Methods of breeding crested wheatgrass, Agropyron cristatum (L.) Beauv

The purpose of these investigations was to study methods of breeding crested wheatgrass. The primary objectives were to study the variability among plants tested in individual plant nurseries and as replicated clonal progenies; and to determine the effects of self-fertilization. These studies were made with plants selected from both the forage and Fairway types. The plants from the forage type had a normal somatic chromosome number of 28 and those from the Fairway type 14. In the forage type only one plant, 58-37, out of 33 had a definite aneuploid chromosome number. Fifteen one-year selfed plants from three different progenies of the forage type all had a 2n chromosome number of 28. Both types of crested wheatgrass were highly unfruitful when self-pollinated. Only one plant, 57-31, which was from the forage type seemed to possess any amount of self-fertility under the conditions of these tests. Some one-year selfed plants and 58-37, the aneuploid plant from the forage type, failed to produce any appreciable amount of seed under open-pollinated conditions. No one-year selfed plants showed an increase in seed setting under conditions of self-pollination over that of their parental plants. The one-year selfed progeny plants from 57-31, the one plant which did possess some degree of self-fertility, were very unfruitful under conditions of self-pollination and some of them produced no seed from open-pollinated heads when spaced-isolated. This may have been caused partly by a lack of vigor which was very noticeable in this selfed progeny. In the forage type some plants produced more seed under conditions of space-isolation than under parchment paper bags. The somewhat self-fertile forage type plant, 57-31, seemed to be as self-fertile when space-isolated as under conditions of open-pollination in the individual plant nursery. Some plants were cross-compatible and others were not when space-isolated in pairs. Some of the one-year and two-year selfed plants produced pollen distinctly smaller in size and showed a reduction in pollen fertility when compared with non-selfed plants, while others were not different. The few non-selfed forage and Fairway type plants studied were not different in pollen size or pollen fertility. Significant differences in yield, plant height, and root rot injury were found among the plants of the forage type which were tested in replicated clonal progenies. The differences in yield among selected plants of the Fairway type tested in replicated clonal progenies were significant. Plants of the Fairway type were significantly higher yielding and shorter in plant height than the forage type and were resistant to root rot injury. The plants from the forage type showed severe injury from root rots during the months of July and August. This injury greatly affected yield as shown by a highly significant correlation coefficient of r=-.80. Most of the one-year selfed plants were greatly reduced in vigor. However, a few one-year selfed plants when tested as clonal progenies seemed to be as vigorous as their parental plants. Some one-year selfed progenies of the Fairway type were as vigorous and one progeny was more vigorous as measured by their mean yield than a group of unselected open-pollinated plants. The variability in yield and root rot injury were rather great within most selfed progenies. The relationships between the character values of the parents and the mean character value of their one-year selfed progenies were very small or lacking. There were no significant differences among 15 plants of the forage type in beta carotene content when they were tested as clonal progenies in replicated trials at University Farm and Waseca. From these studies it seems that a further improvement over individual plant selection can be made in crested wheatgrass by selection among these superior plants after they have been tested in replicated clonal progenies. In addition, it seems that the study of and selection within selfed progenies in crested wheatgrass does not appear to be a very promising means of improvement because of the difficulty of obtaining selfed seed and because of the lack of vigor and uniformity as observed in many of the one-year selfed progenies. However, a few one-year selfed progenies from the Fairway variety were as desirable as unselected open-pollinated plants. If selection within selfed progenies is to be used. it appears that a greater search for lines or strains which set seed under conditions of self-fertilization will be necessary.