12 MASS. EXPERIMENT STATION BULLETIN 450 



In January of the crop year most cranberry bogs are flooded and the vines are 

 relatively dormant. This condition must be considered in any attempt to explain 

 the relation of January sunshine to the size of berries. Reduced sunshine in this 

 month often induces a deficiency of oxygen in the winter flooding waters. i^ When 

 this happens, carbohydrate reserves are diminished and the vines are injured to 

 such an extent that small berries characterize the following crop. Since 1925, a 

 crop of large berries has never followed a January in which there was less than 

 130 hours of sunshine. However, more than normal sunshine maintains sufficient 

 oxygen in the flooding waters, merely preserving the stored carbohydrates with 

 little chance of adding to them. Excessive sunshine in January is, therefore, 

 followed by a crop of either small or large berries, the size being determined by 

 other factors. 



The relation suggested by Franklin^" of the sunshine and temperature of March 

 to the size of berries in the following crop now appears to be due to temperature 

 alone. 



Table 8 shows in detail the relation of the sunshine of the six most important 

 months to the size of cranberries. 



The data in Table 8 give the following correlation coefficients between sun- 

 shine and the size of cranberries: 



September and October._. + .6.317 ± .0884 



October and January + .6746 ± .0802 



March, October, and January ,. + .6757 ± .0799 



September, Octotier, and January + .6724 ± .0806 



March, April, and June (-) -+ .5793 + .0978 



March, June (-), October, and January + .6963 + .0758 



March, April, June ( — ), September, and October + .7233 ± .0702 



March, June ( — ), September, October, and January + .7480 ± .0648 



March, April, June ( — ), September, October, and January + .7176 + .0714 



The coefficients, ranging from + .5793 + .0978 to + .7480 + .0648, indicate 

 that sunshine is more responsible for the size of berries than any other weather 

 element. 



19 Bergman, Mass. Agr. Expt. Sta. Bui. 402, 1943. 



20 Mass. Agr. Expt. Sta. Bui. 433, Table 18, p. 36. 1946. 



