<p>Photosynthesis starts inside the leaf as photosynthetically active radiation (PAR) incident over a green leaf. Water is one of the most essential active and vital elements for photosynthesis, and hence, its function becomes more dispersed in different parts of the leaf during photosynthesis. Biospeckle is a noninvasive and nondestructive technique used to study leaf physiology. This study evaluates biospeckle assessment of the leaves of three plant species- <i>Banyan (Ficus Indica)</i>,<i> Hibiscus mutabilis</i>, and <i>Maize (Zea mays)</i>, which have been subjected to natural variations of photosynthetic photon flux density (<i>PPFD</i>) [0–800 µmol(photons)m⁻²s^− 1] from 6.00 am to 10.30 am during daylight. We observed that the Biospeckle activity (BA) increases as <i>PPFD</i> increases over the leaf surface. We have used the <i>Frequent Motion Image</i> (FMI) algorithm to calculate the average frequency of BA (the quantitative measurement of BA) and for the activity map of leaves. We have also compared the BA result with the chlorophyll fluorescence Quantum yield (Qy) measurement, which is well-established for assessing photosynthetic efficiency. The Average frequency values exhibit a positive correlation with the 1-Qy value. The correlation between both variables has been found to be linear, with a variance of 97% for both the <i>Banyan leaf</i> and the <i>Maize leaf</i> and 94% for the <i>Hibiscus leaf</i>. Our findings demonstrate a positive relationship between biospeckle activity and the chlorophyll fluorescence Qy, highlighting the intricate interplay between photosynthesis and biospeckle activity in leaves. Furthermore, the FMI activity map of leaves at different <i>PPFD</i> demonstrates a strong correlation with photosynthesis.</p>