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Corn in Mississippi

Will center-pivot irrigation hurt pollination?

Corn possesses a vast overabundance of pollen and several traits which make the pollination process relatively immune to overhead irrigation or rainfall disturbance.

Tassels with emerged anthers

emerged silk
Tassels with emerged anthers (left) and emerged silk (right).
Corn produces a huge overabundance of pollen grains (3-5 million per plant) which fertilize about 600-700 kernels per ear (>4000 pollen grains per silk). Physical disturbance caused by overhead irrigation occurs over a very short time period in relation to corn pollination capacity. Pollen shed normally lasts 5 to 8 days, during which pollination may occur at any time. Corn plants also have an innate ability to stop pollen shed when the tassel is too wet or dry and trigger pollen shed when conditions are favorable. Additionally, silks are quite sticky, which makes pollen grains hard to wash off after they land on a silk. Thus, the physical disturbance caused by overhead irrigation will not reduce corn pollination in a normal field/agricultural environment.

Insufficient irrigation during the pollination period is actually much more likely to hurt pollination and kernel set. Corn's water use rate is highest during a four week period following silking. Corn grain yield is extremely sensitive any type of stress, including water deficiency, during this time. Ample moisture helps plants maintain photosynthesis and transpiration rates at high levels. These processes are responsible for producing energy and cooling plants, respectively. Thus, if water deficiency limits corn growth during pollination and early kernel fill, considerable grain yield reduction will occur.