(310) Peach Orchard Systems Management Trial: The First Six Years

Abstract

In 1999, a trial was established at the Clemson University Musser Fruit Research Farm to investigate the effects of training system/tree density, rootstock, and irrigation/fertilization on tree growth, productivity and profitability. The replicated trial comprised three training systems/tree densities (open center–332 trees/ha; quad V–664 trees/ha; and perpendicular V–996 trees/ha). The two rootstocks used were Lovell and Guardian. Three irrigation/fertilization treatments included: natural rainfall only plus granular program; supplemental irrigation plus granular; and supplemental irrigation plus fertigation at a reduced nitrogen rate from the granular program. The scion was the popular midseason cultivar Redglobe. There were a total of 18 treatment combinations replicated 4 times with 5 trees per treatment plot. Soil moisture was determined by TDR and pan evaporation monitored by weather station. Seventy-two minirhizotron tubes were installed in 2002 to monitor fine root growth. During 1999–2001, drought conditions limited rainfall to 35% below the annual average. Spring freeze events in 2001 and 2004 reduced crop load disproportionately in shorter, open-center trees. As tree density within the tree row increased, trunk cross sectional area (TCA) decreased. Trees on Guardian rootstock had significantly greater TCA than Lovell each year. Trees that received supplemental irrigation had greater TCA than nonirrigated trees each year. By reducing N rate through fertigation, TCA was reduced. Cumulative yield was not affected by training system/tree density. Cumulative yield was not affected by rootstock. Cumulative yield was 7% greater by supplemental irrigation. Pruning, thinning and harvesting was easier in V-systems than for open center trees.