Field experiments were conducted during spring 2014 and 2015 at Punjab Agricultural University, Ludhiana, to study the effect of staggered sowing on photosynthetic parameters and the productivity of sunflower (Helianthus annuus L.) in relation to foliar application of boron (B) and TIBA (Tri iodo benzoic acid-TIBA). The experiment was laid out in split plot design with three sowing dates (January 20, February 10 and March2) in main plots and eight foliar spray treatments (Control, water spray, B @ 110, 220, 440 ppm, TIBA @ 100, 200 and 400 ppm) in sub plots replicated thrice. The results indicated that delay in sowing caused significant reduction in biological and seed yield of sunflower probably due to significant reduction in photosynthetic parameters coupled with reduction in crop duration from 119 to 92 days. Foliar application of boron and TIBA improved the dry matter accumulation by leaf and seed as well as total but dry matter accumulation by stem did not vary at 90 DAS. Marked improvement in photosynthetic parameters coupled with better growth indices due to TIBA- 100, 200 and 400 ppm and boron 220 and 440 ppm increased crop productivity over control and water spray by way of improved DM partitioning. Correlation studies indicated significant positive correlation of seed yield with PAR, chlorophyll content and stomatal conductance at 90 DAS, emphasizing the importance of higher growth and photosynthetic rate during reproductive period for best yield accrual from sunflower.