Most of the IR varieties have long slender or medium-long slender grains
with a minimum level of chalkiness. Only IR68 has extra long grains.
Translucent long or medium-long grains give high milling recovery (less grain
breakage during milling). Bold, long, and chalky grains have poor milling
recovery. Thousand-grain weight in the range of 20–28 g is most desirable.
Table 1 gives data on grain length, shape (length/breadth ratio), chalkiness,
and 1,000-grain weight of IR varieties. This table also shows the milling
characteristics of IR varieties. Milling recovery of over 60% is most desirable.
Actual measurements of rough (paddy) rice, brown rice, and milled rice grains
also appear in Table 1