| Celosia cristata L. is a annual herb of Celosia L. in Amaranthaceae, originating in tropical regions of Asia and Africa. It can be used as medicine and food. It is widely distributed in the province of Zhejiang, Anhui, Shandong, Sichuan. Currently, the studies on Celosia cristata are mostly concentrated in the chemical composition, clinical application and pharmacological effects at home and abroad. The studies related to the reactions affected by external environment stress and recovery experiments of Celosia cristata are seldom. Particulary, the studies related to the damage relif of Celosia cristata under drought stress after processed by Exogenous Nitric Oxide Donor SNP, Betaine and Humic Acids are even more seldom.Drought stress can reduces a series of physiological changes of Celosia cristata in the process of cultivation, which is not conducive to Celosia cristata normal growth. Celosia cristata showed inhibition of growth and promoted the symptom such as aging. This study research the influence of some physiological and biochemical indexes of Celosia cristata seedlings after been processed by the different concentrations of exogenous SNP, Betaine and Humic Acids under drought stress of PEG-6000, to discuss how to alleviate the regulating mechanism of drought stress and provide theoretical basis and solutions of the problems in the cultivation of Celosia cristata in drought stress, and provide a basis for the widespread promotion and standardized cultivation of Celosia cristata.The results are as follows:15%PEG-6000simulated drought treatment on Celosia cristata seed germination had obvious inhibitory effect. The change of the germination index (germination potential, germination rate, germination index and vigor index) is obvious; the radicle and hypocotyl growth has also been relatively subdued of Celosia cristata seed after processed by15%PEG-6000. After processed by17%PEG-6000, the plant morphogenesis of Celosia cristata seedlings had many corresponding change being forced. In the main testing index, stem and base stem showed dysplasia phenomenon; leaves growth smaller, the average leaf area become smaller; plant fresh weight, root fresh weight of aerial part and the whole plant dry weight showed a trend of decline. These phenomena reflected that growth and development of plant were blocked, the matter accumulation of plant in the body was falling, the biomass of plant was reduced. Seedling leaf photosynthetic pigment content have taken place different degrees of changes. Drought stress is obviously improved the O2-· and MDA content; reduced leaf osmotic substances (proline, soluble protein and soluble sugar) content; Celosia cristata seedling leaf antioxidant enzymes activity changes in different degree under drought stress. After processed by SNP, betaine and humic acid, each index all have different degree of increase, the recovery effect is significant difference setting up several foreign substances in each concentration gradient. There has been a relatively good treatment concentration effect.Through a series of experiments, it finally indicated that the suitable concentration of the three kinds of exogenous substances could significantly alleviate the inhibitory effect of drought stress on seed germination. After been processed by different exogenous substances, the germination indexes of celosia cristata seed all have varying degrees of increase. The ability of the three kinds of exogenous substances in improving cockscomb seed germination under drought stress effect are different, treatment effect of betaine is best, treatment effect of SNP is a bit poor, effect of humic acid is the worst to restore celosia cristata seed germination ability under drought stress compared to the previous two substances. Drought stress also makes the cockscomb seedling radicle and hypocotyl growth been significant restrained. After been processed by various concentrations of SNP, betaine and humic acid, the radicle and hypocotyl length all have varying degrees of growth, more significant impact on hypocotyl. The degrees of response ofCelosia cristata seed and seedling to the three kinds of exogenous substances were different. In a word, SNP, betaine and humic acid all have obvious relieves on Celosia cristata seed germination under drought stress. In dealing with the SNP, concentration of0.10mmol·L-1has the best effect tendency; in dealing with the betaine, concentration of20mmol·L-1has the best effect tendency; in dealing with the humic acid, concentration of100mg·L-1has the best effect tendency.Under17%PEG-6000simulation drought treatment, stem and base stem showed dysplasia phenomenon; plant leaves decreased, the average leaf area is smaller; plant fresh weight of aerial part, root fresh weight and the whole plant dry weight showed a trend of decline. A certain concentration of exogenous SNP, betaine and humic acid treatment can effectively alleviate drought stress on growth inhibition of Celosia cristata plant stem, promoting stem, base stem, leaves and root parts returned to normal growth. When exogenous SNP concentrations reached0.25mmol·L-1, betaine concentration reached0.50g.L-1, humic acid reached300mg·L-1, after been processed by these three exogenous substances, Celosia cristata plant stems long reach maximum. When exogenous SNP concentrations reached0.25mmol·L-1, betaine concentration reached0.50g.L-1, humic acid reached100mg·L-1, after been processed by these three exogenous substances, Celosia cristata plant base of the stem long reach maximum. With three kinds of exogenous substances processing, the change of Celosia cristata seedling plants (leaf, root, fresh weight, dry weight) under drought stress was similar to the change of stem and base stem. Three kinds of exogenous substances treatment had significant differences in concentration, and present a slightly different best effect. Test results shown that certain concentration of exogenous SNP, betaine, humic acid significantly improve the drought resistance of Celosia cristata seedling, promoting better complete plant morphogenesis process.After a single17%PEG-6000simulation drought treatment, Celosia cristata photosynthetic pigment content have the phenomenon of low compared with blank control grouper, and form a significant difference. And after been treated by different mass concentration of SNP, betaine, humic acid, photosynthetic pigment content in Celosia cristata seedling leaf have taken place changes in different degrees. After been processed by exogenous0.5mmol.L-1SNP,1.0g.L-1betaine and200mg·L-’humic acid, Celosia cristata plant leaves chlorophyll a and chlorophyll b, carotenoids and total chlorophyll content all reached maximum. When exogenous SNP concentration reached0.25mmol.L-1tendency.betaine concentration reached0.25g.L-1, humic acid concentration reached50mg.L-1, Celosia cristata plant leaves carotenoid/chlorophyll ratio reaches a maximum.After dealing with various of experimental conditions, superoxide anion (O2-) and MDA content in Celosia cristata seedling leaves produced different changes. After treated with single PEG-6000(CK2), O2-· and MDA content rised rapidly. After been treated by different concentrations of SNP, betaine, humic acid, the ultra oxygen anion (O2-·) and the content of MDA increased. And when SNP concentrations reached0.5mmol.L-1, betaine concentrations reached1.0g.L-1and humic acid concentrations reached200mg.L-1, the content of ultra oxygen anion (O2-·) and MDA in the plant leaves were reduced to the minimum value, effect was most obvious. It shown that, different concentrations of exogenous SNP, betaine and humic acid treatment can effectively reduced oxidative damage to the cell membrane and oxidation damage to Celosia cristata seedlings.Under pure PEG-6000stress conditions, Celosia cristata seedlings alleviate drought stress damage caused by the drought stress on growth inhibition through the accumulation of soluble osmotic regulation substances. Under drought stress, soluble sugar content in Celosia cristata seedlings leaf significantly increased, soluble protein content decreased significantly, leaf proline content increased significantly, compared with the blank control without any processing, the significance of difference is obvious. When it was recovery processed using SNP, betaine, humic acid, the soluble sugar, soluble protein and free proline content increased to some extent. When SNP concentration was0.5mmol.L-1, betaine concentration was1.0g.L-1, humic acid was200mg.L-1, the soluble sugar, soluble protein reached its maximum. Celosia cristata seedlings soluble osmotic regulation substances content rised, mainly due to exogenous foreign material enhanced the ability of plant to removal active oxygen. Cell membrane accumulated the soluble substances in order to assure the normal metabolism of moisture, improve Celosia cristata seedlings drought resistance. The three kinds of osmotic regulation substances content change present similar change trend after been processed by different concentrations of SNP, betaine and humic acid, but the optimal concentration is slightly different. After been disposed by drought stress, several protective enzyme activity of Celosia cristata seedlings were significantly increased. There were significant differences compared with ck. This shown that Celosia cristata seedling is very sensitivly response to drought stress. After been disposed by different concentrations of exogenous SNP, betaine,and humic acid, enzymes presented a marked increase in overall trend. SOD, POD, CAT, APX protective enzyme system eliminate accumulation of reactive oxygen species (ROS) in synergy, preventing free radical to damage the structure and function of the biofilm. These results reflect that three kinds of exogenous substances can effectively remove accumulated reactive oxygen species produced by membranous peroxide, alleviating the effect of drought stress. Activity of SOD, POD and CAT increase to the maximum, when the SNP concentration is0.5mmol·L-1, betaine concentration is1.0g.L-1, concentration of humic acid is200mg.L-1. APX enzyme activity reached the maximum under dispose by0.25mmol.L-1NO SNP, O.Sg.L"1betaine and100mg.L-1humic acid.From what has been discussed above, in this experiment, the Celosia cristata seed under drought stress were treated by SNP, betaine and humic acid. we calculated the determination of germination potential, germination rate, germination index and vigor index and the change of radicle and hypocotyl length changes to get the best concentration that can relieve Celosia cristata seed germination (0.10mmol·L-1SNP,20mmol·L-1betaine,100-200mg·L-1humic acid). And when the Celosia cristata seedlings under drought stress exerted by SNP, betaine and humic acid, we measured the corresponding physiological indexes. Through comprehensive comparison of three kinds of exogenous substances, the experiment get the most optimal concentration (0.25～0.50mmol·L-1SNP,0.50～1.00g·L-1betaine,200～300mg·L-11humic acid) easing Celosia cristata seedling growth in the process of physical growth under drought stress damage. |
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