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Promotion of Ca Accumulation in Inner Leaves by Air Supply for Prevention of Lettuce Tipburn

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  Transactions of the ASAE. 35(2): 647-650. (doi: 10.13031/2013.28645) @1992
Authors:   E. Goto, T. Takakura
Keywords:   Calcium deficiency, Lettuce, Tipburn, Transpiration

The Ca accumulation in the leaves of lettuce was determined by 45Ca tracer measurements to study the effect of air supply to the inner leaves which were susceptible to tipburn, a Ca-related physiological disorder. Lettuce was exposed in a growth cabinet to various conditions of vapor pressure deficit (VPD), flow rate of air supply, and treatment time of air supply. Air was blown onto the inner developing leaves around a growing point. Without air supply in the light period, Ca accumulation in the outer leaves 7-10 cm in length increased with the increase in VPD in the cabinet air, while that in the inner leaves 1-3 cm long was not affected by VPD in the cabinet air and was extremely low. When air was supplied at a flow rate of 160 mL/min, Ca accumulation in the inner leaves was increased 4.6 times over that in the control. In the dark period, Ca accumulation increased in both the inner and the outer leaves when air was supplied. Air supply was shown to prevent tipburn by increasing Ca accumulation in the inner leaves, because it increased VPD in the air around the inner leaves, encouraged transpiration from the leaves, and consequently promoted Ca uptake from the root to the inner leaves.

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