| Experiment was conducted in experimental station of Institute of agriculture science of Baoding during2012-2013. The effects of sowing dates(May23rd, June5th, June12th, June23th and July6th which denoted by Ⅰ,Ⅱ,Ⅲ,Ⅳ and Ⅴ) and densities(37.5,52.5,67.5;60.0,67.5and75.0plant/m2) and rate of fertilizer(N, P and K) on plant traits, growth and development and yield of different millet varieties were studied. The lodging resistance and biomechanical properties were also studied in order to find out the most suitable sowing date, the suitable density and fertilization rate to provide theoretical basis for lodging resistance, preventing ageing and optimizing cultivation techniques of summer millet. The results were showed as follows:1. Sowing dates and yield were closely related. From the comparison of sowing dates, the higher yield was in the second and fourth sowing date and the lowest in the first sowing date. Dry weight of various organs and per plant were first increased and then decreased with a late sowing date. For different sowing dates, chlorophyll content and photosynthetic rate increased at first and then decreased with the growth process and reached the peak at heading stage.2. Yield was positively correlated with the temperature after15days of emergence (r=0.6364**). The early sowing would make temperature relatively low at seedling stage and the incidence rate of red leaf, rough dwarf and white hair disease was high, which seriously affected the harvest spikes. At the same time, the early sowing and early mature was easy to attract birds and yiled was decreased. The late sowing would make the average temperature decrease during growing period, which was not good or grain filling and yield was decreased.3. With the sowing date delaying, the growth period was significantly shortened. The suitable sowing period of summer millet was June5th～June27th in middle area of Hebei province. Light and water resources and condition during the range of this sowing date was most appropriate which obtained the best yield.4. The effects of different fertilizers on grain yield were N>K>P. According to the results of yield of interaction in density and fertilizer, the grain yield was higher when the density, amount of fertilizer application of N, P and K was60.0plants/m2,15.0g/m2,15.0g/m2and15.0g/m2respectively.5. There were significant influence among different densities on plant height, spike length, grain ratio and dry weight of B213. With the increasing of density, plant height and grain ratio first increased and then decreased, the spike length decreased significantly and the chlorophyll content of flag leaf was lower of B213under the experimental conditions.6. Lodging resistance was closely related to varieties, N fertilizer level and densities. Smaller ratio of length/diameter in the second stem (short and thick), higher bending resistance of stem and breaking resistance, more toots and heavier root weight of summer millet made the lodging resistance ability better. With the increase of density, plant height, center of gravity and ratio of length/diameter increased, internodes were extend and thin, but bending resistance of stem and breaking resistance would be decreased, then stem lodging resistance was weakened. With the increase of N fertilizer level, bending resistance of stem and breaking resistance would be decreased. With the increase of N fertilizer level and densities, dry weight of various organs and internodes, stem bending resistance of40cm and breaking resistance were decreased.7. Under experimental conditions, the grain yield and lodging resistance was higher when the amount of fertilizer application of N was15.0g/m2and the density was50.0plant/m2. |
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