Table VIII.--_Effect of water upon the seed production of sweet clover when growing under droughty conditions at Ames, Iowa, in 1916._
------------------------+-------------------------------------+--------- |Plant not watered.| Plant watered. | +--------+---------+--------+---------+ | | Average | | Average | Stage of development | Number |number of| Number |number of|Increase when labeled. | of |pods per | of |pods per | from |racemes | raceme |racemes | raceme |watering. |labeled.| that |labeled.| that | | | matured.| | matured.| ------------------------+--------+---------+--------+---------+--------- Flowers at the base of | | | | | the racemes just ready| 49 | 27.39 | 110 | 55.63 | 28.24 to open. | | | | | | | | | | Pods 3 to 6 days old | 30 | 21.13 | 112 | 39.81 | 18.68 | | | | | Pods 9 to 12 days old | 35 | 15.23 | 50 | 29.86 | 14.63 | | | | | ------------------------+--------+---------+--------+---------+---------
The effect of the water was noticeable soon after the first application, as the leaves and flowers on this plant became turgid and the anther sacs burst at the proper stage of their development. Very few flowers fell after the second day. The water decidedly checked the aborting of immature pods, as is shown by the results obtained on the racemes which were labeled after the pods had formed. The racemes which contained pods 3 to 6 days old when labeled matured 9.95 pods to the raceme more than those which contained older pods at the beginning of the experiment, but this was expected, as most of the aborting which caused this difference had taken place before the racemes were labeled. As very few pods aborted before they were 3 to 6 days old, the difference of 9.95 pods to the raceme in favor of the ones labeled when the flowers at their bases were just ready to open was largely due to the dropping of the flowers on the older racemes before the experiment was begun.
It will be seen that the production of mature pods on the plant not watered was much greater on the racemes that were labeled before the flowers opened than on the older racemes. This difference is undoubtedly due to the precipitation which fell on the sixth and tenth days of the experiment. It is believed that the yield of 15.23 pods to the raceme on the ones labeled when the pods were 9 to 12 days old is representative of the production of pods per raceme previous to the precipitation and that the other racemes on this plant would have yielded proportionately if conditions had remained the same.