Browsing by Author "Valdes-Gomez, Hector"

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    Effect of cultivar, rootstock, and growing conditions on fruit maturity and postharvest quality as part of a six-year apple trial in Chile
    (2019) Yuri, Jose A.; Moggia, Claudia; Sepulveda, Alvaro; Poblete-Echeverria, Carlos; Valdes-Gomez, Hector; Torres, Carolina A.
    Fruit export is an important economic activity for Chile. Therefore, high productivity and quality fruit is a must in order to succeed in the business. A 6-year project was carried out to assess apple cultivars ('Galaxy', 'Brookfield (R) Gala', 'Super Chief, 'Fuji Raku Raku', 'Braebum', 'Granny Smith', and 'Cripps Pink') and rootstock's (M.M.106 and M.9 EMLA) performance across different Chilean apple-growing areas (Graneros, San Clemente, Chillan, Angol, and Temuco). Fruit maturity (firmness, soluble solids, starch degradation, internal ethylene concentration, and skin color) pre-and-postharvest was assessed weekly starting one-month prior harvest and monthly postharvest during years 4, 5, and 6 of the trial. Physiological disorders were also evaluated monthly for 6 months in RA (0-1oC, > 95% RH) storage. Based on bioclimatic variables, growing sites showed a clear distribution pattern on all principal component analyses, and it was more relevant than the growing season. In general, red skin color of most cultivars increased in sites towards the south of the country (cooler), regardless of the rootstock. Overall fruit firmness increased towards the southern sites in some cultivars, although not always statistically different. The highest softening rates pre-harvest were observed in 'Galaxy' and 'Brookfield (R) Gala'. In 'Galaxy', the lowest softening rate was observed in Temuco (coolest site). Brookfield (R) Gala' and 'Galaxy' apples grown in warmer sites (San Clemente and Angol) showed a sharper increase in internal ethylene concentration (IEC) than cooler sites (Temuco and Chillan) earlier in the season. Fruit quality and condition postharvest is also discussed.
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    Phenolic content, antioxidant and antifungal activity of jackfruit extracts (Artocarpus heterophyllus Lam.)
    (2022) Omar Chavez-Santiago, Joaquin; Concepcion Rodriguez-Castillejos, Guadalupe; Montenegro, Gloria; Bridi, Raquel; Valdes-Gomez, Hector; Alvarado-Reyna, Sofia; Castillo-Ruiz, Octelina; Santiago-Adame, Ruben
    Jackfruit (Artocarpus heterophyllus Lam.) is a fruit of tropical and subtropical zones of the world, is an important source of phytochemicals (phenolic acids, flavonoids and tannins). Several studies have associated phytochemicals with antioxidant and antimicrobial properties. The objective of this work was to analyze the polyphenolic content, the antioxidant and antifungal properties of jackfruit extracts on phytopathogenic fungi. Two phenolic extracts of jackfruit of different maturity level (J1-12) were used. The total polyphenol content (TPC) was determined by Folin-Ciocalteu method and total flavonoids (TFC) by the aluminum chloride method, the free radical trapping potential was measured using FRAP and ORAC methods. The results showed a TPC of 844 and 1,178 mgEAG/100 g and TFC of 37 and 68 mgQE/100 g, of dry jackfruit, the antioxidant potential analysis by FRAP was 7,575 and 8,691, by ORAC was 13.369 and 14.728 umol Trolox/100 g, of dry jackfruit for 11 and J2 respectively. Additionally, it was observed that the phenolic extracts of jackfruit reduced the mycelial growth of: Penicillium digitatum (20-14%), Geotrichum candidum (56-55%), Aspergillus niger (72-67%) and Botrytis cinerea (100%-100%) for J1 and J2 respectively. We conclude that regardless of the degree of maturity, jackfruit has antioxidant and antifungal properties on phytopathogens important in agriculture.
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    Sunscreen Based on Dicarboxylic Acid Salts Applications to Blueberries (Vaccinium corymbosum L.) Plants: Effects on Water Stress Tolerance and Productivity
    (2022) Gutierrez-Gamboa, Gaston; Guerrero-Mendez, Mario; Araya-Alman, Miguel; Verdugo-Vasquez, Nicolas; Valdes-Gomez, Hector; Acevedo-Opazo, Cesar
    Background: Recently, antitranspirant or radiation-reflective products have been studied in several crops to mitigate the negative effects of global warming in Mediterranean climates. Nevertheless, to our knowledge, there is a scarce availability of information studying their effects on blueberries and much less from applications of sunscreens elaborated based on a mixture of dicarboxylic acids. Methods: Controls and three treatments were performed in 'Duke' and 'Star' blueberries as follows: (i) control without water stress (T1 = 100% ETc); (ii) foliar application of sunscreen in plants without water stress (T2 = 100% ETc + sunscreen); (iii) water stress in plants without foliar application of sunscreen (T3 = 50% ETc); (iv) foliar application of the sunscreen in plants with water stress (T4 = 50% ETc + sunscreen). Stem water potential (Psi s), stomatal conductance (g(s)), yield, berry weight and berry total soluble solids were determined. (3) Results: As expected, the decrease in irrigation frequency in water stress treatments (T3 and T4) allowed for a decrease in the water applied at 25% compared to non-stressed plants (T1 and T2). This resulted in an increase in the Psi s on the days closest to harvest in both varieties, decreasing g(s) in blueberries plants subjected to water stress conditions. Sunscreen applications to Duke plants subjected to water stress (T4) induced higher total berry soluble solids than the treatments performed in non-stressed plants (T1 and T2). Sunscreen applications to Star plants subjected to water stress (T4) promoted similar g(s) levels and did not affect total soluble solids concerning irrigated plants (T1 and T2). (4) Conclusions: The results suggest that the response to water stress to sunscreen application based on dicarboxylic acid salts depended on the cultivar. Therefore, despite the novelty of this research, it is necessary to perform long-term studies to establish accurate conclusions.
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    Vigor thresholded NDVI is a key early risk indicator of Botrytis bunch rot in vineyards
    (2020) Panitrur-De la Fuente, Carolina; Valdes-Gomez, Hector; Roudet, Jean; Verdugo-Vasquez, Nicolas; Mirabal, Y.; Laurie, V. F.; Goutouly, Jean-Pascal; Acevedo-Opazo, Cesar; Fermaud, Marc
    Botrytis bunch rot (BBR) is a major disease occurring in vineyards worldwide. Its control is still largely based on the use of synthetic fungicide sprayings at predetermined intervals, which often produces negative residues in grapes and wines that may affect the environment and/or human health. To rationalize BBR management, disease risk indicators were developed and evaluated in a set of field experiments carried out between 2010 and 2019 in France and Chile. Key indicators include early grapevine vegetative growth, i.e. ground-based normalized difference vegetation index (NDVI), and the potential berry susceptibility to Botrytis cinerea, which is driven by tannin content in the skin. Under these contrasting weather and cropping conditions, regression analyses, including weather information, showed a highly significant positive correlation between the early NDVI, measured at berry pea size stage, and BBR incidence or severity at harvest, whereas the opposite was demonstrated for tannin content in the berry skin measured at an early herbaceous fruit stage. The exponential relationship between the final disease severity and the early NDVI allowed us to identify a possible threshold NDVI value, i.e. between 0.5 and 0.6, under which the BBR severity should be lower or close to 5% at harvest (BBR tolerance threshold for wine quality). Accordingly, in a leaf-removal vineyard experiment in France, the NDVI level at berry pea size stage was strictly controlled to correspond to three different increasing index values: 0.45, 0.60, and 0.78. Following this increase in NDVI, a significant increase in final BBR severity was noticeable, i.e. 2.4%, 6.6% and 9.9%, respectively. Very interestingly, the NDVI increase was also related to a significant decrease in the tannin content in the skin of herbaceous berries at veraison, from 47 to 22 mg tannin/g skin. All regression analyses explaining BBR development were highly significant, showing the weather conditions before harvest as the primary factor. They also show that some of the disease risk indicators chosen, especially early NDVI, could be used in the future as tools in decision support systems for deciding to spray and/or scheduling optimized fungicide applications during the season.