Brazil is the fourth largest grain producer in the world. Its agriculture is mainly rainfed, with two cropping seasons per year. While the first crop (i.e., spring/summer) receives greater precipitation, the second crop (i.e., autumn/winter) is associated with greater risk of crop failure mainly due to the low rainfall, suggesting that technologies that could optimize water use during that period are needed. Superabsorbent polymers (SAP) are used in the forestry sector to reduce seedling mortality and the frequency of irrigation of eucalyptus and pinus glue owing to their ability to increase water storage capacity in the soil. However, to our knowledge, very little is known about the use of SAP in annual agricultural crops. To this end, the effects of SAP, as a seed coat or applied in the planting grooves, on the initial development of sorghum seedlings under conditions of water deficit were evaluated in two experiments under greenhouse conditions. In experiment 1, sorghum seeds with and without SAP coating were seeded in trays and subjected to three irrigation intervals to induce water deficit. The percentage of emergence and emergence speed index were evaluated and, at 26 days after sowing, seedling height, number of leaves per plant, survival rate, and dry mass of shoot and root were evaluated. In experiment 2, the seeds of sorghum with and without SAP coating were sown in pots, with SAP applied in the planting grooves. At 30 days after sowing, the plant stand, number of leaves per plant, plant height, and dry matter mass of leaves, stem, and root were evaluated. The results showed that SAP applied both as a seed coat and in planting grooves increased seedling growth and dry mass of aerial parts at 26 days and 30 days for experiments 1 and 2, respectively. In addition, seed coating with SAP increased plant survival rate, but reduced the rate of seedling emergence in both experiments. Therefore, the use of SAP as a seed coat or applied in the planting groove has beneficial effects on the vegetative development of sorghum under low water conditions. Further research is needed to address the effect of SAP on seedling emergence. ResumoO Brasil é o quarto maior produtor de grãos no mundo. Sua agricultura é baseada em cultivos de sequeiro, com duas safras por ano. A segunda safra é a mais afetada, por estar associada à maiores riscos climáticos, principalmente pela baixa pluviosidade nos meses de janeiro à abril. Nesse sentido, tecnologias que otimizem o uso da água podem reduzir os riscos de quebra de safra. O uso de polímeros superabsorventes (PSA) vem sendo consolidado no setor florestal, visando reduzir a mortalidade de mudas e a frequência de irrigações de pegamento de eucalipto e pinus devido ao aumento da capacidade de armazenamento de água no solo. Entretanto, não há relatos sobre o uso do PSA em culturas anuais. O objetivo deste trabalho foi avaliar o efeito do PSA como revestimento de sementes e no sulco de plantio no desenvolvimento inicial de plântulas de sorgo sob condições de déficit hídrico....

The global demand and production of primary energy is expected to grow at a rate of 1.4 % per year by 2035. In the same period, the production of renewable energy is expected to grow at a rate of 6.6 % per year, rising from 3 % to 9 % of world primary energy. Therefore, the biofuels supply assumes a strategic role for world energy security. In this context, sorghum is a promising alternative in the bioenergetic sector, due to its agronomic characteristics and adaptability to limiting edaphoclimatic conditions. This study aimed at evaluating the productive potential of three sorghum agronomic groups (biomass, saccharin and forage), as well as chemically characterizing the biomass of these materials. For that, a field experiment was carried out using a randomized block design, where agronomic and chemical characteristics (cellulose, hemicellulose, lignin and ash), as well as moisture contents, were evaluated. The biomass sorghum cultivars presented a high yield (about 30 t ha-1 of dry stalk), being, for this reason, more suitable for the generation of solid biofuels, i.e., direct burning. On the other hand, the forage sorghum cultivars presented a lower lignin content in the stalks, in relation to the other cultivars, being indicated for the generation of liquid biofuels. It is also worth mentioning the possibility of producing second-generation bioethanol from saccharin sorghum bagasse. Therefore, sorghum presents different use potentials that may be exploited by the bioenergy sector according to the agronomic group and plant physical part.

Sorghum (Sorghum bicolor) is the fifth most cultivated cereal in the world, has high liquidity in the market due to its nutritional and edaphoclimatic characteristics, however, because it is cultivated in marginal conditions, it presents productivity below its potential. The seed coating technique appears to optimize the cultivation of sorghum. The objective of this work was to analyze the quality of graniferous sorghum seeds coated with different filling materials and proportions of glue as a cementing material. After covering, the physical and physiological characteristics of the seeds and the initial development of plants in the greenhouse were evaluated. It was found that the coating with calcium silicate provided the best physical characteristics to the seeds with the highest adherence rates, total area, maximum and minimum diameter. The coatings with dolomitic limestone and dolomitic limestone + sand provided the best physiological performance of the seeds with the highest germination values ​​and root dry matter. The proportion of cementitious material 3: 1 provided good results in addition to being more economical. It is concluded that the combination of the filling material and the cementing material used in the coating of graniferous sorghum seeds interferes with their physiological performance and physical aspect.

Aims: Was to evaluate the productive potential of three sorghum agronomic groups (biomass sorghum, saccharine sorghum and forage sorghum) in two cutting seasons (crop and regrowth) and to perform the energy (GJ/ha/cycle) characterization of biomass. Sample: Six sorghum cultivars in three agronomic groups: biomass sorghum (hybrids BD 7607 and BRS 716), saccharine sorghum (hybrids BD 5404 and BRS 511) and forage sorghum (hybrids BD1615 and BRS 655). Study Design: This cultivars were evaluated in the block design at random, with six replicates and analyzed in time subdivided plots. Place and Duration of the Study: The experiment was conducted in the field being evaluated in two consecutive harvests, during the months of December/2014 to September/2015 and at the end of the cycle of each cultivar the plant evaluations were carried out.

Sorghum (Sorghum bicolor) is highly sensitive to zinc deficiency in soils, which results in decreased productivity and low-quality agricultural products. Our objective was to evaluate the effects of different zinc doses, applied to seeds, on the physiological quality and initial performance of sorghum plants. Six doses (0, 3.5, 7.0, 14.0, 21.0, and 28.0 g kg-1 seeds) were used and an uncoated control. The Zn coating process used dolomitic limestone as the filler and glue. Laboratory tests were conducted in a completely randomized design and greenhouse experiments were conducted in a randomized block design. The control means were 8, 9, and 14% lower than the maximum, minimum, and total seed area of treatments, respectively, relative to that of treatments. The control differed from other treatments by 10.47 in the speed index of emergence. Zinc at a dose of 28 g kg-1 seeds provided greater production of aerial dry matter, with nutrient content of 75.85 mg kg-1. Zinc on sorghum seeds affected length and dry matter production of aerial parts and roots but did not affect physical characteristics, germination, or emergence time. Applied zinc accumulated mainly in the roots, and promotes changes in Ca and Mg in seeds and other plant parts.