Abstract 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.

Abstract This study aimed to evaluate the influence of cladode pruning on apical dominance in the production and post-harvest of pitaya fruits. The experiment was carried out at the Sítio das Pitaya do Pará, which is in the city of Tomé-Açu, State of Pará, Brazil. A randomized block design (RBD) in a 3 x 2 factorial scheme was used, with four replications for each treatment. Treatments consisted of three stand positions in the field (beginning, middle, and end of row) and two pruning regimes (with and without pruning). The interaction of factors Pruning and Stand position (P*SP) inhibited sprouting, while the Pruning factor provided heavier fruits and with a better pulp/peel ratio. Thus, cladode pruning provided benefits to plant management, production parameters, and post-harvest quality.

Resumen El objetivo de este estudio fue evaluar la influencia de la poda de cladodios sobre la dominancia apical en la producción y poscosecha de frutos de pitaya. El experimento se llevó a cabo en el Sitio Pitaya do Brasil, ubicado en el municipio de Tomé-Açu, Estado de Pará, Brasil. Se utilizó un diseño de bloques al azar (RBD) en un esquema factorial 3 x 2 con cuatro repeticiones de cada tratamiento. Los tratamientos consistieron en tres posiciones de rodales en campo (inicio, medio y final de hilera) y dos tipos de poda (con y sin poda). La interacción de los factores Poda y Posición del Stand (P*SP), inhiben la brotación, mientras que el factor Poda proporciona frutos con mayor masa y mejor relación pulpa/cáscara. Así, la poda de cladodios proporcionó beneficios para el manejo de la planta, los parámetros de producción y la calidad poscosecha.

Resumen El objetivo fue evaluar la correlación entre los grados-día de crecimiento (GDC), altura del dosel (AD) y índice de área foliar (IAF) para el pasto Guinea irrigado considerando la diferente combinación de las tasas de nitrógeno y boro y los ciclos de rebrote. El experimento se llevó a cabo de agosto/2017 a agosto/2018, en un experimento de campo y la región climática se clasifica como subtropical. Realizó un experimento factorial (4x3x11), con cuatro repeticiones y corrido en un diseño de bloques completamente aleatorio. Tratos: fertilización con boro: 0, 1 y 2 kg ha-1; fertilización con nitrógeno: 250, 500, 750 y 1,000 kg ha-1 distribuidos en 11 ciclos de crecimiento/corta. Hemos observado la alta correlación entre GDC y los parámetros evaluados para AD y IAF. Los resultados de nitrógeno mostraron una baja influencia en la altura del dosel y el índice de área foliar, y los resultados de boro no presentaron influencia en estos parámetros.

Abstract This study aims to evaluate the correlation among growing degree-days (GDD), canopy height (CH), and leaf area index (LAI) for Guinea grass irrigated, considering the different combinations of the nitrogen and boron rates and cycles of regrowth. The experiment was carried out from August/2017 to August/2018 in a field experiment, and the climate of the region is classified as subtropical. A randomized block design arranged in a factorial scheme (4x3x11) with four replications was used. The treatment was (i) boron fertilization: 0, 1, and 2 kg ha-1; and (ii) nitrogen fertilization: 250, 500, 750, and 1,000 kg ha-1 distributing to 11 growth/cutting cycles. We observed the high correlation between GDD and the parameters evaluated of CH and LAI. The nitrogen results showed a low influence on canopy height and the leaf area index, and boron results did not influence these parameters.

RESUMO O cártamo destina-se à produção de grãos para a obtenção de óleo vegetal. Objetivou-se avaliar o índice de clorofila, as características biométricas e a eficiência no uso da água de plantas de cártamo sob doses de nitrogênio e potássio. O experimento foi conduzido em casa de vegetação, em vasos contendo 8 dm3 de um Latossolo Vermelho. O delineamento experimental foi blocos casualizados, com esquema fatorial 5x5 correspondente a cinco doses de nitrogênio (0, 60, 120, 180 e 240 mg dm-3) e cinco doses de potássio (0, 50, 100, 150 e 200 mg dm-3), com quatro repetições. Avaliou-se o número de folhas, diâmetro de caule, índice de clorofila, número de capítulos, massa seca da parte aérea, massa seca de raízes, massa seca total, consumo de água e eficiência no uso da água. Os dados foram submetidos a 5% de probabilidade de erro a análise de variância pelo teste F e regressão polinomial. O índice de clorofila, as características biométricas e a eficiência no uso da água das plantas de cártamo apresentaram melhores respostas nas doses de nitrogênio entre 82 a 168 mg dm-3. A adubação potássica nas plantas de cártamo proporcionou respostas crescentes com incrementos de 10 a 60% para o índice de clorofila, nas características biométricas e na eficiência de uso da água. As respostas a adubação com nitrogênio e potássio no cártamo ocorrem com efeito isolado.

ABSTRACT Safflower crops is usually intended for production of seeds to oil extraction. The objective of this work was to evaluate the chlorophyll index, biometric characteristics and water use efficiency of safflower plants grown under different nitrogen and potassium rates and controlled soil water tension. The experiment was conducted in a greenhouse, in pots containing 8 dm3 of a Oxisol. A complete randomized block experimental design in a 5x5 factorial arrangement was used, with four replications, consisting of five nitrogen rates (0, 60, 120, 180 and 240 mg dm-3) and five potassium rates (0, 50, 100, 150 and 200 mg dm-3). The safflower number of leaves, stem diameter, chlorophyll index, number of capitula, shoot, root and total dry weights, water consumption and water use efficiency were evaluated. Data were subjected to analysis of variance (F test) at 5% of probability and to polynomial regression. The nitrogen and potassium fertilization, as independent factors, affected the safflower plants. The chlorophyll index, biometric characteristics and water use efficiency of safflower showed better responses under nitrogen rates of 82 to 168 mg dm-3. The responses of chlorophyll index, biometric characteristics and water use efficiency of safflower increased 10 to 60% with potassium fertilization.