Study On Regulation Mechanism Of Nitrogen Forms On Nitrogen And Sucrose Metabolism In Cabernet Sauvignon Grape

“Cabernet Sauvignon”（Vitis vinifera L.）grape was treated with four treatments including NO₃^--N/NH₄⁺-N ratios as 100/0,75/25,50/50,0/100 with total nitrogen being equal amount.Grape leaves and berries were sampled from the solar greenhouse of Northwest Agriculture and Forestry University.We determined the contents of sugars（sucrose,fructose,and glucose）,amino acid,soluble protein,and the activities and relative transcript levels of sucrose and nitrogen metabolism enzymes in the grape leaves and berriesto study the effects of nitrogen forms on sucrose and nitrogen metabolism in the process of maturity of grape.The major results were showed blow:The treatments of NO₃^--N/NH₄⁺-N ratios for 75/25 and 50/50（1）generally increased the average growth of shoot length,internode length,shoot diameter and leaf area of Cabernet sauvignon,compared with the treatments of NO₃^--N/NH₄⁺-N ratios for 100/0 and 0/100;The treatments of NO₃^--N/NH₄⁺-N ratios for75/25 and 50/50 could be conducive to promote the chlorophyll content in leaves of Cabernet sauvignon.（2）were beneficial to increase Fv/Fm,ΦPSII and qP and reduce NPQ of leaf PSII at the period of fruit setting and veraison,compared with the treatments of NO₃^--N/NH₄⁺-N ratios for 100/0 and 0/100.In general,the Pn,Ci,Gs and Tr of grape leaves in the treatments of NO₃^--N/NH₄⁺-N ratios for 75/25 and 50/50 were significantly higher than those for 100/0 and0/100.（3）couldsignificantly be conducive to promote the contents of sucrose,fructose,glucose,and the activities and relative transcript levels of sucrose synthase,sucrose phosphate synthase,invertase in leaves and berries of Cabernet sauvignon,compared with the treatments of NO₃^--N/NH₄⁺-N ratios for 100/0 and 0/100.The activity of acid invertase was significantly higher than that of neutral invertasein berries of Cabernet sauvignonduring the maturity of grape.The activity and relative transcript level ofsucrose phosphate synthase was generallyhigher than that ofsucrose synthasein leaves of Cabernet sauvignon at first growth stages,and the result was opposite at the mature period.（4）couldsignificantly be conducive to promote the contents of amino acid,soluble protein,and the activities and relative transcript levels of nitrate reductase,glutamine synthase in leaves and berries of Cabernet sauvignon,compared with the treatments of NO₃^--N/NH₄⁺-N ratios for 100/0 and 0/100.In general,the content of nitrate nitrogen and ammonium in leaves and berries of Cabernet sauvignon significantly increased with the increase of the nitrate nitrogen and ammonium ratio in fertilizer treatments,respectively.（5）Nitrogen metabolism mainly showed significantpositivecorrelationswith sucrose metabolism in leaves and berries of Cabernet sauvignon.The competition between sucrose metabolism and nitrogen metabolismin leaves and berries of Cabernet sauvignon could be reduced with the treatments of NO₃^--N/NH₄⁺-N ratios for 75/25 and 50/50;both of sucrose metabolism and nitrogen metabolismcould have strong intensity.（6）The treatments of NO₃^--N/NH₄⁺-N ratios for 75/25 and 50/50significantlyincreased the sucrose contentin leaves of Cabernet sauvignon,so that could be conducive to promote the transport of sugar from grape leaves to berries.In conclusion,the results indicated that the treatments of NO₃^--N/NH₄⁺-N ratios for75/25 and 50/50 were better for the growth of shoot,and improving photosynthetic characteristics,sucrose and nitrogen metabolism of Cabernet sauvignon,compared with the treatments of NO₃^--N/NH₄⁺-N ratios for 100/0 and 0/100,and the treatment of NO₃^--N/NH₄⁺-N ratios for 75/25 was better than that for 50/50,so the treatment of NO₃^--N/NH₄⁺-N ratios for 75/25 was relativelyappropriate for the growth of Cabernet Sauvignon.