Catalyzes the hydrolysis of phosphoanhydride bonds of nucleoside tri- and di-phosphates (By similarity). Involved in the regulation of pollen and anther development. a ribonucleoside 5'-triphosphate + 2 H2O = a ribonucleoside 5'-phosphate + 2 H(+) + 2 phosphate Detected in mature pollen grains (at the protein level). Also expressed in the veins and hydathode regions of rosette leaves. No visible phenotype. Apy6 and dapy7 double mutant exhibits late anther dehiscence and low male fertility. Pollen grains of double mutant are largely deformed in shape and in most cases, the cell walls of the pollen grains are interconnected. Belongs to the GDA1/CD39 NTPase family.