ABSTRACT
Aims: To study storage rots in yam varieties cultivated in South East Nigeria and to determine under conditions of experimental storage, the influence of fungal rot on their post harvest storage losses. Place and Duration of Study: Laboratories, Department of Applied Microbiology & Brewing, Nnamdi Azikiwe University, Awka, Nigeria between January 2012 and July 2013. Methodology: Five yam varieties; Dioscorea dumentorum, two varieties each of D. alata and D. rotundata, obtained immediately after harvest were stored in an experimental barn (30ºC and 95% RH) and examined at intervals for storage rots. Fungal causative agents of rots were isolated and identified using the partial ITS rDNA sequencing analysis and a BLAST search using the GenBank sequence database. Post harvest storage losses in terms of weight loss and reduction of shelf life among the varieties were determined. Results: All varieties of yams studied suffered fungal rots, predominantly, dry rots during storage. Seven distinct fungal isolates, which caused these rots, were fully characterized. The species were Aspergillus tamari, Fusarium solani, Lasiodiplodia theobromae, Aspergillus niger, Mucor circinelloides, Aspergillus flavus and Aspergillus sp. In all the yams, storage rots reduced shelf life and aggravated weight loss. Post harvest storage losses varied among the different varieties of yams. Conclusion: The varieties of yams studied suffer rots from various fungi, which are similar to those reported in other parts of the world. Severity of post harvest losses resulting from fungal rots varies among different varieties of yams. This should be taken into consideration in the development of storage techniques.
Subject(s)
Databases, Nucleic Acid , Dioscorea/classification , Dioscorea/metabolism , Dioscorea/microbiology , Food Contamination/prevention & control , Food Microbiology , Food Preservation/methods , Food Storage , Fungi , Nigeria , Plant Diseases/etiology , Sequence Analysis, DNAABSTRACT
La propagación de material de ñame de buena calidad es esencial para incrementar la producción sostenible de este cultivo. El presente trabajo tuvo como propósito optimizar el medio de cultivo de micropropagación de Dioscorea alata L. clon Caraqueño a través de los siguientes objetivos: determinar el efecto de diferentes antioxidantes (carbón activado 0,5 g/L-1 ; carbón activado 1,0 g/L-1; cisteína 10 mg/L-1, 20 mg/L-1 y 30 mg/L-1) y concentraciones de sales de Murashige y Skoog (MS) (25, 50, 75 y 100 %) en el medio de cultivo durante el establecimiento y la multiplicación de las plantas in vitro, y evaluar la utilización de distintas combinaciones de ácido naftalenacético (0,01; 0,1 mg/L-1) y bencilaminopurina (0,01; 0,1 mg/L-1) en el mejor medio de cultivo de multiplicación obtenido en el experimento anterior. A los 35 días se seleccionaron 40 plantas in vitro, a las cuales se les determinaron las siguientes variables: longitud en cm del vástago; número de nudos de novo por explantes; número de hojas por explante y porcentaje de fenolización. Se evaluó además, en el experimento con los reguladores de crecimiento, el número de raíces y longitud de la raíz de mayor tamaño. Se aplicó un diseño experimental completamente aleatorio con análisis de varianza bifactorial y clasificación simple. Se realizó la prueba de comparación de medias de Tukey para un nivel de significación del 5%. Los resultados obtenidos mostraron que las sales MS al 75% de su concentración, el carbón activado (0,5 g/L-1) o la cisteína (10 mg/L-1), en combinación con los reguladores de crecimiento ANA/BAP (0,01/0,01 mg/L-1) en el medio de cultivo MS, incrementaron los indicadores de desarrollo de las plantas in vitro tales como número de nudos de novo (3,5), longitud del vástago (4,1 cm), número de hojas (3,8), número de raíces (5,7) y longitud de las raíces (6 cm).
The material propagation of good quality yam is essential to increase the sustainable production of this cultivation. In the present work the optimization of culture medium of Dioscorea alata L. clone Caraqueño micropropagation was carried out through the following objectives: to determine the effect of different anti-oxydants (activated charcoal 0,5 g.L-1; activated charcoal 1,0 g.L-1; cysteine 10 mg.L-1, 20 mg.L-1 and 30 mg.L-1) and Murashige and Skoog salts concentrations (25, 50, 75 and 100%) in the culture medium during the in vitro plants establishment and the multiplication, and to evaluate the use of different combinations of naftalenacetic acid (0,01; 0,1 mg.L-1) and benzylaminopurine (0,01; 0,1 mg.L-1) in the best multiplication medium obtained in the above experiment. At 35 days, 40 in vitro plants were selected. The following variables were determined in these plants: shoot length, cm; leaf and bud explant number; and oxydation phenolic percentage. In the experiment of plant growth regulators was also evaluated, the roots number and greater size root length. A totally randomized experimental design with one and two factor variance analysis and the Tukey test for means comparison at 5% significance level were applied. The obtained results showed that the salts MS at 75% concentration, the activated charcoal (0,5 g. L-1) or the cysteine (10 mg. L-1), in combination with the growth regulators ANA/BAP (0,01/0,01 mg.L-1) in the MS culture medium, increase the development of the in vitro plants, number of novo buds (3,5), shoot length (4,1 cm), number of leaves (3,8), number of roots (5,7) and greater size root length (6 cm).
Subject(s)
Dioscorea/immunology , Dioscorea/microbiology , Dioscorea/chemistry , Cysteine/economics , Cysteine/adverse effects , Cysteine/pharmacologyABSTRACT
El cultivo in vitro, como técnica, consiste en cultivar asépticamente una porción aislada de la planta bajo condiciones de ambiente controlado, para que las células expresen su potencial intrínseco e inducido. El presente trabajo tuvo como objetivo determinar el efecto de diferentes concentraciones y tiempos de inmersión en hipoclorito de sodio en el establecimiento in vitro de explantes primarios de ñame (Dioscorea alata L) clon caraqueño. Las variantes de desinfección consistieron en la utilización de diferentes concentraciones de hipoclorito de sodio (1,5; 2 y 2,5%) durante distintos tiempos de inmersión (10; 20 y 30 min). A los 7 días se evaluó el porcentaje de contaminación de bacterias y hongos respectivamente, y a los 40 días el número de nudos de novo, la longitud del vástago, el número de hojas, y el porcentaje de explantes establecidos y necrosados. Se aplicó un diseño experimental completamente aleatorizado con análisis de varianza bifactorial y clasificación simple. Se realizó la prueba de comparación de medias de Tukey para un nivel de significación del 5%. Los resultados obtenidos arrojaron que el tratamiento de desinfección de segmentos uninodales de ñame con hipoclorito de sodio al 1,5% durante un tiempo de inmersión 30 min es el de mayor efectividad para el establecimiento in vitro de explantes primarios del ñame (D alata L. clon caraqueño con altos porcentajes de supervivencia en condiciones ex vitro.
The in vitro culture technique consists of aseptically culturing an isolated plant portion in controlled environmental conditions for the cells to express their intrinsic and induced potential. This work was aimed at determining the effect of different sodium hypochlorite concentrations and immersion times on in vitro establishment of yam (Dioscorea alata L) caraqueño clone primary explants. Disinfection varied by using different sodium hypochlorite concentrations (1.5%, 2% and 2.5%) during different immersion times (10, 20 and 30 min). Bacterial and fungal contamination percentages were evaluated after 7 days and de novo bud number, shoot length, leaf number, explant establishment and necrosis percentages were determined after 40 days. A totally randomised experimental design was applied, having one- and two-factor variance analysis; the Tukey test was used for comparing means at 5% significance level. The results showed that the most appropriate disinfection treatment for uninodal yam (D alata L) segments used 1.5% sodium hypochlorite during 30 min immersion; this was most effective for the in vitro establishment of yam (D alata L) clone caraqueño primary explants, having high survival percentage in ex vitro conditions.