20 MASS. EXPERIMENT STATION BULLETIN 402 



is greatly reduced.^ Oxygen deprivation over a longer period caused a further 

 reduction in yield, but even within a variety the reduction did not appear to be 

 in proportion to the length of time during which oxygen was lacking. 



The yield of berries from the Howes vines inside the cylinder was greater than 

 that from the comparable Early Black vines although the water on the Howes 

 vines contained no dissolved oxygen for about 5 weeks and very little for an 

 additional 3 weeks, while the oxygen content of the water on the Early Black 

 vines was very low for only about a month. This probably was because the 

 Early Black vines had been badly injured by a lack of dissolved oxygen in the 

 water during the winter flooding period of 1939-40. 



The lower yield from vines, whether inside or outside the cylinders, was the 

 result of different degrees of injur>' which caused the death of uprights, the death 

 of terminal buds and of flower buds, loss of old leaves, injury to the flower buds 

 which caused them to fail to set, and reduction in the size of fruits. 



When the water was withdrawn from the bog in April there were more dead 

 uprights and dead terminal buds on vines of all three varieties inside the cylinders 

 than on those just outside, and more on Early Black vines than on those of other 

 varieties. There were only a few dead uprights or dead terminal buds on vines 

 outside the cylinders. On the Early Black vines inside the cylinder about 12 

 percent of the uprights that were alive during the blossoming period died before 

 fall; in the Howes and McFarlin varieties, about 3 per cent. Not more than 2 

 per cent of the uprights of vines of any of the three varieties outside but near the 

 cylinders died during the summer. 



The percentage of flower buds killed at various stages of their development 

 ("dead buds" in table 2) was considerably greater on vines of all three varieties 

 in the low areas just outside the cylinders than on vines of the same varieties on 

 slightly higher ground. However, contrary to expectation, more "dead buds" 

 were recorded outside than inside the cylinders on Early Black and Howes 

 varieties. A probable explanation for this discrepancy is that more flower buds 

 inside the cylinders than outside were kil'ed at a very early stage of development 

 and that these dead buds were not noticed when the counts were made. This is 

 indicated by the slightly lower average number of flowers per upright on vines of 

 the Early Black and Howes varieties inside the cylinders than just outside. 

 Another probable reason is that, in making the counts, only uprights on which 

 flowers or dead buds were visible were recorded, no attention being paid to sterile 

 ones, a considerable proportion of which may have been flowering uprights on 

 which all of the buds had been killed at a ver}* early stage of development. 



The percentage of flowers from which fruit matured, in all three varieties, was 

 lowest on vines inside the cylinders, and was lower on vines in shghtly deeper 

 water than on those most shallowly flooded, although in some cases the difference 

 was small. Because of the failure to observe and count flower buds killed at a 

 veiy early stage of development, the percentage given for flowers from which 

 fruit matured on vines of the Early Black and Howes varieties inside the cylmders 

 also are higher than they otherwise might have been. 



Many flowers set fruit that made more or less growth but subsequently died; 

 other berries remained alive although they never became large enough to be 

 picked. The percentage of such fruits could not be determined with certainty 

 but the effect on the size of harvested fruits is shown by their cup-counts (Table 

 2). 



The reduction in the size of fruits and the failure of berries to grow to a size 

 large enough to be picked probably was due to an inadequate food supply during the 



^The results of experiments completed in 1942 show that the yield is reduced if the oxygen content 

 of the water is as low as 3 cc. per liter for two or three days. 



