Physiological Action of Ethylene in Crop Plants : III. Ethylene production in unhulled rice and its effect on preservability of the rice

Abstract

There are many reports about decreasing in quality of unhulled rice during temporary storage in high moisuture content. But so far as we know, no experiment has been made to investigate the relation between preservability of rice and the ethylene production in unhulled rice during temporary storage. This paper is concerned with the relation between them. The results obtained were as follows; 1. The unhulled rice which maintained high moisture content produced much ethylene during temporary storage. The ethylene production was reached maximum at 1 to 2 days after storage. 2. In the unhulled rice that was kept at high moisture content during temporary storage, the preservability decreased rapidly. 3. Ethylene application caused a difference of moisture content in unhulled rice and occurred discolour in brown rice. 4. The temperature of the unhulled rice rised at 1 to 2 days after storage in the vacuum flasks. This results support the view that the rise of temperature was caused respiratory rise owing ethylene evolution. 5. The difference of ethylene production was not clear between wounded unhulled rice and non-wounded one. 6. The difference of ethylene evolution between non-sterilized unhulled rice and sterilized one was seen at 7 to 8 days after storage. This enhancement of ethylene in non-sterilized unhulled rice seemed to be caused by microorganisms. As results, it seems that the ethylene production in unhulled rice were closely associated with the decrease of preservability of rice. Therefore, it is important that harvested rice is dried up immediately to less than 20% of moisture content for reducing ethylene production, and it is necessary that stored rice is ventilated during temporary storage for taking out ethylene from store room.