During stage 1, what effect does mild water stress have on the stage and the size of grapes?

• A. speed up this stage; smaller.
• B. slower stage; larger grapes.
• C. no effect; normal grapes.
• D. reverse this stage; seedless grapes.

Answer: (B)

Stage 1 is the phase of rapid berry growth, driven by cell division and expansion. When mild water stress is applied at this stage, the vine’s growth slows because turgor pressure and overall metabolism are reduced, so the development of the berries takes longer. At the same time, the stress can limit the number of berries or limit competition for resources, so the berries that do form can accumulate more assimilates per berry. The net effect described here is a slower progression through stage 1 with larger berries, compared with fully watered vines.