Division of Plant Physiology, Indian Agricultural Research Institute, New Delhi - 110012.
1Present address: NRC on Banana, 44, Ramalinga Nagar, South Ext Vayalur Road, Trichy-620017.
Bract photosynthetic and respiratory activity in comparison with leaf were studied in sunflower cv. MSFH-8. During the ontogeny, bract net photosynthetic rate was found negative in the initial stage and it gradually increased in the later stages. The highest bract photosynthesis relative to leaf was 9.96 per cent at seed filling stage. The lower photosynthesis rate of bracts relative to leaf was attributed to the lower stomatal conductance, low chlorophyll concentration and nitrogen content. In addition, stomatal CO2 concentration (Ci), which was 20 to 27 per cent higher compared to leaf, indicated lower mesophyll efficiency of bracts compared to leaves.
Bracts, chlorophyll, photosynthesis, respiration, sunflower
