Answer:
Primary productivity is defined as the rate of conversion of photosynthetic and chemo-synthetic energy by the autotrophs into the organic substances. It is affected by the temperature, light, availability of nutrients and some other factors. It measures photosynthetic productivity.
It is important because it forms the basis of the food web in the ecosystem. It can be measured by the rate of sugar formation, the rate of oxygen production and by the amount of carbon dioxide consumed.