| Elymus sibiricus L. is one of excellent quality forages, which has been widely used for artificial grassland establishment, rangeland improvement, and rangeland ecological protection in the Qinghai-Tibet Plateau. Strengthening seed production of E. sibiricus L. may solve the contradiction between demand and supply of seeds. But its relevant technology of seed production has been lagging hehind. In the present study, the State Approved Variety'E. sibiricus L.cv.chuancao NO.2'as being test material, which is mainly applied in the Sichuan Northwestern Plateau, together with the actual technical requirement for seed industrialization, we investigated the effects of the following factors on growth and development, photosynthesis, reproductive investment, production capacity, weed species and seed vigor. The factors studied include different gradient sowing rate, row spacing, fertility, cultivation year, the ways of weed cleaning and harvesting time. After 4-5 years of study, the main results are:1. Row spacing is highly significantly associated with seting percentage, presentation seed yield and harvested seed yield. The highest seed yield was obtained when the row space is 60cm. This may be worth spreading in practice. There are several possible explanations. Row spacing is significantly associated with tiller number and fertile tiller per square, fertile tiller ratio, fertile tiller height, fertile tiller diameter. Row spacing is also significantly associated with length and diameter of ear stalk, cob length, number of spikelet and floret per fertile tiller.2. Row spacing and fertilizing amount are the key factors to affect yield of E. sibisicus L, via effects on density and height of branch, ratio of fertile tiller, and spikelet per fertile branch.The highest grass yield was observed at the row space of 40cm and compound fertilizer of 225kg/hm2, and the highest seed yield was obtained at the row space of 60cm and compound fertilizer of 225kg/hm2.3.Mixing fertilizers and herbicides is significantly associated with tiller, growth rate and production performance of E. sibiricus L. Among different types of mixing of fertilizers and herbicides, seed yield of E. sibiricus L. was higher in the following groups than the control group, including 7500g/hm2 (NH2)2CO+300g/hm2 KH2PO4+27g/hm2 75% tribenuron dry SC,7500g/hm2 (NH2)2CO+75g/hm228% WP T-Y and 15000g/hm2 (NH2)2CO+300g/hm2 KH2PO4+75g/hm228% WP T-Y. Overall, mixing fertilizer and herbicides is worth applying widely, which may reduce the number of field operations, management cost, and achieve the dual effect of fertilizing and weeding.4. Different basal fertilizer and top dressing fertilizer had highly significant effect on traits of inflorescence and seed yield of E. sibiricus L. (P<0.01). The phenotype affected most is the harvested seed yield, and then, potential seed yield, presentation seed yield, fertile tiller density, florets/branch, seeds/branch, and that affected least is the seeding percentage. The harvested seedyield is mainly affected by the interaction of cultural year and fertilizer.5. Supplying nitrogen during the tillerring stage and jointing stage significantly increased hay grass yield of 2nd and 3rd year (P<0.05). However, Supplying nitrogen during the booting stage is negatively correlated to grass yield of the next three years. Supplying potassium and phosphate during any of the following three stages, tillerring, jointing and booting, is negatively correlated to hay grass yield. The component of basal fertilizer is associated with harvested seed yield of 1 to 4 year. Supplying nitrogen in the tillerring stage and jointing stage is associated with higher harvested seed yield. Applying phosphorus or potassium either in the tillerring, jointing or booting stage didn't significantly promote seed yield.6. Photosynthetic rate had a significantly positive correlation to presentation seed yield and harvested seed yield because of the significantly positive correlation between photosynthetic rate and number of floret and seed per fertile tiller. But photosynthetic rate had a significantly negative correlation to grass yield because of the significantly negative correlation between photosynthetic rate and vegetative shoot, total tillers. Therefore, in order to increase seed yield, we may timely irrigate to improve the relative humidity and plant water status in vivo, which may promote photosynthetic rate and accumulate photosynthetic dry matter by changing transpiration rate.7. Seed of E. sibiricus L. began to shatter at 20d-22d after flowering stage. Seeds shattere via two ways-off seedstalk and off spikelet pedicel, with seedstalk shattering being the major one. The shattered rate is 4.73%,20.78%,75.67%,87.73%, respectively, at the time of milk stage, dough stage and to full ripening stage. Therefore, seed of E. sibiricus L. should be harvested in the dough stage (36d-40d after flowering). When seeds are almost mature, lodged, the plant showed low shattered rate and large 1000-seed weight. The starting and ending time of seed shattering is significantly negative correlated to the height of plant and diameter of pedicel. In the early milky stage (26d after flowering), the density of population and diameter of stalk affected seed shattering significantly. However, the length of awn was still the main factor to stimulate seed shattering (R=0.9971). In the ripening stage (32d-36d after flowering), the following factors are associated with larger number of shattered seed, high plant, fine branch, few spikelets/branch, and more florets/branch. In the full ripening stage, the seed shattering is significantly negative correlated to the density of population and diameter of stalk.8. Seed of E. sibiricus L. had strong dormancy, with about 200d dormancy period. After seed is stored 30d, the germination energy is only 0～0.75%, and germination rate is only 0～1.25%. When seed is stored 200d, the germination index is 36.05～85.48, and vigor index is 4.28～26.59.9. For seed of E. sibiricus L., row spacing was significantly positive correlated to the activity of acid phosphatase (R=0.6673). Row spacing had a certain positive correlation to 1000-grain weight, germination index, vigor index and soluble sugar contents. However, negative correlation is observed between row spacing and the relative conductivity and dehydrogenase. Amount of fertilization is positively correlated to germination index, vigor index and soluble sugar content. However, negative association is observed between amount of fertilization and the relative conductivity, dehydrogenase and phosphatase activity. Sowing rate significantly is negatively correlated to soluble sugar content (R=-0.5061), and a certain positive related to 1000-grain weight, germination index, vigor index and soluble sugar contents.
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