| Melon(Cucumis melo L.) is one of top ten fruits in the world. It grows well in warm and hot conditions, but is not suitable to grow in wet and flooded environment. Because of continual rain or hard rain in spring and summer, that leads to growth-preventing and death of seedling and product-decreasing in middle and lower reaches of Changjiang River, as a result, it affluences outdoor melon s yield. It has seldomly been reported that how to influence its physiological and biochemical function in flooded condition and choose the flooded-resistant variety of melon. This experiment creates a system of flooded-resistant identification through screening thirty melon varieties of our reaserch group, and chose two varieties significant difference in flooded-resistance as final experimental materials to make some researches about physiological and biochemical response to flooded and flood-removed condition. This experiment was carried out in order to lay the foundation and serve adversity-resistant breeding and production. The main results are as follows:1. Choose three quick and exact indexes to identify the character of melon’s flooded-resistance from five indexes closely related to flooded-resistance:wilting index, the damage rate of electrical conductivity, the amount of adventitious root.2. Screen the 30 melon lines, using the three indexes from step one. The results are as follows:They have different sensitivity in flooded stress condition, and big significance difference in flooded-resistant characters. The 30 melon lines could be divided into two groups, the first group is no or lower flooded-resistant melon lines:T43、T211、T40、T50、T224、T36、T206、T214、T234、T238、T254、T48、T241, the second group is flooded-resistant or higherflooded-resistant melon lines:T106、T126、T113、T128、T108、T119、T114、T110、T20、T04、T26、T30、T130、T21、T45、T145、T127.3. Adopting big significance in flood-resistant character of two melon lines T106 and T241 as experimental materials to research sorts of physiological, biochemical and morphological indexes of melon seedling in different flood-stress days and flood-removed condition, the results are as follows:(1) The mass growth of two melon strains have been restrained in different extent under the flood-stress condition, and T106 has lower restrained extent than T241.After flooded-stress removal,the mass growth of recovering extent of T106 was higher than T241.(2) The two melon lines have higher content of MDA and the damage rate of electrical conductivity in flood-stress than in non-flood condition. Among the non-flood resistant line T241 is higher than flood resistant line T106. MDA of T106 have bigger decreasing extent than T241.(3) The content of proline, soluble sugar, soluble protein are higher in flooded stress than in non-flood condition, and T106 has bigger increasing extent, higher content and higher soluble protein in same flooded days than T241. The content of soluble protein showed decreasing earlier and increasing later trend. After flood-removal condition, T106 has bigger decreasing extent in proline, soluble sugar and soluble protein content than T241.(4) During the period of flood stress, the content of SOD, POD and CAT of T241 showed increasing trend in earlier stage (first 3 days) but have decreasing trend in later stage (day 4 to 7) as well as the opposite trend of T106. After flood-removal condition the he system of protected enzyme of T106 decreases as well as T241 has little increase earlier and decrease later.(5) Under extended the stage of flood stress, Chl a、Chl b、Car、Chl (a+b)、net photosynthetic rate、transpiration rate,stoma conductivity,inner cellular CO2 concentration have all had decreasing trend, the extent in T106 was smaller than T241, and all the indexes of T106 ware higher than T241 in same flooded days. These indexes of two melon lines increase during the period of flood-removed, and the increasing extent of T106 was bigger than T241. |
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