The Relationship Between Competitive Ability And Yield Of Spring Wheat Varieties In Semiarid Area

By field and pot experiments, deWit series experiments were implemented to measure competitive ability of shoot and root respectively, water use efficiency (WUE) and yield of three spring wheat varieties which include the landrace Heshangtou, the middle variety Dingxi-24, the modern variety Longchun-8275. The subject is to investigate the relationship between competitive ability and yield.Heshangtou and Longchun-8275 were selected as the experimental materials in the field experiments. The two varieties were planted separately and mixed according 1:1. And two water levels were designed.In the pot experiments, two different water levels, three combinations of any two varieties, five special sowing ratio in each combination, and six controls were designed.There are several important results from the two experiments.1. In the field experiments, as for photo synthetic rate, when varieties were planting separately, Longchun-8275> Heshangtou; when mixed under higher water level, the result is the same.2. In the field experiments, as for chlorophyll content, Heshangtou is not influenced by the water level. While Longchun-8275 is effected also by water levels and planting pattern. The results also show that the two varieties' summit of chlorophyll content are both earlier than planted separately when they were mixed under lower water level.3. The dry shoot weight, dry root weight and tillers of Heshangtou and Dingxi-24 are all more than Longchun-8275. While shoot-root ratio and harvest index of Longchun-8275 are both the biggest.4. Longchun-8275 has the highest harvest, followed by Heshangtou and Dingxi-24 in decreased order, while root competitive ability is consistent with shoot's which ranged from highest to lowest is Dingxi-24, Heshangtou, and Longchun-8275. WUE ranged from the higher varieties of Longchun-8275, Dingxi-24 to the lower landrace Heshangtou. The results showed that Longchun-8275 which yield is higher has lower competitive ability and higher WUE, while the other two varieties which yields are lower have higher competitive ability and lower WUE.