Research and Control Techniques for Volunteer Rice

Abstract

Recently, the Japanese government policy has recommended the cultivation of multipurpose high-yield paddy rice cultivars for animal feed (not only in the form of brown rice but also of whole crop silage (WCS) and others) in response to the decrease in demand on palatable rice for human consumption in Japan. However, when palatable cultivars are cropped in the following year of cultivations of high-yield cultivars for animal feed, the seeds of the high-yield cultivars are often left in the paddy field and grow as volunteer rice in the next crop season over winter, resulting in decrease in grain yield and lowering the quality of the palatable rice. Up to date, many ecological studies on overwintering ability of rice seeds have been carried out, and several key techniques on how to reduce volunteer rice were developed. This review summarizes ecological characteristics of volunteer rice, and describes effective countermeasures with cultural method, herbicides, lime nitrogen, and premature harvest (for only WCS).