| Fraxinus chinensis(Roxb) had a very high green value, ornamental value and economic value. In recent years, the fast-growing Fraxinus chinensis(Roxb) had been widely planted, such as Yuanla series and Lula series. Aculus amygdali(Xue & Hong) was a new pest of Fraxinus chinensis(Roxb) that was discovered in 2013. It seriously affected the growth and quality of Fraxinus chinensis(Roxb), and that would have caused great economic losses to the majority of farmers.At present, there were few reports on the gall mite at home and abroad. The experiment was conducted to study the effect of the gall mite on the three varieties of Fraxinus chinensis(Roxb) in terms of the plant increment, the nutrient content, the secondary metabolites content and the activity of protective enzymes. We had a preliminary grasp of hazard characteristics of the gall mite, the physiological and biochemical response mechanism, and put forward a proposal for the identification and selection of the mite-resistant cultivar.1 Effects of mites on the plant incrementIn the field, Aculus amygdale(Xue & Hong) damaged mainly twigs and leaves at the top of trees, the adult mites and larval mites had gathered in twigs and leaves buds around and attack trees by suck. It can cause problems of the short top branch, plant growth arrest, unfolded new leaves, black twigs and leaves. The tree can't grow nor long in the dangerous, and it seriously affects the growth and quality of Fraxinus chinensis(Roxb). The plant height, plant wide, the total number of leaves, leaf length and leaf wide of the feeding mites treating group decreased rapidly respectively by 19.6%, 12.9%, 27.8%, 47.2% and 48.2% on average compared with the normal trees.2 Effects of mites on the nutrient contentEffects of the gall mite can decrease the content of the chlorophyll and the soluble sugar, and the more serious the number of mites, the greater the degree of decline. In the early stage of mite damage, due to the strong growth and compensation ability, the damage of Lula No.5 is small. When a large quantity of mite, mite may be more like Lula No.5, which makes Lula No.5 suffer greatly. Lula No.5, Fraxinus pennsylvanica(Marsh) and Fraxinus(Linn), the content of chlorophyll of treatment 100 mites per leaf decreased rapidly respectively 42.32%, 36.48% and 36.17%, the content of the soluble sugar of treatment 100 mites per leaf decreased rapidly respectively 41.73%, 35.43% and 37.23%, in 21 days compared with the normal leaves. The content of the soluble protein was increased in the short period after freeding mites, but it will decrease with the increase of mite damage. The effect of the treatment 20 mites per leaf and treatment 100 mites per leaf on the content of the soluble protein was small. Effect of the gall mite can increase the content of the free proline, and the more serious the number of mites, the greater the degree of rise. Lula No.5, Fraxinus pennsylvanica(Marsh) and Fraxinus(Linn), the content of free proline of treatment 100 mites per leaf increased rapidly respectively 63.47%, 36.79% and 28.93%, in 21 days compared with the normal leaves.3 Effects of mites on the secondary metabolites contentEffects of the gall mite can increase the content of the total phenolics and the flavonoid, and the more serious the number of mites, the greater the degree of rise, and changes in the content of the total phenolic and flavonoid were related to the stimulation of mite damage. In the early stage of mite damage, the content of the total phenols and the flavonoids will increase, but, with the increase of mite damage, the content of the total phenolic will still increase, while the content of flavonoids will decrease. After feeding mites, the content of the total phenolic and the flavonoid in Lula No.5 was higher and the change of the content was more sensitive. Lula No.5, Fraxinus pennsylvanica(Marsh) and Fraxinus(Linn), the content of free proline of treatment 100 mites per leaf increased rapidly respectively 176.11%, 144.14% and 131.59% in 21 days compared with the normal leaves. The content of flavonoids will decreased, but it was still higher than before feeding mites.4 Effects of mites on the activity of protective enzymesEffects of the gall mite can increase the activity of protective enzymes, and the more serious the number of mites, the greater the degree of rise, in the late stage of mite damage this increase will be reduced. After feeding mites, the activity of protective enzymes in Lula No.5 was higher and the change of the content was more sensitive. Lula No.5, Fraxinus pennsylvanica(Marsh) and Fraxinus(Linn), the activity of SOD of treatment 100 amounts per leaf increased rapidly respectively 6.29 times, 4.42 times and 2.59 times, the activity of POD of treatment 100 mites per leaf increased rapidly respectively 6.47 times, 5.76 times and 3.43 times, the activity of CAT of treatment 100 mites per leaf increased rapidly respectively 1.78 times, 1.26 times and 1.09 times, in 21 days compared with the normal leaves. |
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