Response Of Tomato Yield And Quality To Potassium Application Rate And Period

Tomato is the second largest vegetable, uptake potassium more than other elements. Potassium is recognized as “quality element”. However, potassium apply too much and be ignored coexisted in tomato production. Thus, in order to realize high quality and efficient production, studying how to supply potassium reasonably, especially at stages of tomato growth is important. So we divided the tomato growth stage into seedling stage, flowering stage, fruit early grow stage, inflation stage and quality formation stage according to rule of tomato growth and the first spike fruit development. Pot experiment was adopted, with “JinPeng 10”as test material. High level K was applied at fives stage and three level K was set at inflation and quality formation stage and high level K application at seedling stage, inflation stage and quality formation stage(CK). SSC, soluble sugar, titritable acid, lycopene, vitamin C et al. quality index, and tomato yield and absorption and utilization of K were measured to study the effects of different K application rate at five stages on tomato yield and quality, and on dry biomass and potassium accumulation and distribution. The main results were as follows:(1) Effect of K supply on tomato yield and dry biomass accumulation and distributionPotassium supply at fruit inflation stage significantly affected the yield of tomato comparing to other four stages. The interaction of K supply at inflation and quality formation stage on yield was significant(P<0.01), as inflation stage with low or without K supply, quality formation stage with K supply significantly increased the yield of tomato. Too much K supply decreased yield. K application period had little influence on dry biomass of root, stem and leaf, the impact on fruit dry matter and total dry biomass were larger, and influence of K supply at fruit inflation and quality formation stage on dry biomass was larger than other three stages. K supply at fruit inflation and quality formation stage had no influence on tomato dry matter, but their interaction on stem, fruit and total dry matter was significant(P<0.05). As inflation stage with low K supply, quality formation stage with K supply significantly increased the fruit and total dry biomass.(2) Effect of K supply on tomato qualityK supply at different stages decreased water content of tomato fruit; K supply at different stages increased lycopene content significantly, and increased Vc content except seedling stage. Only high level K supply at quality formation stage increased SSC, sugar, acid and their ratio significantly.K supply at quality formation stage affected water content significantly(P<0.05). K supply at inflation stage and quality formation stage and their interaction had significant or extremely significant effect on lycopene, Vc, soluble sugar, acid and SSC(except K supply at inflation stage an lycopene and quality formation stage on acid). A certain change rule of lycopene and Vc occurred as K supply at inflation and quality formation stage: when no K supplied at inflation stage, lycopene and Vc content increased as K supply at quality formation stage increased; when middle and high level K supplied at inflation stage, and middle level K applied at quality formation stage, lycopene and Vc content reached the maximum. K supply at inflation stage significantly increased titratable acid content comparing to other stages. K supply at inflation and quality formation stage affected soluble sugar and SSC content coincidently: when no K applied at inflation stage, K supply at quality formation stage increased sugar and SSC significantly; there was no difference between sugar and SSC when middle level K supplied at inflation stage; when K supply at inflation stage was high, middle level K supply at quality formation stage facilitated sugar and SSC increasing more.(3) Effect of different K treatment on tomato quality variation during fruit ripeningLycopene content in tomato fruit was zero at early color turning, and as fruit ripening, lycopene content increased in line, reaching the maximum when picked. As fruit ripening, lycopene content increased fastest when middle level K supply at both inflation stage and quality formation stage. When K supply at inflation stage was high, middle level K supply at quality formation stage increased lycopene the most. Vc content without K supply always less than K supply, high K supply increased Vc comparing to other K supply after fruit turning red. Soluble sugar content increased rapidly first, then kept stable and then rapidly increased again. Among K treatments, high K supply at inflation stage and middle K supply at quality formation stage increased sugar content most, and so did titratable acid and soluble solid content. As fruit ripening, sugar-acid ratio increased under different K treatment(4) Effect of K supply on potassium absorption and distributionK supply at inflation stage had extremely significant effect on potassium content in root and stem(P<0.01), and affect K content in fruit significantly(P<0.05); K supply at quality formation stage had no influence on K content in tomato, but their interaction on K content in root and stem was significant. K supply at inflation had extremely significant effect on K accumulation in root, stem, and total K accumulation, K supply at quality formation stage affected K accumulation in leaf, fruit and total K accumulation significantly, and their interaction on K accumulation in stem, leaf, fruit and total K accumulation were all extremely significant. When no K applied at inflation stage, K supply at quality formation stage increased K accumulation in leaf, fruit and total K accumulation significantly; when middle level K supplied at inflation stage, also middle K at quality formation stage K accumulation in root reached the maximum but decreased stem K accumulation. Custom K supply(CK)increased K content in leaf significant comparing to other treatments.(5) Correlation analysis among single quality index and potassium condition in tamatoSingle fruit weight was negative correlated to other quality, and so did water content. SSC and Vc were significantly and extremely significantly negative correlated to weight, and water content was significantly correlated to lycopene. Correlation between lycopene and Vc, sugar, acid and SSC were all positive, and correlation between lycopene and Vc was significant, and so did Vc and SSC. Correlation between SSC and sugar and acid were extremely significant. K content in root was significantly positively correlated to Vc and titratable acid. K content in leaf had significant positive correlation with single fruit weight, while K content in fruit was significantly negatively correlated to single fruit weight.