Effects of Ratio between Basal Fertilizer and Top-dressing on the Accumulation of Dry Matter and Carbon-nitrogen Metabolism of Flue-cured Tobacco

According to the research of the accumulation of dry matter and carbon-nitrogen metabolism which are affected by the ratio between basal fertilizer and top-dressing,the results show that,1.the accumulation of dry matter was focus on 30～60 days after transplant.Under the same condition of fertilization,the speed and quantity of accumulation of dry matter increases with the increase of top-dressing ratio.The leaves accumulation of dry matter was focused on 30～60 days,the stalks 45～75 days,the roots 45～60 days,the accumulation of dry matter in every part of plant enhance with the increase of top-dressing ratio.2.the photosynthesis was declined quickly on 30 days,within 30～60 days was steady,and with the increase of top-dressing ratio,the photosynthesis was smaller,declined after 60 days,after 75 days declined was slowing,along with the increase of top-dressing ratio the descend slowly.The chlorophyll of tobacco was steady in the early growth period,and the effect by ratio between base fertilizer and top-dressing was small;in later stage of growth,it declined quickly,with the increase of top-dressing ratio,the chlorophyll was enhanced.3.the nitrate reductase activity was higher in the early growth period,declined quickly after 45 days,60 days later it's steady and increased slightly.4.the yield of tobacco was increased with the increase of top-dressing ratio,but after more than 70% it decreased.Fertilization with basal fertilizer and top-dressing better than only use basal fertilizer or top-dressing.Integrated consider production value、average price and ratio of good grade tobacco,we believe that the disposal of C is best.