18 MASS. EXPERIMENT STATION BULLETIN 402 



THE REDUCTION OF THE DISSOLVED OXYGEN CONTENT OF THE 

 WATER UNDER EXPERIMENTAL CONDITIONS 



An attempt was made to provide conditions which would insure a low dissolved 

 oxygen content indefinitely in order to determine the effect on cranberry vines 

 of a very low oxygen content in the flooding water over a longer period than might 

 occur under natural conditions. Three sheet-iron cylinders about five feet in 

 diameter were placed on the State Bog, one at each of three stations^ on sections 

 planted with vines of the Early Black, Howes, and McFarlln varieties, respec- 

 tively. The bog was flooded on December 5, 1940. It froze over within two or 

 three days and was completely covered with ice until about the middle of March. 

 Covers were placed on the cylinders on January 18 to exclude light and prevent 

 any increase in the oxygen content of the water by photosy-nthesis. The oxygen 

 content of the water inside the cylinders was determined first on January 15, 

 and thereafter weekly until March 19. Its course during the winter is shown in 

 Figure 4. 



The reduction in the dissolved oxygen content of the water inside the cylinders 

 after the covers were placed on them and the low oxygen content thereafter, at 

 least up to February 27, shows that the initial purpose of the experiment was 

 achieved, although not as completely in cylinders 2 and 3 as in cylinder 1. The 

 reason for the higher oxygen content of the water inside cylinders 2 and 3 on 

 February 12 is not known; the higher content on March 5 was because about 9 

 inches of water of high oxygen content had been pumped onto the bog on Feb- 

 ruary 28. The increase in cylinder 1 was only slight; this cylinder was located 

 on a high corner of the bog and, probably, very little of the water pumped onto 

 the bog reached it. 



EFFECT OF OXYGEN DEFICIENCY ON CRANBERRY VINES 



The flood water was drained from the bog April 1, 1941, and the cylinders 

 were then removed. 



The detrimental effect on the cranberry vines held within the cylinders during 

 the winter flooding period under water with a low dissolved oxygen content began 

 to show a few days after the cylinders were removed, and the effects were evident 

 throughout the growing season. The leaves of these vines were of a very dull 

 reddish color and a large proportion of the leaves subsequently dropped off. 

 Man> of the terminal buds were killed also, and those not killed developed slowly. 

 Vines of the Early Black variety^ were injured most. Within a month after the 

 cylinders were removed, this variety lost nearly all the old leaves and the bare 

 vines were dull and grayish, having the appearance of dead vines. The vines 

 near the cylinders showed considerably less injury than those held within the 

 cylinders. The vines that grew on slightly higher ground, consequently in shal- 

 lower water, were in better condition than any of the other vines. They had no 

 dead terminal buds, and the development of the new growth of uprights was 

 normal. 



During the summer and fall, records were taken of the number of flowers per 

 upright, dead flower buds, flowers from which fruit matured, yield of crop, and 

 size of berries on vines held within the cylinders, on those outside but near them, 

 and on vines that grew on slightly higher ground. These records are shown in 

 Table 2. 



The effect of an insufiicient supply or a complete absence of oxygen over 

 periods of time varying from a few days to several weeks during the winter- 



^The cylinders were numbered the same as the stations at which they were located. 



