High temperature injuries in tomato. V

Fertilization and development of embryo with special reference to the abnormalities caused by high temperature

Abstract

The experiments were conducted to study the fertilization processes and the development of proembryo in the artificially pollinated flowers of the tomato plants grown under the condition of 20°C constant, and to observe the abnormalities of ovules caused by high temperature of 40°C for four hours.
Pollen grains began to germinate three hours after pollination on the stigma. Fertilization took place 18 hours in the fastest one and 24-30 hours in the majority of ovules after pollination. Two-, four-, and eight-nucleate endosperm stages were observed 48, 72, and 96 hours after pollination, respectively, in the endosperm which showed the cellular type in the early formative stage. Two-, and four-celled proembryo were observed 96, and 120 hours after pollination, respectively. Proembryo was consisted of more than ten cells 196 hours after pollination.
The ovules which had been treated with high temperature 18 hours after pollination aborted. This might be attributed to the retardation or the stoppage of pollen tube elongation by high temperature.
In the ovules treated 24-96 hours after pollination, degeneration of endosperm was observed. In that case it was found that cytoplasm and nucleus were deeply stained or their contents were empty. In a few ovules the retardation of proembryo development was observed. In the ovules treated 120 hours after pollination, however, the abnormalities of the ovules were hardly observed.