|dc.description.abstract||The importance of shattering and weathering in cereal crops has increased greatly in the last two decades. The almost universal adoption of the combine in harvesting operations has meant that cereal crops, particularly wheat and barley, have been left standing for a considerable length of time after maturity. Due to larger farm units, the performance of timely harvesting operations has been made more difficult and length of the period between maturity and harvesting has been further increased. During this after-maturity period the standing grain is often exposed to conditions which are particularly conducive to shattering and weathering. Losses occur yearly and concern has been and is being expressed by both farmer and plant breeder.
Losses in wheat are mainly due to shattering. This type of loss may be defined as the dropping of the grain from spikelet. It may occur either before or after ripening, but the majority of shattering takes place after the crop is ripe. It may also occur where the material is handled a great deal during the period following maturity.
Losses in barley are not confined to shattering. During varying periods of weathering the crop is subject to a number of types of breaking. Neck breaking is the loss of the head due to a breaking of the stem above the upper internode. Stem breaking is due to a breaking of stem below the upper internode. Rachis breaking is a breaking of the rachis causing a loss of total or partial heads.
Varietal differences in resistance to shattering and weathering are evident in both wheat and barley. In breeding programs selections are among the hybrids for those types which tend to maintain their grain in a harvestable position after ripening. Because of annual and seasonal difference in the conditions conducive to shattering and weathering, there are yearly differences in shattering and weathering resistance. Therefore, in any breeding program in which selections are method of testing were devised by which the plant breeder could readily determine the shattering and weathering propensities of hybrid material even in years when little natural shattering and weathering occurred, his work would be less difficult and less expensive. The experiments conducted in this study were designed with a view to determining such a method. They were undertaken upon the reccomendation of previous workers and were designed to provide further knowledge on shattering in the cereals, wheat and barley. It must be kept in mind that losses due to shattering and weathering may be no less important in other crops.||en_US