Regulation of root development in sweetpotato and cassava by soil moisture during their establishment period

In order to affect a better management for sweetpotato and cassava, especially during their establishment period, a series of experiments were conducted to determine possible regulation of root development of sweetpotato and cassava as a function of (i) moisture regime in the soil and variety, and, (ii) shifting soil moisture. In both sweetpotato and cassava, the production (formation) and growth (elongation) of the adventitious roots and their contemporaneous lateral roots were greatly affected by soil moisture, a deficiency of which generally suppressed their formation and subsequent growth. Genotype variation likewise influenced the individual root system development but this was more apparent in sweetpotato than in cassava. Fluctuation in the amount of water in the soil brought about variable development in the individual component roots in a root system of both sweetpotato and cassava, with deficient moisture as the most depressive, even though the plants had been exposed previously to well watered (normal) condition. In both crops, the individual root system componentsʹ growth under deficient soil moisture were in all instances improved when exposed afterwards to normal soil moisture.