Abstract
The influence of rootstock cultivars on the skin and flesh firmness of eggplant fruit was examined. ‘Mizunasu’ was grafted to three kinds of rootstock cultivars, ‘Torero’, ‘Hiranasu’ and ‘AE-RS01’. The samples 19 mm in diameter and 10 mm thickness including skin were prepared for puncture test using the universal testing machine, Instron 5540. A disc shaped plunger 1.5 mm in diameter punctured the samples at a speed of 20 mm per minute. The samples were punctured in both a centripetal direction (through the skin into the flesh) and a centrifugal direction (through the flesh against the skin). In both directions, the skin of the fruit was significantly firmer in ‘Mizunasu’ grafted to ‘Torero’ (M/T) than in ‘Mizunasu’ grafted to ‘Hiranasu’ (M/H) or in ‘Mizunasu’ grafted to ‘AE-RS01’ (M/A). The results of flesh firmness differed according to the puncture directions. The M/T plants showed more vigorous growth than the M/H or M/A plants. It was considered that ‘Mizunasu’ grafted to vigorous rootstock cultivar produced fruit with a firm skin.
