Study On The Germination Barriers And The Method Of Improving Germination Of Qinghuajiao Seed(Zanthoxylum Armatum)

Because the seed quantity of Qinghuajiao is very and the germination rate is very low in the production, so in this text,the seed of two species(Jinyang Qinghuajiao and Tengjiao)of Zanthoxylum armatum (Zanthoxylum armatum commonly known as Qinghuajiao) as the research material. Through the experiments such as seed quality, obstacle of testa, inhibitory substances, different5℃low temperature stratification time to find out the impact of the seed germination and how to improve seed germination rate. The text in order to provide reference.of seedling breeding of Qing huajiao.The results were shown as:(1)The fruit of Qing huajiao contains one or two seeds.The shape of one seed is oval,and the shape of two seeds is semi oval. The quantity proportion of ovoid seed is59.5%-66.9%.Longitudinal diameter of ovoid seed is3.34-3.76mm and transverse diamete is2.86-3.15mm. Longitudinal diameter of semi ovoid seed is3.23-3.67mm and transverse diamete is1.56～1.78mm. The surface of the mature seed is black and shiny and is composed of testa, endosperm and embryo.The embryo as a spatula type contains two pieces of white cotyledons, which are oval.The grain weight of Jinyang Qinghuajiao and Tengjiao was14.31g、20.44g, the water content was127%、17.8%. The grain weight of ovoid seed and semi ovoid seed iwas22.60g、17.14g, the water content was17.4%、18.1%.(2)Through water, the floating rate of Qinghuajiao seed was50%-77%.The embryo rate of floating and sinking seed respectively was1%below and86%-95%.If the embryo accounts for three-quarters of the volume of the entire seed is good as the standard, the good embryo seed of floating and sinking seed respectively was0and60%-70%. The seed quality of sinking was significantly higher than the seed quality of floating and the seed quality of Qinghuajiao seed was not high.(3)The seed viability of the sinking seed was80.00%～83.33%and the average value was82.2%.The germination rate was15.56%～17.78%and the average value was16.7%. The difference between viability and germination rate was65.5%.These results indicated that the Qinghuajiao seed had dormancy. (4) The peeled seed of Qinghuajiao could reach saturation, but the complete seed could not reach saturated water absorption.When the seed did not absorb water, the water absorption rate of peeled seed(79.1%) was more than two times than the the water absorption rate of complete seed. The permeability of testa was poor.Three layers were found in the testa of Qinghuajiao under the scanning electron microscope:external testa, mid testa, and inner testa. The total thickness is0.26-0.32mm. The cells of inner testa arranged closely, which the thickness accounting for more than half of The total thickness of testais0.172-0.194mm. Because of poor permeability, the structuresof testa maybe restrain radicel growilig. Through comprehensive analysis, the testa obstacle was one of the mian reasons to cause the low germination rate of Qinghuajiao.(5) The biotic measurement results of Qinghuajiao seed showed that each part of Qinghuajiao seed contained inhibitory substances which had the inhibitory effeets on the germination rate and root growth of Cabbage seed. The inhibiting effects of inhibitors in these parts were different, it showed as:peeled seed>testa, and the higher of the concentration, the stronger of the inhibitory effect. The inhibiting effects of inhibitors on different receptors were different.This is the second reason of the dormancy.After30d in5℃low temperature stratification, the inhibitory effeets on the germination rate and root growth of Cabbage seed were not difference with that in water.5℃low temperature stratification maybe reduce the inhibitory substances(6) After30d in5℃low temperature stratification, the germination rate of removal oil seed snd no remoral oil seed achieved respectively40%、24.44%,which showed the oil layer of testa had the inhibitory effeets on the germination rate and futher5℃low temperature stratification could improve seed germination rate.In a word, the main reason of the effects of seed germination of Qinghuajiao seed was such as:the poor of obstacle seed quality、obstacle of testa and inhibitory substances. The dormaney reason of Qinghuajiao seed is obstacle of testa which is the main reason and endogenous inhibitory substances. After30d in5℃low temperature stratification, the germination rate is improved.