Study On The Apparent And Physiological Characteristics Of Malus Hupehensis Rehd Leaves And The Supplementation For Deficiency Of Elements

Leaf yellowing caused by lack of nutrient elements is a common physiological disease in fruit tree cultivation,and it is very limited to use human eyes to judge the lack of elements in plants early based on the apparent characteristics of leaves.The phenomenon of leaf yellowing caused by nitrogen,iron and magnesium deficiency is relatively common.In this study,apple rootstock Malus hupehensis seedlings were used as test materials.After nitrogen,iron and magnesium deficiency treatment respectively,digital image processing technology was used to extract leaf color and texture.The characteristics of Malus hupehensis seedlings were discussed,and the changes in leaf appearance and physiological characteristics of Malus hupehensis seedlings were discussed,and the correlation analysis between the leaf color and texture characteristics and the physiological characteristics of leaves was carried out.The main results are as follows:1.Nitrogen,iron and magnesium deficiency treatments significantly changed leaf color characteristics.In the process of nutrient deficiency,the leaf color characteristic value of nitrogen deficiency changed first,followed by iron deficiency,and finally magnesium deficiency.Among them,the blue component（B value）reflecting leaf characteristics began to decrease significantly on the 5th day of nitrogen deficiency treatment and the 7th day of iron deficiency treatment;on the 7th day of nitrogen deficiency and iron deficiency treatment,the leaf green component（G value）began to decrease Significantly decreased,G/B（green component/blue component value）and R/B（red component value/blue component value）further increased,but the improvement in nitrogen deficiency treatment was greater than that in iron deficiency treatment;in nitrogen,iron and magnesium Within 21 days of nutrient deficiency treatment,the changes of leaf texture characteristics of Malus hupehensis seedlings were not as obvious as the changes of color characteristics.2.Nitrogen,iron and magnesium deficiency treatment inhibited the synthesis of chlorophyll and increased the content of malondialdehyde.Among them,nitrogen deficiency treatment inhibited the synthesis of 5-aminolevulinic acid,Proporphyrin and magnesium Proporphyrin in Malus hupehensis seedling leaves,reduced chlorophyll content,inhibited photosynthesis,reduced peroxidase activity,and increased malondialdehyde content.Reduced leaf iron and magnesium content.Iron deficiency treatment promoted the synthesis of 5-aminolevulinic acid in leaves of Malus hupehensis seedlings,inhibited the synthesis of Proporphyrin and magnesium Proporphyrin in leaves,decreased the relative content of chlorophyll,inhibited photosynthesis in leaves,decreased peroxidase activity,and increased Dialdehyde content had no significant effect on leaf nitrogen and magnesium content.Magnesium deficiency treatment promoted the synthesis of 5-aminolevulinic acid in the leaves of Malus hupehensis seedlings,inhibited the synthesis of Proporphyrin and magnesium Proporphyrin,inhibited the synthesis of chlorophyll and leaf photosynthesis,and increased the activity of peroxidase and malondialdehyde content in leaves.Nitrogen and iron content had no significant effect.3.Under nitrogen,iron and magnesium deficiency treatments,leaf color characteristics were closely related to leaf physiological characteristics.The linear regression equation of leaf nitrogen content（x）and G/（R+B+G）value（y）is y=-0.0955x+0.4406,when G/（R+B+G）>0.347,it is in a nitrogen-deficient state,The nitrogen content is relatively sufficient when G/（R+B+G）<0.347.The linear regression equation of leaf iron content（x）and G/（R+B+G）value（y）is y=-0.0003x+0.3856,when R/（R+B+G）>0.354,it is in iron deficiency state,The iron content is relatively sufficient when R/（R+B+G）<0.354.The linear regression equation of leaf magnesium content（x）and G/（R+B）（y）is y=0.00003x+0.4994,when G/（R+B）<0.518,it is in the state of magnesium deficiency,and G/（R+B）>0.518 when the magnesium content is relatively sufficient.4.Under nitrogen deficiency,the contents of chlorophyll,5-aminolevulinic acid,Proporphyrin and magnesium Proporphyrin in leaves were significantly negatively correlated with G/（R+B+G）.And magnesium Proporphyrin content was significantly negatively correlated with G/（R+B+G）,and 5-aminolevulinic acid was significantly positively correlated with G/（R+B+G）.Under magnesium deficiency treatment,the contents of chlorophyll,Proporphyrin and magnesium Proporphyrin were significantly positively correlated with G/（R+B）.5.The G/B value and ALA content of leaf can distinguish the differences of nitrogen deficiency,iron deficiency and magnesium deficiency in Malus hupehensis seedlings.After the contents of nitrogen,iron and magnesium decreased significantly respectively,the leaf ALA content showed iron deficiency>magnesium deficiency>nitrogen deficiency,and the leaf G/B value showed nitrogen deficiency>iron deficiency>magnesium deficiency.In addition,the leaf G/B value gradually increased with the extension of nitrogen deficiency and iron deficiency time,but it gradually decreased with the extension of magnesium deficiency time.6.Different concentrations of Na NO₃,Fe SO₄and Mg Cl₂ were added to the culture solution of Malus hupehensis treated with nitrogen deficiency,iron deficiency and magnesium deficiency for 21 days.The contents of corresponding elements in leaves rose significantly within7days.The leaves of seedlings treated with nitrogen deficiency and iron deficiency The content of chlorophyll and its synthetic precursors increased significantly.The content of chlorophyll synthesis precursors in the leaves of the magnesium-deficient seedlings increased significantly,but the relative content of chlorophyll did not increase significantly.