Analysis Of Leaf Structure And Nutrient Content Of Different Cucumber Aphid-resistant Materials

Cucumber is one of the most popular vegetables with high nutritional value. Aphid is one of the main pests in cucumber cultivation. At present, people usually use pesticides to control aphids, but pesticides have many drawbacks, which encourages people to seek new useful methods. It is the most economical and effective measures to control the pests for us to use the plant resistance. In order to explore the relationship between nutrients and aphid–resistance, and to provide theoretical basis for breeding resistant variety, we had this research. In this test, we used a susceptible cucumber as control, and other materials including No.118 resistant, No.227 and No.311 moderately resistant, No.321 lowly resistant, to explore the relationship between blade structure and resistance. In addition, by measuring nutrients including soluble sugar, soluble protein, free amino acid, proline and Vc at the seedling stage,early flowering, and fruiting period, we analyzed the relationship between the nutrient contents and the resistance to aphids. The results were as follows:1. The array of the tissue and the spongy tissue of resistant material blade were more closely than those of the control. Therefore, the more tightly the array of the tissue and the spongy tissue of cucumber blade was, the stronger the resistance to aphids was. The upper and lower epidermis of aphid-resistant materials were significantly thicker than those of the control, and the ranking order of upper and lower epidermis thickness was in agreement with the ranking order of the aphid-resistant ability from low to high. Therefore, the thickness of the upper and lower epidermis had a certain effect on the resistance of cucumber to aphids.2. The soluble sugar and proline contents of aphid-resistant materials were significantly higher than those of the control, and the soluble sugar and proline contents of all cucumber materials were significantly increased after inoculation, therefore, the contents of soluble sugar and proline in cucumber leaves were positively correlated with the resistance to aphids.The content of free amino acids in all aphid-resistant materials was significantly lower than that of control. After inoculation, the contents of all materials showed a downward trend.Therefore, the content of free amino acid of cucumber leaves was negatively correlated with the resistance to aphids. The soluble protein of aphid-resistant material cucumber was lower than that of susceptible aphids. After inoculation, the soluble protein contents of all cucumbermaterials showed a trend of decreasing first and then increasing. The higher the increasing range of protein content was, the higher the resistance to aphids was. The vitamin C content of cucumber leaves was higher than the control or lower than the control, and after aphid inoculation, the trend was not uniform, therefore, the content of Vc of cucumber leaves might have no relationship with the resistance to aphids.3. When the aphids were not inoculated, the ranking order of the content of soluble sugar of different materials in cucumber seedlings was consistent with that in the early flowering stage,but a little difference in fruiting period. The ranking orders of soluble protein, free amino acid,proline content of different cucumber materials are consistent in different periods. After aphid-inoculation the tendency of above nutrients variation was consistent in different stages,and in seedling period, the response to aphids was more quickly than in other period.Therefore the insect resistance of cucumber in different growth stage had certain consistency.