Studies On The Field Performance And Cultivation Technique Of Sweet Spring Tangelo In Lishui, Zhejiang Province

Sweet spring,a late-mature hybrid citrus between satsuma mandarin×hassaku orange(Citrus unshiu Marc×Citrus hassaku hort.ex Tanaka),was introduced from Japan in 1990s.In recent years,Sweet spring has been extened increasingly owing to the advantages of good storagebility,stable yield,high quality and easy cultivation.In present investigation,the adaptability and related cultivation techniques were studied;the main results were as follows:1.Adaptability and bio-characteristics observation revealed that Sweet Spring tangelo could well adapte in Lishui,Zhejiang provine;and could flower and set fruit normally.2.Fruit quality analyses showed that Sweet spring could be harvested from December 1st to December 10 in open field cultivation in Lishui.However,the fruits were ususlly partially coloured;and the soluble solid,total sugar,reducing sugar and titratable acid were 13.8%,10.18%,4.67%and 0.70%respectively.While the vitamin C contents were 33.71 mg/100ml and the eatable rate was 70.74%.3.Storagebility analyses demonstrated that fruits to be consumed before the spring festival could be stored in common ventilating warehouse after been antisepsis-treated with 8500×45%Mirage emutsum and fresh-keeper with 100 mg/kg of 2.4-dichlorophenoxyacetic acid(2.4-D).However,if the fruits were prepared to be sold after the spring festival,which should be antisepsis and fresh-kept treated before packaged individualy.By these treatments,fruits could be stored till the end of April, with a storge life of 140 days,without off flavor but silghtly puffing.Quality monitered on April 25 showed that the soluble solid,total sugar,reducing sugar and titratable acid ranged 10.6%,8.32%,3.56%and 0.36%respectively.The vitamin C contents were 22.24mg/100ml and edible rate was 71.04%.4.Fruit bagging experiments showed that Sweet spring fruits could be bagged around Aug 20 with double layer shade bag,and the bag was removed on 7 to 10 days before harvesting.When the bagged fruits were picked during December 1 to December 10,all fruits were well coloured with clean surface.The internal quality analyses showed that the soluble solid,total sugar,reducing sugar and titratable acid was 12.5%,8.84%, 4.42%and 0.71%respectively.While the vitamin C contents were 32.93mg/100ml and the edible rate was 72.42%.5.Testing of fertility showed that the ovary of Sweet spring was normally developed, seedy fruits were usually obtained when pollinated with the pollens of Xuegan mandarin with an average seeds of 12.4 per fruit;while the pollen of Sweet spring were sterile,the stainability was 23.2%and 26.1%when stained by 0.5%acetic acid-carmine and KI-I₂ respectively,however the pollen germination was 0,which resulted to the sddelessness of Sweet spring.If Sweet spring was planted on large scale,the fruit setting rate could be kept at 2.1%when protection treatments were adopted,which ensured the economical production and the advance trait of seedlessness.6.Top grafting experiments revealed that side graf in spring could obtain the highest twig growing rate(96.8%) and middle survival rate(91.1%),while the average flush times were 3.4 per year.However,budding with wood attached in autumn could obtain the highest survival rate(93.6%) and low twig growing rate(87.1%);and the average flush times were 3.2 per year.The main factors affecting flush were the age and growth vigor of the plants.