Studies On The Effects Of Fertilization, Irrigation And Some Other Means To The Seed Production Of Wild Elymus Nutans In Tibet Area

Tibet is located in the westerlies of the North Hemisphere, where the average altitude is more than 4 000 meters and the climate condition is extremely severe with the oxygen deficiency. According to the statistics, the area of its natural grassland is about 8.1 million hm2. But recently, due to the unreasonable utilization of the grassland and the change of the climate, the degeneration becomes serious and the degeneration area comes up to 1.1428 million hm2. The change of the climate in the Qinghai-Tibet Plateau(including Tibet) not only affected the climate in China, but also affected that in the whole North Hemisphere. It is also the place of the origin of many rivers both in China and East and South Asia, and usually called "the Water Tower of China "or "Roof of the World". So the exploitation on the grassland animal husbandry and research on its ecology are meaningful to the politics, economy and society both in China and the whole world.In this study, four kinds of wild Elymus nutans which were collected in different regions of Tibet and one cultivar planted in Qinghai Province were planted in the base of Seed Production Techniques of High Quality Wild Forage in Tibet of the countryside Caina, qushui, Lasa, Tibet(N 29°28′09″,E 90°56′45″, altitude is 3 602 m). All the seeds were provided by the Animal husbandry Terminus of Tibet. A random group, mixed-orthogonal, three factors quadratic regressional orthogonal rotation design was adopted in order to make some studies on the effects of fertilization, irrigation and some other means to the seed production and seed production's constituents. Some conclusions were obtained as follows:(1) Nitrogen can contribute significantly to the promotion of Fertile tiller and fertile Florets of baqing wild Elymus nutans. With the increase of N thousand-seed weigh also will be increased, but there was no a significant effect in Spikelets per fertile tiller and florets per spikelet. Nitrogen can be increased the actual seed yield of Tibetan wild Elymus nutans. The result indicated that N 250 kg / hm2 produced the optimal effect, to assume 2 016.5 kg / hm2 seed yield. The more reprodutive shoots per area there are, the higher seed yield will be got, so the suggestion is more attention should be paid to the ways of increasing the number of effective tillering and reproductive shoots on the seeds production of Elymus nutans in Tibet.(2) Through these experiments, it is found that all treatments would get the highest yield when the nitrogen was applied 250 kg/hm2. Among all the four species, the Seed production of Baqing wild Elymus nutans was the highest, Nagqu wild Elymus nutans and vertical spike Shenza wild Elymus nutans respectively came to the second and the third while the cultivated specie from Qinghai preformed the worst. So, in the restoration process of the grassland ecosystem in Tibet, Palestinian and Nagqu wild Elymus nutans should be spreaded as the dominat species.(3) The two main factors affected the seed production of Wild Elymus nutans in Tibet were cultivars and nitrogen, then came to water. Under the condition of this experiment, the application of P had no significant effect on the seed production.