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Dilma Daniela Silva and Richard C. Beeson Jr.

Although root growth is central to overall plant performance, the study of natural root development has remained a challenge as a result of the difficulty of observation. Attempts to observe roots over time date back to at least the early 1900s

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De-Xing Chen and J. Heinrich Lieth

A two-dimensional mathematical model was developed to describe the time course of root growth and its spatial distribution for container-grown plants, using chrysanthemum [Dendranthema ×grandiflorum (Ramat.) Kitamura] as the model system. Potential root growth was considered as consisting of several concurrent processes, including branching, extension, and death. Branching rate was assumed to be related sigmoidally to existing root weight density. Root growth extension rate was assumed to be proportional to the existing root weight density above some threshold root weight density in adjacent cells. The senescence rate of root weight density was assumed to be proportional to existing root mass. The effects of soil matric potential and temperature on root growth were quantified with an exponential function and the modified Arrhenius equation, respectively. The actual root growth rate was limited by the amount of carbohydrate supplied by the canopy to roots. Parameters in the model were estimated by fitting the model to experimental data using nonlinear regression. Required inputs into the model included initial root dry weight density distribution, soil temperature, and soil water potential data. Being a submodel of the whole-plant growth model, the supply of carbohydrates from canopy to roots was required; the total root weight incremental rate was used to represent this factor. Rather than linking to a complex whole-plant C balance model, the total root weight growth over time was described by a logistic equation. The model was validated by comparing the predicted results with independently measured data. The model described root growth dynamics and its spatial distribution well. A sensitivity analysis of modeled root weight density to the estimated parameters indicated that the model was more sensitive to carbohydrate supply parameters than to root growth distribution parameters.

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Jesús Gallegos, Juan E. Álvaro, and Miguel Urrestarazu

The response of roots to mechanical impedance has intrigued horticulturists, plant biologists, and substrate physicists for at least two centuries ( Araki and Iijima, 2001 ; Atwell, 1993 ), whereas the model of root growth as a function of multiple

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Julie Guckenberger Price, Amy N. Wright, Kenneth M. Tilt, and Robert L. Boyd

areas, where most shrubs are planted as part of a larger landscape installation, often lack the natural topsoil, and what remains is often alkaline with high clay content. These areas may also have restricted space for root growth, poor aeration, and

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Patrice Cannavo, Houda Hafdhi, and Jean-Charles Michel

an extensive list of abiotic factors that influence root growth in containers in their review. Among them, the physical properties of growing substrate are of great importance. The air-filled porosity and the water retention capacity and availability

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H.M. Mathers, S.B. Lowe, C. Scagel, D.K. Struve, and L.T. Case

growth in containers to achieve optimal benefits from container production. This review addresses several abiotic factors influencing root growth in containers: physical and chemical properties of substrates, pot characteristics, and temperature. We will

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Mara Grossman, John Freeborn, Holly Scoggins, and Joyce Latimer

plant production cycle. Some commercial producers of liners have reported reduced root mass in plants treated with BA (personal communication). BA has been shown to reduce root growth in in vitro Arabidopsis seedlings ( Auer, 1996 ). Sedum leaf

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Shengrui Yao, Ian A. Merwin, and Michael G. Brown

have shown that GMSs influence aboveground tree growth and yield ( Merwin and Stiles, 1994 ; Neilsen et al., 2003b ; Pedersen, 1997 ), whereas only a few studies have investigated how GMSs affect root growth. Atkinson and White (1976) reported that

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Raquel Valdés, Julián Miralles, Jesús Ochoa, Sebastián Bañón, and María Jesús Sánchez-Blanco

salinity (control or saline irrigation) during a spring–summer growing season determining the effects on substrate and leachate EC, root growth, shoot growth, leaf damage, plant physiological status, and leaching fraction. Materials and Methods Plant

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Lesley A. Judd, Brian E. Jackson, Ted C. Yap, and William C. Fonteno

A large portion of the U.S. green industry is involved with growing plants in containers, including bedding plants, vegetable plants, foliage plants, potted flowering plants, potted nursery stock, and other assorted floriculture crops. Root growth