Impact Of Tree Growth And Fruit Bearing On Fruit Qualities Of Nanfengmiju

Nanfengmiju(Citrus reticulata Blanco cv. Kinokuni) is one of the most excellent Chinese varieties in local citrus. Recently, with the enlargement of cultivation areas, sharply increased production and blindly early picking fruits of nanfengmiju, the phenomena of the degradation and decreased qualities of nanfengmiju gradually are becoming more common, especially the mastication. Based on the quantitative evaluation for Nanfengmiju’s mastication index, the effects of different trees, fruit positions and fruit sizes on fruit qualities were analyzed in the present study. The main results were as follow:1. The segment-cutted force and the thickness of the segment membrane could be used to judge the Nanfengmiju’s mastication. By a combination of the segment-cutted force, the thickness in the central part of the segment membrane and the tasting test, nanfengmiiju’s mastication was classified into three levels. Superior mastication was defined as the thickness in the central part of the segment membrane between0.09-0.12cm and the segment-cutted force between1.15～1.64kg; medium mastication was defined as the thickness of0.12-0.14cm and the segment-cutted force of1.64～2.63kg; inferior mastication was defined as the thickness of0.14-0.17cm and the segment-cutted force of2.63-5.70kg.2. Significant difference of fruit quality was found among different ways of Nanfengmiju bearing fruits. Compared with the fruit of the lower position, the fruits of the upper position had higher TSS and TA values, but a worse mastication; whereas the fruits of the middle position showed higher TSS, TA and a better mastication. The fruit quality became better from inside to outside crown. Irrespective of shoot length and fruit setting, no difference of TSS or TA was observed; while longer shoots and more fruit setting led to a better mastication when compared with the shorter shoots and less fruit setting respectively. The bigger fruit and medium fruit possessed more excellent quality on TSS and TA than the small fruit, but the small fruit and medium fruit had a better mastication than the big fruit. The tree with more fruit setting had a better fruit quality than the one with less fruit load. A better fruit quality was obtained at fully ripe stage than at commercially harvest stage. 3. No significant difference was observed for the component of cell wall of different fruits. With the exception of TP, the contents of NDF, ADF, CEL, HC and lignin were similar among treatments. The content of TP in inside crown, branch and tree with more fruit setting as well as in the big fruit were higher than in outside crown, branch and tree with less fruit setting, in the small fruit. However, there was no accordance between TP and mastication.