Study On Desiccation Tolerance Of Recalcitrant Chestnut Seed

There are abundant nutrition in chestnut seed, such as carbohydrate, protein, fat,multiform vitamin, amine acid as well as important medicine value. Chestnut seed istypical recalcitrant seed, and is sensitive highly to drought and low temperature; it isdifficult of store and conservation of species resource. Castanea mollissima Blume of eightyears was used as experimental material, which has planted at FeiDong county, AnHuiprovince. It was studied of the changes of protein (soluble protein, LEA protein), sugar(soluble sugar, sucrose, faecula), antioxidative systems (SOD, CAT, APX), ABA andperoxidation of membrane lipids in chestnut seed at developing period and droughttreatment. The purpose is to find the of chestnut seed that has strongest desiccationtolerance, and physiological reasons of desiccation sensitivity in recalcitrant seed, whichprovides theoretical gist for reasonable harvest of chestnut seed, and theoretical instructionfor conservation of species resource and store of chestnut seed. Main results were asfollowed: 1. Electric conductivity and respiration intensity of chestnut seed at differentdeveloping period increased rapidly on natural drought of seed. The more mature chestnutseed was, the more little their increasing scope was. They after anthesis for 100 days werelowest. The degree hurt and metabolism of chestnut seed for 100 days after anthesis wereleast. These showed that the time of peeling thorn shell had been late, which would benefitstore and conservation of species resource of chestnut seed. Therefore, this way that storedchestnut seed with thorn shell was suggested at possible condition. 2. During natural drought of seed, germination rate and vigour index of chestnut seed atdifferent developing period showed descendent tendency. To immature chestnut seed, lightdrought could increase germination rate and vigour index of those. As drought went on,germination rate and vigour index descended quickly. These showed that moderate droughtpromoted the germination of immature chestnut seed. To mature chestnut seed, droughtmade both of them descend. The desiccation tolerance of chestnut seed at differentdeveloping period displayed specifically to be 80dï¹¥90dï¹¥100dï¹¥70dï¹¥60d after anthesis.Chestnut seed after anthesis for 80 days displayed the strongest desiccation tolerance.Therefore the physiological mature period of chestnut seed should be among 80-90 daysafter anthesis, which was the optimum harvest. 3. To chestnut seed after anthesis for 80 days, its soluble protein, faecula and solublesugar were maximal at embryonic axis and cotyledon, and the content of ABA was highquite in embryonic axis. As the development of chestnut seed went on, complex storagesubstance, ABA, LEA protein descended quickly, but soluble sugar and sucrose increasedrapidly. Presumably there was watershed in chestnut seed among 80-90 days after anthesis,which development turned to germination. Therefore desiccation tolerance decreased inmature chestnut seed. 4. During natural drought of chestnut seed at 80 days after anthesis, its soluble proteinand carbohydrate were always in upper level though they decreased continuously. Itsactivities of antioxidative enzymes showed superior. Its ABA kept higher still though itdecreased. LEA protein disappeared partly as extent of drought deepened, but its amountwas uppermost. These could be the reason why it had showed well desiccation tolerance tochestnut seed at 80 days after anthesis. 5. On different drought methods, the desiccation sensitivity of excided matureembryonic axis was different. That of silica gel drought was weakest. It might shorten thetime of middle water content, decrease oxygen entrance and accumulation of harmfulreaction, and it increased tolerance to harmful reaction, and started antioxidative systemquickly. Moreover storage substances were consumed slowly. The result indicated thatdesiccation tolerance had showed well, and benefited store of chestnut seed when watercontent in embryonic axis had decreased to 40% by quick drought. 6. During the development of chestnut...