Relationship between characteristics and germination ability of cuttings in cassava (Manihot esculenta Crantz)

En Rayong Field Crop Research Center, Tailandia, se examinaron la relacion entre las diferentes caracteristicas de estacas de yuca, tomadas de las partes superior, media e inferior de tallos de las plantas madres a diferentes edades (7, 10 y 14 meses), y la capacidad germinativa de las estacas sembradas. Se usaron 2 var. de diferente tipo de planta (Rayong 1, erecto, y Rayong 3, ramificado) durante la estacion seca y la lluviosa. Las caracteristicas medidas fueron peso fresco y seco, vol., densidad de vol. (peso fresco/vol.), tasa respiratoria y contenido de agua. La capacidad germinativa, expresada en la tasa de supervivencia de las estacas, se correlaciono positivamente con densidad de vol., vol. y peso fresco. La tasa respiratoria mostro una correlacion negativa, y el contenido de agua ninguna correlacion. Un analisis de regresion multiple indico que los principales factores que determinan la tasa de supervivencia en la estacion seca fueron densidad de vol., peso fresco y vol. de las estacas y densidad de vol. en la estacion lluviosa. La densidad de vol. fue el principal factor determinante de la capacidad germinativa en ambas estaciones. Se recomienda que los materiales de siembra de yuca se tomen de las partes media e inferior de los tallos que muestren una densidad de vol. superior a los 0.8 g/centimetro cubico, lo que corresponde a una tasa de supervivencia de aprox. 80 por ciento en ambas estaciones. (RA- CIAT)

The relationship between different characteristics of cassava cuttings, taken from upper, middle, and lower parts of stems of the mother plants at different ages (7, 10, and 14 mo.) and the germination ability of the cuttings planted were examined at the Rayong Field Crop Research Center in Thailand. Two var. of different plant type (Rayong 1, erect, and Rayong 3, branching) were used both in dry and rainy seasons. The characteristics measured were fresh and dry wt., vol., vol. density (fresh wt./vol.), respiratory rate, and water content. The germination ability as expressed by the survival rate of the cuttings was positively correlated with vol. density, vol., and fresh wt. The respiratory rate showed a negative correlation, and the water content no correlation. A multiple regression analysis showed that the main factors determining the survival rate were vol. density, fresh wt., and vol. of cuttings in the dry season and vol. density in the rainy season. Thus, vol. density was the main determinant of germination ability in both seasons. It is recommended that cassava planting materials be taken from the middle and lower parts of the stems showing a vol. density of more than 0.8 g/cubic centimeter, which corresponds to a survival rate of approx. 80 percent in both seasons. (AS)