Effects Of Different Potassium Application Rates On Fruit Yield And Quality And Potassium Nutrion Of ’Huangguan’ Pear

Potassium is the most abundant nutrient elements in most fruits,and it is one of the essential nutrients that fruit trees need to grow,develop and bear fruits.Potassium will not be involved in material composition in trees,mainly by ionic form.It has a vital role on fruit quality,as referred to "quality element" of the fruit.Potassium in cells participate in a variety of metabolic activities,such as maintaining charge balance,enhance the photosynthetic rate and photosynthetic product transport over long distances,and enhance cell osmotic pressure to promote fruit growth.Potassium levels in fruit trees has important influence on tree production capacity.This paper used 14 years old ’huangguan pear’ as material,designed different K gradients levels:0,150,300,150 kg/ha,to study the effects of K application on fruit yield and quality and the effect of potassium nutrition concentration in fruits and leaves in different fruit stages,and analyze the relations between leaf potassium nutrition and production,inorder to putout a critical value of leave potassium.The main results were as follows:The application rate of K improved the production in different extents,the increments of yield in 2014 were K450>K300>K150 in both high yield orchard and middle yield orchard.And K450 treatment both decreased in 2015.Compared the same treatments in two orchards,the increase of pear production in middle yield orchard are less than that in high yield orchard.The application of K quantity and yield conforms better to the quadratic curve equation,which means that within a certain range,fruit yield increased with the increase of amount of K,beyond the certainrange,output will reduce with the increase of K application,2014 had the biggest K contribution rate,and maximum value appeared in K450 treatment.K contribution rate under K 450 treatment were lower than that under K 300 treatment in 2015.Single fruit weight increased with K levels increasing in two orchards.Fruit sugar acid ratio increase with the increase of amount of K application.Titratable acid content and soluble sugar content changes opposite.Fruit soluble sugar content in 2015 had increased greatly than that in 2014,titratable acid content were lower than that in 2014.The tree accumulated the most leaf biomass in young fruit stage,the accumulation in young fruit stage reached 68.7%to 71.7%of the total amountin maturity.And K to deal with different levels raised the biological accumulation.Fruit biomass gradually increased along with the growth period advance.In 2014 the maximum physiological utilization in high yield orchard appeard to K450 processing,middle garden for K300 processing,physiological utilization in 2015 under the various processing were lower than that in 2014,luxury absorption enhanced.Potassium content in fruits and leaves were increased with the increasing of K application.From young fruit stage to the mature,potassium content in leaf gradually decreased.Fruit postharvest a month ago,leaf potassium levels continue to decline in high yield orchard,while it increased in the middle garden.Potassium content in fruits showed a trend of gradual decline,the content in maturation is the lowest,about 10 g/kg.K application significantly increased fruit and leaf potassium accumulation.It accumulated the most Leaf potassium in young fruit stage,and potassium accumulation gradually reduced during mature.Fruit potassium:young fruit stage accumulated the most,followed by mature peroid and young fruit period accumulated the least.The leaf potassium content of 4-5 leaf of fresh treetop in young fruit stage,expansion I stage and mature showed a good linear correlation with relative yield.The correlation in young fruit period of high-yield and middle-yield orchard were highly significant.When relative yield is 90%,the critical value of pear leaf potassiumin in three periods is:19.65 g/kg,17.26 g/kg,16.16 g/kg respectively,middle yield orchard is:18.37 g/kg,16.78 g/kg,13.86 g/kg.In conclusion:K can improve fruit quality and yield,improve the fruit and leaf biomass.Production in a certain range increased with the increase of amount of K,beyond a certain range,decreased with increasing amount of K application.Leaf potassium nutrition change is different in different yield orchard,and so as the potassium levels.Under same treatments,the yield increases are higher in high yield orchard than middle yield orchard.But,the middle garden potash contribution rate is higher than that in high yield orchard.Young fruit period is the best nutrition diagnosis period.When relative yield is 90%,the critical value of potassium content in leaf in the two orchards are 19.65 g/kg and 18.37 g/kg.