Seed setting in red clover
1944
Bird, J.N.
A 5-year study of seed setting based upon number of seeds per head was carried out with a strain of early, double-cut red clover. The natural blooming period of the crop was greatly extended by a series of cutting treatments made at weekly intervals during June, which postponed the time of blooming of their respective aftermaths until successively later periods of the summer. Tagging of heads was carried out at approximately 2-days intervals at each of which at least 60 heads were tagged on plots in bloom as a result of the various cutting treatments. When the seeds ripened they were threshed out by hand and counted. The seasonal trend of seeds per head, although varying somewhat from year to year, showed rather low seed setting in the first growth. gradually declining to a marked low level during late June and early July then rising to a maximum in late July and early August. The seasonal and yearly trends of seeds per head agreed fairly closely with those of numbers of bumble bees for the same periods reported earlier. Under the conditions of this study it was concluded that the number of bumble bee visitors was a much more important factor in seed setting than number of honey bee visitors or number of florets per head. Aftermath crops of red clover brought into full bloom during late July or early August have a much better chance of receiving satisfactory pollination than the first growth blooming earlier in the season or aftermath crops brought into full bloom at a later date.
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