The Variations of the Starch Accumulation during Fruit Development of the Walnut(Juglans regia L)
The presence and the distribution of the starch in the fruit of Juglans regia during its development were investigated by using the usual histo-chemical methods. The results are as follows:1. At the beginning of the formation of ovule primordium many starch grains accumulate in the ovary wall. At 7-celled embryo sac stage the starch content in the ovary wall which developed into green peridium slightly diminishes, but in the ovary wall which developed into hard peridium starch disappears. After fertilization, with the growth of the proembryo in the green peridium the starch accumulates again, with which ceils are filled, the starch content is at a second maximum. When the fruit ripens the starch content of green peridium is gradually decreased untill it disappears at all.2. In the integuments the starch accumulation begins at the time of the formation of a megaspore mother cell and gradually increases with the development of ovule. As the seed matures the starch content of testa gradually decreases with the collapse of greater part of the parenchymatous cells in the testa.There is a little accumulation of starch in the early stage of the nucellus, but it lacks at the end of the stage.3. The starch grains are always deposit in endosperm at the free nuclear stage, but at the time of the formation of endosperm cells, its accumulation has never been found.4. A marked quantity of starch is accumulated in the egg cell and zygote itself. It is supposed that the starch is used for early development of the proembryo. In the spherical embryo the starch grains appear at its base. Starch grains of proembryo then diminish in quantity and disappear later. The starch accumulation appears again at the stage of differentiation of the embryo organ, then in the center of root cap, the starch deposits partly. Finally within cotyledon of matured embryo, no starch is found to be stored as food, but fat drops.It can be concluded that the starch grains participate actively in the metablism of carbohydrates and finally are almost entirely consumed off. Therefore, they are not the main reserve material of the walnut embryo.