Effects Of Fertilizer Application On Seed Yield Formation And Seed Physiological And Biochemical Characters During The Seed Development Of Grasses

Special climatic conditions and field management techniques are essential for forage seed production. It is very suitable for North of China to produce forage seed because of its broad area and enough tradition, but is unfavorable because of its higher altitude, lower temperature, less rainfall and shorter frostless period. Studies were conducted to determine effects of fertilizer application on seed yield formation of grasses and physiological and biochemical characters during the seed development by applying fertilizer, lodging resistance matter (PP333) and thinning within rows in the field, '948' item from 2002 to 2003 in Saibei Administration District. Zhangjiakou, Hebei. The results showed that:Nitrogen (N) was the essential element in forage seed production by comparison with phosphorus (P) and potassium (K). Seed yield increased significantly at N, P and K fertilizer application together. Seed yield of Agropyron cristatum increased significantly at fertilizer application from 2002 to 2003, and was 924.3 kg/hm2 highest in Row Spacing 45 cm at application 45 kgN/hm2 in autumn and 90 kgN/hm2 in spring. In the same amount of N application, seed yield at N application in autumn and spring was higher than that only in spring, the maximum seed yield was 1723.1 kg/hm2 for Bromus inermis at application 135 kgN/hm2 in autumn and 90 kgN/hm2 in spring, 718.9 kg/hm2 for Phleum pratense at application 45 kgN/hm2 in autumn and 135 kgN/hm2 in spring, and 341.4 kg/hm2 for Agropyron smithii at application 45 kgN/hm2 in autumn and 90 kgN/hm2 in spring. Effects of P fertilizer (P2O5) application on the seed yield of Psathyrostachys juncea is greater, and the maximum seed yield was 265.1 kg/hm2 at application 45 kgP2O5/hm2 + 45 kgN/hm2 in autumn and 90 kgN/hm2 in spring, and 341.4 kg/hm2. The lodging percentage of Agropyron cristatum, Phleum pratense and Agropyron smithii increased at the amount of N application over 90 kgN/hm2 and decreased at K fertilizer (K2O) and lodging resistance matter (PP333) application to a certain extent.Fertile tiller number was the most important factor in all the seed yield components. Fertile tillers of Bromus inermis, Agropyron cristatum, Phleum pratense and Agropyron smithii developed mainly from short vegetative shoots after fruit last year which of Agropyron cristatum and Phleum pratense developed from Primary tillers of elongation tillers and which of Bromus inermis developed from Primary tillers of elongation tillers and tillers developing from rhizome this year, and those of Psathyrostachys juncea developed from short vegetative shoots before fruit last year. N application in spring increased fertile tillers of Psathyrostachys juncea next year by increasing mainly short vegetative shoots before fruit this year, and N application in autumn increased fertile tillers of Bromus inermis, Agropyron cristatum, Phleum pratense and Agropyron smithii next year by increasing mainly short vegetative shoots after fruit this year.N application in spring increased seed yield components of grasses, and N application in autumn and spring was in favor of seed yield components of Agropyron cristatum and Agropyron smithii than that in spring in the same amount of N application. P fertilizer (P2O5) application increased mainlyfertile tiller, spikelet number and thousand-seed weight of Agropyron cristatum, and K fertilizer application was in favor of floret, seed number and thousand-seed weight of Agropyron cristatum. Spikelet, floret, seed number and thousand-seed weight of Agropyron cristatum improved by thinning row spacing in two years, and fertile tiller number thinning within row spacing promoted greatly at N application.Different fertilizer application accelerated the increase of seed fresh and dry weight of Agropyron cristatum, Bromus inermis and Agropyron smithii in the developing prophase, and promoted dry weight of seedling and delayed decline of seed moisture content in the seed developing anaphase, and accelerated the increase of germination percentage and seedling length of Agr...