(a) Cloudy days the rate of photosynthesis will decrease because sunlight is necessary for photosynthesis . On a cloudy day , threre will be less sunlight.
(b) No rainfall in the area the rate of photosynthesis will decrease because water is one of the raw material needed by plant for photosynthesis . If there is no rainfall in an area, there will be less water available to plant.
(c ) Good manuring in the area the rate will increased because plants need raw minerals such as N,P,Fe, Mg, etc., for building their body and take these minerals from thr soil. Good manuring in the area will increase the amount of these minerals in the soil thus increasing photosynthesis.
Stomata get blocked due to dust the rete will decrease because `CO_(2)` gas required for photosynthesis enters the leaves through the stomata. If the stomata gets blocked due to dust , less `CO_(2)` or no `CO_(2)` would enter the leave and the rate of photosynthesis will drop .
