钾镁肥优化施用对烤烟后期光合荧光特性和碳氮代谢酶活性的影响

Effects of Optimal Application of Potassium and Magnesium Fertilizer on Photosynthetic Fluorescence Characteristics and Enzyme Activities of Carbon and Nitrogen Metabolism in Late Flue-cured Tobacco

为研究烤烟生产过程中适宜的钾镁比例,通过开展田间随机区组试验,以农户常规施肥(N∶P_(2)O_(5)∶K_(2)O=1∶0.68∶3,施K_(2)O量为315 kg/hm^(2))为对照,研究了优化钾肥处理(N∶P_(2)O_(5)∶K_(2)O=1∶0.68∶2,施K_(2)O量为210 kg/hm^(2)),优化钾肥+MgO 19.5 kg/hm^(2)处理,以及优化钾肥+MgO 39.0 kg/hm^(2)处理对烟株成熟期光合特性、荧光特性和碳氮代谢酶活性的影响。结果表明:降低钾镁比例,烤烟各处理叶绿素中Chl含量的增幅分别为2.2%、11.8%、18.3%;Car含量的增幅分别为3.5%、17.5%、19.7%;最大荧光(F_(m))的增幅分别为13.3%、18.0%、24.1%;可变荧光(F_(v))的增幅分别为17.3%、23.6%、30.9%;F_(v)/F_(o)的增幅分别为11.0%、17.2%、23.1%;F_(v)/F_(m)的增幅分别为3.7%、4.7%、5.5%。活性反应中心效率ET_(o)/ABS、ET_(o)/TR_(o)上升,单位面积电子传递的有效性(ET_(o)/CS_(m))提高,减少荧光产生(TR_(o)/RC、ABS/RC下降),提升采收期烤烟光反应系统功能的协调性,提高光反应系统的整体活性(PI_(ABS)、PI_(total)上升)。RuBP羧化酶(RuBPCase)、谷氨酰胺合成酶(GS)、硝酸还原酶(NR)、蔗糖合成酶(SS)的活性均以优化钾肥+MgO 19.5 kg/hm^(2)处理最高。优化钾镁比例可以提高光反应系统的活性,提高烤烟的光合作用效率,对平衡碳氮代谢具有积极作用,以钾镁比例为10.77∶1左右、优化钾肥+MgO 19.5 kg/hm^(2)处理下生理代谢最佳。

In order to explore the appropriate proportion of K and Mg in tobacco planting,a randomized block field experiment was carried out.The effects of 4 treatments[the routine fertilization of farmers(the control,N∶P_(2)O_(5)∶K_(2)O=1∶0.68∶3,total K_(2)O 315 kg/hm^(2)),optimized treatment(N∶P_(2)O_(5)∶K_(2)O=1∶0.68∶2,total K_(2)O 210 kg/hm^(2)),optimized treatment+19.5 kg/hm^(2) MgO,and optimized treatment+39.0 kg/hm^(2) MgO]on the photosynthetic characteristics,chlorophyll fluorescence characteristics and enzyme activities of carbon and nitrogen metabolism were studied at maturity stage of tobacco plants.The results showed that with the decrease of the ratio of potassium to magnesium,the chlorophylls content increased by 2.2%,11.8%and 18.3%;Car increased by 3.5%,17.5%and 19.7%;maximum fluorescence(F_(m))increased by 13.3%,18.0%and 24.1%,and variable fluorescence(F_(v))increased by 17.3%,23.6%and 30.9%,respectively.F_(v)/F_(o) were 11.0%,17.2%,23.1%,F_(v)/F_(m) increased by 3.7%,4.7%and 5.5%,respectively.The efficiencies of photoreactive active centers per unit area(ET_(o)/ABS,ET_(o)/TR_(o))increased,and the efficiency of electron transport(ET_(o)/CS_(m))increased.Invalid fluorescence production decreased(TR_(o)/RC,ABS/RCdecreased),thus the function of the photoreaction system was improved,and overall activity of the photoreaction system was increased(PI_(ABS),PI_(total) increased).The activities of RuBP carboxylase(RuBPCase),glutamine synthase(GS),nitrate reductase(NR)and sucrose synthase(SS)were the highest in the optimal potassium treatment with 19.5 kg/hm^(2) MgO supplement.Optimization of K and Mg fertilizer ratio could improve the photon transfer efficiency in the light reaction system,and had a positive effect on the balance of carbon and nitrogen metabolism.The physiological metabolism was the best under optimized treatment+19.5 kg/hm^(2) MgO(the ratio of potassium to magnesium was about 10.77∶1).