Effects Of Saline-alkali Stress On Growth Physiology Of Eight Ilex Species

In order to determine the salt and alkali tolerance of Ilex plants and provide basis for the determination of their cultivation areas,we use Ilex × attenuata 'Forstery'?Ilex×attenuata 'Savannah'?Ilex cassine 'Tensaw'?Ilex 'Emily Bruner'?Ilex'Mary Nell'?Ilex×meservea 'Blue Maid'?Ilex vomitoria 'Anna's Choice' and Ilex Centrochinensis,which were cuttage in 2016 as materials.We set up three saline-alkali stresses,includeing neutral salt NaCl,alkaline salt Na₂CO₃,mixed salt-alkali stress of neutral salt NaCl and alkaline salt Na₂CO₃ mixed at 1:1 mass.In each stress,we have 4 concentration gradients,0 g/L?control?,3 g/L?mild?,6 g/L?moderate?,9 g/L?severe?.The conclusions of this study are as follows:1.Under NaCl stress,the salt damage grade of leaves,the salt damage index of leaves and the death of eight species of Ilex increased with the prolongation of stress days and the increase of stress concentration.At the 30th day of NaCl stress,some plants began to suffer from injury symptoms.At the 50th day of NaCl stress,all treatments showed injury symptoms.The salt damage grade of leaves ranged from 0 to 7,the salt damage index of leaves ranged from 0%to 100%,and the mortality rate ranged from 0%to 100%.Ilex × meservea 'Blue Maid' has the smallest salt damage grade of leaves,salt damage index of leaves,and the mortality rate is 0.The inhibitory effect of NaCl stress on plant height growth of eight species of Ilex increased with the increase of NaCl stress concentration,especially under severe NaCl stress.2.Under Na₂CO₃ stress,the salt damage grade of leaves,the salt damage index of leaves and the death of eight species of Ilex increased with the prolongation of stress days and the increase of stress concentration.At the 20th day of Na₂CO₃ stress,some plants began to suffer from injury symptoms.At the 40th day of Na₂CO₃ stress,all treatments showed injury symptoms.The salt damage grade of leaves ranged from 0 to 7,the salt damage index of leaves ranged from 0%to 100%,and the mortality rate ranged from 0%to 100%.Ilex Centrochinensis has the smallest salt damage grade of leaves,salt damage index of leaves,and the mortality rate is 0.The inhibitory effect of Na₂CO₃ stress on plant height growth of eight species of Ilex increased with the increase of Na₂CO₃ stress concentration,especially under moderate and severe Na₂CO₃ stress.3.Under mixed stress,the salt damage grade of leaves,the salt damage index of leaves and the death of eight species of Ilex increased with the prolongation of stress days and the increase of stress concentration.At the 20th day of mixed stress,some plants began to suffer from injury symptoms.At the 50th day of mixed stress,except for Ilex Centrochinensis under mild stress,all other treatments showed symptoms of injury.The salt damage grade of leaves ranged from 0 to 7,the salt damage index of leaves ranged from 0%to 100%,and the mortality rate ranged from 0%to 100%.Ilex×attenuata'Savannah'and Ilex Centrochinensis has the smallest salt damage grade of leaves,salt damage index of leaves,and the mortality rate is 0.The inhibitory effect of mixed stress on plant height growth of eight species of Ilex increased with the increase of mixed stress concentration,especially under moderate and severe mixed stress.4.Under NaCl stress,the relative conductivity and malondialdehyde content of eight species of Ilex increased continuously with the prolongation of stress days and the increase of stress concentration.The SOD activity of eight species of Ilex showed the same trend,which increased first and then decreased with the prolongation of stress days.The POD activity of Ilex × meservea 'Blue Maid'continued to increase with the prolongation of stress days.The POD activity of the other seven cultivars showed the same trend,which increased first and then decreased with the prolongation of stress days.The change trend of soluble protein content in eight-species of Ilex was the same,which increased first and then decreased with the prolongation of stress days.The change trend of chlorophyll content of eight species of Ilex is the same,with the prolongation of stress days,the chlorophyll content first increased slightly and then decreased sharply.5.Under Na₂CO₃ stress,the relative conductivity and malondialdehyde content of eight species of Ilex increased continuously with the prolongation of stress days and the increase of stress concentration.The SOD activity,the POD activity and the soluble protein content of eight species of Ilex showed the same trend,which increased first and then decreased with the prolongation of stress days.the change trend of chlorophyll content in eight species of Ilex was the same,which showed a downward trend with the prolongation of stress days.The variation trend of different varieties was the same,but the variation range was different.6.Under mixed stress,the relative conductivity and malondialdehyde content of eight species of Ilex increased continuously with the prolongation of stress days and the increase of stress concentration.The SOD activity,the POD activity and the soluble protein content of eight species of Ilex showed the same trend,which increased first and then decreased with the prolongation of stress days,the change trend of chlorophyll content in eight species of Ilex was the same,which showed a downward trend with the prolongation of stress days.The variation trend of different varieties was the same,but the variation range was different.7.According to the value of the membership function,the NaCl stress tolerance of eight species of Ilex was as follows:Ilex × meservea 'Blue Maid'>Ilex 'Emily Bruner'>Ilex Centrochinensis>Ilex cassine 'Tensaw',>Ilex vomitoria 'Ana' s Choice'>Ilex 'Mary Nell'>Ilex×attenuata'Savannah'>Ilex×attenuata'Forstery'.8.According to the value of the membership function,the Na₂CO₃ stress tolerance of eight species of Ilex was as follows:Ilex Centrochinensis>Ilex cassine'Tensaw'>Ilex X attenuata 'Savannah'>Ilex vomitoria 'Anna's Choice'>Ilex 'Mary Nell'>Ilex'Emily Bruner'>Ilex × attenuata 'Forstery'>Ilex × meservea-Blue Maid'.9.According to the value of the membership function,the mixed stress of NaCl and Na₂CO₃ tolerance of eight species of Ilex was as follows:Ilex×attenuata'Savannah'>Ilex Centrochinensis>Ilex vomitoria 'Anna's Choice'>Ilex cassine'Tensaw,>Ilex 'Mary Nell'>Ilex'Emily Bruner'>Ilex×attenuata'Forstery'>Ilex×meservea 'Blue Maid'.