WATER TRANSFER DIMINISHES ROOT COMPETITION BETWEEN PEACH AND TALL FESCUE

Seedling 'Tennessee Natural' peach [Prunus persica (L.) Batsch] trees were grown in a series of five greenhouse experiments to determine how peach root development was affected by the interaction of soil pressu re potential and the presence of Kentucky-31 (K-31) tall fescue (Festu ca arundinaceae Schreb.). Peach trees were grown in split-root rhizotr ons that had four separate root growth sections. When two of the four sections had live sod (LS) and two remained bare soil (BS), there was no effect of the LS on peach root development when the trees were irri gated daily. Peach root development was reduced in BS and LS treatment s when soil pressure potential was less than -0.06 MPa. In contrast, w hen trees were grown in rhizotrons that had all four sections with eit her LS or a killed K-31 sod (KS), peach root development was reduced i n the LS treatment compared to the KS treatments when irrigated daily or when soil pressure potential reached -0.03 MPa. The apparent root s urface water potential of peach trees in the LS treatment was -0.4 MPa lower than that in the KS treatment under daily irrigation due to the interference of the K-31 tall fescue. In two additional experiments u sing peach trees with BS in all four sections, we maintained three sec tions at field capacity and allowed one section to dry to -0.06 to 1.5 MPa. During the night, when transpiration was low, water was transfer red to the dry soil section via the peach root system from the three w et soil sections. It appears that the root system of peach can maintai n root development in the presence of tall fescue by transferring wate r from regions of high water availability to those of low availability .