Suboptimal (too low or too high depending on the crop) temperatures and humidity at the time of the pollination are known to cause erratic pollen tube growth, resulting in lower fertilization rates and the emergence of poor seed set among crops. Windy, cool or wet weather might prevent pollinators from operating normally, and rain can impede the movement of pollen in wind-pollinated species by soaking pollen as anthers open and washing much of it to the ground. Those factors as well as the general landscape configuration are intrinsically linked to the pollinator population that is present in the area of operation, which must be of adequate size to ensure the good pollination of crops grown for seed production. Dense urban areas are reputably known to be a challenge and often call for the implementation of appropriate solutions when natural pollinator population is insufficient (i.e., physical crop isolation with manual introduction of pollinators). Regardless of your location, it is often considered good practice to plant herbs and flowers known to attract pollinators, which will increase the chance of your seed crops being pollinated.
Caused and aggravated by habitat destruction, insecticides such as neonicotinoids, parasitism/diseases, and climate change, pollinator decline can lead to significant phenological and spatial disturbances. In the first case, species that normally occur in similar seasons or time cycles, now have different responses to environmental changes and therefore no longer interact (i.e., a tree may flower sooner than usual, while the pollinator may reproduce later in the year and therefore the two species no longer coincide in time). Spatial disturbances occur when two species that would normally share the same distribution now respond differently to climate change and are shifting to different regions.
The presence of sufficient airflow also constitutes an essential factor in the pollination of self and wind-pollinated plants especially – helping to move the pollen from the anthers onto the stigma of the same closed flower in selfers (tomatoes, peppers, common beans, peas). In case where airflow is lacking, selfers can be manually shaken to induce pollination and thus fertilization. A high insect activity can, however, increase the overall amount of seed set in self-pollinated crops by stimulating the effectiveness of pollen shed by physically moving the flowers. In the case of plants relying on wind such as corn or amaranth, several consecutive days of still air during the flowering phase can indeed hinder full seed set due to low pollen circulation in the air.