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Copyright of Agrociencia is the property of Colegio de Postgraduados and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The genus Physalis includes species used for food, medicinal and artisanal purposes. The wild tomato (Physalis angulata L.), which is common in the mixed maize cultivation called "the milpa", is cultivated in some localities of Jalisco because of its importance in the preparation of sauces. It is hypothesized that the management of planting density and fertilization application can improve the yield of this tomato. The objective of this study was to evaluate the leaf area and yield of P. angulata L. as a function of slow-release urea doses and planting densities, under open-field rainfed conditions. Nine treatments were evaluated, resulting from the combination of three planting densities and three fertilizer doses. The experimental design was randomized complete blocks with factorial arrangement. The data were analyzed with analysis of variance and the means of the treatments were compared with Tukey's test (p = 0.05). The relationship between yield and study variables was estimated with simple linear regressions. The results indicated that with 2.5 plants m-2 the highest yield was obtained (6.4 Mg ha-1); while with 140 units of slow-release urea the average yield was 5.76 Mg ha-1. The interaction effect showed that with densities of 2.0 and 2.5 plants m-2 and with 120 kg of slow-release urea, the highest fruit yields were obtained, 6.44 and 6.87 Mg ha-1. For each unit increase in the variables leaf area, leaf area index, number of fruits per plant and fruit weight per plant, fruit yield increased as well. The yield of P. angulata responded differently to planting densities and slow-release urea doses. The best yield could be obtained with the planting density of 2.5 plants m-2 and with the application of 30.4 g m-2 slow-release urea. [ABSTRACT FROM AUTHOR]

Copyright of Agrociencia is the property of Colegio de Postgraduados and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wilting of sugarcane is produced by a complex of Fusarium species, such as F. andiyazi and F. sacchari, which induce rotting of roots. In order to control this disease and reduce the use of fungicides, biological control has been proposed by means of antagonists of the genus Trichoderma. The objective of this study was to evaluate in vitro and in sugar cane plants the antagonistic capacity of strains of Trichoderma against F. andiyazi and F. sacchari. The hypothesis was that at least one strain of Trichoderma inhibits the growth in vitro of Fusarium and favors the development of the sugarcane plants. Eighteen strains of Trichoderma were isolated and their percentage of inhibition was determined on the mycelial growth of Fusarium species with the technique of dual culture in potato dextrose agar culture medium. The experimental design was completely randomized, with four replicates per treatment. The degree of antagonism of Trichoderma was evaluated at 13 d. The strains T2 and T8 which showed the best characteristics of antagonism were selected for the in vivo bioassay. For the evaluation in vivo, the sterile substrate was inoculated with F. andiyazi and F. sacchari, and the roots of sugarcane plants with strains T2 and T8 of Trichoderma in a design of randomized blocks, with three blocks and three replicates for each treatment. The variables evaluated were plant height (cm), fresh and dry root biomass (g), number and diameter of stems (mm) and root length (cm). The strains T2 and T8 were determined with morphological and molecular identification as T. asperellum and T. koningiopsis. The effect of these species on the sugarcane plants was beneficial, given that they increased plant height, along with length, wet and dry biomass of roots. [ABSTRACT FROM AUTHOR]

Copyright of Agrociencia is the property of Colegio de Postgraduados and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The industrial production of xylitol is carried out with the chemical hydrogenation of D-xylose and it is a costly process. An alternative procedure is the fermentation of lignocellulosic residues with yeasts such as Debaryomyces hansenii (Zopf) Lodder and Kreger-van Rij. Therefore, the objective of this study was to evaluate the extraction of xylitol from sorghum straw, in detoxified and non-detoxified media. White sorghum straw [Sorghum bicolor (L.) Moench.], variety RB-Paloma, was hydrolyzed with H2SO4 at 2, 4 and 6 %; solid liquid ratio 1:6, 1:8 and 1:10; all treatments at 120 °C for 80 min. Those hydrolyzed were neutralized and used to evaluate the production of xylitol; culture media contained 30, 40 or 50 g L-1 xylose were inoculated with D. hansenii and incubated at 30 and 35 °C, 150 and 200 RPM for 96 h. In addition, the data were analyzed with ANDEVA and means tests (p £ 0.05). The maximum concentration of xylitol in the detoxified media was 28.8 g L-1 (40 g xylose, 35 °C, 200 rpm), and in non-detoxified, the maximum found was 29.23 g L-1 (30 g xylose, 35 °C, 150 rpm). The straw evaluated could be used to obtain xylose with a potential use in media for fermentation, and results also suggest that D. hansenii can metabolize xylose in the presence of acetic acid and furfural. [ABSTRACT FROM AUTHOR]

Forest litter emits CO2 into the atmosphere, but there are few studies on the subject and it is important to generate this information to improve inventories of greenhouse gases (GHGs). Methods to quantify this emission are performed in situ during long periods of measurements and others require the use of high cost instruments; some measure the loss of organic matter over time and others are indirect and are based on measurements dependent on weather conditions. The aim of this study was to generate a standardized operation protocol (PEO, its Spanish acronym) to measure the CO2 emission potential of in vitro litter using a manometric respirometer (OxiTop OC110®) in a maximum time of 10 d incubation. Litter samples were collected in a Quercus spp forest in Tequexquinahuac, Estado de Mexico, at the beginning of 2012. The experimental design was completely randomized, treatments were incubations (25 °C) with four litter moisture percentages (20, 40, 60 and 80% dry weight) and four sample sizes (5, 10, 20, 40 g), and each treatment was replicated three times. Based on the data ANOVA was performed and treatment means were compared with the Tukey test (p≤0.05). The response variables were: CO2 emission, CO2 emission rate and percentage of oxidized carbon compared to total carbon at the start of incubation. The optimum conditions for the measurement were 10 g sample and 60% humidity. Under these conditions the maximum CO2 emission was recorded (23554 mg CO2 kg-1) as well as the lowest standard deviation (331 mg CO2 kg-1), the lowest of the 16 treatments resulting from combining sample sizes and moisture percentage. In these conditions the percentage of carbon emitted compared to the initial carbon was the highest (5.26%). The measurement of respiration in such assay depends on the humidity of the sample and the availability of oxygen present in the system, which is the condition for determining the optimal operating environment using the OxiTop OC. The data generated by OxiTop are indicators of the potential emission of CO2 by different types of litter and have a similar value to that of the incubations performed to evaluate the potential mineralization of nitrogen. [ABSTRACT FROM AUTHOR]