Examinando por Materia "Viability"

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Massive production of Hemileia vastatrix uredospores for infection of Coffea arabica seedlings
(Universidad Nacional de Trujillo, 2023-07-10) Hernández Amasifuen, Angel David; Rivadeneyra Chisquipama, Lenin; Padilla Dominguez, Amner; Paredes Espinosa, Richard; Guerrero Abad, Juan Carlos; Torres Flores, Elías; Peláez Rivera, Jorge Luis; Carvajal Vallejos, Fernando Marcelo; Gutiérrez Reynoso, Dina Lida; Corazon Guivin, Mike Anderson
Coffee leaf rust (Hemileia vastatrix) is the most important disease in coffee crops around the world. Currently, there is limited knowledge about mass production methodologies and ex-situ infection of H. vastatrix that lead to the development of different health characterization studies of Coffea or disease phenotyping. In this context, the aim of this research was to develop a simple protocol for the mass production of coffee rust uredospores under controlled conditions and to determine their infection in coffee seedlings. Uredospores of H. vastatrix were collected from infected plants in the “Chontal” coffee-growing area in San Martín, Peru. The viability of uredospore germination was evaluated, and a uredospores suspension (2 x 105 uredospores/mL) was prepared to inoculate coffee seedlings. Incidence and sporulation rates were evaluated after 43 days of inoculation. During the multiplication process of H. vastatrix uredospores, using controlled conditions (23±1 °C, ≈ 80% relative humidity and photoperiod of 16 hours of light) under an innovative system, the first symptoms of chlorosis were observed on coffee leaves 20 days after inoculation. Our findings show a 100% incidence of inoculated coffee plants with an average of 54 mg of H. vastatrix uredospores per plant and a 1.38 x 10-1 mg/cm2 sporulation rate. Finally, here we report a protocol that allows mass multiplication of H. vastatrix uredospores under controlled conditions, that would be useful in any time for coffee leaf rust bioassays.
Performance and physiological quality of Escallonia resinosa seeds: prospects for their use in reforestation and restoration
(John Wiley and Sons Inc, 2022-12-10) Huayta Hinojosa, Luis David; Nolasco Lozano, Emily Gisella Ninfa; Guerra, Damaris; Hermoza Gamboa, Joel; Quispe Melgar, Harold Rusbelth
In the Andes, many native forest species are not used in reforestation or restoration programs mainly due to a lack of information about their propagation. In this study, we evaluated the performance of the seeds of Escallonia resinosa by analyzing fruit and seed productivity and characteristics, seed physiological quality, and the germination rate of seeds collected at different stages of fruit physiological maturity, using tetrazolium and standard germination tests. Our results show an estimated production (mean ± SD) of 34,252.5 ± 25,900 fruits per tree and 26.5 ± 20 million seeds per tree. Seed length was 1.0 ± 0.13 mm and seed weight was 12.4 ± 1 μg. We recognized two different morphological types of seeds: Type I seeds (lacking testa) were unviable, whereas all Type II seeds (with testa) germinated. Seed viability and germination rates were 10.5 and 48.6%, respectively; therefore, the viability test underestimated the actual germination rate. Morphological or microsite variables of the parent tree did not influence seed viability or germination. Germination rates were highest (41.8 ± 2.5%) for the seeds of fruits harvested at the initial maturity stage (green fruits). Our results show that E. resinosa is a species with potential for reforestation and restoration projects in the Andes: it has high seed production and good germination performance, and seeds can be harvested from fruits collected at different stages of physiological maturity.