Abstract

S6-11

Electric Capacitance: A Potential Method for Estimating Root Yield

González J.E., H. Ceballos, J.C. Pérez, and F. Calle.

Cassava is a perennial crop, it has no physiological maturity and plants fail to exhibit signs when they are ready for harvest.  Cassava can be harvested any time from few months after being planted, generally harvests are at 9-10 months after planting.  Early bulking is a highly desirable traits for improvement in this crop.  However, since the plant does not exhibit any particular above-ground sign, it is impossible to detect early bulking genotypes without harvesting the plants.  A method to monitor the status of the root system is, therefore, highly desirable.  A hand-held capacitance meter was evaluated for its potential to quantify root mass and, therefore, root yield.  A group of clones showing variation in yield potential, 0.0 to 104 t/ha of fresh roots, was evaluated.  In one experiment, capacitance and root yield were measured individually on four plants from each of 75 clones. In the second experiment, average yield and capacitance, also based on four plants, from 364 clones were measured.  Results indicated that capacitance is positively correlated with root yield. The correlation coefficients improved considerably when dry matter content was taken into account, suggesting that the root mass-capacitance relationship is affected by the water content in the roots.