Effect of Paddy Discoloration on Apparent Quality, Milling Properties and Grain Bending Strength

Grain discoloration caused by fungi agents, in crop season that the mature grain stage coincides with rain, it causes many damages. In this research effect of paddy discoloration of three varieties (Hashemi, Gohar and Khazar) and disease index in two levels (high and low disease index levels) on grain apparent quality, milling properties and grain bending strength was investigated in a factorial experiment based in randomized complete design with four replications. The milling recovery, degree of whitening, bending strength, length and thickness of the grains (brown rice) in high disease index was significantly lower than those of in low disease index. Also, the broken grains percentage of the three varieties of Hashemi, Gohar and Khazar in high disease index was increased by 5.33, 1.53 and 2.52% as compared to low disease index. Therefore, grain discoloration disease reduces the bending strength and grain size resulting in lower milling recovery, head rice yield and degree of whitening of rice.