Este trabalho foi realizado com o objetivo de estudar a eficácia de óleos essenciais de Lippia gracilis, no crescimento in vitro de Xcv. Foram utilizados oito óleos extraídos de L. gracilis, obtidos de diferentes manejos de cultivo, em três dosagens diferentes (200; 250 e 300 µL.L-1), testemunha com o oxicloreto de cobre (controle padrão) e a testemunha absoluta. A suscetibilidade do isolado Xcv3 aos óleos testados foi avaliada na primeira etapa pela presença e ausência do crescimento bacteriano e, na segunda etapa, pela porcentagem de inibição do crescimento bacteriano. A análise da composição química dos óleos essenciais extraídos de L. gracilis, mostrou, o carvacrol (73,9 a 77%) como composto majoritário e o timol (4,9 a 10,3%). Os óleos referentes aos tratamentos 01, 06 e 07 foram os que proporcionaram maiores porcentagens de inibição no crescimento bacteriano de Xcv: 94,75%, 96,50% e 94,02%, respectivamente, sendo superiores ao oxicloreto de cobre (49,6%).

No abstract

Micropropagation requires controlling contamination that might compromise the success of the process. Thermal sterilization is traditionally used; however, costs deriving from equipment acquisition and maintenance render this technique costly. With the purpose of finding an alternative to thermal sterilization, this research aimed at assessing the efficiency and ideal concentration of sodium hypochlorite for sterilization of culture media and glassware used during rooting of micropropagated Gerbera hybrida cv. Essandre. Two experiments were carried out. In the first one, treatments consisted of control I (no sterilization), control II (thermal sterilization), and total active chlorine concentrations of 0.0005, 0.001, 0.002 and 0.003%. In the second experiment, based on the results observed in the first experiment, treatments consisted of control I (thermal sterilization) and II (chemical sterilization), and total active chlorine concentrations of 0.002, 0.0025 and 0.003%. Plant behavior was assessed based on the length of aerial part and roots, number of roots, and dry biomass of plants. Results showed that the addition of an active chlorine concentration of 0.003% to culture media provided total control of contaminants, and there were no significant differences regarding the variables analyzed between plants obtained with thermal sterilization and with sodium hypochlorite sterilization. Thus, chemical sterilization can be used as a replacement for thermal sterilization of nutrition media for rooting of gerbera in vitro.

No abstract

In micropropagation, potassium nitrate (KNO3), an ACS reagent grade chemical, used in the preparation of growing mediums is expensive and its procurement depends on bureaucratic procedures, as it is controlled by the Brazilian Army. This research to assessed the effect of replacing the ACS KNO3 for a commercially available fertilizer (KNO3- based) on the micropropagation of the prickly pear cactus (Opuntia stricta (Haw.) Haw. cv. Elephant Ear. Treatments used six different fertilizer concentrations (0, 0.5, 1, 1.5, 2 and 2.5 g L-1) and a control consisting of 1.9 g L-1 KNO3, as shown in the MS salts. The survival, size and number of sprouts and the value of fresh biomass were evaluated. After seedling acclimation, we assessed the survival, number of sprouts, length, and number of roots, racket formation, average fresh biomass mass, macronutrient absorption and morphological changes of the seedlings. Explants inoculated with fertilizers at concentrations of 0.0; 2.0 and 2.5 g L-¹ did not grow. The response of explants at concentrations of 0.5 and 1.5 g L-1 of the fertilizer were the same as those developed in a KNO3 medium, and at a concentration of 1.0 g L-1, in all variables, the means were higher than those of the control medium. Therefore, it showed the feasibility of using fertilizers in the in vitro cultivation of the prickly pear cactus, which may remove bureaucratic barriers and reduce product costs by 99.12%.

Post-harvest mango decay is caused by multiple pathogens in tropical conditions but concerns regarding the risk of food contamination by fungicides established biocontrol as a promising alternative. However, occurrence of quiescent infections requires pre-harvest applications of biocontrol agents (BCA), exposing them to harmful UV radiation effects. The objective of this work was to evaluate UV sensitivity of yeast BCA strains previously selected against multiple pathogens that cause mango decay and evaluate suitable UV protectants. In a first bioassay conducted exposing yeast suspensions sprayed on glass plates, it was verified that Saccharomyces sp. ESA47 and Pichia kudriavzevii CMIAT171 were highly sensitive to UV, while Saccharomyces cerevisiae ESA45 had a slightly lower mortality. A bioassay using fragments of mango peels evaluated UV protection from increasing concentrations of starch, dextrin, casein, benzophenone, and cinnamic acid derivative compounds. Results showed that starch and isoamyl p-methoxycinnamate (NHE-1000) resulted in higher survival for yeast strains in doses of 10.0 and 1.0 g kg −1 , respectively. Application of the yeast BCA in a semi-commercial mango orchard resulted in a significant reduction of post-harvest disease incidence and severity. Field application of the yeasts in technical grade preparations containing both UV protectants enhanced the control efficiency by 52.5, 31.9, and 37.7% for ESA45, ESA47, and CMIAT171, respectively.

No abstract

No abstract