The plants synthetize a big quantity of chemically diverse compounds, which discharged into the environment influence in a decisive manner in the species dynamics that form the agroecosystems, phenomenon denominated allelopathy. The study had the aim of the evaluation of allelopathic effects of turnip aqueous extract under beans and corn seeds. The experimental design was completely randomized with five treatments (concentrations of 0%, 25%, 50%, 75% and 100% of raw extract) and four repetitions. The gross extract was prepared through the mixture of 50 g of turnips aerial part fresh mass in 450 mL of cold distilled water and then blended in a blender. The mixture was kept in rest in absence of light for 24 hours at 25˚C for posterior filtration and dilution of concentrations. They were evaluated the percentage of germination and the germination velocity index in Germitest paper rolls dampened with the extract or distilled water, according to the treatments and each roll was distributed 50 seeds, kept in germination chamber at 25˚C ± 3˚C and 12 hours of photoperiod. At the end of seven (corn) and nine (beans) days, the root length (RL) and the aerial part (APL) were evaluated, and after drying in a hothouse (50˚C), the dry mass of root system (DMR) and aerial part (DMAP) was determined, by the measure of 20 plantlets of each treatment. The results were submitted to an analysis of variance by F test and, when there was statistical significance, it was made the regression analysis test. For the realization of the statistical analysis, the ASSISTAT software was used. The turnip aqueous extract affected negatively the germination and initial development of bean and corn plantlets.

O tamanho das sementes pode ser um indicativo do potencial fisiológico da mesma, apresentando uma relação direta com a germinação e vigor, entretanto, existe divergência nos resultados encontrados em relação à espécie e cultivar. Portanto, o objetivo do trabalho foi avaliar o potencial fisiológico de duas cultivares de trigo sarraceno (IPR 91-Baili e IPR 92-Altar), em função do tamanho da semente. Inicialmente foi realizada uma caracterização das cultivares, quanto à porcentagem de sementes retidas em peneiras de 3,5; 4,0; 4,5; 5,0 e 5,5 mm e em seguida, a construção de um histograma para tomada de decisão sobre quais peneiras utilizar. Após a seleção, as sementes pertencentes ao lote original e as classificadas em peneiras de 3,5; 4,0; 4,5 e 5,0 mm foram submetidas a avaliações de germinação, e vigor (índice de velocidade de germinação, comprimento e massa seca de parte aérea e raiz). Constatou-se que o tamanho da semente influenciou a porcentagem de germinação e o vigor das mesmas. A germinação e o vigor das sementes foram maiores quando provenientes da peneira de tamanho 5,0 mm. A cultivar IPR 91-Baili apresentou melhor desempenho, ao produzir plântulas com maior comprimento de raiz em relação a cultivar IPR 92-Altar.

No abstract

The quality of seeds produced is the result of the management practices used and environmental conditions during growing. The aim of this study was to evaluate the physiological potential and the health of soybean seeds produced in an organic and conventional system. The genotypes UEL 110 and 122 and BRS 257 and 284 were tested in organic and conventional systems in a randomized block design. The following characteristics were evaluated: moisture content; thousand seed weight (TSW); germination (G) and first count of germination (FCG); tetrazolium (TZ); classification, length, and dry matter of seedlings; and seed health. Analysis of variance was performed separately for the management systems, followed by combined analysis. When significant, the Tukey test (p<0.05) was applied. Multivariate analysis was performed using R software. There was not significance between genotypes and management systems. The conventional management system performed positively for the characteristics TSW, G, TZ, FCG, classification, and length and dry matter of seedling roots, as well as for plant health. The UEL genotypes obtained higher TSW; UEL 110, lower germination; and BRS 257, a smaller number of ungerminated seeds and higher infestation by Cladosporium spp. The seeds produced under the organic system have greater weight and lower infestation by contaminants, whereas the conventional system produces seeds of better physiological quality and lower contamination by Phomopsis and bacteria. The genotype BRS 257 may have seeds multiplied in the organic and conventional management systems.

In vitro cultivation is a highly important biotechnological method widely used for the production of orchid seedlings, but it is necessary to study the suitability of the nutrients used in different kinds of formulation, as the nutritional requirement varies according to the species. The objective was to evaluate different concentrations of iron in the in vitro cultivation of Schomburgkia crispa Lindl seedlings. Seedlings were obtained from seeds germinated in vitro. Modified MS culture medium was used with half of the macronutrient concentration. The micronutrients were added according to the original formulation, except for the iron which was added from a stock solution of FeEDTA (FeSO4.7H2O: 5.6 g L-1 and EDTA: 7.48 g L-1) at 0.0; 2.5; 5.0; 7.5; 10.0 and 12.5mL L-1. At 200 days after seedling transplantation, shoot height, root length, number of leaves, shoot number, leaf length, leaf width, aerial and root dry mass, chlorophyll a, b and carotenoids content were evaluated. A completely randomized design was used, with six treatments and ten replicates of five seedlings. Regression analysis was performed at 5% of significance. The increase in iron concentration caused a reduction in root length and an increase in the number of leaves and shoots. The concentration of 4.13 mL L-1 of FeEDTA was the one that provided the best in vitro growth of S. crispa plants. High concentrations of iron caused a reduction of initial development, but stimulated an increase in the number of shoots.