| Lily(Lilium)is a perennial bulblet plant,which is an important ornamental flower.It is suitable for growing in slightly acidic soil and is sensitive to saline alkali.Therefore,it is very important to study the salt and alkaline tolerance of lily.Salt and alkali stress is not a single physiological toxicity to lily,which is often accompanied by the synergistic effect of two or more physiological injuries,such as ion toxicity,osmotic injury and high p H injury.In this study,five kinds of wild lilies,(Lilium sargentiae,Lilium dauricum,Lilium sulphureum,Lilium leucanthum,Lilium henryi)and two kinds of cultivated lilies(Lilium asiaticum(L.’foison’)and tiepao(L.’triumph’)were selected as experimental materials.The effect of saline alkali stress on morphological and physiological indexes of Lily was evaluated by membership function method.In addition,the cultivar(L.’foison’)with poor salt and alkaline tolerance was selected as the experimental material.The effects of different concentrations of exogenous hormone melatonin on the salt and alkaline tolerance of lily were studied to screen the most favorable concentration of exogenous hormone melatonin for Lily resistance to stress.The main results are as follows:(1)Effects of saline alkali stress on photosynthetic pigments of different Lilium species.With the increase of saline alkali stress,the contents of chlorophyll a,chlorophyll b and total chlorophyll of 7 species of Lilium showed a downward trend.The carotenoid contents of Lilium dauricum、Lilium sulphureum、Lilium leucanthum increased and decreased,while the carotenoid contents of the other 5 species of Lilium decreased.When the stress concentration was 160 mmol / L,the chlorophyll content of seven species of lilies decreased more than CK,among which the chlorophyll a,total chlorophyll and carotenoid content of L.‘Foison’decreased the most;the chlorophyll b content was Lilium dauricum;the chlorophyll content of Lilium leucanthum decreased the least.The content of chlorophyll and carotenoid in L.‘Foison’increased in varying degrees after the application of exogenous hormone melatonin,with the increase of exogenous hormone melatonin concentration,the content of chlorophyll and carotenoid first increased and then decreased,and the fastest increase occurred when the concentration of melatonin was 200 μ mol / L(T3).(2)Effects of saline alkali stress on osmotic adjustment substances of different Lilium species.The soluble protein content of Lilium sargentiae、Lilium dauricum、Lilium sulphureum increased at first and then decreased with the increase of salt and alkali stress concentration,while the other four lilies all increased continuously,and the increase of L.‘Foison’ was the largest at the stress concentration of 160 mmol / L.The soluble sugar content of Lilium sulphureum、 Lilium henryi showed an increasing trend,while the content of other Lilium species increased first and then decreased,with the largest increase at 80 mmol / L.With the increase of stress,except for the Pro content of L.‘Foison’increased first and then decreased,the Pro content of the other six lily species showed an increasing trend,and Lilium leucanthum had the most accumulation of Pro content among the six lily species.After applying exogenous hormone melatonin,the contents of soluble protein,soluble sugar and Pro in L.‘Foison’increased significantly,and increased first and then decreased with the increase of melatonin concentration.Exogenous hormone melatonin could increase the contents of soluble protein,soluble sugar and pro in Lily leaves under saline alkali stress at the same time,and weaken the osmotic stress on leaves under saline alkali stress The increase was the largest at T3,and the content of Pro was the largest at T2.(3)Effects of saline alkali stress on the stability of plasma membrane in different Lilium species.With the increase of saline alkali stress concentration,REC of 7 species of Lilium showed a slow rising trend,and there was no significant difference among species;MDA content increased first and then decreased,and the difference was obvious.When the stress reached the highest concentration of 160 mmol / L,the REC of Lilium dauricum increased greatly,and the MDA content of Lilium henryi was higher than that of the other six species before and after salt and alkali stress.After adding exogenous hormone melatonin,the REC and MDA contents of L.‘Foison’were lower than those of net saline alkali treatment group,and with the increase of melatonin concentration,the REC first decreased and then increased,especially in T3 group,the REC was the lowest,while the MDA decreased the most in 100 μ mol / l hormone MT(T2).(4)Effects of saline alkali stress on active oxygen metabolism of different Lilium species.With the increase of salt and alkali stress concentration,the SOD activity of 7lily species increased at first and then decreased.The SOD activity of Lilium henryi and L.‘Foison’ reached the maximum when the stress concentration was 120 mmol / L,while that of the other five lily species reached the peak at 80 mmol / L,indicating that the SOD activity was inhibited with the increase of saline alkali stress.The SOD activity of L.‘Foison’ treated with exogenous hormone melatonin was higher than that of CK and T0 groups.With the increase of exogenous hormone melatonin concentration,SOD activity first increased and then decreased.The activity of T2 and T3 groups was stronger and significantly higher than that of T0 group(P < 0.05).(5)Taking the average subordinate function values of the physiological indexes of seven species of Lilium as the comprehensive evaluation criteria of salt and alkaline tolerance,the salt and alkaline tolerance of L.‘Triumph’> Lilium sulphureum > Lilium sargentiae > Lilium dauricum > Lilium henryi > Lilium leucanthum> L.‘Foison’.According to the order of the average membership function values of physiological indexes of L.‘Foison’under different concentrations of exogenous hormone melatonin,for L.‘Foison’,when the concentration of exogenous hormone melatonin was 200 μmol / L,its salt and alkaline tolerance was the strongest,followed by 100 μ mol / L and300 μ mol / L.Appropriate concentration of melatonin can slow down the degradation of light and pigment,increase the concentration of cell osmotic adjustment substances,inhibit membrane lipid peroxidation,protect the stability of membrane structure,and enhance the activity of plant protective enzymes. |
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