Effects Of NPK Application Levels On Photosynthetic Capacity And Nitrogen Metabolism Key Enzymes In Sugar Beet

We used the current sugar beet cultivars KWS0143as materials in this study, the dynamic changes of photosynthesis rate, chlorophyll content, leaf area and key enzymes of nitrogen assimilation in sugar beet at different growth phase under different treatment condition, and the impact of nitrogen, phosphorus, potassium on the yield and quality of sugar beet were systematically studied by3414regression design. We comprehensively analyzed the relationship among various enzyme activities and their effect on yield and quality of sugar beet. The regulation law of NPK on the photosynthetic characteristics and the key enzyme activity were studied. This study will provide some basic document for the physiological study of sugar beet, and provide theoretical basis for enhancing fertilizer utilization rate and formulating reasonable cultivation practices. Results of the experiment are described as follows:1. The order of effects of different nitrogen levels on photosynthetic rate was:N3≈N2>N1>N0. N2and N3did not have obvious influence on the chlorophyll content, but order was N2、N3>N1>NO at defferent growth phase. The effect on leaf area was in the order: N3>N2>N1>N0. The order of the effect of different phosphonium and potassium levels on photosynthetic rate, chlorophyll content and leaf area were:P3>P2>P1>PO and K3>K2>K1>K0, respectively.2. The dynamic change of NRA and NiRA were diauxie curve. NRA has the highest activity on June6, the second peak appeared in telophase of leafage form to initial stage of root growth (July24and August7). The peaks of leaf NiRA appeared on June22and August7, the peaks of NiRA were on August7and September11in root. There was significant or very significant positive correlation between NRA and nitrogen application level all growth phase.There was significant or very significant positive correlation between leaf NiRA and nitrogen application at all growth phase except the period on July24. There was significant or very significant positive correlation between leaf NiRA and phosphorus, potassium application level at all growth stage except the period on July8, July24, September11. There was significant or very significant positive correlation between root NiRA and nitrogen application level at all growth stage. The time of NiRA peak appearance lagged a growth period (15d) than NRA’s. There was significant or very significant positive correlation between NRA and NiRA. The change of NR and NiR were extremely synchronal, and had coupling effect between them.3. GSA showed diauxie curve changes in leaf and apperaed the peaks on June6and August7, root GSA and GOGATA were single-peak curve changes and has the highest activity on August7.There was significant or very significant positive correlation between GSA and nitrogen application level at all growth stage except the period on June22, July8, and August25. There was significant positive correlation between GSA and phosphorus application in the early of growth period, potassium application on June6, June22, and August7. There was significant or very significant positive correlation between GOGATA and nitrogen application level at all growth stage. There was significant or very significant positive correlation between GOGATA and phosphorus, potassium application level on June and August.GSA and GOGATA were the higest on August7, GSA was positive related with GOGATA in all growth stages of sugar beet, these indicated that GS and GOGAT were synergistic action for ammonia assimilation in nitrogen metabolism4. The condition of the experiment, the best treatment of sugar beets with maximum yield of63935.39kg·hm-2was N3P2K2, it increased79.79%than the treatment of no fertilizer. The best treatment of sugar beets with maximum sugar content of17.01%was NOP2K2. The best treatment of sugar beets with maximum sugar yield of10531.85kg·hm-2was N2P2K2, it increased74.60%than the treatment of no fertilizer.