VARIATIONS IN PROTEIN CONTENTS OF PLANTS, HEADS, SPIKELETS, AND INDIVIDUAL KERNELS, OF WHEAT

Abstract

Protein contents of individual kernels of wheat, representing random samples taken from two plots of 0.1 acre and two plots of 0.23 acre, were found to be distributed within samples in an approximately normal manner over a range of at least 6 percentage units with a standard deviation of 1.4 units.Protein contents of grain of 68 Thatcher plants, comprising a 10 ft., 1-row plot, had a range of 2.7% and a standard deviation of 0.6%. Within plants, the average range for single heads was 1.7%; the maximum range was 4.9%. Heads with high protein contents tended to occur on the shorter tillers of plants containing more than three tillers.Determinations were made on each of the kernels in three plants. Mean values for individual spikelets were normally distributed over a range of 5.1%; two extreme values, representing spikelets containing only one kernel, increased the range to 9.6%; the standard deviation for spikelets within heads was about 1.1%. Protein contents of spikelets tended to decrease towards the top from about the top third of the head; the top two spikelets of each head generally had decidedly lower protein contents than the remaining spikelets.Within spikelets containing three kernels, the top kernel tended to be decidedly lower in protein content (mean, 14.7%) than the remaining two; the middle kernel (15.9%) tended to be slightly higher than the lowest one (15.7%). In spikelets containing only two kernels, the top one tended to be about 0.3% lower in protein content. Within plants, the protein contents of individual kernels were normally distributed over a range of about 6% with a standard deviation of 1.2%.