Studies on the abnormal rice kernel “Kokutenmai”
V. Mechanism of the symptoms development
1976 Volume 6 Pages 67-72
Details
1976 Volume 6 Pages 67-72
The occurrence of two types of Kokutenmai seemed to be closely related to the development of endosperm. When the rice white tip nematodes injured the kernel during the early milk ripe stage, the abnormal rice of longitudinal type (longitudinally cracked and blackened kernels) may be developed, and that of horizontal type (transversely crack wedged kernels) may also be developed from the late milk ripe stage to the early yellow ripe stage. The symptoms of these abnormal rices appeared mostly on the ventral side of the kernel. It was considered the reason was that the nematodes likely lived in space between the hull and the ventral side of developing endosperm, and also that the epidermis of the ventral side of kernels were more easily cracked because the number of aleuron cell layers on this side were less by two to four layers than that of the dorsal side. When inoculating some fungi and bacteria separated from Kokutenmai, the symptoms were hardly found. However, when the ears of the rice plant infected with the nematode were immersed in the solution of Streptomycin at the concentration of 1, 000 ppm at the heading time, the abnormal rices were decreased by half. It was suggested that these rices might be caused by infection of bacteria following the injury by the nematodes.
