área foliar por planta (cm²), número de frutos por planta e produtividade (kg ha-1). A interação entre os fatores doses de CO2 e a cobertura do solo apresentaram efeito significativo sobre as variáveis analisadas. A maior produtividade de abobrinha foi de 15.433 kg ha-1 obtida com o uso de 58,6 kg ha-1 de CO2 associado à cobertura plástica. The experiment was carried out in Piracicaba, SP, in order to evaluate the effects of different carbon dioxide levels applied with irrigation water, associated or not to the mulch plastic, on yield of summer squash. The experimental design was in random blocks in split plot design, with the factor levels of CO2 in the plot and the mulch plastic in split-plot. The treatments constituted on the following levels: 0; 59; 148 and 247 kg ha-1 of CO2. The irrigation was scheduled daily based on a tank class A, using a drip irrigation system. The leaf area, the number of fruit and the yield were evaluated. The levels of CO2 and mulch plastic influenced the leaf area; consequently, it provided increment in the number of fruit and yield of summer squash. The best yield of 15, 433 kg ha-1was obtained by 58.6 kg ha-1 of CO2 with the plastic mulch.