| Due to the imbalance of potassium fertilization, the potassium content of citrus is deficient or excess. So recommendation fertilization according to the citrus K nutrition diagnosis is one of the important measures to ensure high yield and high quality. At present, the mature leaves diagnosis recommended sampling period is too late to correct citrus and improve the yield and quality in the same year. While using floral analysis can predict early nutrient status, improve fruit yield and quality in time. Field trials with Satsuma mandarin(Citrus unshiu Marc.)(5 application rates of potassium fertilizers) and’Newhall’, ’Cara cara’ navel orange(4 application rates of potassium fertilizers), were carried out. Mineral nutrients concentrations of flowers, leaves, fruit and soil, and fruit quality were analyzed, aimed to ascertaining the effect of potassium on citrus quality and determining floral potassium diagnosis of Satsuma mandarin, ’Newhall’ and ’Cara cara’navel orange. The main results were as following:1. Flower K content can be used to diagnosis the potassium nutrition of Satsuma mandarin, ’Newhall’ and ’Cara cara’ navel orange.Significant differences in K concentrations of the leaves and fruits between 2014 and2015 were showed. The yield of Satsuma mandarin orchard in 2014 was significantly higher than 2015, 2014 and 2015 were on year and off year respectively. The fruit weight of 2014 was significantly lower than 2015, the fruit titratable acid(TA) content of 2014 was significantly lower than 2015, the ratio of total soluble solid(TSS) to titratable acid of 2014 was significantly higher than 2015.The K content of Satsuma mandarin flower was significant higher than that of leaves and fruits. There were significant correlations between the concentrations of K and Fe, B of Satsuma mandarin flowers in 2014, which the best fitting curves were linear and quadratic function respectively. Significant correlations were obtained between the concentrations of K and N, Mg of Satsuma mandarin flowers in 2015, which the best fitting curves were quadratic function and linear respectively. Significant differences in correlations of K and other elements of flowers between on-year and off-year were also showed. In on-year(2014), there were significant correlations between the Kconcentrations of Satsuma mandarin flowers and leaves, which the best fitting curves was quadratic function, the floral diagnosis standard values of K was 2.23%. In off-year(2015), there were no significant correlations between the K concentrations of Satsuma mandarin flowers and leaves. In on-year(2014), the flower K content can be used to diagnosis the potassium nutrition of Satsuma mandarin.The K content of ’Newhall’ navel orange flower was significant higher than that of leaves and fruits. There were significant correlations between the concentrations of K and N, P, Mn, Cu, Zn, B in ’Newhall’ navel orange flowers, which the best fitting curves were cubic, linear, cubic, power, quadratic and quadratic function respectively. There was significant correlations between the K concentrations of ’Newhall’ navel orange flowers and leaves, which the best fitting curves was linear function, the floral diagnosis standard values of K was 2.23%. the flower K content can be used to diagnosis potassium nutrition of ’Newhall’ navel orange.The K content of ’Cara cara’ navel orange flower was significant higher than that of leaves and fruits. There were significant correlations between the concentrations of K and N of’ Cara cara’ navel orange flowers, which the best fitting curves was linear function. There was significant correlations between the K concentrations of ’Cara cara’navel orange flowers and leaves, which the best fitting curves was linear function, the floral diagnosis standard values of K was 2.30%. The flower K content can be used to diagnosis potassium nutrition of Cara cara’ navel orange.2.In 2014, the K concentrations of Satsuma mandarin flower was significant related to the edible rate, TA, vitamin C(Vc) concentration of fruits, which the best fitting curves were both quadratic function. In 2015, the K concentrations of Satsuma mandarin flower was significant related to the fruits weight, edible rate, TA, Vc, TSS and ratio TSS/TA of fruits. The valuation of comprehensive fruit quality for both 2014 and 2015.The best quality for 2014 fruits showed that the fruits weight, TSS, ratio TSS/TA were higher while the edible rate, TA, Vc were lower,which the average K concentration of flowers was 2.23±0.09%. The best quality for 2015 fruits characterized that the edible rate, TSS, ratio TSS/TA were higher while the fruits weight, TA, Vc were lower, whichthe average K concentration of flowers was 2.23±0.15%.In 2014, the K concentrations of ’Newhall’ navel orange flower were significant related to the fruit weight, which the best fitting curves were quadratic function. The best comprehensive fruit quality for 2014 fruits was characterized that the fruits weight,edible rate, TSS, ratio TSS/TA were higher while the TA, Vc were lower,which the average K concentration of flowers was 2.15±0.17%.The best comprehensive fruit quality of Cara cara’ navel orange fruits in 2014 was characterized that the fruits weight, edible rate, ratio TSS/TA were higher while the TSS,TA, Vc were lower, which the average K concentration of flowers was 2.22±0.07%. |
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