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Os fosfitos e os silicatos, embora considerados nutrientes minerais das plantas, podem também funcionar como produtos alternativos no controlo de doenças em diferentes culturas. Estes minerais inorgânicos podem atuar diretamente contra os microrganismos patogénicos e/ou induzir as respostas de defesa das plantas info:eu-repo/semantics/publishedVersion

Coffea canephora is one of the most economically important coffee species and in Brazil, Conilon being the most widely cultivated plant of this species. Abiotic stresses such as temperature variations and drought periods are factors that significantly affect their production and tend to worsen with globally recognized climate changes. Rationale: In an attempt to understand the molecular responses of coffee plants in water deficit conditions, recent studies have identified candidate genes as CcDREB1D (Dehydration Responsive Element Binding Protein). This gene showed increased expression in response to drought in the leaves of clone 14 (drought tolerant) in relation to the clone 22 (drought susceptible) of C canephora Conilon (Marraccini et al., 2012). Methods: The main objectives of this work were (1) to identify DREB genes and their subgroups (SGs) of C. canephora, and (2) to analyze their expression by reverse transcription-quantitative PCR in leaves and roots of drought-tolerant (14, 73 and 120) and drought-susceptible (22) clones of C canephora Conilon submitted (or not) to drought stress. Results: Among the four subgroups (I-IV) of coffee DREB genes (Alves, 2015), we identified several DREB genes showing differential expression profiles in leaves in response to drought. For several of them, differential expression profiles under drought were observed between drought-tolerant and drought-susceptible clones of C. canephora. This was the case for Cc05_g06840 (SG-I) and Cc08_g13960 (SG-III) DREB that were highly up-regulated by drought in leaves of drought-tolerant clones 14 and 73, but not in those of the drought-susceptible clone 22. Conclusions and Perspectives: The fact that several DREB genes were differentially expressed under drought between drought-tolerant and drought-susceptible clones of C. canephora highly suggests that these genes play a key role in response of coffee plants to this abiotic stress. (Texte intégral)

The objective of this study was to evaluate the effect of extracts obtained from leaves of Jatropha curcas L. on germination and initial growth of wheat. The aqueous and alcohol (ethanol and methanol) extracts of dried leaves were prepared in the concentration of 50 mg/mL. From the crude extract were made dilutions and obtained different concentrations. Some of the aqueous extracts tested were autoclaved. Over seven days, the germination characteristics and growth of wheat seedlings were evaluated with the different treatments. There was no effect of aqueous extracts on percentage of seed germination, however the methanolic and ethanolic extracts 5% affected the germination of a cultivar in study. There was a decrease in the germination speed index when the seeds were incubated with crude aqueous extract and methanol extract. The extracts affected the growth of seedlings and the most phytotoxic was the ethanol extract 5%. The autoclaved extracts promoted a reduction in all parameters evaluated. The results presented here show the extracts of dried leaves of jatropha promoted allelopathic effects on wheat. El objetivo de la investigación fue evaluar el efecto de los extractos obtenidos a partir de hojas de Jatropha curcas L. sobre la germinación y el crecimiento inicial del trigo. Las acuosas y alcohol (etanol y metanol) extractos de hojas secas se prepararon de la concentración de 50 mg/ml. A partir del extracto crudo se hicieron diluciones, obteniendo diferentes concentraciones. Algunos de los extractos acuosos ensayados se trataron en autoclave. Durante siete días, las características de germinación y crecimiento de plántulas de trigo fueron evaluados con los diferentes tratamientos. No hubo efecto de extractos acuosos en el porcentaje de germinación de las semillas; sin embargo, los extractos metanólicos y etanólicos 5% afectaba la germinación de un cultivar en estudio. Hubo una disminución en el índice de velocidad de germinación cuando las semillas se incubaron con extracto crudo acuoso y extracto de metanol. Los extractos afectaron el crecimiento de las plántulas y el más fitotóxico era el extracto en etanol 5%. Los extractos autoclave promovieron una reducción en todos los parámetros evaluados. Los resultados aquí presentados muestran los extractos de hojas secas de Jatropha que promueven efectos alelopáticos sobre el trigo.