Dry matter accumulation and tuber yield in potato as affected by defoliation

Field experiments were conducted at the Central Potato Research Institute, Shimla for three years to investigate the optimal leaf area required for maximum efficiency in an ideal potato plant. Different leaf areas were maintained at different levels following the defoliation technique. During the first two years, when only top four leaves were retained, the reduction in total dry matter ranged from 40.3 to 50.1% while reduction in tuber yield varied from 34.3 to 51.8%. Yield reduction was, however, maximum when only the middle leaves were retained and the remaining leaves removed. There was an increase in the net photosynthetic rate of the fourth leaf from top when the lower leaves were removed indicating the existence of a compensatory mechanism. But no such compensation was observed in case of leaf chlorophyll content.