Correlation Between Yielding Ability, Reaction to Certain Diseases, and Other Characters of Spring and Winter Wheats in Rod‐Row Trials¹

Abstract

The reason why certain varieties perform more satisfactorily than others is of great importance to the plant breeder. Such information furnishes the basis for a logical plan for the improveme~t of the crop. At present it is not possible by plant physiological methods alone to obtain all necessary infonnation regarding the reasons for differential responses of various important varieties. By growing the varieties in .a field trial, however, it is possible to obtain comparable data on such characters as yielding ability, time of maturity, reaction to prevalent diseases, and certain morphological characters. By biometrical methods the data can be analyzed for the purpose of learning the relative importance of various characters in their influence on yielding ability.A series of rod-row trials were made at the Waseca branch station in 1926. Conditions were so favorable for the study that it was planned to determine, by means of correlation coefficients, the 1 The studies of disease resistance are a phase of the cooperative studies conducted by the sections of plant breeding and plant pathology, Minnesota Agricultural Experiment Station, St. Paul, Minn. The breeding of spring and winter wheat is

Analysis of Factors Determining Yield in Crop Plants. II. The Influence of Photoperiodic Treatments on Characters Determining Yield in Wheat with Special Reference to the Temperature of the Ripening Period.

“…Nevertheless, a highly significant positive correlation between yield per plant and thousand grain weight (correlation coefficient 16, table III) indicated that grain yield was determined by grain filling processes. Positive correlation between the thousand grain weight and yield has also been reported by some other workers (3,15,17,18,25,26). Immer and Stevenson (16) working with oats found a strong correlation between plumpness of grain and the yielding ability.…”

“…There was no change in dry weight between seed kernel and the 5-day-old seedlings; such respiratory loss of dry matter as may have occurred during germination was evidently regained by photosynthesis during the fifth day. One rather unexpected feature of the data was the loss in weight per plant of P during the first five days and the continued decrease in P concentration during the first 15 days. The gain in Ca (extremely low in the seed) was continuous during the full 30-day period,…”

Correlated Inheritance with Special Reference to Disease Resistance in Spring Wheat1

“…The inheritance in wheat, under field conditions, of "mature plant" reaction to stem rust and of seedling resistance in the greenhouse has been studied by several investigators (7, 8,9,Io,13) . 3 The existence of a large number of physiologic forms appeared less serious from the standpoint of plant breeding when Aamodt (I) showed that the inheritance of resistance in the seedling stage to r I physiologic forms was governed by a single pair of genetic factors.…”

“…From the results of studies of several investigators (2,7,8,9), it has become quite clear that the reaction of wheat varieties and hybrids in the seedling stage to single forms of rust as determined by greenhouse tests is not necessarily a criterion of the reaction under field conditions to these same physiologic forms or to a collection of forms.…”

Associations of Morphological Characters and Earliness in Oats1

“…Hayes et al ( 6) found a low positive correlation between height and heading in winter wheat, while Bridgeford and Hayes ( 4) found a high negative correlation in spring wheat. Alim\ working with wheat, reported a low positive correlation between height and heading and a low negative correlation between heading and tiller number; all were non-significant.…”