Resumo A pitaia vermelha (Hylocereus costaricensis) é uma promissora espécie, com elevado potencial de cultivo devido às qualidades organolépticas e funcionais de seus frutos. Entretanto, a salinidade da água de irrigação pode afetar o rendimento produtivo da cultura. Diante disso, materiais ricos em substâncias orgânicas podem minimizar os danos provocados pelo excesso de sais no solo e/ou na água. Assim, o objetivo deste trabalho foi avaliar a influência de fontes de matéria orgânica como atenuante do estresse salino na produção e respostas bioquímicas de mudas de pitaia vermelha. O delineamento inteiramente casualizado em esquema fatorial 4 × 5, com cinco fontes de matéria orgânica (húmus, esterco ovino, biofertilizante, composto orgânico e areia + solo) e quatro salinidade (0.6, 2.6, 4.6 e 6.6 dS m-1), com quatro repetições e duas plantas por vaso foi utilizado. O comprimento da parte aérea, comprimento da raiz, diâmetro do cladódio, número de cladódios, número de brotos, volume da raiz, massa seca da parte aérea, massa seca da raiz e massa seca total, razão da massa seca da raiz e da parte aérea, clorofila a, b e total, aminoácidos e os açúcares solúveis foram avaliados aos 120 dias após o início da aplicação dos tratamentos. A pitaia vermelha é moderadamente tolerante a salinidade. O composto orgânico e estrume ovino atenuam os efeitos nocivos da salinidade nas mudas de pitaia vermelha. Sob condições de estresse salino, as plantas aumentam os níveis de aminoácidos e açúcares totais.

Abstract Red pitaya (Hylocereus costaricensis) is a promising species, with high cultivation potential due to the organoleptic and functional qualities of its fruits. However, irrigation water salinity can affect the crop yield. Therefore, materials rich in organic substances can minimize the damage caused by excess salts in soil and/or water. Thus, the objective of this study was to evaluate the influence of organic matter sources as attenuators of salt stress on the production and biochemical responses of red pitaya seedlings. A completely randomized design in 4 × 5 factorial scheme, with five sources of organic matter (humus, sheep manure, biofertilizer, organic compost and sand + soil) and four salinities (0.6, 2.6, 4.6 and 6.6 dS m-1) with four replicates and two plants per plot was used. The shoot length, root length, cladode diameter, number of cladodes, number of sprotus, root volume, shoot dry mass, root dry mass and total dry mass, root and shoot dry mass ratio, chlorophyll a, b and total, amino acids and soluble sugars were evaluated at 120 days after the treatments began to be applied. Red pitaya is moderately tolerant to salinity (ECw from 4.0 to 6.0 dS m-1). Organic compost and sheep manure attenuate the harmful effects of salinity on red pitaya seedlings. Under salt stress conditions, red pitaya plants increase their levels of proline, amino acids and total sugars.

Abstract Forage cactus presents high phytomass production in semiarid regions, due to its high energy value, high non-fibrous carbohydrate contents, high acceptability, high water reserves and easy propagation. The aim of this study was to define the best relation between plant height and cladode number of Nopalea cochenillifera with and without "pornunça". The design was performed in randomized blocks, with single cacti and "pornunça" consortium, with three repetitions. The experimental unit was composed of three rows of cactus, with spacing between rows of 1.60m and between plants of 0.20m, which is equivalent to a population density of 31,250 plants ha-1. The plant height and cladode number were related through regression models, which were evaluated by four criteria of selection. There was no difference between plant height and cladode number of cactus with and without consortium. The Nopalea cochenillifera consortium with "pornunça" is promising, and it presents agronomic viability and advantages. The adoption of the hyperbolic tangent model H=80.78*tanh(0.059*DAP0.67CN-0.052) allows the explanation of the height of Nopalea cochenillifera, with high precision and low cost, depending on the age of the plant and total number of cladode per plant.

Resumen El cactus forrajero presenta alta producción de fitomasa en regiones semiáridas, debido a su alto valor energético, gran contenido de carbohidratos no fibrosos, elevada aceptabilidad, grandes reservas de agua y fácil propagación. El objetivo de este estudio fue definir la mejor relación entre la altura de la planta y el número de cladodios de Nopalea cochenillifera con y sin "pornunça". El diseño se realizó en bloques al azar, con asociación de cactus único y "pornunça", con tres repeticiones. La unidad experimental estuvo compuesta por tres hileras de cactus, con un espacio de 1.60 m entre hileras y 0.20 m entre plantas, lo que equivale a una densidad de población de 31 250 plantas ha-1. La altura de la planta y el número de cladodios se relacionaron mediante modelos de regresión, que fueron evaluados por cuatro criterios de selección. No hubo diferencia entre la altura de la planta y el número de cladodios de cactus con y sin asociación. La asociación de Nopalea cochenillifera con "pornunça" es prometedor y presenta ventajas y viabilidad agronómica. La adopción del modelo de tangente hiperbólica H=80.78 * tanh (0.059 * DAP0.67 CN-0.052) permite la explicación de la altura de Nopalea cochenillifera, con alta precisión y bajo costo, dependiendo de la edad de la planta y el número total de cladodios por planta.

Natural fibers, mainly those lignocellulosic extracted from plants, have, in the past few decades, attracted the attention not only of scientists but also of industrial technologists of our society interested in their engineering materials. As it is well known, uses of natural fiber in clothes carpets, baskets, ropes and low cost construction roofing has existed from the beginning of our civilization. Today environmental and energy saving issues are motivating research works on new uses of lignocellulosic fibers in polymer composites. Moreover, industrial application of lignocellulosic fiber composites are already in technological sectors such the automobile industry, packing and civil construction. In addition to environmental, economical and social benefits, some lignocellulosic fibers present specific properties that are not comparable to those of other synthetic fiber used for polymer composite reinforcement. In fact, the mechanical strength and stiffness of any natural fibers is, however, significantly inferior and needs to be improved in order to compete with those of the synthetic fibers. The present work investigated the effect of electron beam irradiation on the mechanical behavior of the buriti petiole fiber, which presents a potential for composite reinforcement. Distinct lots of buriti fibers were irradiated at 50, 250 and 500 kGy using a 1.5 MeV electron beam accelerator. The results showed marked changes in the tensile properties of the buriti petiole fiber. This was discussed in terms of the structural modifications occurring in the irradiated lignocellulosic structure.