Effects of high-boron soil planting tobacco on growth of flue-cured tobacco and potassium fertilizer regulation measures

ObjectiveThe aim of this study was to investigate the effects of high boron content in tobacco-planted soil on growth and development of tobacco and mitigation effects of potassium fertilizer on high boron toxicity to provide scientific fertilization basis for producing high quality flue-cured tobacco in high-boron soil.MethodTaking K326,a flue-cured tobacco cultivar,as material,a field experiment was conducted to compare soil with suitable boron content(no potassium application)with different application rates of potassium(no potassium application,potassium fertilizer 112.5 kg/ha,potassium fertilizer 330.0 kg/ha and potassium fertilizer 420.0 kg/ha)in high-boron soil in effects on the growth, physiological characteristics and economic benefit of tobacco.ResultSoil with high boron content significantly inhibited the physiological metabolism and growth of flue-cured tobacco compared with that of suitable boron content soil under no application of potassium. The main agronomic characters ,net photosynthetic rate ,SPAD value ,peroxidase(POD) activity and dry matter content of flue-cured tobacco were significantly reduced(P<0.05,the same below),the disease indexes of main diseases and malondialdehyde(MDA)content of tobacco were increased significantly,the economic bene-fit decreased significantly and the phenomenon of boron toxicity was obvious. Application of potassium fertilizer in high-boron soil could reduce the toxic effect of high-boron soil planting tobacco,which the most of agronomic characters,net photosynthetic rate,SPAD value,POD activity,and dry matter content was significantly increased,economic benefit gradually enhanced and leaf MDA was significantly decreased as compared with those of treatment with no potassium application. Among them,potassium 420.0 kg/ha treatment achieved the highest economic benefit,the yield increased by 20.61%compared with high boron no potassium application treatment,the output value increased by 57.50%,the propor-tion of high-middle quality tobacco increased by 21.10%(absolut value),and the average price increased by 7.17 yuan/kg.ConclusionHigh boron soil which plants tobacco inhibites the physiological metabolism and growth of flue-cured tobac-co,and the application of potassium fertilizer can alleviate boron toxicity from flue-cured tobacco,and then increase the economic benefits. The optimum potassium application rates is 420.0 kg/ha.