Nitrate reductase was found in leaves of apricot Prunus armeniaca, sour cherry P. cerasus, sweet cherry P. avium, and plum P. domestica, but not in peach P. persica, from trees grown in sand culture receiving a nitrate containing nutrient solution. Nitrate was found in the leaves of all species. Nitrate and nitrate reductase were found in leaves of field-grown apricot, sour cherry, and plum tre...