ABSTRACT. Cowpea (Vigna unguiculata) crops produce a poor yield in northeastern Brazil compared to the other regions. The goal of this study was to assess the effects of irrigated cropping systems and sowing seasons on cowpea yield and profitability in Vitória da Conquista, Bahia, Brazil. Field studies were performed in four experiments during the rainy and dry seasons during 2016/2017 and 2017/2018, which denoted harvests 1, 2, 3, and 4, respectively. A randomized block design was used for each experiment with four replicates and the following treatments for cropping systems: (1) manual weeding; (2) liming and manual weeding; (3) liming and phosphorus (P) fertilization at sowing, nitrogen (N) and potassium (K) topdressing fertilization, and chemical weed control; (4) liming and P fertilization at sowing, K topdressing fertilization, rhizobia inoculation, and chemical weed control; (5) liming and P fertilization at sowing, N and K topdressing fertilization, rhizobia inoculation, and chemical weed control; and (6) seed pretreatment with cobalt (Co) and molybdenum (Mo), liming and P fertilization at sowing, N and K topdressing fertilization, rhizobia inoculation, and chemical weed control. The technology added to cropping systems increased the number of pods per plant, pod length, seeds per pod, and 100-seed weight, irrespective of the rainy or dry sowing season. Economic analysis, in turn, showed that the technology decreased the total operating cost despite increasing the cost of mechanical operations, inputs, and materials because of the replacement of manual weeding by chemical weed control. However, these costs were not influenced by the sowing seasons. We concluded that technologically enhanced cropping systems, especially systems 4 and 6, improved grain yield and provided greater profitability, which translated into improved economic benefits for farmers. Conversely, the sowing season influenced profitability, which was higher for dry season harvests, when there was less product offered and prices became higher.

Neste trabalho avaliou-se o levantamento fitossociológico e determinaram-se os períodos críticos de competição com a cultura da mandioca, submetida ou não à adubação NPK. Para tanto, as plantas infestantes foram colhidas a cada 35 dias, até os 525 dias após a plantação da mandioca, por meio do lançamento aleatório de um quadrado de ferro vazado de 0,5 x 0,5 m (0,25 m²) na área útil das parcelas com e sem adubação. As plantas no interior do quadrado foram cortadas rente ao solo, contadas e identificadas por espécie. Sida rhombifolia, Brachiaria plantaginea e Cynodon dactylon apresentaram os maiores índices de frequência relativa (FR), densidade relativa (DR), abundância relativa (AR) e índice de valor de importância (IVI). Posteriormente, os dados de produtividade de raízes tuberosas foram ajustados ao modelo de regressão não linear sigmoidal de Boltzmann, para determinação dos períodos críticos de competição: período anterior à interferência (PAI), período total de prevenção à interferência PTPI e período crítico de prevenção à interferência (PCPI). A adubação fornecida à cultura da mandioca influenciou a determinação de diferentes índices fitossociológicos e períodos críticos de competição.

The objective of this study was to evaluate the phytosociological survey and determine the critical periods of weeds competition with the cassava crop, submitted or not to NPK fertilization. Therefore, the weeds were collected every 35 days, until 525 days after cassava planting, through the random release of a cast iron square 0.5 m x 0.5 m (0.25 m²) in plots with and without fertilization. The plants inside the square were cut close to the ground, counted and identified by species. Sida rhombifolia, Brachiaria plantaginea and Cynodon dactylon showed the highest FR, DR, AR and IVI. Subsequently, the yield data of storage roots were adjusted to non-linear regression model sigmoidal Boltzmann to determine the critical periods of competition: PAI, TPIC and PCPI. The fertilizer supplied to cassava crop contributed to the determination of different phytosociological indices and critical periods of competition.

Myracrodruon urundeuva Fr. All. é uma espécie pertencente à família Anacardiaceae, cuja planta pode ser utilizada como medicinal, na indústria de curtimento de couro, na regeneração de áreas degradadas e para aproveitamento madeireiro. Diante disso, o objetivo deste trabalho foi avaliar o potencial fisiológico dos frutos e sementes de M. urundeuva, oriundos de lotes colhidos no mês de setembro no ano de 2012 e armazenados até setembro de 2013, em ambiente não controlado, com a utilização de diferentes substratos e estruturas (exocarpo e mesocarpo). Os parâmetros avaliados com as unidades de propagação foram o teste de germinação e a condutividade elétrica. No teste de germinação, os frutos e sementes foram colocados para germinar nos substratos de areia grossa lavada, entre papel e em vermiculita, em caixas gerbox, em germinador, sob temperatura constante de 25 °C e fotoperíodo de 8 h de luz. Em condições de laboratório, a maior geminação ocorreu para frutos nos substratos papel e vermiculita, porém, a perda de eletrólitos foi maior nos lotes de frutos do que nos lotes de sementes. O armazenamento das sementes e dos frutos de M. urundeuva, em condições ambientais, mostrou-se inadequado para a conservação das características de vigor das unidades de propagação.

Myracrodruon urundeuva Fr. All. is a species of the Anacardiaceae family, whose plant can be used as medicine, in the leather tanning industry, in the regeneration of degraded areas and for timber use. Thus, the objective of this study was to evaluate the physiological potential of the fruits and seeds of M. urundeuva, coming from lots harvested in September in 2012 and stored until September 2013, under uncontrolled conditions, with the use of different substrates and structures (exocarp and mesocarp). The parameters evaluated in the propagation units were the germination test and the electrical conductivity. In the germination test, the fruits and seeds were placed to germinate in washed gravel substrates, including paper and vermiculite in gerboxes in germination under constant temperature of 25 °C and photoperiod of 8 h of light. In laboratory conditions, the highest germination rate occurred in the paper and vermiculite, however, the electrolyte loss was higher in fruit lots than in seed lots. The storage of seeds and fruits of M. urundeuva in environmental conditions was inadequate for the preservation of the vigor characteristics of the propagation units.