Review of walnut breeding research at the Shandong institute of pomology

At present, problems exist in walnut production in China. These include the diversity and at times low quality of available cultivars suggesting a need to simplify types and uses, the prevalence of serious diseases and the susceptibility to late frost damage. Together these are restricting the sustainable development of the industry. In the 21st century, Shandong Institute of Pomology, using intraspecific plus interspecific hybridization breeding and seedling selection, has created a collection of new walnut germplasms. Intraspecific hybridization breeding has created 15 new early fruiting walnut cultivars and 20 superior lines with independent intellectual property rights. Lines have been developed for different uses (fruit and timber, spur type, big fruit type), capable of avoiding frost, containing disease and cold resistance. The Institute has created 2 cultivars, with cultivar rights of plant in China registration, and 12 superior lines by cross breeding (early fruiting walnut × wild walnut). 3 superior plants have been bred by hybridizing early fruiting walnut and American black walnut. The characters of these cultivars, superior lines, and superior plants are a major breakthrough in Chinese walnut breeding.