why heavy rainfalls on a fruit orchard might reslts in a poor fruit yield?

Answer 1

A plant's defense to stress is to increase seed production. This will help with the chances that future generations will carry on. Drought is definitely a stressor. You can notice an increased fruit / seed production following a drought. If a plant is completely happy it will put less effort into reproduction and more effort into growing.

Answer 2

heavy rainfall can damage the forming fruit - pitting the skin and letting bacteria enter. They can also swell the fruit too much, if the rainfall goes on too long, causing the skin to burst.

Either way, a lot of fruit can be damaged, which lowers the yield of healthy fruit

Answer 3

If the rain falls when in flower and the flowers have not been pollinated, you lose a lot of fruit. It happens to my cherry trees all the time.

Answer 4

the polination levels will be dropped. Resuilting poor fruit yield