Most commercial papaya varieties segregate hermaphrodite and female plants. Growers normally select hermaphrodite plants in the field, due to market preferences. This requires planting multiple plants per site and later thinning of the females, distinguished by flower bud inspection. Micropropagation or the use of molecular markers are two possibilities to grow only hermaphrodite plants. Under the tropical conditions of this study, the field performance of hermaphrodite papaya plants developed by both of these methods was described. Moreover, a multiplex qPCR reaction was optimized. Hermaphrodite seedlings selected by molecular markers and plants obtained by micropropagation, had a lower slenderness ratio and initiated fruit production at a lower height than those selected by the conventional practice of the orchard. An analysis of flower types between the sex determination methods indicated that growing one hermaphrodite papaya plant per hole reduces the percentage of female-sterile flowers, resulting in fruit set at a lower trunk height and higher yields.
Abstract. Ascochyta lentis was isolated from necrotic lesions on lentil seed purchased in commercial markets throughout Bolivia in 2000. Incidence of seed infection ranged from 1% to 34% and the fungi isolated were able to reinfect lentil foliage in artificial inoculations. Disease spread from seed to seedling in the field was confirmed by planting infected seed in a field previously free of the disease and observing Ascochyta blight on the foliage. In addition, disease spread between plants initiated from infected seedlots to those initiated from clean seedlots and from infected plants back to seed was also detected. These observations indicate that A. lentis infection of lentil seed is common in Bolivia and may represent an important inoculum source for Ascochyta blight epidemics in commercial lentil plantings.Lentil (Lens culinaris) is a minor crop that has been grown in Bolivia for several hundred years. Lentils are imported from several countries including Argentina, Canada, Chile and the United States, as local production does not meet consumer demand for quantity and quality. In a sample of lentil seeds purchased in the central market in Sucre, Bolivia in May 2000, some seeds were discolored with necrotic lesions. Isolations were made from the discolored seeds on potato dextrose agar and 2% water agar (WA). A pycnidial fungus was consistently isolated from the discoloured seeds, which was identified as Ascochyta lentis (teleomorph: Didymella lentis). Ascochyta blight of lentil in South America has previously been reported from Argentina and Chile (Bascur 1993). A larger sample of lentil seeds was obtained from markets in Aiquile, Cochabamba, Comarapa, La Paz, Monteagudo, Oruro, Padilla, Potosi, Santa Cruz, Sucre, Tarija and Tupiza. Vendors indicated that most seeds were imported from the four countries mentioned above. One hundred seeds from each market in each location were surface sterilised in 0.25% NaOCl for 5 min, plated on WA (20 seeds per 9 cm Petri dish), and incubated at room temperature. Ascochyta lentis was isolated from seeds of all samples, with seed infection rates varying from 1% to 34%. Koch's postulates were fulfilled by inoculating foliage of 20-day-old seedlings of lentil cv. Pardina with spore suspensions (1 × 10 6 conidia/mL) of three isolates of the pathogen from Potosi, Sucre and Tarija. Inoculated plants and controls (plants inoculated with sterile water only) were incubated in a moist chamber for 5 days at ambient temperatures and natural daylight. The fungus was reisolated from necrotic lesions on the leaflets, petioles and stems of all inoculated seedlings but not from control plants. The fungus was identified as A. lentis based on symptoms, cultural and morphological
En Costa Rica, como una alternativa al uso de hidrocarburos, se ha venido buscando el empleo de cultivos bionergéticos de los cuales se pueda hacer un mayor aprovechamiento de la biomasa producida y la obtención de aceite. Durante los últimos ocho años, un grupo de interdisciplinario de investigadores de las universidades estatales de Costa Rica, han venido realizando estudios sistemáticos sobre el cultivo de Jatropha curcas (Tempate) para su uso comercial como fuente de aceite para producir biodiesel y a la vez en el 2017 inició el trabajo con otras especies con potencial bioenergético en el país como higuerilla (Ricinus comunis) y coyol (Acrocomia aculeata), entre otras. La investigación que se llevó a cabo, cubre tres objetivos donde el primero tiene que ver con el establecimiento de cultivos de estas especies en diferentes zonas bioclimáticas del país, así como ensayos sistemáticos alternativos con (tempate, higuerilla y coyol), combinándolos con plantas que se utilizan para alimento humano y animal. El segundo objetivo está relacionado con ofrecer a largo plazo variedades más productivas y menos tóxicas del tempate (Jatropha curcas). Y el último objetivo tiene que ver con el proceso de transferencia de información y resultados obtenidos. La información obtenida permitirá ofrecer opciones a los agricultores que les ayude a minimizar el impacto del cambio climático en su actividad y contribuir a las metas que Costa Rica se ha propuesto para reducir la emisión de contaminantes al ambiente y mejorar la calidad de vida de la población costarricense.
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