Effects of fungicides and bactericides and germicidal time on the growth of residual root of Pachira macrocarpa

【Objective】To screen the best fungicide and the best germicidal time of Pachira macrocarpa.【Method】 The effects of different fungicides and bactericides with different germicidal times on the residual root of reclaimed P. macrocarpa were investigated through pot experiments with peat soil. Five fungicides and bactericides （carbendazim, metalaxyl mancozeb, agricultural streptomycin, thiophanate methyl and potassium permanganate） were selected to study their effects on the shoot length，leaf mass，root length，root numbers，root mass，and root activities of the residual root of the reclaimed P. macrocarpa. The concentration of carbendazim, metalaxyl mancozeb, agricultural streptomycin, and thiophanate methyl was 1.25 g·L^-1 while potassium permanganate was 2.0 g·L^-1.【Result and conclusion】 The results showed that the best fungicide and bactericide was carbendazim, followed by thiophanate methyl， with the third being metalaxyl mancozeb and potassium permanganate and the least effective fungicide and bactericide being agricultural streptomycin. The preferred germicidal time was 0.5 and 1.0 h. The growth of the residual root of P. macrocarpa was significantly inhibited when it was disinfected over time（12 h）.