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Studies concerning the elimination of experimental error in comparative crop tests
Abstract
1. In determining the effect of competition between single-row test plats as a source of experimental error in crop yield tests, the relative yields of two crops planted in blocks containing several rows have been regarded as the true relative values for the crops tested. In ascertaining some of these true values, the outer rows of the plats have been discarded in order to eliminate almost entirely plat com- petition. Plats were sufficiently replicated to secure quite reliable relative yields for the conditions under which they were grown.In plat competition tests in 1913 with two rates of planting Turkey Red wheat, the thin rate yielded 68 per cent as much as the thick rate when grown in single alternating rows, while in five-row blocks the thin rate yielded 90 per cent as much as the thick rate. Competition in rows with a thicker rate of planting caused the thin rate to yield relatively 24.4 per cent too low. In a similar test in 1914 the thin rate yielded relatively 56.8 per cent too low.2. In 1913, competition between alternating rows of two rates of planting with Kherson oats caused the thin rate to yield relatively 20 per cent too low. In 1914, similar single- row competition caused the thin rate to yield relatively 34.3 per cent too low.3. In 1914, competition between alternating single-row plats of Turkey Red wheat sown at two rates reduced the relative number of stools per plant approximately 37 per cent for the thin rate. There was a similar reduction of 20 per cent for Kherson oats, due to plat competition.5. In 1913 in alternating single-row test plats of Burt and Kherson oats, the Burt yielded relatively 16 per cent too high, while in 1914 the yield was relatively 37.6 per cent too high, due to plat competition.In 1913, competition with Kherson oats in alternating one- row plats caused Swedish Select oats to yield relatively 7 per cent too high, while in 1914 its yield was relatively 4.3 per cent too low.6. When large and small seeds of wheat were planted in competition in the same row, the small seed, as a result of competition, yielded relatively 15 per cent too little grain, 20 per cent too little straw, and made 18 per cent too small total yield.Similar competition was found between varieties of wheat planted in the same row.7. In a single-row test of 80 strains of Turkey Red wheat grown in the same order each of four years, there are evidences of plat competition between strains. As an aver- age for four years, the poorest strain, No. 75, grew between strains No. 74 and No. 76, ranking one and five. A special test of these three strains in 1915 and 1916 disclosed that strains No. 74 and No. 76 were favored 20 and 15 per cent respectively thru competition with a less vigorous strain.8. In a rate-of-planting test with Nebraska White Prize corn,-in which two rates of planting, namely two and four plants per hill, were compared in alternating single row plats, -the thin rate yielded relatively 29.3 per cent too low in 1914 because of plat competition. In 1915 the thin rate. yielded 9 per cent too low because of plat competition. In 1916 such competition caused the thin rate to yield relatively 16.1 per cent too low.9. A large, medium, and small variety of corn were grown in plat competition studies during 1912 and 1914. These varieties were Hogue's Yellow Dent, University No. 3, and Pride of the North, respectively. In 1912, Pride of the North yielded 85 per cent as much as Hogue's Yellow Dent in alternating three-row plats, while it yielded 66 per cent as much in alternating single rows. When compared in the same hill by the intra-hill method, the Pride of the North yielded only 47 per cent as much as Hogue's Yellow Dent. Due to competition, the Pride of the North yielded relatively 44.7 per cent too low when compared in the same hill, and22 per cent too low in alternating one-row plats.4. The relative competitive effect of varieties varies in different years, due to difference in adaptation to the seasonal conditions.In 1913, competition with Turkey Red winter wheat in single rows caused Big Frame winter wheat to yield relatively 10.3 per cent too high. In similar competition in 1914 Big Frame yielded relatively 12.4 per cent too low.In 1913 there was practically no competitive effect be- tween alternating rows of Turkey Red and Nebraska No. 28 winter wheat varieties. This was due to abnormal climatic conditions. However, in 1914 under rather normal conditions competition between single-row plats caused the Nebraska No. 28 to yield relatively 25.9 per cent too low.
Subject Area
Agronomy
Recommended Citation
Kiesselbach, T. A, "Studies concerning the elimination of experimental error in comparative crop tests" (1917). ETD collection for University of Nebraska-Lincoln. AAIDP14101.
https://digitalcommons.unl.edu/dissertations/AAIDP14101