Abstract
Quercus variabilis is a widely distributed species of cork oak in East Asia, with significant ecological and economic value. However, its slow growth rate limits its overall value and applications, and the ploidy advantage of multiploidy can improve its growth rate. Therefore, it is of great significance to establish a technological system to artificially induce polyploidization (2n) pollen for of Q. variabilis. Colchicine injections and high-temperature treatments were administered to the floral buds to induce 2n pollen in Q. variabilis. The impact of colchicine injection and high-temperature treatments on the surface structure of 2n pollen grains and pollen viability was examined using scanning electron microscopy and in vitro germination tests. This study differentiated the characteristics of flower bud development and meiotic stages of microspore mother cells of Q. variabilis, induced 2n pollen in Q. variabilis through colchicine and high-temperature, respectively, and compared the effects of different induction methods on pollen. The most effective condition for inducing 2n pollen (13.54%) using colchicine is to inject a 0.5% colchicine solution seven times when microspore cells enter the pachytene stage. The most effective condition for high-temperature induction of 2n pollen (29.63%) is to apply a six hours of 42°C heat treatment as microspore cells enter the metaphase Ⅰ stage. Comparatively, high-temperature treatment is more effective in inducing 2n pollen in Q. variabilis. This lays an important foundation for further development of triploid germplasm innovation in Q. variabilis. It also provides a new approach for the polyploidy of Quercus species.