| The cassava is the perennial tropical plants, generally it carries on the asexual reproduction by the cane, and harvests the vegetative organ primarily, may carries on rapid clone propagation through the tissue culture method, therefore is very suitable to apply the polyploid breeding.This experiment took the cassava stem section as the material, obtained the diploid cassava's plantlets, then took the tissue culture plantlets as material, matched the different concentrations as the mutagen, after the processing different time, tried to obtain to a pure tetraploid cassava plants in the tissue culture condition. And established a system that suitable for the mutation, the purification and the appraisal technology had been suitable for the cassava tissue culture plantlets, simultaneously took diploid as the comparison, studied changes of the variation in morphology, cytology and other aspects. In addition, tested and exploredthe best growth ,rooting culture medium formula. which was suitable for the quick numerous system of cassava diploid, the polyploid tissue culture plantlets.And compared with diploid, established a method to suit for the cassava polyploid appraisal. Its test result indicated:1,The different hormone allocated proportion induced a very small difference between the two varieties cassava bud of the Hua nan 124 and the ZM, 6-BA and KT had the obvious function to bud's induction, the MS+6-BA2.0 formula for both beginning generation of cassava bud and subculture of tuft bud had a quite good culture effect.2,The Cassava callus induction is more difficult than bud. Under the single factor condition, hormone 2,4-D had the induction callus ability; Under the double factor condition, MS+2,4-D2.0+6-BA0.05 induction rate was the highest, achieved 92.86%; But the MS+2,4-D2.0+NAA0.1 induction effect was the best, had a higher induction rate, moreover the induced callus was able to quickly induct bud under the suitable environmental condition.3,The radication of cassava bud was very easy, NAA-induced effects, was better than IAA and KT, NAA add on 6 - BA, that was the formula: MS + NAA2.0 +6- BA0.05 had the biggest influence to radication.4,The induction experiment that cassava callus differentiation budindicated, the MS+2,4-D2.0+NAA2.0 formula colud induce buds from callus. From the cassava leaves of asepsis seeding induced callus, then from callus induced cassava bud was a innovation of this experimental.5,The field polyploidy induction always uses the colchicin stem point daubing method and sprout germinates marinate method, from the processing comprehensive effect looked that the stem point daubing method of 60% was superior to the sprout germinates marinate method of 40%.6,Using colchicin induction in tissue culture, its effect and the field induction difference are not big.The rate both are about 40%.7,Colchicin's concentration range was between 0.1% -0.5%, more appropriate time was within 72 hours, specially when induced under tissue culture's condition, was more suitable for short time (below 48 hours) and low concentration (below 0.5%).8,Under the big field condition, the polyploid mutation compares with its diploid had many differences, the concrete manifestation was that laminae thickens, the color of leaves for the changes depth, the difference of the stoma size and stoma density between the cassava polyploid and the diploid is remarkable, as well as through the chlorophyll content and the starch content's determination, polyploid compared with diploid had a obvious difference.9,Identification of cytology results indicated that the polyploid root tip chromosome number was obviously more than diploid.
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