Protected cultivation of vegetable crops, which was given a high priority, developed very rapidly during the past 15 years in China. Sunlight-heated greenhouse and plastic tunnel house were the most common types of protective structures for winter and early spring cultivation of vegetable crops in north and middle China. In 1995, the total area of sunlight-heated greenhouses and plastic tunnel houses was 160,000 ha and 466,800 ha, respectively. Initially, vegetable cultivars commonly used for open field production were grown in protected conditions. Despite various measures, many problems arose due to unfavorable ecological conditions in protected environments. Since the late 1980's and early 1990's, breeding of vegetable cultivars for protected conditions has been carried out. One of the main research efforts included screening and evaluation of breeding materials for tolerance to low temperature, low light conditions, and resistance to diseases. Another effort focused on the creation and development of new breeding materials for protected conditions by selection, introduction, crossing and biotechnological methods, including isolating from good F1 genotypes, wide crosses, tissue and cell culture, protoplast regeneration, and gene transfer techniques. As most hydroponic cultivation is carried out in protected conditions, more cultivars adapted to this type of culture are also urgently needed. There is still a lot of work required to meet the growing demands of protected vegetable production.
