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The leather industry produces a large quantity of solid waste (wet blue leather), which contains a high amount of chromium. After its removal from wet blue leather, a solid collagenic material is recovered, containing high nitrogen levels, which can be used as a nitrogen source in agriculture. In order to take more advantage of the collagen, it was enriched with mineral P and K in order to produce NPK formulations. The objective was also to evaluate the efficiency of such formulations as a nutrient supply for rice plants in an Oxisoil, under greenhouse conditions. The application of PK enriched-collagen formulations resulted in N contents in the vegetative parts and grains of rice plants which were equivalent or superior to those obtained with urea and commercial NPK formulations.

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-The objective of this paper was to evaluate the effect of nitric oxide (NO) as a protecting agent of sesame seeds submitted to different concentrations of cadmium. The treatments were: water (control), water increased by sodium nitroprusside (SNP) and other treatments regarding the concentrations of cadmium increased by SNP. The following determinations were done: germination, first count of germination, germination speed index, length of hypocotyl and radicle and dry matter of hypocotyl and radicle, besides quantification of enzyme activities, superoxide dismutase, catalase, ascorbate peroxidase and total peroxidases. The statistical design was entirely randomized with five replicates. The data was submitted to a variance analysis and the averages obtained for the treatments were compared by the Tukey test at 5% significance. The averages obtained in the treatments with and without SNP were compared by the F test at 5% probability. The NO due to the application of SNP was beneficial, providing an increase in germination, vigor and growth of seedlings. There was a progressive increase of the antioxidant enzymes activity in the period of 0 to 24 hours, showing an organization of the antioxidant system in the sesame seeds throughout germination time.Index terms: SNP, vigor, germination, antioxidant system. Ação protetora do óxido nítrico em sementes de gergelim (Sesamum indicum L.) submetidas ao estresse por cádmio RESUMO -Objetivou-se avaliar o efeito do óxido nítrico (ON) como agente protetor em sementes de gergelim submetidas a diferentes concentrações de cádmio. Os tratamentos foram: água (controle), água acrescida de nitroprussiato de sódio (SNP) e os demais tratamentos referentes às concentrações de cádmio e cádmio acrescido de SNP. Foram feitas as seguintes determinações: germinação, primeira contagem de germinação, índice de velocidade de germinação, comprimento de hipocótilo e radícula e massa seca de hipocótilo e radícula, além da quantificação da atividade das enzimas, superóxido dismutase, catalase, ascorbato peroxidase e peroxidases totais. O delineamento estatístico utilizado foi o inteiramente casualizado com cinco repetições. Os dados foram submetidos à análise de variância e as médias obtidas para os tratamentos foram comparadas pelo teste de Tukey a 5% de significância. As médias obtidas nos tratamentos com e sem SNP foram comparadas pelo teste F a 5% de probabilidade. O ON devido à aplicação de SNP foi benéfico, proporcionando aumento na germinação, vigor e crescimento de plântulas. Houve aumento progressivo da atividade das enzimas antioxidativas no período de 0 a 24 horas, demonstrando organização do sistema antioxidante nas sementes de gergelim com o decorrer do tempo de germinação.Termos para indexação: SNP, vigor, germinação, sistema antioxidativo.

The leather industry generates large amounts of a Cr-containing solid waste (wet blue leather). This material is classified by the Brazilian Environmental Council as a category-one waste, requiring a special disposal. The patented process Br n. PI 001538 is a technique to remove chromium from wet blue leather, with the recovery of a solid collagenic material (collagen), containing high nitrogen levels. This work aimed to evaluate the residual effect of soil application of collagen on the production of dry matter, content and accumulation of N in common bean plants (Phaseolus vulgarisL.), after the previous growth of elephantgrass (Pennisetum purpureumSchumach.) cv. Napier, as well as to quantify the mineralization rate of N in the soil. The application of collagen, at rates equivalent to 16 and 32 t ha−1, provided greater N contents in the common bean plants, indicating residual effect of these rates of application; the same was observed for the rates of 4 and 8 t ha−1, though in smaller proportions. Higher mineralization rates of N collagen occurred next to 16 days after soil incubation. During the 216 days of incubation, the treatments with collagen showed higher amounts of mineralized nitrogen.

Abstract:In this article, the authors aimed to analyze the physiological and biochemical alterations in Melanoxylon brauna seeds subjected to heat stress. For this, seed germination, electric conductivity (EC), the production of reactive oxygen species (ROS), and the activity of antioxidant enzymes were assessed. Seeds were incubated at constant temperatures of 25, 35, and 45 • C. Independent samples were first incubated at 35 and 45 • C and then transferred to 25 • C after the intervals of 24, 48, 72, and 96 h. To evaluate EC, seeds were soaked for 0, 24, 48, and 72 h, at 25, 35, and 45 • C and then transferred to Erlenmeyer flasks containing 75 mL of deionized water at 25 • C, for 24 h. ROS production and enzyme activity were assessed every 24 h in seeds soaked at the aforementioned temperatures. Germination did not occur at 45 • C. Seeds soaked at 35 • C for 72 h and then transferred to 25 • C showed higher percentages of germination and a higher germination speed. Seed soaking at 45 • C increased peroxide production, which compromised the antioxidant enzyme system due to a reduction in the activity of enzymes APX, POX, and CAT, thus ultimately also compromising the cell membrane system.

Studies that evaluate the physiological and biochemical mechanisms of germination within forest species are needed in order to improve our understanding of such processes. Mercury and dithiothreitol are indicated as important tools in studies that assess the activity of aquaporins during imbibition and germination of seeds. To investigate the alterations caused by mercury in Plathymenia reticulata seeds, different doses of mercury were used in the presence and absence of dithiothreitol. Mercury had a dose-dependent effect on the seeds; in the most dilute solutions mercury partially inhibited the imbibition process, whereas in the most concentrated solutions it caused the death of the embryos. A delay in the hydration of the seeds may have caused decreased germination as a result of the reduced functionality of the aquaporins that were oxidized by mercury. In the presence of the reducing agent dithiothreitol, the activity of these proteins was restored and the germination process was re-established. These findings indicate the importance of aquaporins in the imbibition and germination stages of P. reticulata seeds, and they provide a better understanding of these important developmental events in plants.