Abstract
Degree of grain shedding expressed by strength required to detach rice grain from its pedicel or rachilla was measured with an unbonded gauge type transducer and null balancing recorder.Materials used were 59 paddy rice cultivars from South VietNam, 9 from U. S. A. and 52 from Japan. Results obtained were as follows.
1. In each of floating, single- and double-transplanting rices, both strengths of the breaking tensile and the breaking bending decreased from 1 to 3 weeks after heading, and it did not vary afterwards. On the other hand, grain weight reached nearly maximum 3 weeks after heading.
2. About 4 weeks after heading (the most suitable time for harvest), the breaking tensile strength was 89 to 130 g in floating rices, 75 to 143 g in singletransplanting ones and 64 to 120g in double-transplanting ones. The breaking bending stregth was 9 to 20 g in the first, 4 to 20 g in the next and 5 to 17 g in the last.
3. The breaking tensile and the breaking bending strengths in single-and double-transplanting rices were weaker than those of long grain type in American rices and most easily-shedding type in Japanese rices.
4. It seems that new varieties of single- and doubletransplanting rices which have similar degree of grain shedding to long grain type in American rices may be desired to be bred.
