As has already been proved, the varieties intro duced from foreign lands have been found to be most valuable for producing new varieties by crossing. These wheats, coming as they do from those regions near the original habitat of the wheat plant, are found to have many of the very features it is desirable to reproduce.
A study of the needs of any region is always the first requirement when new creations are to be pro duced. If the region needs a hardier variety or one able to withstand some insect pest or disease ; if it needs a stiffer straw, or a head less likely to shat ter, the proper combinations most be made to secure these.
The second natural step will be the study of those varieties which may show the desired charac teristics. It is not always the case that a perfect combination will result even when the parents with which the crossing is effected present the desired characteristics. The resultant cross may show a weakening instead of a strengthening of some desired quality.
Rigid selection is the third step which must fol low hybridization. It is not a difficult thing arti ficially to produce new wheats, but the real task is found in selecting those of value and growing them true to the type secured.
The good results secured by cross-fertilizing wheats in order to produce new varieties are numerous. Among these which almost always fol low, are two : increased vigor and greater produc tiveness. On the other hand, so great is the disturb ance caused by the crossing that difficulty often follows the effort to select fixed types.
Hybridizing wheats.—The first step in cross fertilizing wheat is to remove the anthers from all the flowers on the spike to be fertilized. This most be done while the anthers are yet green and the pollen immature. If the head of wheat is com pact it is well to remove each alternate spikelet and also the less perfect ones at the base and tip of the spike. The work is done by using ordinary botanist's tweezers. Care must be taken not to break any of the anthers. It is best to protect the emasculated head by wrapping it with tissue paper. In a few days when the flowers on adjoining plants are seen to be ready to open, pollen may be brought from the chosen variety and deposited on the stigmas of the emasculated head, and this again protected as before. When ripe, the heads are threshed out by hand and the matured grains planted the following season. It often happens that
the head is so injured in the process that the grain is shrunken or defective although still retaining vitality. Often it will be found that the work has not been properly timed and cross-fertilization has not followed. By making several identical crosses a sufficient number of seeds can ba secured for further plantings.
Various methods of growing such seed are sug gested. Whatever the method followed, it should permit of the greatest possible development of the lants from each individual seed. It will be found that a great difference will appear in the plants succeeding from the first cross. A close study of these will reveal that only certain ones will pos sess the characters desired, and when these are planted and another generation secured, some will be found to reproduce as fixed types while others will show an unstable character. It is generally conceded by wheat-breeders that four to five years are necessary firmly to fix any desired type so that it will reproduce itself perfectly.
Selection.—It is possible from a single cross to secure a considerable number of new varieties. As soon as these are secured they must be carefully studied before being finally selected as desirable types. This study may reveal that further crossing with either of the parents or other types is needed to effect the improvement desired. In fact, many of the standard pedigreed wheats of the country are the product of successive crosses and inbreed ing. This is well illustrated in the well-known variety, Genesee Giant, which is the result of no less than eight successive cross-fertilizations. This process increases the necessity for the important work of selection since the variations secured are so numerous.
Selection must begin with the individual plants. From these may be chosen the best and most per fect heads. In any number of plants which are the result of a single cross the most vigorous and pro ductive can easily be noted. When a fixed type is secured and decided on as worthy of propagation, the next step will be to increase the amount of seed as quickly as possible. Selection should not cease even then, for further improvement in the quality produced is possible.