56 PLANT BREEDING. 



new varieties no heed need be taken of them. In the stndy of scientific 

 questions, however, two or three grains should be planted in each hill, and 

 early thinned to one plant, that the stand may be complete, giving to all 

 plants an equal chance.) 

 IV. 37. Making a strain or variety of wheat from a single mother plant r.s. from 

 several mother plants. 

 (The comparison is not completed. But numerous strains, each from a 

 single mother plant, have been grown for eight years in field-test plots, 

 and they continue to average as much supe ior to the parent variety as at 

 first, showing, so far, no signs of deterioration. ) 

 IV. 38. Distance apart for wheat plants in the field-crop nursery. 



(Four inches apart each way for spring varieties and ."> inches apart for 

 winter varieties have proved the most satisfactory. ) 

 IV. 39. Methods of handling the spike in cross-pollinating wheat. 



(The best of several methods tried is 'as follows: Remove the smaller 

 upper and lower spikelets and the smaller florets on the central spikelets, 

 leaving ten to twenty of the best. Emasculate these early, about the time 

 the first tinge of yellow appears in the anthers. Cover the spike with 

 tissue paper. Twenty-four to forty-eight hours later, when the florets on 

 neighboring spikes of similar age are opening, bring pollen from the 

 plant chosen for the male parent and, removing the covering, apply pollen 

 to each floret. ) 

 IV. 42. Methods for treatment of hybrids during the first several years. 



(One conclusion is that wheat hybrids should be grown in quantity 

 during the first three to five years, that variation may have its full oppor- 

 tunity; then the selection of superior plants should be from among large 

 numbers, as from among several thousand in the nursery plots, ) 

 IV. 49. Crop from mother plants with low percentage of nitrogen r.s-. crop from 



mother plants with high percentage of nitrogen. 

 IV. 69. Should the plants in the wheat nursery be fed heavily, medium, or lightly 

 in seeking plants best adapted to heavy yield in the ordinary field? 



HYBRIDIZING AS A CAUSE OF VARIATION IN WHEAT. 



In Plate A"I (fig. 1) are shown sijikes of two parent wheats, and 

 between them an average spike of their hj^brid progeny, as selected 

 in 1895 by Mr. Warren W. Pendergast from the hybrid wheats at 

 the Minnesota experiment station. In the upper ro\v the right-hand 

 spike is the Blue Stem parent, the left-hand one the Fife parent, and 

 the central spike is the average spike of the single h3^brid plant of 

 the first generation. The spikes i-n the middle and lower rows are 

 forms which appeared in the 100 plants of tlie second generation, all 

 of which came from seeds from the single plant of the previous year. 

 The "reaction" here was unusually strong, and the types of wheat 

 produced are neither like the two parent plants nor yet intermediate 

 between them, but several are verj' much like various of the so-called 

 "species" of wheat. Henry Vilmorin, of France, showed the writer 

 most of the so-called " botanical " classes of wiieat growing in his 

 garden, all of which were produced by hybridizing two varieties. He 

 believed that this is proof "that all the domesticated wheats origi- 

 nated from a single species. " It certainly indicates blood relationships 

 between the classes of wheats. Whether this is wholly the result of 



