Effects of plowing on the growth of seminal and nodal roots and on root branching of maize (Zea mays L.) in upland fields converted from paddy fields in Andosol

Abstract

We clarified the effects of plowing on root branching and seminal and nodal root development in maize (Zea mays L.), and identified the factors affecting the shallower root system in soils prepared by plowing tillage (PT). PT affects maize root systems, which are shallower in PT plots than in RT plots, mainly due to the high soil hardness of upland fields converted from paddy fields. The effect of soil hardness by difference of tillage on root systems was greater than the effect of fertilizer distribution. PT suppressed seminal root length density (RLD) at the 2^nd leaf, 3^rd leaf and milk stages, but promoted RLD of nodal roots after the 6^th leaf stages and branching of nodal roots at the 6^th leaf and tassel formation stages, as well as primary root elongation of nodal roots at the milk stage. After the 6^th leaf stage, RLD of seminal roots decreased, but RLD of nodal roots increased and PT promotes RLD of nodal roots. The results suggest that the shallower root system associated with PT is due to affecting nodal roots.