| Dictamnus dasycarpus Turcz. belongs to the perennianl herbaceous plants of Rutaceae Dictamnus,which is a traditional Chinese herbal medicines, with its dried root bark. Its artificial cultivation andbreeding research is still in its early days, and the seeds of D.dasycarpus Turcz. possess the biologicalcharacter of dormancy, it takes inconvenience to the cultivation and breeding research, therefore, thestudy on the seed dormancy characteristics and the methods of breaking would take a certain theoreticaland practical significance for D.dasycarpus Turcz.genetic resources conservation and artificialcultivation. The seed dormancy characteristic, seed dormancy mechanism, and the methods to break theseed dormancy were studied in this paper.The results were showed as follows:1. The observation of embryo and cultued in vitro embryos showed that radicle, germ, hypocotyl,cotyledon were clearly visible. The embryo length is 3.40±0.25 mm, the embryo rate is 95.31±2.76%,the embryo could grow into seedlings, which indicated that various parts of the embryo is fullydeveloped; It satisfied the physiological needs of seed germination when the water absorption reached44.09% after 10 hours absorbed for the whole seeds. The results of cabbage seed germination inhibitiontest showed inhibitor in seed coat, embryo of D. dasycarpus Turcz. seeds strongly inhibit the growth ofcabbage seed germination, and the growth of seedling root and stem, the seed coat and embryo allcontained germination inhibition substance. In vitro embryo experiments, embryo had the tendency ofgermination, but the radicle growth was restrained, using methanol solution with seed coat to cultivateembryonic, found that the embryo germination trend greatly decreased, it proved the existence of seedcoat and embryo had germination inhibition. Therefore, The seed dormancy types of D. dasycarpusTurcz. seed belongs physiological dormancy.2. It showed that the method of cleaning seeds with water for 24 h and 48 h,with 40% NaOHtreated for 1 h, 2 h, and with 1%, 3%, 5% H2O2 for 12 h, could not break the dormancy of D.dasycarpus Turcz. seed. The method of that with 98% H2SO4 treated for 15 min could promote theseed’s germination, when using 50, 75, 100, 300, 500 mg·L-1 GA3 treated the seeds,the germination rateincreased by GA3’s concentration, until 100 mg·L-1, the germination rate reached its highest point,11.25 %, then the rate decreased. When treated it by stratification,after 14~16 weeks of coldstratification, the germination rate was 63.9%; The better concentration of GA3 in the combinationtreatment of GA3 treatment + cold stratification was 50~100 mg·L-1, the effective concentration was 50mg·L-1, it could improve the germination rate of 30%, and less the time of stratification about 2 weeks.3. Through analysis the physiological indexes based on the seeds in the process of coldstratification, soluble sugar content showed a trend of increase with the extension of stratification time,the starch content reduced in the seed, protein, fat, slow down before they fell sharply. Nutrientconsumption strengthened the seeds of life activities, their trend changed such as the germination rateincreased during cold stratification. During the time,the endogenous hormone contents had differentchange along the stratification time. Compared with began, each hormone content increased. During9~14 weeks, the hormone GA3,IAA,ZR kept increasing,such as GA3/ABA,IAA/ABA,ZR/ABA,andABA content was no obvious change. |
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