Effects Of Humic Acid Potassium On The Nutrient Supply Of Soil And Quality Of Tobacco

The experiments of potted planting and field condition were carred out separately in the Education Technical Center of Henan Agriculture University and in Jiaxian pingdingshan of Henan province with China Tobacco-100.The effects of different applying amount of humic acid potassium on the root system growth and their physiology characteristics of flue-cured tobacco,photosynthetic rate(Pn) during squaring stage,potassium content in every part of tobacco during Tobacco Development,nutrient supply of soil,conventional ingredients and flavour components of flue-cured tobacco were studied.The results are as follows.1.Effect of Different Applying Amount of Humic Acid Potassium on the Root SystemApplication of humic acid potassium could promote the elongation of main root, but beyond a certain amount it would inhibit its elongation,with the growth and development,this phenomenon was all the more obviously.Comparatively speaking, humic acid potassium could promote the elongation of root more better at the late development stage,and with a huge amount of K₂SO₄ was unfavorable to it,resulting in its root length was lower than that of control;dry weight and volume of root,total absorption area and active absorption area of roots increased at first,and then dcreased with the increasing of potassium rate,humic acid potassium could promote the dry weight of root more better at the late development stage,while K₂SO₄ could promote the volume of root;active absorption area percentage increased at first,and then decreased with the increasing of potassium rate except treatments which were supplied with K₂SO₄ after transplant 90 days.2.Effect of Different Applying Amount of Humic Acid Potassium on the Photosynthetic RateThe results showed that:Photosynthesis rate increased with the increasing of humic acid potassium rate at 9:00,it increased at first,and then dcreased at other testing point.Application of a certain amount of humic acid potassium could improve it very significantly at 13:00 and 17:00,but at 15:00 it would decreased very significantly(supplied with humic acid potassium) or significantly(supplied with K₂SO₄) when were applied potassium beyond a certain amount.The phosynthesis of control and those treatment supplied with K₂SO₄ had a noon-nap.3.Effect of Different Applying Amount of Humic Acid Potassium on the K contents of tobacco in Different Growth StagesAfter transplant,K content of the leaves increased with the increasing of potassium rate before 60th day,it would not increase but decrease when were applied potassium beyond a certain amount,this phenomenon first appeared in K₂SO₄ Treatment and cutters and upper leaves;K content of the root and stem increased at first,and then decreased with the increasing of potassium rate except increasing after transplant 30 days.K content of the control were root＞stem after transplant 60 days and 75 days,others were stem＞root during Tobacco Development.4.Effect of Different Applying Amount of Humic Acid Potassium on the Nutrient Supply of SoilWith the increasing of potassium rate,the changes of the contents of nutrient and organic matter were on the whole similar to each other.Application of K₂SO₄ had great influence on soil total potassium,Increasing application of K₂SO₄ could increase or decrease soil total potassium most prominently,while humic acid potassium could make it stabilize in a certain level.Humic acid potassium Treatment could maintain the soil available potassium in stable range after the peak of K uptake.The content of slowly available potassium increased with the increasing of potassium rate,and those treatment which were supplyed with K₂SO₄ contained higher content slowly available potassium than the humic acid potassium Treatment except rosette stage.5.Effect of Different Applying Amount of Humic Acid Potassium on the Quality of Flue-cured TobaccoK content of the leaves increased with the increasing of potassium rate, Comparatively speaking,when were applied K₂SO₄ beyond a certain amount,the K content of the lower leaves increased,but cutters and upper leaves decreased,especially the cutters decreased sharply.K/Ca and K/(Ca+Mg) increased at first,and then dcreased with the increasing of humic acid potassium rate,in K₂SO₄ Treatment the ratio were increased at first,and then dcreased of the upper leaves,others were dcreased with the increasing of K₂SO₄.The fertilizer application of potassium could increase the B content of the leaves,the effects of potassium on the content of Cu,Fe,Mn,P,Zn were variable in different situations.Analysis on neutral aroma components showed that the content of browning products in cutters decreased with the increasing of humic acid potassium rate,besides,the fertilizer application of potassium could increase other kinds of neutral aroma components.The ratio of total sugar to reducing sugar of G3,L6 were suitable of the upper leaves and the lower,whlie G2,G3 were suitable of the cutters.The total nitrogen to nicotine ratio of G1,G2,G3 were suitable of the upper leaves,G3,G4,L8 were suitable of the cutters, G1,G2,L7 were suitable of the lower.G1 had the largest content of the petroleum ether extracts of the lower,L6 took second place,of the cutters and upperleaves G3 had the largest content,L6 took second place.