ABSTRACT Technologies once applied exclusively in conventional systems have maximized gains in hydroponic systems; however, they still need information for proper use. Thus, the study aimed to evaluate the effect of foliar application of thiamine and niacin on growth and gas exchange activities in two lettuce cultivars in an ebb and flow hydroponic system. The completely randomized design (CRD) was used with four treatments and eight replications. The treatments were as follows: T1 - control, T2 - thiamine at a concentration of 200 mg L-1, T3 - niacin at 200 mg L-1, and T4 - thiamine and niacin combined at 100 mg L-1 of each vitamin. Each experimental plot consisted of a lettuce plant. The combined application of thiamine and niacin stood out, increasing the activity of gas exchange of lettuce plants and increasing by about 30% the fresh mass, concerning the control, for both cultivars, followed by the isolated application of niacin. For thiamine, the application alone did not result in significant changes. The vitamins affect the morphophysiology of lettuce, where the use of niacin has the potential for use in hydroponic production systems. Its combined use with thiamine increases this potential, with a synergistic effect between the compounds being verified.

RESUMO Tecnologias outrora aplicadas exclusivamente em sistemas convencionais, têm maximizado os ganhos em sistemas hidropônicos, porém, necessitando ainda de informações para uma adequada utilização. Assim, o estudo teve como objetivo avaliar o efeito da aplicação foliar de tiamina e niacina sobre o crescimento e atividades de troca gasosa em duas cultivares de alface em sistema hidropônico de fluxo e refluxo. O delineamento experimental utilizado foi o inteiramente casualizado (DIC), com quatro tratamentos e oito repetições. Os tratamentos foram: T1 - controle; T2 - tiamina em concentração de 200 mg L-1; T3 - niacina em concentração de 200 mg L-1; T4 - tiamina e niacina combinadas, em concentração de 100 mg L-1 de cada vitamina. Cada parcela experimental foi constituída por um vaso, contendo uma muda de alface. A aplicação conjunta de tiamina e niacina elevou as trocas gasosas das plantas de alface, aumentando em cerca de 30% a massa fresca, em relação ao controle, para ambas as cultivares, seguida pela aplicação isolada de niacina. Para a tiamina, a aplicação de forma isolada não resultou em alterações significativas. As vitaminas afetam a morfofisiologia da alface, onde o uso da niacina tem potencial para uso em sistemas de produção hidropônicos, sendo esse potencial aumentado pelo seu uso conjunto com a tiamina, verificando-se um efeito sinérgico entre os compostos.

ABSTRACT The quality of the basal cut of sugarcane during harvest can affect the longevity of the crop, and the cutting tool is one of the main causes of damage during harvesting. The aim of this study was to evaluate the performance of two cutting tools: an impact cutting system (ICS) using knives and a continuous cutting system (CCS) using saws. Laboratory tests were carried out to obtain the stalk damage index at different device travel speeds and to determine the invisible losses caused by each cutting system. The results showed that both cutting systems presented acceptable levels for the stalk damage index; however, the CCS obtained better cut quality, corresponding with decreased general damage. The invisible losses caused by the cutting tools in relation to the total harvested mass were 0.52% and 0.54% for the CCS and ICS, respectively. The highest invisible losses were obtained at speeds of 2, 3, and 4 km h-1 for the ICS, showing a statistical difference in relation to the CCS. No statistical difference was noted for both the systems at 5 and 6 km h-1.

ABSTRACT Plant ambiance studies the environmental condition favorable to plant growth at the initial stage of seedlings or the complete production cycle. This study aimed to evaluate the cultivation of the ornamental pepper ‘Pyramid’ under protected environments and growing benches with and without reflective material. The protected environments consisted of a greenhouse covered with low-density polyethylene film and 42/50% shading thermo-reflective screen under the film, structure with 35% shading thermo-reflective aluminized screen, and structure with 30% shading black screen. The growing benches were tested in environments without and with reflective material made of aluminized screen. The environment of the agricultural greenhouse covered with low-density polyethylene film and 42/50% thermo-reflective screen under the film favored the growth of ornamental pepper plants regarding height and diameter and provided early flowering and high fruit production. The use of the reflective material showed no significant results for plant height, stem diameter, and the number of leaves. The use of reflective material increased the number of fruits in plants under the environments with 35% shading aluminized screen and 30% shading black screen.

ABSTRACT Operational conditions of mechanized harvesting can affect the quality of harvested sugarcane. Therefore, the aim of this study was to assess the influence of the displacement speed and cutting height on the quality of the raw material during the mechanized harvest of sugarcane. Vegetable losses were accounted for in the field by manual collection of the fractions left after harvest. Vegetable and mineral impurities were determined at the processing stage in the laboratory. Both the displacement speed and cutting height did not affect vegetable losses. However, the increase in vegetal impurities occurred at higher displacement speeds, whereas lower cutting heights resulted in higher amounts of mineral impurities.