Lodging in small grains

Rates of tillering were studied in 24 varieties of spring and durum wheat and 17 varieties of barley grown in the 1/40 acre varietal plats at University Farm, St. Paul, Minn., in 1931. No differences in the tillering rates of wheat plats were found which could be attributed to genetic differences in the varieties, since the variance between the average tillering rates was not statistically significant. However, a study of the partial correlation between tillering rates in series I and tillering in series II, holding stand constant, indicated that differences in tillering were associated with differences in stand. It is suggested that these differences in stand may have been due to differences in the number of seeds sown on unit areas, since the plats were sown at uniform rates by weight and the varieties varied somewhat in size of seed. No correlation was found between the tillering rates of wheat varieties in these trials and the lodging behavior of the same varieties at Morris in 1930. The 17 varieties of barley differed significantly in rates of tillering. These differences in tillering were not entirely associated with differences in stand. It is believed that these differences may be genetic. The breaking strength of wheat culms was determined by breaking 10 culms from each of the three plats of each variety. The differences in breaking strength were found to be significant. The correlation coefficient between breaking strength and diameter of culm was .537 +/- .148. The breaking strength of the varieties as determined in these trials was compared with the lodging behavior of the same varieties at Morris in 1930 and at four Minnesota stations in 1928, 1929, and 1930. No correlation was found between breaking strength and lodging in either of these comparisons. Three durum varieties included in the study had higher breaking strength, greater diameter of culm, and lower tillering rate than the common wheat varieties.