The effect of cycocel (0, 750, 1500, 2250 ppm), nitrogen (0, 50, 100 and 150 kg N/ha) and their interaction was studied, for manipulating the haulm growth under long day conditions in Shillong and Simla hills towards higher tuber yields during 1980 and '81. Visual observations indicated that cycocel sprayed plants were shorter but no significant effect on plant height and shoot number was recorded in the end. Cycocel tended to increase the mean weight per tuber. Application of nitrogen significantly increased the plant height and main stems up to 50 kg N/ha. Tuber number also increased significantly up to 100 kg N/ha both at Shillong at Shimla. The mean weight pee tuber increased significantly up to 100 kg N/ha at Shillong and 150 kg N/ha at Simla. The interaction of cycocel and nitrogen was non-significant.
