En los últimos años el Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias ha generado tecnología para la producción de semillas. Los objetivos del presente documento es analizar los logros de la investigación científica, determinar áreas de oportunidad y colaborar en la mejora del proceso de multiplicación de semillas. Se concluyó que, con excepción de maíz, en los últimos 30 años la producción de semilla calificada en México descendió. El instituto ha generado para los principales cultivos, tecnología para multiplicar semilla de genotipos mejorados y de especies nativas, en ambos casos, la investigación en manejo postcosecha es marginal. A pesar del vínculo institucional con empresas semilleras de capital nacional, la adopción de sus semillas mejoradas ha sido reducida.
The efficacy of entomopathogenic fungi in the field depends on the influence of various environmental factors, including temperature and level of exposure to UV light. It is hypothesized that temperature and level of UV light exposure of Metarhizium anisopliae (Hypocreales, Clavicipiceae) may affect its efficiency in controlling the sweetpotato weevil (Cylas formicarius, Fabricius; Coleoptera, Brentidae). The objective of this study was to evaluate the influence of temperature and ultraviolet light radiation on the growth and pathogenicity of different native strains of Cuban origin of the M. anisopliae Sorokin complex with biological activity against C. formicarius. Colony diameter was measured at 28, 30, 32 and 34 °C temperature and exposed to ultraviolet light (254 nm) for 10, 15, 20, 30, 30, 60 and 120 minutes. Under laboratory conditions, the percentage germination of conidia of strains LBMa-11, LBM-30, LBM-41 and LBM-146 was determined, as well as their pathogenic capacity by means of bioassays with adults of C. formicarius in terms of the percentage of cumulative mortality and the mean lethal time (TL50). Results proved that temperature and UV light affect the ability of M. anisopliae to control C. formicarius. A delay in cumulative mortality was detected for all strains exposed to UV light, with an increase in TL50. The optimum temperature range was between 28 and 30 °C. The strain LBM-127 showed the highest sensitivity to temperature, LBMa-11 the highest tolerance to UV light, and LBM-146 was the most virulent according to Probit regression analysis.
Eighteen yam (Dioscorea spp.) cultivars from five species were evaluated for yield and severity of mosaic, anthracnose, and black leafspot (Curvularia spp.). Plantings were established at Mayagüez and Isabela, Puerto Rico, in the 1985-86 and 1986-87 growing seasons. Severe mosaic was found on D. trifida (Mina), which was the lowest producing cultivar both seasons. Five cultivars of D. esculenta (Kombi, Seti, Doli, Muni, and Beti) showed moderately severe mosaic symptoms in 1985-86, and black leafspot symptoms in 1986-87. Among these cultivars, Doli produced the highest tuber yields, 21,000 kg/ha (9.4 tons/acre). Among D. alata cultivars, differences in anthracnose were related to genotype, location, and season. Leon Globe and Forastero were the most susceptible and lowest yielding cultivars. Gunung produced the highest yield, a maximum of about 40,000 kg/ha (17.9 tons/acre). It was least affected by anthracnose, with less than 15% defoliation in November. Tuber yields in D. alata cultivars were highly associated with anthracnose severity ratings (r = —0.81 * *) . Both seasons more anthracnose was found in Isabela than in Mayagüez. Anthracnose was more severe in 1986-87 than 1985-86.
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