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Agriculture depends on biotic and abiotic factors, and one of them is allelopathy, defined as the chemical interference that one plant has on others, which can negatively affect germination. The objective of this work is to evaluate the allelopathic effects of Sorghum bicolor and Digitaria insularis on seed germination and initial development of canola seedlings (Brassica napus L.). A completely randomized design was used in a 2x5 factorial scheme (two extracts: D. insularis and S. bicolor) and five concentrations (0, 25, 50, 75, and 100%), with four replicates of fifty seeds, the plot being constituted by a 'gerbox' box containing 50 seeds evenly distributed. The variable analyzed were germination percentage (G), abnormal seedlings (AS), dead seeds (DS), length of the shoot (SL) and primary root (RL), total length (TL) of the seedling, shoot ratio (S/T), and root ratio (R/T). The aqueous extracts of D. insularis interfere in all variables studied, which compromises the formation of normal seedlings, regardless of concentration. The extract of S. bicolor expressed allelopathic effects only in concentrations above 75%. Both species can inhibit the initial development of canola plants.

Este estudo teve como objetivo avaliar os efeitos da inoculação das sementes de trigo com microrganismos eficientes, testando diferentes concentrações e produtos comerciais, afim de obter o controle da contaminação de possíveis agentes patogênicos associados a semente da cultura, assim como, um efeito positivo na germinação destas sementes. Utilizou-se o delineamento inteiramente casualizado em esquema fatorial 2 x 5 + 1, sendo o primeiro fator composto por dois produtos contendo microrganismos eficientes (EM comercial e EM convencional), o segundo fator foi constituído por cinco níveis da concentração dos produtos (20, 40, 60, 80 e 100%), adicionando mais um tratamento contendo somente água deionizada, com quatro repetições, totalizando 44 parcelas experimentais. Os produtos contendo microrganismos eficientes e as concentrações apresentaram interação significativa somente para as variáveis porcentagem da presença de fungos e porcentagem da ausência de fungos. No teste de germinação, verificou-se uma interação significativa nas variáveis porcentagem de germinação e índice de velocidade de germinação. Os resultados obtidos permitem concluir que ambos os produtos utilizados (comercial e convencional), apresentaram eficiência no controle de fungos infectantes nas sementes de trigo, assim como, incrementaram o desenvolvimento inicial das plântulas.

The effect of different water regimes on Jatropha curcas seedling growth was investigated. The study was carried out in a greenhouse covered with transparent plastic. Seeds were sown in five-liter recipients containing substrate consisting of 3:1:0.5 soil, sand and manure, respectively. A completely randomized plot design was used with seven treatments and five replications. The plants were irrigated with 100% substrate retention capacity until 30 days of age when they were submitted to water volumes of 25%, 50%, 75%, 100%, 125%, 150% and 175% substrate retention capacity for 30 days. The short duration of the research explains the slight decreases in the RMR and TRA but they were sufficient to support the assertion that excess water may have inhibited aquaporin activity and partially reduced soil solution absorption and TRA. Thus, both water deficit and excess water inhibited the growth of J. curcas plants, however, the water deficit inhibited more strongly the development of the species at the initial stages of the restriction, while excess water only caused damage after a longer period of exposure. The assessments were made when the plants were 60 days old. The J. curcas plants showed an isohydric mechanism of stomatal control and maintained turgidity under water shortage, and, under excess water, the alterations in the root system and relative water content preceded reduction in stomatal conductance. The initial growth of J. curcas plants was shown to be sensitive to water shortage and but not very vulnerable to water excess

Pasture leafhoppers are considered highly important pests in forage grasses in Brazil due to their widespread occurrence. This insect is one of the most relevant pests in pasture degradation. In order for the control of spittlebugs to be efficient, it is important to know the population behavior of the species of this insect, identify the period of greatest occurrence, as well as the climatic and environmental conditions that favor the development of the pest. Thus, this study aimed to evaluate the population dynamics of spittlebugs, at a quantitative level, in Brachiaria decumbens and Panicum maximum pastures, associating the results with meteorological data from the municipality of Conceição do Araguaia, Southeast Pará. To study the population dynamics of spittlebugs, samples were taken every two weeks, in two types of pastures aged between 5 and 7 years, kept under rotational grazing, with a stocking of 1.5 animal units. The method of monitoring nymphs and adults of leafhoppers was adopted, through walking within the observation area. The level of infestation of spittlebugs in both forage species was evaluated and all results were submitted to analysis of variance by the F test. It was found that the species B. decumbens had a greater number of adults and nymphs when compared to the forage species P. maximum. The population dynamics of spittlebugs occur gradually according to climatic conditions, and the period with not-so-high temperatures (22 ºC to 34 ºC) and good rainfall provide an infestation of this insect pest in the pasture.

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The use of soil remineralizers with efficient microorganisms (EM) can represent an effective and sustainable alternative to improve the growth, development, and yield of cultivated plants. Thus, the present study aimed to evaluate the effect of different doses of EM, in the presence or absence of rock dust (RD), on the development of iceberg lettuce, cultivar Lucy Brown. The design used was completely randomized, arranged in a 2 x 5 factorial scheme, with four replications. The treatments consisted of the presence and absence of RD in the substrate composition, combined with five commercial product doses based on EM (0, 2, 4, 6, and 8 L ha-1). At 30 days after transplanting, root and stem length, head circumference, the number of leaves, stem diameter, leaf area, fresh matter of root, stem, leaf, and shoot, and dry matter of root, stem, leaf, and shoot were evaluated. There was an interaction between the factors for most variables of economic importance. The dose of 4.5 L ha-1 of the product based on EM, combined with PR, implied the best performance of iceberg lettuce under the studied cultivation conditions.