In vitro growth of sweet potato fed with potassium phosphite

the main objective of this work was to verify the effect of the substitution of phosphate by its related compound phosphite on the in vitro growth of sweet potato nodal segments. segments from a previous culture were incubated in ms media with the following combinations of phosphate:phosphite: control (100 / 0%); t1 (87.5 / 12.5%); t2 (75 / 25%); t3 (50 / 50%) and t4 (0 / 100%) in a 5 x 5 factorial arrangement, with five treatments (control, t1, t2, t3 and t4) and five evaluation periods (7, 14, 21, 28 and 35 days). the design was completely random, with three replicates of two explants per period. the evaluations were made weekly by counting the number of shoots and the length and dry weight of shoots and roots. increasing the phosphite concentration decreased all attributes measured, including growth velocity, length and dry weight. these results indicate that phosphite cannot be used as substituted of phosphate in sweet potato tissue cultures.