Without pollination the seeds and fruit will not develop. Most plants have male and female flowers parts on the same flower and are easily pollinated by wind or insects. One cause of poor fruit set is too much nitrogen, which can result in mostly vegetative growth. This is especially true with tomatoes, peppers, and cucumbers. Too much shade or not enough light is another cause of poor fruit set.
Extreme temperatures can reduce fruit set.
If temperatures during flowering are below 55 degrees or above 90 degrees, the pollen grains of many warm-season vegetables are damaged and become unable to cause pollination. To produce fruit, pollen from the male bloom must be transferred to the female bloom. Insects, mostly bumblebees and honeybees, transfer the pollen. Unless the plant is actively producing both male and female bloom or if insects are not working the bloom, pollination and fruit development will not occur. Corn plants produce a female flower, the silks, and a male flower, the tassel.