Which stage of photosynthesis requires water to complete the chemical reaction?

The reaction is the conversion of NADP+ TO NADPH'. Photosynthesis happens in an organelle of plant cell known as chloroplasts. This contain the pigment chlorophyll needed for the reactions for photosynthesis. Water is needed in LIGHT REACTION. The reactants needed in this reaction are water, carbon dioxide. The products that are usually produced are glucose and oxygen.  Light reaction is the initial step in photosynthesis. The energy from sunglight is absorbed by chlorophyll. The energy is then converted to two molecules ATP and NADPH which are both needed in the second reaction of photosynthesis, the electron transport chain.