Effects Of Potassium On Absorption Of Mineral Elements And Expression Of Potassium Transporters In Pineapple Leaves At Seedling Stage

Pineapple is one of the main economic crops at tropical and subtropical area in China.Potassium is one of the essential elements of pineapple growth and development.Current research on pineapple mainly focused on the yield and quality of pineapple,the absorption and transportation mechanism of potassium during the growth and development of pineapple is largely unkown.In order to explore the response of pineapple on external potassium fertilizer and its internal transport mechanism,In this thesis,using "golden pineapple" as material,effects of different potassium fertilizer treatment,MS solution(MS),Potassium dihydrogen phosphate(T1),potassium nitrate(T2),potassium chloride(T3),on chlorophyll content,carbon and nitrogen metabolites and mineral elements absorption of pineapple leaves were studied.The main results obtained are as follows:(1)During the all stages of the treatments,the SPAD value of pineapple leaves was significantly increased by the treatment of potassium nitrate(T2),while the SPAD value of pineapple leaves had no significant change under the treatment of potassium dihydrogen phosphate(T1).(2)Potassium fertilizer treatments had significant effects on carbon metabolites of pineapple leaves.4 d after treatment of potassium chloride(T3),pineapple leaves soluble total sugar content was the highest;10 d after treatment of potassium nitrate(T2),pineapple leaves soluble total sugar content was the highest.Among all the treatments,the starch content of pineapple leaves was mainly affected by dipotassium hydrogen phosphate(T1).(3)Potassium fertilizer treatment also had significant effects on nitrogen metabolites of pineapple leaves.Among all the treatments,the soluble protein content of pineapple leaves treated with potassium dihydrogen phosphate(T1),potassium nitrate(T2)and potassium chloride(T3)increased gradually,indicating that the three kinds of potassium fertilizer could affect the synthesis of protein.The amino acid contents of leaf under treatments of dipotassium hydrogen phosphate(T1),potassium nitrate(T2)and potassium chloride(T3)were the highest at the 10 th day after fertilization.(4)Among different K treatments,the uptake of N and P of pineapple leaves showed antagonistic effects;however,both promoted the absorption of potassium.After treatments with potassium dihydrogen phosphate(T1),potassium nitrate(T2)and potassium chloride(T3),potassium contents of pineapple leaves increased significantly,while nitrogen and phosphorus contents decreased,which was significantly lower than that of water treatment(CK1),possibly because that the application of potassium inhibited the accumulation of N and P contents.(5)The absorption of B,Fe,Mg and Zn of pineapple leaves was affected differently under different K treatments.The content of boron element of pineapple leaves treated with clear water(CK1),MS nutrient solution(MS)and potassium chloride(T3)was higher than that of dipotassium hydrogen phosphate treatment(T1).Potassium nitrate treatment(T2)resulted in higher iron content in leaf than potassium chloride treatment(T3).The magnesium content of pineapple leaves treated with dipotassium hydrogen phosphate(T1),potassium nitrate(T2)and potassium chloride(T3)was the highest after 4 d,which was beneficial to the accumulation of magnesium content in pineapple plants.Ten days after treatment,the zinc content of pineapple plants treated with potassium nitrate(T2)and potassium chloride(T3)increased significantly.(6)There was a correlation between the contents of carbon and nitrogen metabolites and mineral elements of pineapple leaves treated with potassium fertilizer.The contents of soluble total sugar,soluble protein,amino acid and mineral elements B,Fe,Mg,Zn were significantly positively correlated with the number of days after treatment,while the contents of N,P were significantly negatively correlated with the number of days after treatment.(7)The relative expression levels of potassium transporter KUP family related genes and glutamate synthase(GOGAT)genes of pineapple leaves were affected differently by different potassium treatments.Ac KUP4,Ac KUP5 and Ac KUP6 were sensitive to potassium dihydrogen phosphate(T1).Ac KUP2 and Ac GOGAT1 were sensitive to potassium chloride(T3).Ac KUP1,Ac KUP3,Ac KUP5,Ac KUP6 and Ac GOGAT2 were more sensitive to potassium nitrate(T2).(8)Under different potassium fertilizer treatments,pineapple potassium transporter KUP family Ac KUP5 was significantly negatively correlated with leaf potassium content,Ac GOGAT1 was significantly positively correlated with leaf potassium contents.