Changes in carbohydrate and water content with ovule growth of Ginkgo biloba L.

SummaryThe carbohydrate and water contents of the ovule of Ginkgo biloba L. (ginkgo) were evaluated during its development. The ovule grew rapidly (stage I) after pollination in early May, temporarily stopped growing, in mid-July (stage II), and resumed growth slowly (stage III) from mid-August until maturation. The water content in the endosperm and outer integument were highest in June, and decreased thereafter, accompanied by ovule development. In the endosperm, the sugar content decreased rapidly during stage I, followed by a rapid increase in the starch content which is high level in early September. In the outer integument, the sugar content increased in early June, and remained nearly constant until early August. Then it transiently decreased in mid-August, when meso-integument hardening was completed, followed by a rapid increase. The starch content in the outer integument was low, but peaked in mid-August, when the sugar content was lowest. Although ginkgo nuts are usually harvested in October, w...