| Nowadays, the effective ways to recover the summer maize after waterlogging are relatively few. In order to alleviate the damage of waterlogging on summer maize production, the effect of exogenous polyamine on the resistance of water flooding at different terms in summer maize different growth periods was studied with test-pit and pot experiments. The pot experiments with 3 days of water flooding were set in Three-leaf stage of summer maize. Exogenous polyamine solutions or equivalent distilled water were sprayed 2 times one day(at 8:00 a.m. and 18:00 p.m.) during the 3 days of water flooding in every treatment, and the control(CK) was normal growth. Samples were taken at 1, 3, 5 and 7 days respectively after the water flooding. The changes of malondialdehyde(MDA), soluble sugar, and soluble protein content of leaf, the changes of mass of shoot dry matter were explored. The test-pit experiments with 3, 5, 7 and 9 days of water flooding were set in Five-leaf stage of summer maize. and the control(CK) was normal growth. Samples were taken at 1, 3, 5 and 7 days respectively after the water flooding. The changes of MDA, soluble protein content of leaf, the changes of yield were explored, and comparing the difference between polyamines dressing maize and distilled water dressing. The plot experiments with 3, 5, 7 and 9 days of water flooding was set in early filling stage. Exogenous polyamine solutions or equivalent distilled water were sprayed 2 times one day(at 8:00 a.m. and 18:00 p.m.) during the last 3 days of water flooding in every flooding period treatment, and the control(CK) was normal growth. Samples were taken at 3, 6, 9 and 12 days respectively after the water flooding. The changes of soluble sugar content of leaves, root activity, shoot dry biomass, endogenous spermidine content of leaves, dynamics changes of grain weight, yield and its composition were explored. The experiments were carried out during 2014 and 2015 maize growing seasons in Shangqiu Scientific Observing and Experimental Station of Agro-Environment, Ministry of Agriculture(24°35 N、115°34′E,altitude 50.2 m). The results showed that:(1)After water flooding in Three-leaf stage, compared with CK, the content of MDA, soluble sugar, soluble protein of leaves increased, mass of shoot dry matter decreased; While the content of MDA dropped, soluble sugar content further increased, root activity enhanced and mass of shoot dry matter after the foliar spraying exogenous polyamine.(2)After water flooding in Three-leaf stage, the MDA concentration of polyamine dressing plant was lower than that without dressing plant after flooding, and MDA content of polyamine dressing plant could decrease to the CK level after flooding; the mass fraction of both soluble protein increased after flooding, showing the trend of increasing first and then decreasing; Soluble protein contents of polyamine dressing plant in each treatment period were lower than distilled water dressing, 100 seed weight and the actual yield fell drastically after flooding. After 3, 5, 7 and 9 days water flooding,the 100 grain weight of polyamine dressing treatment and no dressing treatment decreased by 2.94%, 14.42%, 21.88%, 22.11% and 16.24%, 18.30%, 25.59%, 27.99%, respectively, and the yields decreased by 32.10%, 43.20%, 48.74%, 43.94% and 35.13%, 47.65%, 53.67%, 48.86%, respectively. Polyamines dressing could increase the maize yield by 625.11kg/hm2 in the maximum in durative waterlogging.(3)After the flooding in early filling stage, compared with CK, the soluble sugar content of leaf of flooding 3,5,7,9 days treatment decreased, respectively. All flooding treatments dry matter weight of shoot reduced significantly to CK. The content of endogenous spermidine of leaf increased in short-term(3days and 5days) flooding while the long-term(7days and 9days) flooding endogenous spermidine content of leaf decreased. Filling rate of seed dropped, significantly. Grain weight per spike and yield were decreased, significantly(P<0.05). After the foliar spraying exogenous polyamine, compared between the same flooding day treatments, we found that: The soluble sugar content of leaf increased after the foliar spraying exogenous polyamine in flooding 3, 5, 7, 9days treatment, significantly. The root activity of all treatment was enhanced in the flooded condition after the foliar spraying exogenous polyamine. Dry matter weight of shoot of flooding 5,7,9 days treatment increased after the foliar spraying exogenous polyamine. The content of endogenous spermidine of leaf decreased in short-term(3days and 5days) flooding while the long-term(7days and 9days) flooding increased after the foliar spraying exogenous polyamine, significantly. Filling rate rose and flooding the shorter the greater magnitude of the rise after the foliar spraying exogenous polyamine. After the foliar spraying exogenous polyamine, grain weight per spike and yield improved. The rate of increase of grain weight per spike were9.85%、8.90%、1.99%、4.22%at 3,5,7,9days flooding treatment, respectively, significantly different(P<0.05). The rate of increase of yield were8.15%、5.85%、3.09%、1.61%at 3,5,7,9days flooding treatment, respectively, significantly different(P<0.05).The 100 grains weigh of flooding 5 days treatment rose after the foliar spraying exogenous polyamine, significantly different(P<0.05). In summary, it was foliar spraying of exogenous polyamine that could improve the ability of resisting waterlogging stress when summer corn suffered flooding in 5 days in early filling. |
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