Studies On Physiological Adaptation Mechanism Of The Root System Of Floating Nursing Cotton Seedling In Nutritional Water-bed

Floating nursing seedling in nutritional water-bed(FNSNWB) has widespread application in hubei and hunan province, after been transplanted, with advantages such as high disease-resistant ability and cotton yield improved, In this study, TM-1, CRI-12, Xiangzamian10as experimental materials, comparing FNSNWB with nutritive bowls nursing seedling(NBNS) from physical characteristics and endogenous ethylene biosynthesis metabolism in different cotton seedling physiological periods, trying to analyse cotton seedling root of aquatic environment adaptability. The purpose is to provide scientific and theoretical basis of cultivating healthy cotton seedling for FNSWB. The main results are as follows:1.The mechanism of physiological adaptation(1)The changes of root activity of two seedling ways almost unanimously, the root activity increased to3leaves stage and then drops down; Cotton seedlings roots of FNSNWB were significantly higher than that in NBNS(P<0.05); of seedling root system having strong absorption, synthesis, transport capacity, is conducive to the seedling cultivation.(2)From1leaf to4leaves stages, the content of free proline nutritional in roots cultivated by FNSNWB increased firstly and then decreased, and was significantly higher than that of controlled by NBNS(P<0.05).(3) It is found that MDA content of Floating nursing cotton seedling root in1leaf and four leaves stages less than NBNS,2leaves and3leaves stage more than NBNS, but there was no significant difference(P>0.05). During the stage of seedling, floating cotton seedling root showed a rising trend in the SOD activity, from the1leaf to3leaves stages the POD activity had slowly rising and then obviously enhanced, the activities of two enzymes were higher than those of contrast.(4)According to the results of research on cellulase activity, the cotton seedling roots of FNSNWB in2leaves stage of maximal activity, then reduced gradually. It was significantly higher than contrast when in2leaves and3leaves stage(P<0.05). (5)Each physiological index of cotton seedling root is manifested in the varieties:TM-1> CRI12> Xiangzamian10.2.Endogenous ethylene biosynthesis metabolism(1)From1leaf to2leaves stage, the endogenous ethylene production in the cotton seedling roots of FNSNWB increased gradually, reached a maximum and then decreased gradually, and were significantly higher than those of contrast(P<0.05). The seedling period, ethylene production of TM-1floating nursing cotton seedling root was the most, ethylene production of Xiangzamian10floating nursing cotton seedling root was the least.(2)In the2leaves stage, TM-1, CRI-12, Xiangzamian10floating nursing cotton seedling root ACC content above17.18%,14.05%,13.76%, compared contrast with significant difference(P<0.05); ACS enzymes activity is significantly higher than contrast(P <0.05); ACO enzymes activity in seedling of cotton seedlings roots were2.62times,2.01times,1.83times, significantly higher than the control(P<0.01).