The relationship between chlorophyll a fluorescence parameters and yield components in sunflower hybrids

The sunflower is considered one of the four most important oilseeds globally. The study was conducted on 16 sunflower hybrids in field conditions to link photosynthesis parameters with yield components using chlorophyll a fluorescence parameters (ChlF), chlorophyll content, leaf temperature and agronomic traits. By analysing the ChlF parameters in the flowering stage of sunflower hybrids, a statistically significant difference was found between the studied hybrids for all the ChlF parameters except for the photosynthetic efficiency index of energy required from exciton to the reduction of ultimate electron acceptors on photosystem I (PItotal). At the same time, the results confirmed the significance of the chlorophyll content, leaf temperature, and agronomic traits for the studied hybrids. The indicators of photosynthetic efficiency showed a significant correlation between the efficiency with which the electron can reduce the final electron acceptors to photosystem I (RE0/ET0), PItotal and plant height. Also, the number of seeds per head showed a positive and very significant correlation with variable fluorescence in step I (VI) and a very highly significant negative correlation with the energy flow which reduces electron end acceptors on the acceptor side of photosystem I (RE0/RC). Using these analyses in sunflower breeding programmes could improve productivity and performance optimisation under changeable growing conditions.