Nursery Production Method Affects Root Growth
Edward F. Gilman and Richard C. Beeson, Jr.
Environmental Horticulture Department
University of Florida, Gainesville, FL 32611

Abstract. This study compared growth and biomass distribution on two commonly grown trees produced in plastic containers with those in fabric containers and in the field. Shoot:root ratio on field-grown and fabric container-grown laurel oak (Quercus laurifolia Michx.) was higher than on holly Ilex x attenuata Ashe. 'East Palatka'). Ratios were similar for trees grown in plastic containers. Compared to oaks, a larger portion of holly root balls was comprised of small diameter roots. Root spread of field-grown laurel oak was similar to those produced in fabric containers. Trees of both species growing in plastic containers had several times more fine root mass (roots 2 mm or less diameter) within the root ball than those dug from the field or fabric containers. Total root ball root weight in plastic containers was less than in field- and fabric container grown trees. Root weight inside the root balls for field-grown and fabric container-grown tree was similar but field-grown root balls were twice the volume. Only 17% (field) and 26% (fabric containers) of holly root weight within the root ball was from roots 10 mm or less in diameter. However, 48% percent of root weight on trees grown in plastic containers was in this diameter class. Between 68 and 84%, depending on species and production method, of total-tree root weight was inside the root ball. Between 10% and 18.1%, depending on species and production method, of roots 2 mm or less in diameter was inside the root ball.

Edward F. Gilman and Richard C. Beeson, Jr.
Environmental Horticulture Department
University of Florida, Gainesville, FL 32611

Abstract. Trunk growth rates one year after transplanting 5 cm (2 in) caliper laurel oak (Quercus laurifolia Michx.) from above-ground plastic containers, from in-ground fabric containers or from the field (B&B) matched or exceeded growth rates before transplanting. Growth rates for all three treatments were similar seven months after transplanting. Shoots on field-grown trees grew more in the first year after transplanting than those from fabric or plastic containers. Roots removed at the time of digging were completely replaced on field and fabric container trees six months after transplanting. One year after transplanting, roots occupied the same soil volume as just
prior to transplanting. Trees from plastic containers regenerated roots slower than B&B trees or those from fabric containers. When irrigation frequency was reduced 14 weeks after transplanting (WAT), trees from plastic containers were water stressed more (had more negative xylem potential) than B&B or fabric container trees. Growth rates of East Palatka holly (Ilex x attenuata Ashe. `East Palatka') responded similarly to laurel oak; however hollies took longer to establish roots into landscape soil and took longer for the trunk growth rate to match that on trees prior to transplanting.

Fertilizer, Irrigation And Root Ball Slicing Affects Burford Holly Growth After Planting
Edward F. Gilman, Thomas H. Yeager, and Diane Weigle
Environmental Horticulture Department
University of Florida, Gainesville, FL 32611

Abstract. Dwarf burford holly (Ilex cornuta `Burfordii Nana') fertilized with 22.1g N/container/yr of nitrogen during production in the nursery generated more new shoot weight but less root weight after transplanting to a landscape than those receiving 14.8g N/container/yr. Slicing the root ball at planting, compared to not slicing, resulted in comparable regenerated root weight but reduced new shoot number, new shoot dry weight and new shoot:regenerated root dry weight ratio when irrigation was not applied daily after transplanting. Although irrigation frequency did not impact total weight of regenerated roots into landscape soil, more roots grew from the bottom half of the root ball when plants were irrigated periodically after planting than when plants received daily irrigation. Plants irrigated other than daily produced fewer shoots and less shoot weight than those receiving irrigation daily after transplanting. When plants were without irrigation for 4 or 6 days in the first week after transplanting, those planted without the nursery container on the root ball were more stressed (more negative xylem potential) than those planted with the container still on the root ball. However, two weeks later, plants without the nursery container were less stressed due to root growth into landscape soil.

 

Micro-Irrigation Affects Growth And Root Distribution Of Trees In Fabric Containers
Edward F. Gilman, Gary W. Knox, Catherine A. Neal, and Uday Yadav

Abstract. Lagerstroemia x 'Natchez' ('Natchez' crape myrtle) crown width increased after 13 months as irrigation frequency increased from every 3 days to every day, and irrigated area around the fabric container increased from 20% to 100% beyond the container. Restricting irrigation to within the fabric container plus 20% of the area 20 cm beyond the container edge resulted in reduced height and width for crape myrtle, but not root growth, compared to irrigating 100% of area 20cm beyond the container. Restricting the pattern of irrigation to the container plus 20% of the area 20 cm beyond the container resulted in increased fine root weight (roots less than 5 mm diameter) within the container for laurel oak (Quercus laurifolia) compared to irrigating the container plus 100% of the area 20 cm beyond the container. Height, width and caliper of oak were not different among treatments.

Effects of Nursery Container Type on Root Growth and Landscape Establishment of Acer Rubrum L.
Journal of Environmental Horticulture (16)(1):55-59
Marshall, M. D.; Gilman, E. F., 1998.

Abstract.  Trees of red maple (Acer rubrum L.) were planted into seven container types evaluated for their ability to reduce number of roots deflected by the container wall.  Seedlings were grown 70 weeks (production phase) in seven container types to a mean trunk diameter of 3.9cm (1.5 in) and were transplanted into a sandy soil and grown with frequent or periodic irrigation for 24 weeks (landscape phase).  There was no effect of container type on total root mass, trunk diameter or height during the production phase.  Total deflected root length was less in low-profile plastic containers, chemical root pruning containers, air root pruning containers (ARPC), and wood boxes than in standard black plastic containers (SBPC).  Trees produced in the SBPC had the most horizontally-oriented deflected root length while the ARPC and the SBPC had the most vertically-oriented deflected root length.  Trees grown in the ARPC had less roots on the inside of the root ball than all other container types.  Container type did not influence root and shoot growth, but impacted stem water potential in the first five months after transplanting to the landscape.  Trees frequently irrigated during the landscape phase had greater trunk diameter, height, and generated more new root mass than those which were infrequently irrigated.

Production Method and Irrigation Affect Root Morphology of Live Oak
Journal of Environmental Horticulture (15)(2): 84-87
Marshall, M. D.; Gilman, E. F., 1997.

Trees of live oak (Quercus viriginiana Mill.) were container-grown (CG) or field-grown (FG) to a mean trunk diameter of 9.4 cm (3.7 in), transplanted into sandy soil, and established with frequent or periodic irrigation.  Three years after transplanting, trees were harvested with a 1.5 m (60in) diameter tree spade.  Root number and root cross-sectional area was evaluated for all roots at the periphery of the tree-spade-dug root ball.  Despite similar increases in trunk diameter, FG trees had greater root number and root cross-sectional area than CG trees.  The greater root cross-sectional area occurred in roots 5-20 mm (0.2-0.8 in) in diameter at soil depths of 0-25 cm (0-9.8 in) and 75-100 cm (29.5-39.3 in).  Irrigation frequency after transplanting had no effect on root number in FG trees.  However, root number in CG trees was lower without frequent irrigation.

Copper Hydroxide Affects Root Distribution of Ilex cassine in Plastic Containers
Hort Technology (5)(1): 48-49
Gilman, E. F.; Beeson, R. J., 1995.

 The root: shoot ratio for Ilex cassine L. grown 7 months in copper-treated containers was less than in nontreated containers.  There was less dry weight for roots <5mm in diameter in copper-treated containers than in nontreated containers in the outer 1 cm of the rootball.  Dry weight of roots >5 mm in diameter within the rootball were not affected by copper hydroxide treatment.  Coating the interior of a plastic container with cupric hydroxide eliminated coarse roots (>5 mm in diameter) and significantly reduced fine root weight from the outer 1 cm of the rootball.  Fine roots inside the rootball did not replace fine roots lacking in the outer 1 cm.

Production Method Affects Growth and Post-transplant Establishment of ‘East Palatka’ Holly
Journal of the American Society of Horticulture Science (118)(2): 194-200
Harris, J. R.; Gilman, E. F., 1993

Growth and physiological responses before and after transplanting to a simulated landscape were studied for ‘East Palatka’ holly (Ilex x attenuata Ashe ‘East Palatka’) grown in plastic containers (PC), in the ground in fabric containers (FC), or in the ground conventionally.  At the end of a 15-month production period, trees grown in PC had more shoot dry weight and leaf area than trees grown in FC, and they had thinner trunks than field-grown trees.  Root balls on harvested field-grown trees contained 55% and those grown in FC 65% of total-tree root surface area.  Trees transplanted from FC had the lowest predawn leaf xylem potential and required more frequent post-transplant irrigation than trees grown in PC or in the ground.  Carbon assimilation rate and stomatal conductance in the first week after transplanting were highest for trees planted from PC.  Dry weight of regenerated roots was similar for all production methods 4 months after transplanting from the nursery, but trees grown in PC had 50% more regenerated root length, and the roots extended further into the back-fill soil.