The relative frequency, relative density, relative dominance and importance value index of each species were used to determine the effect the weeds. The most important weeds based on the Importance value index were Commelina benghalensis L., Cynodon dactylon (L.) Pers., Eleusine indica L., Phyllanthus niruri L. and Alternanthera tenella Colla. The period prior to interference and the total period of interference prevention were respectively of 12 and 36 days after emergence. The weed community caused yield losses of around 51%. In okra organic cropping system, weed control should be done early to boost okra plant growth in order to provide shade on the weeds to reduce the need for long control period.
In organic systems during the dry season, competition of weeds with okra increases the critical period of interference of these species and yield losses. The objective of this research was to determine the critical period of weed interference in organic okra during the dry season in São Luís - MA. The experiment was conducted from October/2014 to January/2015 in randomized blocks, with four replicates. The treatments were the periods of 07, 14, 21, 28, 35, 42 days after the transplanting of the crop with control and coexistence of the infesting community. The species with the highest importance value index were Cynodon dactylon, Eleusine indica, Amaranthus spinosus and Commelina benghalensis. The CPWI was 04 to 53 days after transplanting and yield losses were 69.5%. The organic okra cropping system during the season dry should be free of weeds until the beginning of the harvest to avoid high yield loss.
Vegetable biodiversity in Brazil accounts for almost 67% of the plants on the planet, which are part of studies with focus on determinants of food security and access to adequate and healthy food, while preserving natural resources. Studies indicate that Hibiscus sabdariffa L. is one of the most studied unconventional food crops because of its nutraceutical quality as antioxidant and prevention of hypertension and cancer. Although relevant, substrate and temperature information for seedling production of this species are scarce. Thus, the aim of this study was to evaluate the best substrate and temperature for the vigor and germination test of H. sabdariffa seeds of the Talo Roxo and Rubra varieties. The experiment was laid out in a randomized complete design, in a 7 × 5 factorial arrangement, consisting of the combinations of seven substrates (paper towel, filter paper, vermiculite, between sand, on sand, plantmax® and compost) with five temperatures (20, 25, 30, 35 and 20-30 °C), with four replicates with 50 seeds each. The following variables were evaluated: germination, germination speed index, seedling length and dry mass. For germination and vigor tests of Hibiscus sabdariffa var. Talo Roxo seeds the paper roll substrate is recommended at temperatures of 25 or 35 °C and for var. Rubra seeds, plantmax® at 25 °C and plantmax® and vermiculite at temperatures of 25 or 20-30 °C, respectively.
Dinâmica da decomposição dos adubos verdes na manutenção da fertilidade do solo, disponibilidade de nutrientes e manejo agroecológico de plantas espontâneas em hortaliças
The use of effective technologies for the monitoring of agricultural crops should seek methodologies that provide information regarding crop development, preferably before harvesting. The study of the monitoring and/or estimation of areas using vegetation indices derived from multitemporal data from MODIS sensors is being studied in the search for greater objectivity of the generated values. In this context, the objective of this study was to map areas with winter and second-crop corn using EVI/MODIS time series from the Terra and Aqua satellites, for the seasons from 2012 to 2014 in the Paraná state of Brazil. Accuracy analysis of the mappings was performed in spatial resolution images of 30 m (LISS-III and Landsat-8), to identify and validate the masks the crops of interest. The accuracy of the mapping obtained values of global precision 87.5%, 79.5%, and 82.0%, with Kappa index of 0.81, 0.69, and 0.73, in the 2012, 2013, and 2014 harvests, respectively. Comparing with data from the Brazilian Institute of Geography and Statistics (IBGE), the areas obtained by the mappings were underestimated for the second-crop corn in the 2012 and 2013 seasons and overestimated in 2014. The winter crops were overestimated for the three seasons investigated. The use of remote sensing data and techniques can contribute to a quick estimation of crop area information, and can assist in the surveys conducted by official institutions.
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