This invention describes a new method to increase grain yields in any crop plant by modifying pollination to effect an increase in grain yield, a change in grain content or characteristics, a decrease in contamination, or a combination of these attributes. The process involves the intentional delivery of pollen of the male plant at will, as available either in a preserved pollen bank, or real-time collection from male plants as they become available, in a growth chamber for example. Desired pollen is delivered to fertile females. The delivered pollenM is in such amounts and fortuitously timed that it preferentially pollinates the females and optionally, avoids or enhances self-pollination or pollination from neighboring plants. The intentional delivery of genetically different pollen will result in increased heterosis and accompanying grain yield increases resulting from increased grain size and the potential to influence grain content and constituents. The invention also permits real-time agronomic decision making in order to maximize grain yield by overcoming biotic and abiotic challenges in the growing season which may or may not have been anticipated. The intentional delivery of self- or sib-pollen results in a decrease in contamination from undesirable outcrossing.