Weed-Resistant Potential Assessment Of Main Cultivated Wheat Varieties In Guanzhong Plain

Wheat, a major kind of grain and forage crop, occupies an important position in agriculture.Guanzhong plain is the chief wheat-grown area in Shaanxi Province, and the stable and high wheat production in this region is of great significance to the grain production in the whole province. Descurainia sophia and Galium tricorne, which are dominant weed species in Guanzhong irrigation area, accompany and interfere the growth of wheat during the whole vegetative and developmental phases, and lead to serious losses in quantity and quality in wheat production. Reducing weeds by exploiting allelopathy of some wheat varieties would result in less application of chemical herbicide to agricultural ecosystem to a certain degree, therefore, it could be possible to control weeds and protect the entironment effectively and sustainably.The main work and results of this study are as follows:1. Choosing D. sophia and G. tricorne as donors, effects of water extracts of their seedlings'overground part on 15 wheat vatieties were studied on seed germination and seedling growth. It was found that allelopathic effects of the two weeds on the same wheat varieties were different, and allelopathic effects on different wheat varieties of the same weed were also different.The results showed that four varieties—Xiaoyan 22, Xinong 88, Xinong 979 and Xinong 889 were insensitive to the two weeds'allelopathy, i.e., the four varieties showed relatively strong resistance to the two weeds'allelopathy.2. The results indicated that by means of comparing total subjection values or chuster analysis, RI values of vigor index, shoot height, root fresh mass and primary root number could be used as indicators to select wheat varieties that may have strong resistance to D. sophia and G. tricorne's allelopathic effects.3. By means of simultaneous-seeding cultivation, relay-seeding cultivation and potted cultivation, allelopathic effects of different wheat vatieties on D. sophia and G. tricorne were determined. Accoring to the results, the outcomes of bioassay under different cultivation were significantly different. Among the three culture methods, relay-seeding cultivation could reflect the difference in allelopathic property among wheat vatieties the most effectively.4. Assessing the allelopathy of the wheat varieties tested according to the results of relay-seeding cultivation, it was found that Zhengmai 9023, Xinong 889 and Xiaoyan 6 had strong allelopathic effects on D. sophia, while Tongmai 3, Yuanfeng 175 and Shaannong 981 had strong allelopathic effects on G. tricorne.5. The results indicated that RI values of whole plant fresh mass could reflect the difference in allelopathy among wheat vatieties the most effectively. However, it was preferred to assess the difference in comprehensively allelopathic effects of wheat varieties by means of comparing total subjection values or chuster analysis.