After mixing with different substrates, Trichoderma TCT-P003 was subjected to liquid fermentation and subsequently applied to top-grafted pear cultivation. Under identical cultivation conditions, the treatment enhanced leaf stomatal conductance and net photosynthetic rate, thereby increasing carbohydrate accumulation in plant tissues. These physiological improvements contributed to cell membrane protection, alleviation of low-temperature-induced damage, and regulation of osmotic pressure, ultimately sustaining the growth of both scions and fruits. Furthermore, the application significantly reduced stress injury while markedly improving fruit quality and weight.