TOKYO, JAPAN To increase the sugar concentration and resulting marketability of tomato juice, growers have traditionally used techniques such as subjecting plants to salt and water stresses. In a new study published in HortTechnology (February 2014), Ken Takahata and Hiroyuki Miura from Tokyo University of Agriculture reported on a prototypic method known as "basal wire coiling" that shows potential as a simple and effective method for increasing the sugar concentration in tomato fruit juice.
"We investigated whether coiling wire around the lower part of the plant stems to reduce the capacity of xylem to transport water to the shoot would result in low shoot moisture conditions and increase the sugar concentration of fruit like salt and water stresses," the authors said. They noted that basal wire coiling is less complex than other treatments, such as subjecting tomato plants to salt or water stress, which can require special equipment and techniques.
Takahata and Miura's study involved coiling bonsai wire around the stems of tomato seedlings between the cotyledon node and the first leaf node. "Eleven days after treatment, the stem diameters immediately above the wire coils were markedly greater in treated plants compared with the corresponding stem regions of control plants," they said. The stems of treated plants were less elongated and developed fewer nodes at 39 and 51 days after treatment than did the control plants.
Several months after the application of the treatment, marketable fruit harvested from the first to third trusses of the treated plants had average weights that were 49% to 89% of the weights of fruit from control plants. The juice of fruit from the first to third trusses in the treated plants had soluble solids concentrations of 116% to 120%, sucrose concentrations of 263% to 483%, and fructose and glucose concentrations of 135% to 155%, compared with juice from corresponding control fruit. At 112 days after
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American Society for Horticultural Science