Effect of iron fertilizer siphon transfusion on photosynthetic physiological indices and chlorophyll fluorescence parameters of iron deficiency chlorosis in apple trees

The objective of this study was to explore a new approach of correcting iron deficiency chlorosis in apple trees. The regreen of yellow leaves, anatomical structure of leaves, pigment content, photosynthetic physiological indicators and chlorophyll fluorescence parameters were researched by means of iron fertilizer siphon transfusion. The results show that the number of chloroplast of retrieved green leaves is increased by 3.6 under the siphon transfusion treatment, while the starch grains are reduced. The chloroplast grana structure is clearer under the siphon transfusion treatment, and the stacked chloroplast lamellae is increased. The number of the cristae in mitochondrion is increased and the structure is clearer under the siphon transfusion treatment. The biofilm structures of chloroplast and mitochondrion are repaired under the siphon transfusion treatment. The scale of the chlorosis is resumed from 2.00 to 0.49 after the siphon transfusion. The photosynthetic rate and stomatal conductance are significantly improved by the iron fertilizer siphoning infusion, and the CO2 concentration of the cell gap is reduced. The maximum photochemical efficiency (Fv/Fm) and PS Ⅱ potential activity (Fv/Fo) under the iron fertilizer transfusion treatment are the highest. The chlorophyll a and chlorophyll b contents of iron deficient leaves are increased by 2.97 times and 3.18 times, respectively, compared with the control 2(no liquid transfusion). It is concluded that iron deficency chlorosis can be corrected by the iorn fertilizer siphon transfusion. .