Tissue Structure Of Sea Buckthorn And Insect Resistance To Holcocerus Hippophaecolus

Hippophae rhamnoides as one of the unique species in China, not only has high ecological and economic value, but also plays very important role in ecological environment construction and regional economic development in the three northern regions in China. In recent years, the serious harm of H. hippophaecolus caused the death of large area of sea buckthorn. In order to understand the mechanism=of H. hippophaecolus disasters, and take effective prevention measures, in this paper, six sea buckthorn subspecies (varieties, hybrids) were selected, and SEM scanning, paraffin sectioning and xylotomy etc. were used to analyze the characters of tissue structure of the root, stem and leaf and the relationship between structure and H. hippophaecolus resistance. The main results are as follows:(1) Leaf tissue structure:thirteen indicators of leaf structure characters were observed, and for each indicator there were significant differences among different subspecies (varieties and hybrids) and gender. Dorsal trichome density and SR were negatively correlated with insect resistance, oppositely, upper surface trichome density,lower epidermal thickness, CTR and palisade/spongy showed a certain degree of positive correlation with insect resistance and other indicators were almost irrelevant. Drought tolerance and insect resistance in different male subspecies (varieties, hybrids) were same, while the female plants showed no significant relationship.(2) Backbone tissue structure:the relationship between structure of bark and sapwood density and H. hippophaecolus resistance was clarified. The six indicators of bark, regardless of male and female, the water content, crack ratio and lenticel size of Zhongguoshaji were all higher among different subspecies (varieties, hybrids), bark thickness was significantly different among different subspecies (varieties, hybrids), while other five indicators were not. The indicators of bark thickness, bark density and crack ratio were closely related with insect resistance, and the bark density and crack ratio were a certain positively correlated with insect resistance, but bark thickness showed negative correlation; water content, lenticel size and density were unrelated with insect resistance. Among subspecies (varieties, hybrids), height and gender, the subspecies (varieties, hybrids) had the most significant effec on backbone sapwood density. For backbone sapwood density in different female H. rhamnoides subspecies (varieties, hybrids), there were significant differences at60cm height, the impact of density at30cm on insect resistance was largest, but the correlation was not significant.(3) Root tissue structure:root tissue structure and the relationship of that with insect resistance in different subspecies (varieties, hybrids) were pointed out. In different sea buckthorn subspecies (varieties, hybrids) wood rays were extremely thin with high density. Zhongguoshaji and Taiyang were semi-diffuse porous wood, and other three subspecies (varieties, hybrids) were ring porous wood. Indicators showed significant difference among different subspecies (varieties, hybrids) and little differences between sexes. Subspecies (varieties, hybrids) with wider wood rays, greater density had smaller comprehensive spawning index and stronger insect resistance; subspecies (varieties, hybrids) with greater catheter density and earlywood catheter had weaker insect resistance; the thicher duct wall, the stronger insect resistance.