Studies on turgor pressure as related to growth rate in fruit

1992 Fiscal Year Final Research Report Summary

• Project/Area Number: 03454045
• Research Category: Grant-in-Aid for General Scientific Research (B)
• Allocation Type: Single-year Grants
• Research Field: 園芸・造園学
• Research Institution: The University of Tokyo
• Principal Investigator: SAKIYAMA Ryozo UNIVERSITY OF TOKYO FAC.AGR.PROFESSOR, 農学部, 教授 (70011955)
• Project Period (FY): 1991 – 1992
• Keywords: Fruit / Growth in volume / Turgor pressure / Sugar concentration / Cucumber / Peach

Research Abstract

Sugar concentration in peach fruit as it becomes mature is thought to decrease when it rains. If this assumption is true, a decrease in sugar concentration will be prevented by controlling water inflow into a fruit. In this study, enlargement of fruit volume was suppressed by covering an acrylic sleeve. Since more than 90% of fruit flesh volume is occupied by water, restriction of fruit volume leads to suppress of water inflow.
For a short period after the restriction of volume occurred by the treatment, water inflow was restricted more than dry matter influx. For the rest of a period the rates of restriction was not clearly different. At harvest, treated fruit showed a higher content of dry matter and sugars than control fruit. In the experiments at orchards at different locations and years, treated fruit showed always higher sugar concentrations than control fruit. However, it was variable. Changes in leaf and fruit ratio did not affect sugar concentration of treated fruit. It suggested that sugar concentration was not influenced by an amount of assimilate supply.
Turgor pressure determined by psychrometery was not different between treated and control fruit. Turgor pressure decreased as fruit became mature.
An instrument to determine the pressure of fruit tissue in a acrylic sleeve was assembled. In cucumber and peach fruit, pressure of fruit tissue showed a daily change that was affected remarkably by radiation.