The aim of the current study is to assess the growth response, biochemical changes, photosynthetic pigments content and gas exchanges of physic nut (Jatropha curcas) grown under natural saline conditions. The experiment was arranged in a completely randomized design based on the following soil electrical conductivities: 0.29 dS.m -1 (control), 1.76 dS.m -1 (moderate salt concentration), 2.61 dS.m -1 (high salt concentration), 3.79 dS.m -1 (very high salt concentration). Physic nut plants were kept under saline conditions for 19 days in greenhouse. Plant growth analyses were performed on a weekly basis. Plant biomass allocation was quantified at the end of the experiment. Leaf gas exchange, stomatal conductance, Fv/Fm and quantum yield were quantified 102 days after planting. Photosynthetic pigments, amino acids, proline and carbohydrates in fresh leaf tissue were also quantified. The leaf antioxidant enzymes catalase (CAT) and ascorbate peroxidase (APX) were quantified. Although there was no alteration in biomass allocation, the initial growth of J. curcas was gradually reduced by increasing salt concentration, which was observed through reduced plant height, stem diameter, and total number of leaves. Soil electrical conductivity 3.79 dS.m -1 was lethal to seedlings. Seedlings exposed to salt stress had their photosynthesis, stomatal conductance, transpiration and effective photochemical efficiency reduced, and their catalase and ascorbate peroxidase enzyme activity increased. Amino acids, proline and carbohydrate concentrations increased due to salt stress, whereas there was decrease in the chlorophyll content. J. curcas is sensitive to soil salinity at electrical conductivity levels higher than 1.76 dS.m -1 . To some extent, salinity effects can be relieved by osmolyte accumulation and by greater antioxidant activity; however, these factors were not sufficient to keep plant growth within normal rates.
Seeds associated to fungal pathogens are efficient vehicles for disease dissemination in the field. Such pathogens affect the seed quality and longevity, causing a decrease or loss of germination, discoloration, necrosis, and decay, in addition to leading to the production of mycotoxins in some pathosystems. To control them several synthetic chemicals are used. Nevertheless, the use of synthetic chemicals poses a risk to human health and the environment. Therefore, there is a growing demand for the use of alternative methods for the treatment of seeds, such as plant extracts. This review evaluated the use and efficacy of plant extracts for the control of fungal pathogens associated to seeds. Some control methods are used in seed treatment, plant extracts stand out due to the secondary metabolic in their constitution, which inhibit pathogen growth. The literature review showed that 100% of the studies reported that plant extracts were efficient to control the different pathogens evaluated, 63% stated an increase in seed germination, 21% reported no change in germination, 5% mentioned negative interference, and 11% did not evaluate the use of plant extracts. The aqueous extracts were used as extractors in 72% of the studies. Plant extracts were reported as promising to replace synthetic fungicides in 33% of the studies; however, 67% did not compare their use. Nevertheless, efficient extraction methods are required, considering low persistence and volatilization of plant extracts in the field. Plant extracts are efficient to control fungal pathogens.
Alternative control of the black aphid of cowpea Aphis craccivora (Koch) with the use of the alcoholic extract of Momordica charantia L.
O objetivo do trabalho foi investigar qual a melhor concentração de substratos para produção de mudas de Moringa Oleifera Lam, com a finalidade de se obter plantas mais saudáveis, vigorosas e resistentes. O experimento foi conduzido em casa de vegetação na unidade da Embrapa Tabuleiro Costeiro, localizado no Campus de Engenharias e Ciências Agrárias – CECA/UFAL, Rio Largo, AL. Foi realizado o delineamento inteiramente casualizado (DIC) com 7 tratamentos: T0 – 100% solo (testemunha); T1 - solo + 10% de esterco ovino; T2 – solo + 20% de esterco ovino; T3 – solo + 33% de esterco ovino; T4 – solo + 10% de borra de café; T5 – solo + 20% de borra de café; T6 – solo + 33% de borra de café, com cinco repetições, totalizando 35 saquinhos de polietileno, com volume de 3litros, foi utilizada análise de regressão quadrática e cúbica, adotando-se o nível de 5% de significância. Ao contrário do esperado, as mudas produzidas em ambos substratos não apresentam maiores valores. Em relação ao substrato contendo esterco ovino, foi observado que sua utilização em maiores concentrações prejudica sua decomposição e consequentemente a disponibilidade de nutrientes para as plantas. O substrato contendo borra de café, mostrou mais inviável e que sua utilização “in natura” acidifica o solo e torna lenta a mineralização dos nutrientes. Assim é possível recomendar a produção de mudas de Moringa oleifera Lam com substrato de esterco ovino na concentração de 20%.
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