Research Bulletin (Iowa Agriculture and Home Economics Experiment Station)


In 1927 yield and moisture data were secured at semi-weekly harvest intervals for four varieties of oats, two of winter wheat and two of barley. In 1928 this experiment was repeated using six varieties of oats, two of winter wheat and four of barley.

The data secured in these studies show increases in yields which indicate that photosynthesis and translocation of food material to the kernel may continue much longer than has been previously reported. The yields continued to rise until the moisture content of the grain had fallen to percentages varying, in 1927, between 33.6 and 10.0, and in 1928 between 45.0 and 19.4, as shown in table I, page 335.

The results of these experiments indicate that a considerable part of the grain crop is usually harvested before maximum production has been attained. In 1927 several of the varieties increased in yield as much as 10 percent after the date on which they normally would have been harvested. In some cases these increases extended over a period of 10 days. In 1928, probably due to intermittent storms, the increases were much smaller than in the previous year, but continued over approximately the same length of time.

The results confirm the accepted idea that the corresponding losses from delayed harvesting are lower for wheat than for other grains.

The experiments with oats show a distinct relation between varieties and the length of profitable harvest period.



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