Masayuki Toda

Studies on the Chilling Injury in Wheat Plants : IX. Field investigations on injury caused by low temperature before and after the flowering stage

1. Field investigations were carried out on the abnormal ripening of wheat occurred in Kawanakazima-machi. The results of investigations were as follows. l) There was no difference in culm- and ear-length between the injured plants and the normal ones. 2) Earlier developed ears in an individual were severely injured, but later developed ears were not injured. 3) The injured grains were able to classify into two kinds, sterile or immature grains and shrivelled or concaved grains. 4) Most of the injured grains were the immature grains which mostly showed the interruption of development at 2-6 days after the flowering. 5) Size of the immature grain at each floret-position of an injured ear paralleled generally with the developmental order of the normal grains in a normal ear. 6) The shrivelled or concaved grains occurred with low frequency, and were scattered at random in an ear. 2. According to the investigation on the air temperature in Kawanakazima-machi, the low temperature, near to 0°C, attacked on the 16th of May corresponding to end of the flowering stage. 3. In order to explain the results of investigations mentioned above without discrepancy, it may be reasonable to propose an idea that the injury resulted from the attack of the low temperature at the flowering stage. The injuries occurred in some other regions than the region were also presumed to be the injury caused by a low temperature before and after the flowering stage.