Roots of terrestrial plants perform many functions such as anchorage, acquisition of water and nutrients, storage, synthesis of growth regulators, propagation, and dispersal (Fitter, 2002). Therefore, assessment of the developing root is important for the proper growth of the plant (Atkinson, 2000).
Plant roots are buried in the ground wherein environmental conditions vary with respect to space and time. In the field, the experimental design and treatments carried out during root research are often marked by unforeseen changes in the environmental conditions (Polomski and Kuhn, 2002). The known root measurement methods are tedious and time-consuming. The results are often inaccurate (Böhm, 1979). Thus, several pieces of equipment and tools have been developed for root analysis and measurement (McMichael and Person, 1991; Smit et al., 2000; Waisel et al., 2002). The methods of length estimation, based on the line intersect principle, were developed and tested during a program of root growth investigation (Marsh, 1971; Newman, 1966; Tennant, 1975). However, no information is available on nondestructive techniques based on the line intersect principle that can investigate simultaneously more traits of root growth, including the number, fresh weight, dry weight, and length.
It has been observed that roots of Phalaenopsis plants, grown in pots for commercial production, often grow into the gaps between the medium and pot wall. The condition of the newly grown roots is an indicator of not only the growth of Phalaenopsis plants, but also its marketable value (van der Knaap et al., 2005). Thus, it is standard practice to measure the newly grown roots of Phalaenopsis plants for number of roots, length, and biomass (Kubota and Yoneda, 1993; Wang, 1995, 1998; Wang and Konow, 2002; Yoneda et al., 1997). In addition, the commonly used methods for root measurement of Phalaenopsis are tedious and time-consuming. The use of a simple and nondestructive technique for the measurement of developing roots of Phalaenopsis remains unexplored. Therefore, the objective of this study was to develop a simple and nondestructive technique based on the line intersect principle for evaluating simultaneously more traits of the newly grown roots of potted Phalaenopsis plants.
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