Through years of research, Yang put forward a new viewpoint and technology of classified evolution and root induction of apple root system and root structure, clarified the relationship between polyamines and apple root growth and development, found that auxin can regulate root calcium absorption through protein phosphorylation, and revealed the role of mitochondria in programmed cell death of apple root system. It is reported for the first time that protein phosphorylation is involved in the triggering of stress messengers in roots under water stress, and three stages of stress signal transmission in fruit trees are defined. It is found that root cutting and pruning can improve the water use efficiency of apples, and many new measures to improve the water use efficiency of fruit trees through roots are put forward, such as "reducing root redundancy, making full use of a few roots", "optimizing the ratio of upper and lower roots" and "implementing alternate irrigation". The construction and research of pollution-free fruit production base was carried out earlier in China, and the paper "Pollution-free Fruit Production Technology" was first published. The systematic technology of producing "green fruit" and the development strategy of "organic gardening" in China were put forward. Four kinds of apple resistance inducers were screened out, and the viewpoint and technology of polyamine, nitric oxide and calcium to alleviate the harm of heavy metal cadmium in apples were put forward. Three books in the field of "fruit safety" were published.
Yang has taught undergraduate courses such as fruit tree research methods, fruit tree cultivation physiology, introduction to pollution-free fruit and vegetable production, introduction to horticulture, introduction to organic agriculture, and postgraduate courses such as fruit tree physiology, plant hormones and chemical control of fruit trees, introduction to agricultural research methods, horticultural plant roots and modern horticulture (fruit trees). He presided over the "Shandong Postgraduate Education Innovation Plan" 1 project, and directed more than 30 masters, doctors and postdoctoral students, among which the postgraduate thesis on "Ultra-weak luminescence of apples, peaches and apricots and its physiological and biochemical mechanism" won the "Excellent Dissertation of Shandong Province".