Abstract: The invention relates to a method of impacting the fruit production of a plant or crop by applying short-duration thermal shock streams of hot air to the plant periodically to impact the flavonoid biosynthetic pathway mechanisms in a plant thereby improving its fruit. The method includes the steps of (1) passing by the plant in a row at a speed in an improved Thermal Plant Treatment (TPT) machine, (2) ejecting from the TPT machine at least one hot stream of air in the direction of the unit plant area, (3) optionally measuring the thermal shock profile that the plant is subjected with thermal sensors, and (4) repeating the thermal shock profile treatment steps (1) and (2) at pre-determined regular intervals over at least a fraction of the crop year.