6 MASS. EXPERIMENT STATION BULLETIN 450 



Table 3. — AIonthly Sunshine at Boston and Massachusetts 

 Cranberry Production. 



(Correlation coefficient and probable error for each month.) 



Year Before Year of Crop Year nf Crop 



January ..+ .0409 + .0989 January - .0848 + .0969 



February ...+ .0409 ± .0971 February + .2211 + .0916 



March.... + .0499 ± .0960 March + .0455 ± .0961 



April + .1601 ± .0957 April - .0462 + .0961 



May + .3288 ± .0867 May + .1001 ± .0953 



June . ..+ .0264 ± .0972 June - .1062 + .0952 



July . .+ .1481 ± .0951 . July . + .0533 + .0960 



August.. + .2777 + .0898 August - .1219 ± .0948 



September.. ..+ .2593 ± .0907 September... + .0742 ± .0958 



October - .0178 ± .0971 



November + .3600 ± .0847 



December + 0140 ± .0973 



Table 3 includes five months with a correlation coefficient more than twice as 

 large as the probable error. The sunshine of these five months — May, August, 

 September, and November of the preceding year and February of the crop \ ear 

 — seems, therefore, to be responsible to a considerable extent for the size of 

 Massachusetts cranberry crops. 



May 



On many Massachusetts bogs, the winter flood is retained for a large part of 

 May. The oxygen demand of flooded vines is greater at this time than in pre- 

 ceding months because of the higher temperatures prevailing. Consequently, 

 sunshine is of great value because it contributes to the maintenance of high 

 oxygen content in the flooding water. On bogs from w'hich the winter flood has 

 been withdrawn earlier, the sun contributes substantially toward building the 

 reserves for the coming season's growth. 



Atigust, September, November 



The value of more than normal sunshine in August, September, and November 

 of the year before the crop year is apparently' related to the accumulation of 

 sugars and starches which help the vines to withstand the rigors of winter and 

 provide the necessary supplies for new growth, flowering, and fruiting the follow- 

 ing year. Harvesting operations may be responsible for the lack of correlation 

 between the sunshine of October and the size of the crop. The disturbed vines 

 are exposed to drying weather, the leaves lose their orientation to the sun's ra\s, 

 and the roots are injured so that water rather than sunshine becomes the Hniiting 

 factor. 



February 



As a result of careful and prolonged studx' of the relationship of winter sun- 

 shine to flooded cranberry vines, Bergman^' has concluded that reduced sunshine 

 results in oxygen deficiency in the flooding waters and this in turn affects the 

 vines. Leaf drop and loss of flower buds occur and tend to reduce the crop. The 



" Mass. Agr. Expt. Sta. Bui. 402, 1943. 



