YIELD OF RIPE WHEAT CROP

Press, Volume LXXIX, Issue 23919, 10 April 1943, Page 3

YIELD OF RIPE WHEAT CROP

“WEATHERING” TESTS REDOUT ON LINCOLN EXPERIMENTS No significant loss in grain weight was reported after a trial for wheat “weathering,” while the ripe wheat crops waiting for the header were exposed to repeated wetting and drying, at Lincoln by the Wheat Research Institute. The influence of “weathering” on yield was the subject of a report to the Wheat Research Committee this week by Mr L. G. L. Copp, assistant Wheat Research Officer.

“Wheatgrowers have frequently asked whether a ripe wheat crop, exposed to severe weathering while waiting for the header harvester, suffers a loss in grain weight and therefore yield, under the influence of rain water,” he wrote. Such loss could occur through leaching or respiration. The influence on bushel weight of repeated welting and drying of grain is well known. Recently Swanson reviewed the literature on this subject. In general, weathering tends to reduce bushel weight. Swanson found that the percentage of flour extraction was not influenced by repeated welting and drying. In New Zealand, work carried out by the Wheat Research Institute in 1931 showed that the bushel weight of a sample of Velvet wheat, after being wetted and air-dried seven times, fell from 62.51b to 56.51b. The grain weight was unchanged, a slight loss in milling extracation was within the error expected on the experimental mill, and the baking score was unaffected. An examination of the grain showed that after wetting and drying individual grains had opened at the crease and thereby had increased the volume of the sample. No reference has been found in the literature to the effect of repeated wetting and drying under field conditions on the absolute grain weight as distinct from the bushel weight. The following experiment was set up at the Wheat Research Institute, Lincoln. Six lines of “header” wheats were, transplanted when dead ripe, arranged to resemble field conditions as closely as possible, and subjected to repeated drying and wetting for a period of three weeks, while a check was kept on moisture content and grain weight. The six lines used were; Cross 7 from three sources, Fife-Tus-can from two sources, and Tuscan. The wheat was gathered from standing crops, sufficient plants being pulled by the roots to give four replications of over 30 plants for each “treatment.” The replications were arranged at random in an area seven feet in diameter, with the roots of the plants packed in soil a little more closely than they were in the field, and the stems of each unit loosely enclosed in a nine-inch diameter wire cage. A rain gauge was mounted level with the ears and a rotary lawn sprinkler was fixed above the whole experiment to provide artificial rain. Samples were taken six times during the trial. Moisture tests were made on each of these samples and the changes in weight of grain—and therefore in yield—were followed throughout the experiment by weighing a 200-grain sample from each replication at each sampling and correcting these weights, to 15 per cent, moisture. The only exception from this procedure was the third sampling, when a composite sample from the four replications of each treatment was used.

Natural rain fell sometimes at night and it was then not possible to determine the exact number of hours the ears were wet. It was found that when the sprinkler was used much more water fell in a given time than was likely to occur naturally. io imitate the effect of extensive natural rainfall it thus became necessary to give excessive amounts of water in the course of a desired period of wet weamcr. This, however, would have merely tended to accentuate any leaching effect. Since at one of the samplings the samples from the replications were bulked, the method used for the statistical analysis of results had to be that given by Snedecor for the analysis of variance of data classified in groups of unequal numbers of items. All calculations are based on the weights of 1000 grains corrected to 15 per cent, moisture. “The results of the experiment show that in spite of severe weathering the grain weights at the conclusion of the test were not significantly lower than they were at the start,” concluded Mr Copp’s report.