Submitted to: Plant Growth Regulation Society of America Quarterly
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/22/2003
Publication Date: 2/9/2004
Citation: TWORKOSKI, T., DAW, T., GLENN, D.M. "EFFECTS OF A ROOT BARRIER AND LOCALIZED FERTILIZER APPLICATION ON ROOT GROWTH OF YOUNG PEACH (PRUNUS PERSICA)TREES.". PLANT GROWTH REGULATOR SOCIETY OF AMERICA QUARTERLY. 2004. 31:133-142 Interpretive Summary: Peach tree size must be kept small so that protective sprays can be effectively applied and not interfere with fruit harvest. Peach trees are kept small by pruning, but pruning is costly and injures trees. Confining the root system of peach trees has been proposed as an alternative to pruning to manage the size of peach tree shoots. In this experiment, one- year-old peach seedlings were planted in pots with a unique"y-shaped" configuration that enabled us to test the effects of root restriction on one part of the root system, on root growth in a distant, untreated part of the root system, and on shoot growth. Root confinement with fabric caused more roots to grow near the fabric and when fertilizer was applied in the vicinity of these roots both root density and root weight increased more than if no fabric was present. Root growth commenced about 1 week after fertilizer treatment but shoot growth began about 3 weeks after fertilizer treatment. This difference in time may be associated with root demands fo mineral nutrients taking precedence over shoot demands. Fabric caused a slight inhibition of shoot growth compared to untreated controls, but when fertilizer was applied to fabric-treated plants shoot growth was significantly greater than untreated plants or plants treated with fertilizer but without fabric. This range of growth response indicates that growth of peach trees planted in fabric-restricted soil can be managed with fertilizer applications better than trees planted without fabric restriction.
Technical Abstract: The response of two-year-old peach trees (Prunus persica (L.) Batsch 'Sentry' on 'Lovell' rootstock) to localized fertilizer application and restriction of half the root system was measured in greenhouse studies. Root containers had a split root design so that half the peach roots were not treated and the other half received one of four treatments at one location, 43 cm from the root collar: 1) root volume restricted with polypropylene nonwoven fabric (FAB); 2) fertilizer alone (FER, 8 N-5.2 P- 26.6 K); 3) FAB+FER; and 4) untreated control (UTC). In FER and FAB+FER, fertilizer was applied once each week until 16 weeks after planting (WAP) and then all treatments were fertilized daily from 17 to 19 WAP at the same root location. At final harvest, 24 WAP, FER increased root weight and length (116 and 57 percent, respectively, compared to UTC) on the treated half. Greatest root growth occurred in the root half that received FAB+FER, particularly in the soil within 5 cm of the fabric (4.6 cm.cm-3 compared to 0.8 cm.cm-3 in UTC). Compared to UTC, FAB did not reduce total root weight or length, even though roots did not grow past the fabric barrier. Specific root length (root length per gram dry weight) tended to be highest in UTC, indicating that both fertilizer and root restriction modified root morphology. Shoot length was least in FAB and, in general, shoot length increased most in FAB+FER following daily fertilization. Manipulation of roots with physical barriers and selective application of fertilizers may be useful to manage growth of peach trees.