Influence of leaf angle atlerations on photosynthetic rate and tuber yield in potato*

The effect of leaf angle on net photosynthetic rate (P_N) and yield was studied in two potato cultivars viz. Kufri Jyoti with naturally oriented leaf angles ranging from 45° (upper) to 85° (bottom) and Kufri Chandramukhi having leaf angles ranging from 40° to 63°. Leaf positions were altered with the help of aluminium wires to get leaf angles of 30° (erect), 60° (intermediate) and 90° (horizontal). There was no significant difference in the chlorophyll content between control and 30° in the pre-tuberisation stage in Kufri Jyoti but in Kufri Chandramukhi, chlorophyll content was higher in 30° and 60° compared to control. In the post-tuberisation stage the differences in chlorophyll content between treatments were non-significant. The P_N of the fourth leaf was higher in control at 40 days after planting (DAP) but at 70 DAP and beyond, the differences were non-significant. The tuber yield was reduced by 38.9% and 30% with leaf angles at 60° and 90° respectively, but there was no significant difference between control and 30° leaf angle. P_N did not correlate significantly with the tuber yield while there was a negative correlation between leaf angle and tuber yield (r=−0.69; P<0.01). The results of this study indicate that altering the leaf angle to 30° did not improve the net photosynthetic rate or tuber yield in potato.