Effects Of Different Nitrogen Levels On Carbon And Nitrogen Metabolism, Yield And Quality Of Potato

Field plot experiments were conducted to study the effects of nitrogen rate on photosynthesis, carbon and nitrogen, dry matter accumulation, yield and quality of potatoes using ’Kexin 1’ as material, aiming at find the optimal nitrogen application rate in the potato production region north of Yin Mountain. The main conclusions are as follows:1. In the whole growth period, potato SPAD values gradually reduce, Pn, Gs, Tr is unimodal curve changes, Ci have been reduced after rising, SPAD values, Pn, Gs, Tr werw gradually rising, Ci is gradually reduce with the increase of nitrogen application rate, WUE, RuBPCase activity, PEPCase activity as N4 has masimum value.2. The potato Pn diurnal variation present as a double-peak curve, exists obvious midday depression of photosynthesis, the amout of increased nitrogen can reduce midday depression of photosynthesis Stomatal factor and non-stomatal factor caused midday depression of photosynthesis, the Pn, Gs, Ls. Tr of potato dtrengthened with the increase of N application, but gradually the Ci. It showed that nitrogen fertilizer for the diurnal variation of photosynthesis of potato played a larger adjustment.3. In the whole growth period, The sucrose, fructose, glucose, and total soluble suger content of potato leaves increased after the first reduce. SPS activity. SS activity, AI activity and NI activity present as a single-peak curve, the above indexes as N4 has maximum value. It showed that reasonable amount of nitrogen can enhance plant carbon composite function.4. In the whole growth period, the nitrate content and total nitrogen content of potato leaves gradually reduce, soluble protein, NR activity and GS activity present as a single-peak curve. The nitrate content and total nitrogen content of potato leaves gradually rising with the increase of N application, soluble protein, NR activity and GS activity as N4 has maximum value. It showed that reasonable amount of nitrogen can enhance plant nitrogen assimilation and improves plant nitrogen nutrition.5. The dry matter accumulation of potato increased firstly and then reduced with the increase of nitrogen application rate. The dry matter accumulation, leaf dry matter accumulation, tuber dry matter accumulation of potato were maximal when nitrogen was applied at the rate of 360 kg/ha, being 5989.81 kg/ha,20.03g/plant, 84.32g/plant.6. The yield as N4 has maximum value, being 55548.75 kg/ha. The reasonable nitrogen fertilizer can significantly improve commodity potato weight, but nitrogen did not enhance potato chips number per plant, even reduced with the increase of N application. The amylase, amylopectin, total starch content gradually reduce with the increase of N application, the sugar content and protein content increase.