Effects of Nitrogen Fertilizer for Ear Manuring, Date of Planting and the Kind of Cultivar on Hardness of Glutinous Rice-Cake

Abstract

Glutinous rice is often processed to rice-cake (Mochi) and rice-crackers (Arare). Hot Mochi dough is difficult to cut and pack, and thus hardness of Mochi after cooling is an important processing property to shorten the manufacturing time. We evaluated the effect of cultivation method, including the amount of nitrogen fertilizer for ear manuring, date of planting and the kind of cultivar on hardness. The amount of nitrogen fertilizer was found to have a small effect on the hardness, but the interaction between the nitrogen fertilizer and cultivars was significant. There was a varietal difference in the response to the nitrogen fertilizer. The hardness of Wataboushi decreased but that of Koganemochi increased with increasing nitrogen fertilizer application. The date of planting and the kind of cultivar also significantly influenced the hardness, and their contribution rates were 6.4 % and 81.0 %, respectively. Decrease in temperature due to the 15-day delay of planting caused a 0.90 kg cm^-2 decrease in hardness, and the hardness of Wataboushi was 3.10 kg cm^-2 lower than that of Koganemochi. From these results, we conclude that selection of cultivar is of primary importance, and early planting is necessary to produce superior glutinous rice for processing. Thus, we recommend high-yield cultivation without palatability because the nitrogen fertilizer has only a small effect on the hardness.