PARENT SESSION
Poster Session # 10: Soil Ecology.

Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Fine root dynamics of peach (Prunus persica) under two irrigation regimes.

Wells, Christina^*,1, Layne, Desmond¹, ¹ Department of Horticulture, Clemson, SC, 29634

ABSTRACT- The use of minirhizotrons (root observation tubes) has generated information on fine root dynamics in many plant species and ecosystems. However, the extent to which specific environmental variables affect rates of root production, aging and mortality is still poorly understood. We installed 72 minirhizotron tubes beneath 4-yr-old trees in a peach production systems trial to determine how root morphology, architecture and demography differed in trees with and without supplemental irrigation. 'Red Globe' peach trees were grown on one of two rootstocks (Lovell or Guardian™) and received one of two irrigation regimes (rainfall only or 1 inch of supplemental irrigation per week). Beginning in May 2002, videotaped images from each minirhizotron tube were collected at two week intervals; notes on tree phenology were also recorded on these dates. Videotapes were digitized in the lab, and information on root length, diameter and appearance was extracted from the images. Soil temperature, soil volumetric water content and pan evaporation were also measured in the orchard throughout the growing season. Initial data indicate that non-irrigated trees produced thinner fine roots (P < 0.05) that were more highly branched (P < 0.05) than those of irrigated trees. Non-irrigated trees also allocated more of their fine root length to deeper soil layers (P < 0.08). There were significant differences in root length production between rootstocks, with the nematode-tolerant rootstock, Guardian™, producing more length per tube under both irrigation regimes (P < 0.01). Analysis of fine root demography will begin in 2003, one year after the disturbance of minirhizotron installation. Previous research in peach has shown that thinner roots and roots of lower branching order have shorter life spans than thicker, higher-order roots. Whether the thinner, highly-branched root system of non-irrigated trees experiences higher rates of root turnover is a question we will address in the coming year.

Key words: minirhizotron, root demography