Physiological Response Of Iris Japonica To Drought And Shade Stress

Water and light are important ecological factors affecting plant growth.Iris japonica evergreen four seasons,unique flower,has a high ornamental value,is a good ground cover plant.In this experiment,Iris japonica was taken as the research object.Two water stress conditions(normal watering and continuous drought)and four shading treatments(0%,79%,90% and 99%)were set respectively to study the effects of drought and shading on the growth status and important physiological indicators of Iris japonica.It can provide a theoretical basis for the popularization and application of Iris japonica in water-deficient areas and urban shade environments.The main results are as follows:1.Under the stress of drought,the root growth of Iris japonica is affected first,followed by leaves and rhizomes,and finally terrestrial stem.Iris japonica can regulate the osmotic potential of the cells by increasing the content of proline and soluble protein.In terms of anatomical structure,the intercellular space of leaves became larger under shade,while the anatomical structure of roots did not change significantly.Under drought,Iris japonica leaf peroxidase(POD),superoxide dismutase(SOD)and ascorbic acid oxidase(AAO)activity increased,and the leaf photosynthetic pigment,soluble sugar,reducing sugar and reduced ascorbic acid(As A)and reduced glutathione(GSH)and terrestrial stem soluble sugar contents are reduced,and leaf of ascorbic acid peroxidase(APX)and glutathione reductase(GR),monodehydroascorbate reductase(MDHAR)activity and root activity are decreased.In general,between April and June,27 days of drought may not have a significant impact on Iris japonica,while 45 days of drought may have a significant impact on Iris japonica.2.Shading promotes aboveground growth while inhibiting underground growth.When the shading rate reached 99%,the number of tillers decreased,and the water content of the aboveground stem was too high,which affected the growth of the leaves.In terms of anatomical structure,the intercellular space of leaves became larger under shade,while the anatomical structure of roots did not change significantly.Proline plays an important role in shade tolerance of Iris japonica.Under shading conditions,the activities of As A,POD,CAT(catalase),APX,GR and MDHAR in leaves were decreased,while the content of hydrogen peroxide was also decreased.These results showed that the weak light stress did not make the plants accumulate too much reactive oxygen species,phalaenopsis has a strong ability to adapt to weak light.The photosynthetic pigments contents under shade were higher than that without shade,but the contents under 99% gradient were significantly lower than 79% and 90%,indicating that Iris japonica could not adapt well to99% shade.Combined with the above indicators,Iris japonica can tolerate 90% shade,99% shade will cause great harm to Iris japonica.