MINIRHIZOTRON OBSERVATION OF PIGEONPEA ROOT-SYSTEM AFTER WATERLOGGING

The root growth of pigeonpea plants [Cajanus cajan (L) Millsp.] was st udied with a micro-video camera inserted into a glass tube embedded in the soil, and the effects of soil waterlogging were quantified. Daily changes in root length density (RLD) and the differences in root grow th between waterlogged and control plants were calculated by adopting curve-fitting into the time-course data of RLD. Roots which suffered f rom waterlogging exhibited higher daily changes in RLD during the reco very process than unstressed roots. After waterlogging, an increase in RLD was first observed in the upper soil layers, and then in progress ively deeper layers. This study demonstrates that root growth can be s uccessfully studied by frequent observations of the same soil-plant in terface through glass tubes. Furthermore, the effects of waterlogging can be adequately studied using this technique.