Effects Of Different Potassium Fertilizer On Growth And Physiological Characteristics Of Tobacco

Heilongjiang province has a long history of planting flue-cured tobacco,which has larger planting areas in Northeast China.Because of the large demand of potassium?K?in flue-cured tobacco and low availability of K in soil,potassium fertilizer need to be supplemented.The rational application of potassium fertilizer can not only promote the yield formation of tobacco,but also improve the quality of tobacco leaves.The application of potassium fertilizer has not been well resolved for a long time,which has affected the development of flue-cured tobacco production.The effect of potassium fertilizer on plant yield and quality varies with different forms.Currently,K fertilizers commonly used in agricultural production are mainly potassium chloride?KCl?and potassium sulphate?K₂SO₄?.To explore the scientific method of applying potassium fertilizer and clarify the effects of KCl and K₂SO₄ on the growth and physiology of tobacco leaves,the test set two kinds of potassium fertilizer KCl and K₂SO₄ and 5 levels which are respectively 0,50,100,150 and 200mg·kg^-1.The effects of two kinds of K fertilizers on the morphological indexes,physiological indexes and chlorophyll fluorescence characteristics of the tobacco plants were studied,and the theoretical basis for the selection and application of K fertilizer in Heilongjiang tobacco production was provided.The results were as follows:?1?The effects of different potassium fertilizers on the growth of tobacco plants vary greatly.At different levels of K₂SO₄ treatment,the growth indexes of tobacco plants were all higher than those of KCl treatment and the difference was greatest at K application level of 100mg·kg^-1.The height of tobacco plant,maximum leaf area and total dry matter weight of tobacco plants under K₂SO₄ treatment were higher than those of KCl,which were respectively 10.75 cm,311.09 cm² and 9.09g,indicating that proper qpplication of K₂SO₄ was beneficial to tobacco growth.?2?Different potassium fertilizer had different effects on Physiological Indexes of tobacco plants.Moderate K₂SO₄ had a protective effect on the growth of tobacco plants.With the increase of KCl application,the toxicity of tobacco leaves increased.Under K₂SO₄ treatment,malonaldehyde?MDA?content,superoxide anion?O₂^–·?and hydrogen peroxide?H₂O₂?content were gradually decreased below the potassium application level at 150 mg·kg^-1.On the 30^th day after transplating,they were 50%,56%and 4%lower than CK respectively,indicating that proper SO₄^2-had protective effects on tobacco growth.Under KCl treatment,MDA?O₂^–·and H₂O₂ content had a gradually increasing trend at 0²00 mg·kg^-1.On the 30th day after transplating,they were 24%,45%and 5%higher than CK respectively,indicating that the application of Cl^-produced toxic effects on tobacco leaves.Appropriate amount of K₂SO₄ could promote the chlorophyll synthesis of tobacco leaves,and KCl inhibited the chlorophyll synthesis of tobacco leaves.Under K₂SO₄ treatment,the chlorophyll content of tobacco leaves could be increased when the potassium level was between0¹50 mg·kg^-1 and was 27%higher than CK.While the content of chlorophyll gradually degreased and was 165%lower than CK,indicating that the application of KCl inhibited the chlorophyll synthesis of tobacco leaves.?3?Different potassium levels had different effects on chlorophyll fluorescence parameters of tobacco leaves.The rational application of K₂SO₄ could increase the photosynthetic capacity of tobacco leaves,and the application of KCl had a certain inhibitory effect.The PI_ABS and PI_total of K₂SO₄ treated horizontal tobacco plants were higher than CK,and reached the maximum at 150 mg·kg^-1.,420%and 630%higher than CK,while V_J,V_I,V_K and V_l were significantly lower than CK.With the increase of KCl application,the leaves V_J,V_K,both increased,both at 200 mg·kg^-1,and increased by 18%and 13%respectively.The main inhibitory site of KCl treatment on PS II reaction center activity was QB receiving electron ability and reduced the function of the donor side oxygen complex OEC.?4?The Effects of Different of Potassium Fertilizer Nutrition Levels on Chemical Composition of Tobacco PlantsThe quality indicators such as nicotine,total sugar,reducing sugar and total nitrogen were all higher than those of KCl treatment at 0²00 mg·kg^-1,indicating that the application of K₂SO₄ was benefit for the improvement of tobacco quality.