Studied the buffer ability of the stand tube hydrponics that under every kind of adverse nutrient solution.The results indicted that the stand tube hydrponics has the certain buffer ability if under the low oxygen nutrient solution,bad water quality or abnormal consistency of nutrient solution.Root's length,unfold degrees,leaf's length,leaf's width,leaf area of lettuce was higher 11.37%,19.89%,23.10%,28.59% and 44.42% than normal Hydrponics if used the stand tube hydrponics.The upper ground weight,root weig...