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Effect of varying levels of nitrogen, phosphorous, potassium, and calcium on the quality of the Newburgh raspberry Enns, Peter Bernhard


The Newburgh raspberry, ever since its development at the New York State Experiment Station, Geneva, New York, has been noted for its superior vigor and productiveness, and its ability to withstand winter injury even in areas in which, a high water table is common. In many districts of the Fraser Valley, in which restricted sub-surface drainage is prevalent the variety was received enthusiastically largely because of these qualities. During the period of World War II and the immediate postwar years there was an increasing market for sulphur dioxide preserved berries to supply the overseas demand. Since a ready market awaited all the fruit that could be produced, yield became of paramount importance, and quality received little attention. Under these circumstances the Newburgh became the dominant variety in the new plantings. In some of the newer districts of Sumas Prairie, Yarrow and Chilliwack, this variety accounted for as high as 90% of the total raspberry acreage. With the termination of the overseas contract in 1945, the market for sulphur dioxide preserved berries was virtually wiped out, leaving the berry industry dependent largely on local and American markets for the fresh and frozen product. This situation brought the weakness of the Newburgh into the limelight. Its low sugar content, resulting in a rather acid flavor, began to draw increasing criticism. Likewise its adaptability for the quick freeze method of preserving became rather doubtful. A product is said to possess freezing qualities to the extent that it retains, during and after freezing, its natural shape, colour and flavor. Due to its high water content, the Newburgh does not retain its shape very well. Its relatively low sugar content often results in too tart a flavor, or, if acidity also is lacking, gives it a flat taste. Since the Newburgh possesses characteristics which make it particularly suited to certain areas, the question arose, whether fertilizer treatments could be used to improve its quality. Considerable work has been done in the past on the effect of fertilizer treatment on plant growth, general vigor and yield. Not until quite recently, however, has any attention been given to its effect on the quality of the crop produced. The purpose of the present experiment was to ascertain the effect of varying amounts of nitrogen, phosphorous and potassium in the fertilizer applied on the quality of the Newburgh raspberry. Determinations were made on sugar content, vitamin C. content, total solids, soluble solids, proteins, acidity, total minerals, flavor, and freezing quality, all of which are important characteristics of quality.

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