Prosopis juliflora é uma árvore invasora e que tem efeito alelopático negativo sobre várias espécies nativas da caatinga. O objetivo deste estudo foi verificar o efeito alelopático do extrato de folhas e sementes de algaroba sobre a germinação de alface. Para cada parte da planta foi obtido o extrato a 25 ºC e a 100 ºC. Foi usado o delineamento experimental inteiramente casualizado com cinco tratamentos constituídos pelas concentrações do extrato obtidas por diluição em água destilada (0, 25, 50, 75 e 100%), com quatro repetições de 25 sementes de alface. O extrato de folhas frescas de P. juliflora obtido com água a 25 ºC não afetou a germinação de alface que variou de 92,5 a 100%. O extrato de folhas secas de P. juliflora a 25 ºC diminuiu a germinação de alface nas maiores concentrações. Os extratos de folhas frescas e secas de P. juliflora a 100 ºC reduziram a germinação nas maiores concentrações e o índice de efeito alelopático é negativo. O extrato de sementes de P. juliflora em ambas as temperaturas afeta negativamente a germinação, tempo médio de germinação, comprimento da parte aérea e da raiz de alface, e proporciona plântulas anormais. O uso de bio-herbicidas a partir de Prosopis juliflora poderá ser interessante na agricultura familiar e agroecológica, e a pesquisa deve avançar nesta área, identificando os compostos responsáveis por esses efeitos.
This study aimed to evaluate the phytotoxic activity of aqueous extracts of species from the Cerrado of Mato Grosso on the germination and initial development of lettuce seedlings, as well as to determine the chemical composition of the extracts. The species studied were: Davilla elliptica, Combretum laxum, Himatanthus obovatus, Diteryx alata, Curatella americana, Qualea grandiflora, Aspidosperma macrocarpon, Caryocar brasiliense, Pleroma candolleanum and Miconia albicans. Fourier Transform Infrared Spectroscopy (FTIR) and Thin Layer Chromatography (TLC) techniques were used to identify functional groups and chemical compounds. The extracts of the species D. elliptica, C. laxum, C. brasiliense and Q. grandiflora showed greater phytotoxic activity on the germination of lettuce seeds which varied between 96 and 17%. The presence of compounds such as: phenols, alkaloids, flavonoids and terpenes with phytotoxic properties was confirmed.
Plants have organic components produced as secondary metabolites able to positively or negatively interfere on normal development of other species. The objective of this research was to determine the phytotoxic effects of aqueous leaf extract from two species Rubiaceae family: Tocoyena formosa and Rudgea viburnoides on the germination and initial development of lettuce (Lactuca sativa L). The extract was obtained from mixing 50 g of fresh leaf and 500 mL of distilled water. The experiment was arranged in completely randomized design for each specie, subjected to five extract concentrations: 0, 25, 50, 75 and 100%; and 4 repetitions of 50 seed each. The bioassays were performed in laboratory at controlled temperature and luminosity during seven days. Results showed that the aqueous extract of both species do not affected the germination and the percent of abnormal lettuce seedlings. R. viburnoides showed no pronounced difference in relation to shoot length and dry biomass; however, the root length was reduced by 85%. The extract of T. formosa at higher concentrations, drastically reduce the dry biomass and length of shoots and roots. Therefore, both species have phytotoxic effect on seedling growth of lettuce being the length root the most affected variable.
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The tara (Caesalpinia spinosa(Mol.) Kuntze) is a non-timber forest species whose pods are of economic importance to various industries; however, attacks by pests such as Tanaostigmodessp. the leaves and young stems decrease the production of this species. The aim of this study was to determine the morphological and biological characteristics of Tanaostigmodessp. and percentage of incidence in C. spinosa. 1399 insects were identified in which evaluations of the duration of the stages, the morphometry and the damage to the plant were carried out. The egg, larva, pupa and adult measure 0.2, 2.0, 2.1 and 2.0 to 2.3 mm long, last 13.1, 71.8, 20.6 and 10.1 days respectively,totaling its development cycle in 115.1 days; the larvae when feeding make mines in the rachis of the leaves and in young stems, reaching maximum attacks of up to 84.5% causing defoliation. Tanaostigmodessp. it is a major tare pest, with average attack records of 24.6% on leaves. Knowing its biological aspects and its interaction with tara phenology will allow the adoption of efficient strategies for its integrated management and control.
Production of herbaceous cotton in rainfed is subject to water-deficit risks due to climatic variations, such as precipitation with non-homogeneous spatial-temporal distribution. In this sense, the objective of this study was to evaluate the yield response factor to water of FMX 993, FMT 701 and FMX 910 cotton varieties, in Campo Verde County, Mato Grosso State, Brazil. Real yield data of the 2009/10 and 2010/11 seasons of the three varieties were obtained. Meteorological data were used to estimate the maximum yield and to calculate the daily water balance for each variety and seasons. From these values the yield response factor to water (Ky) was obtained. Ky values ranged from 0 to 0.9, with the lowest and highest values for FMX 910 for the 2009/10 and 2010/11 seasons, respectively. These values obtained from Ky indicate that all varieties studied present increasing tolerance to water-deficit. The FMX 993 variety had a lower variation in Ky values between 0.3 and 0.5 for the 2009/10 and 2010/11 seasons, in that order. Therefore, among the cotton varieties evaluated in this study, recommend FMX 993 for the conditions of Campo Verde County, Mato Grosso State, due to its greater tolerance to the water-deficit.
Adubos e coberturas orgânicas, fontes de nutrientes de liberação lenta na produção de acelga de colheitas múltiplasFertilizers and organic covers, slow release nutrient sources in the production of multiple harvest Swiss chard
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