Efefct Of Plant Density, Nitrogen, Phosphorus And Potassium Application Rates On Sugar Content And Biomass Of Sweet Sorghum

The new sorghum Jida104，selected by Jilin University were used as the trialmaterial. Using orthogonal experiment design, through the study on the effect ofplanting density and fertilizer application rates on morphology traits, photosynthetictraits, ultimately sugar yield and biological yield of sweet sorghum, to seek theoptimal planting density and fertilizer applications in the highest sugar yield forsweet sorghum, and to provide a theoretical basis and technical support for sweetsorghum cultivation. The study made following conclusions:(1) Nitrogen fertilizer application rates and planting density bring a significanteffect on plant height of sweet sorghum. Effects of nitrogen application rates andplanting density on sweet sorghum stem diameter have reached a significant level.The effect of phosphate and potash fertilizer application rates on plant height andstem diameter traits of sweet sorghum is smaller. Plant height and stem diameter ofsweet sorghum was positively corrected with nitrogen fertilizer application rates.With the planting density increased, the plant height increased, but the stem diameterdecreased.(2) Planting density bring an extremely significant effect on sweet sorghum LAI,Nitrogen fertilizer application rates bring a significant effect on sweet sorghumLAI.Effects of nitrogen and potassium fertilizer application rates on leaf chlorophyllcontent of sweet sorghum have reached a significant level. Nitrogen and potassiumfertilizer application rates have an extremely significant effect on leaf photosyntheticrate.The effect of planting density on leaf photosynthetic rate have reached asignificant level, the effect of phosphate fertilizer application rates on photosynthetictraits is smaller. As the amount of nitrogen fertilizer increased, LAI, chlorophyllcontent and photosynthetic rate of sweet sorghum increased, Controlling the amountof nitrogen fertilizer in200kg/hm~2, increasing nitrogen application rates can improvethe photosynthetic rate, it’s beneficial to improve the photosynthesis of sweetsorghum. As the planting density increased, LAI increased, but the chlorophyll content and photosynthetic rate decreased.(3)Potassium application rates have reached an extremely significant level onaverage sugar Brix of sweet sorghum stalks, Planting density bring a significanteffect on average Brix of sweet sorghum stalks, and the effect of nitrogen fertilizerapplication rates on average Brix of sweet sorghum stalks is the minimum. Theaverage Brix of stalks increased with the amount of Potassium application increased.the planting density increased, the average Brix decreased. From the bottom up,internodes Brix of Jida104is low-high-low trend changes, the internodes of highestBrix of Jida104appears in the upper part, is the tenth internodes from bottom.(4)The effect of nitrogen and phosphorus fertilizer application rates on drymatter accumulation of sweet sorghum have reached an extremely significant level,planting density have a significant effect on dry matter accumulation of sweetsorghum, potash fertilizer has little effect on the total weight of the plant dry matter.Along with the nitrogen and phosphate fertilizer application increased, the dryweight accumulation increased and then decreased, with the increasing of theplanting density, plant stem leaf ratio increasing continuously, is helpful for stalkaccumulation.(5)Planting density bring a significant effect on straw yield and sugaryield,and the influence on grain yield have reached an extremely significant level.Sweet sorghum yield increased with the planting density increased. Effects ofnitrogen and potassium fertilizer application rates on sugar content have reached asignificant level. The effect of phosphorus fertilizer application rates on yield ofsweet sorghum is smaller.(6)Considering physiological process, biological yield and economical benefitsof sweet sorghum, The optimal cultivation condition is the amount of nitrogenapplication amount is200kg/hm~2, Phosphorus application amount is150kg/hm~2,Potassium application amount is120kg/hm~2,and the optimal plantingdensity is150,000plants/hm~2.