| Thrips palmi Karny, commonly known as the melon thrips, is a major serious insect from the genus Thrips in the order Thysanoptera, which is a primary vector of plant viruses. In this research,23varied types of Cucurbits, including cucumber, bitter gourd, sponge gourd, zucchini and pumpkin, have been systematically studied to determine the effects of leaf nutrient contents and structure of leaf villus during the vine stretching on the thrips palmi growth using correlation and multiple regression model analysis. The preliminary study explored the biochemical and morphological resistance mechanisms of the5categories Cucurbits to provide an experimental basis for improving controlling skill and breed resistant variety. The results are summarized as following:1. Among five varieties of cucumber, GH-16showed the lowest resistance to thrips palmi, and Amino acid and crude fat with significant difference from the other four varieties. On the other hand, amino acid content in GH-16was significantly different from the others, while the leaf villi of Beijing Chunjie No.1were significantly shorter than the others. According to the correlation analysis, there was a significant positive correlation (P<0.01) between the amino acid content and the quantities of thrips palmi, while all protein, soluble sugar, crude fat, villus density and length have no effect on thrips palmi amounts. Further established multiple regression model results illustrated that13.5thrips palmi were raised as one unit of amino acids increased, but the other factors made no difference.2. Thrips palmi was not found on all five varieties of bitter gourd. Taiwan Yuxiu demonstrated the highest contents of amino acids and crude fat as well as protein with significant and crude fat difference from the other four varieties. In terms of soluble sugar content, Yuanfeng Hybrid was the highest, followed by Taiwan Yinxiu. Both of them were significantly different from the others. Moreover, the villi of Taiwan Yinxiu were significantly denser than the other ones, while the villi of Fenglv No.8and Taiwan Yuxiu were longer than the others remarkably.3. It was not notable of insect resistance among five varied sponge gourds. The soluble sugar content of Nanbo Cuitian was up to1.17%, saliently higher than the others, so was its villus density. As for the length of villi, Liuxiang Duanbang was the longest with striking difference. Based on the comprehensive correlation analysis, Amino acids, protein, soluble sugar, crude fat,villi density and length had no relevance to the amount of Thrips palmi.4. Four varied vzucchinis showed no significant resistance to thrips palmi. In terms of significant difference, Guifu No.6had highest soluble sugar content and lowest amino acid content, while the villi and Crude fat of Yufeng No.3were the notably densest. The correlation analysis indicated that amount of thrips palmi was saliently and positively correlative to the density of villi (p<0.01), but the other factors, such as protein, amino acids, villus length, were uninfluential. According to multiple regression model results,1.84thrips palmi were raised as one unit of soluble sugar increased, while2.976raised as on unit of villus density increased.2.82thrips palmi were reduced as one unit of Crude fat increased5. Among four varieties of pumpkin, Meili, Qingpi-chuanling, Huapi-chuanling demonstrated good insect resistance, but Chaotinmibenwang the worst. As for content of soluble sugar, Meili was significantly lower than the others. As illustrated in correlation analysis, the amount of thrips palmi is strong and positively irrelative to villus density and especially amino acid content and villus length of pumpkin (p<0.01). Multiple regression model results revealed that0.413thrips palmi were raised as one unit of soluble sugar decreased. Besides, on unit of villus density and length increased could give raise2.15and2.12thrips palmi, respectively, while relative0.55and0.1for each increased unit of protein and amino acids. |
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