Leila de Castro Louback Ferraz

Non-destructive prediction of pigment content in lettuce based on visible-NIR spectroscopy.

BACKGROUND Lettuce (Lactuca sativa L.) is one of the most important salad vegetables in the world, with a number of head shapes, leaf types and colors. The lettuce pigments play important physiological functions, such as photosynthetic processes and light stress defense, but they also benefit human health because of their antioxidant action and anticarcinogenic properties. In this study three lettuce cultivars were grown under different farming systems, and partial least squares models were built to predict the leaf chlorophyll, carotenoid and anthocyanin content. RESULTS The three proposed models resulted in high coefficients of determination and variable importance for the projection values, as well as low estimative errors for calibration and external validation datasets. These results confirmed that it is possible to accurately predict chlorophyll, carotenoid and anthocyanin content of green and red lettuces, grown in different farming systems, based on the spectral reflectance from 500 to 1000 nm. CONCLUSION The proposed models were adequate for estimating lettuce pigments in a quick and non-destructive way, representing an alternative to conventional measurement methods. Prediction accuracies were improved by using the detrending, smoothing and first derivative pretreatments to the original spectral signatures prior to estimating lettuce chlorophyll, carotenoid and anthocyanin content, respectively.

Characterization of two types of azedinha in the region of Sete Lagoas, Brazil

Azedinha (Rumex acetosa) is a vegetable crop species consumed in natura in salads and pertains to the group of non-conventional vegetables. These rustic plants are often considered weeds plants. There exist two types of native azedinha in the Sete Lagoas region, Minas Gerais state, Brazil, that are usually grown in family gardens and here denominated Type I and Type II. In this study we characterized the morphologic, physic-chemical and chromatic characteristic of these two types of azedinha. The study was carried out in randomized complete blocks with four replications in dependences of the EPAMIG (Non-Conventional Vegetable Bank) in Prudente de Morais, Brazil. Plants were trained to the point of harvest, 90 days after the planting of seedlings, when they were harvested for analysis. We evaluated the characteristics on the leaves: weight, length, width, number of veins, width/length ratio, transverse and longitudinal diameter of the base of the petiole and longitudinal and transverse diameter ratio of the base of the petiole. We also evaluated the contents of macro and micronutrients and chemical characteristics of the plant. There are significant differences between the assessed characteristics between azedinha types I and II. We concluded that the plants probably belong to two different varieties.

Viabilidade de escleródios de Sclerotinia sclerotiorum e incidência de fungos antagonistas em solo de Cerrado

ABSTRACT The viability of sclerotia of Sclerotinia sclerotiorum was assessedfor eight months in three cultivated Cerrado soils. Sclerotia producedin vitro were placed in nylon mesh bags and buried 5 cm deep in soilseither previously treated or untreated with methyl bromide. After 10days of incubation, sclerotia were retrieved and were examined forviability and presence of antagonistic fungi. Viability was assessedbased on the number of sclerotia germinated after a 7-day incubationperiod on semi-selective Neon-S medium. Viability of the sclerotia Ferraz, L.C.L.; Nasser, L.C.B.; Cafe-Filho, A.C. Viability of sclerotia of Sclerotinia sclerotiorum and incidence of antagonistic fungi in Cerradosoils. Summa Phytopathologica, v.37, n.4, p.208-210, 2011. varied among Cerrado soils. Sclerotia from soils not treated withmethyl bromide were less viable and were often contaminated byantagonistic fungi, indicating the presence of suppressive elementsof biological origin in the untreated Cerrado soils.