Date of Award:

1973

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Advisor/Chair:

R. S. Albrecthsen

Abstract

Inia 66 and Siete Cerros wheat varieties, and Steveland and Woodvale barley varieties were grown in mixtures and in pure stands for two years in irrigated nurseries at Logan. These four varieties were also grown the first year in a dryland nursery at Blue Creek. Another set of four varieties was used the second year in the dryland nursery. These four varieties as well as the first set, were tested in seven combinations, with the following percentages of one barley and one wheat variety : 100:0, 90:10, 75:25, 50:50, 25:75, 10:90, and 0:100.

Grain yield of mixtures was higher than that of the mid-component value in most cases and was higher than that of the best component in a few cases. Only a few of the observed differences were statistically significant.

All mixtures had significantly lower test weight than that of the best component. Ninety percent of the mixtures were significantly lower in test weight than the mid-component value.

Tillering of both wheat varieties consistently decreased as the percentage of wheat in the seeded mixture decreased. Conversely, tillering in barley increased as the percentage of barley in the seeded mixture decreased.

Most of the mixtures showed an excess of barley in the harvested crop, compared to that in the seeded mixture. These excesses were usually greatest around the 50:50 mixture level.

A consistent pattern of slight increase in kernel weight of barley was observed as the amount of barley decreased in the seeded mixture. Wheat showed the reverse situation. None of these differences were statistically significant.

Inter-relationships among yield components were evaluated by simple correlation coefficients. The correlations were subdivided into direct and indirect effects by the use of path coefficient analyses. Correlation coefficients and path coefficients showed consistent changes as the percentage of crop mixtures changed. Coefficients of determination for both wheat and barley decreased as the percentage of that crop in the seeded mixture was decreased.

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