摘 要：
To explore the effects of spraying different concentrations of foliar potassium fertilizer on the fruit quality of apple variety'Ruixue',the most suitable concentration of potassium fertilizer for'Ruixue'was deter-mined.Four-year-old'Ruixue'was used as the experimental material.The type of foliar potash fertilizer was K2SO4,and three concentration gradients were set as T1(0.1%),T2(0.3%)and T3(0.5%),respectively.Spraying clear water was used as control(CK).Foliar potash fertilizer was divided into 5 stages,the first fertiliza-tion time was May 22(38 days after bloom),and then sprayed every other month.Fruit samples were collected at 45,75,105,135 d and 180 d after anthesis,respectively.The indexes of sugar components,activities of enzymes related to glucose metabolism and basic fruit quality were determined.The results showed that compared with the control,the treatment group(T1,T2,T3)significantly improved the fruit quality of'Ruixue',which was 12.6%,25.9%and 4.4%higher than CK,respectively;the fruit firmness of the treatment group was 7.7%,29.6%and 12.1%higher than that of CK,respectively;and the soluble solid content of the treatment group was signifi-cantly increased by 1.14,1.95 and 0.87 percentage points,respectively.The titratable acid content in the treatment group was significantly reduced by 0.04,0.05 and 0.09 percentage points,respectively(P<0.05).Among them,the single fruit weight,firmness and soluble solids of T2 treatment were the highest,the mass of single fruit was 335.75 g,the firmness was 9.82 kg·cm-2,and the content of soluble solids was 16.35%.The titratable acid con-tent of the fruit treated with T3 was the lowest,and the content was 0.19%.Potassium application significantly in-creased the contents of N,P,K,Ca,and Mg in leaves,and significantly increased the contents of N,K,Ca,and Mg in fruit,but the content of P in fruit did not increase significantly.After T2 treatment,the contents of fructose,sucrose and glucose in mature fruits increased significantly,increased by 35.54%,33.22%and 25.31%respective-ly compared with CK.Potassium increased the activities of acid invertase(AI),sorbitol oxidase(SOX),sorbitol dehydrogenase(SDH)and sucrose synthase(SS)in fruits.At 180 days after anthesis,the activities of AI,SOX,SDH and SS in T2 treatment increased by 4.54%,2.08%,19.11%and 12.81%respectively compared with CK.In terms of correlation analysis,there was an extremely positive correlation between potassium application rate and glu-cose content in fruit at 45 days and 75 days after anthesis(r45DAB=0.879**,r75DAB=0.893**),and an extremely significant negative correlation with sorbitol content at 180 days after anthesis(r180DAB=-0.861**).There was an extremely significant positive correlation between potassium application rate and neutral invertase activity in fruit at 135 days after anthesis(r135DAB=0.763**),an extremely significant positive correlation with sorbitol oxidase activ-ity at 45 days and 75 days after anthesis(r45DAB=0.717**,r75DAB=0.880),and an extremely significant positive correlation with sucrose synthase activity at 180 days after anthesis(r180DAB=0.739**).The most suitable concentration of K2SO4 fertilizer sprayed on the leaves of'Ruixue'apple was 0.3%(T2),which could significant-ly improve the fruit yield and quality.
