| Citrus is not only the most important fruit in the world, but also the main fruit trees cultivated in Changjiang Drainage Area. Citrus cultivation has a long history in Northern Fujian, where the cultivation area and the total output of citrus fruits occupied the No.l position of fruit cultivation. In present, the citrus cultivation area is about 3.4×104 hm2, among which, medium or late matured Citrus Unshiu Marc, adding with Citrus Neticulata Blanco possessing nearly 70%. Then coms the early matured Citrus Unshiu Marc. possessing less then 20%, and Citrus Sinensis (L.) Osbeck possessing no more then 10%. Which means the citrus variety combination is irrational and therefore it is need to be adjusted since their rippening time were so concerntrated and the mass production of these law quality citrus fruit tends to strick the fruit comsumption market. Tarocco Xinxi (Citrus Sinensis Osbeck) is the new extension variety of the Ministry of the People Republic of China in the 9th Five Years' Plan, which had been introduced to Northern Fujian since the early 1999 and the cultivation area is up to 533hm2. today. Tarocco Xinxi demonstrated well in Northern Fujian, high yield, late matured and highly resistant to freez injury and the disease of Xanthomonas Citrus (Hasse) Dowson. The quality of the fruit of Taracoo Xinxi is excellent, also it has a nice external apperence and had a long shelflife, and thus a high selling price and good economic benefit for the fruit farmer. One of the disadvantages of Taracco Xinxi is its serions fruit dehiscence (fruit cracking). In present investigations, the relationships between the fruit dehiscence and the landfarm (hill orchard or valley orchard), tree stocks (root stock or intermediate stocks). The effects of different cultivation measures on the fruit dehiscence control and futher more, the fruit quality were carefully studied. The result of present investigations were described as following and I hope it will be benefit for the merchandising plan for Taracco Xinxi in Northern Fujian.1. The severity of fruit dehiscence of Tarocco Xinxi has a very closed relationship with the orchard landform. The orchard had better be established in the east or south-east slope of a open valley. It is the most effective and economic measure for fruit dehiscence control via landfarm or slope aspect selection.2. The stocks had a siganificant impact on the severity of fruit dehiscence. Using Minbei Seedless Grapefruit (Citrus Paradisi Macf.) and Citrus Sinensis (L.) Osbeck as the intermediate stock can siganificantly reduce the severity of fruit dehiscence. It is suggested that Citrus Sinensis (L.) Osbeck instead of Citrus Unshiu Marc. could be used as intermediate stocks in Tarocco Xinxi mass cultivation. Among many kinds of rootstocks, Citrus Erythrosa Hort. Ex. Tan is the best choice since it has the double effectiveness on both fruit dehiscence control and bark cracking disease prevention.3. The fruit dehiscence often happened in the end of a heavy rainning after a serious drought period in the autum and winter, especially in the hill orhard where usually lack of the facility for a bulk irrigation. In order to reduce the loss of fruit dehiscence in such a situation economically, several measures like applying K2SO4, fruit bagging, orchard mutch, spraying Gibberellin+KH2PO4 to the fruit and the crown, or both orchard mulch and Gibberellin+KH2PO4 spraying can siganificantly reduce the severity of fruit dehiscence. An effective and comprehensive measure is orchard mulch before drought season coming and spraying 20×10-6 Gibberellin+0.5%(wt/wt) KH2PO4 3-4 times during the late July and the early September.4. The measures of fruit dehiscence control had also definite impact on fruit quality and fruit spoilage rate during storage. Early stage potassium fertilization may increase the solid content of the fruit juice, promote colouring of the rind and the pulp of the fruits.
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