Evaluation Of Iron Deficiency Tolerance And Analysis Of Related Physiological Indexes Of Apple Dwarfing Rootstocks And Cultivars

Iron is essential for the growth of apples and the completion of fruit quality,while the salinization of our soil is serious and the solubility of iron is low,which induces leaf yellowing of fruit trees.Therefore,Iron deficient chlorosis in apple is an urgent problem to be solved during agricultural production.The experiment was carried out with three major apple dwarfing self-rootstocks and three cultivars,which were‘M9T337’,‘M26’,‘MM106’and‘Hirosaki Fuji’,‘Red Star’and‘Yanfu 3’were used to investigate the physiological effects of iron deficiency and normal iron treatment and screen out iron efficient apple dwarfing self-rootstocks and cultivars.This study has important theoretical value and guiding significance for agricultural production,and it also lays a foundation for further research on the molecular mechanism of iron deficiency resistance in apple dwarfing self-rootstocks and cultivars.1.Iron stress affected the growth of new shoots of three apple rootstocks,and the new shoots of‘M26’were most affected by iron stress,while‘MM106’and‘M9T337’were less affected by iron deficiency stress.The chlorophyll content of three rootstock under ferrous stress was significantly lower than that of the plants treated with normal iron,with‘M9T337’showing the smallest change in chlorophyll content,‘MM106’the second largest,and‘M26’the largest.Under iron stress,the antioxidant enzyme activity and proline content of the leaves of each rootstock were higher than those of the iron addition treatment.The antioxidant enzyme activity and proline content of‘M9T337’were higher than those of‘MM106’,and the content of‘M26’was the lowest.‘M26’showed the greatest increase in cell membrane permeability and MDA content under iron stress,followed by‘MM106’,and the smallest in‘M9T337’.The active and total iron content in leaves of the three apple dwarf rootstocks treated with iron were significantly higher than those under iron deficiency condition,and the active and total iron contents within the leaves of‘M26’were the most reduced compared with the control,while‘M9T337’and‘MM106’were less different from the control.2.The reduction ability of apple roots to Fe³⁺is an important indicator to measure iron absorption and utilization efficiency.The Fe³⁺reductase activity in the roots of three apple dwarf rootstocks was significantly higher in the iron deficiency treatment than that of iron supply plants.The Fe³⁺reductase activity of‘M9T337’has the biggest difference with the control under ferrous stress,indicating that its roots was more capable of Fe³⁺reduction,while‘M9T337’and‘MM106’were less different from the control.The roots of‘M9T337’and‘MM106’are more dense than the control after iron deficiency treatment,while‘M26’showed no significant difference.3.All apple cultivars showed leaf chlorosis at day 50 of iron deficiency treatment,with‘Red Star’showing the highest yellowing index under iron stress,followed by‘Yanfu 3’,and‘Hirosaki Fuji’the lowest.The new shoot growth of‘Red Star’was most affected by iron deficiency,while the new shoot growth of‘Hirosaki Fuji’and‘Yanfu 3’was less affected by iron stress.The decrease in chlorophyll content of each apple cultivars under ferrous stress was the smallest for‘Hirosaki Fuji’,followed by‘Yanfu 3’,and the largest for‘Red Star’.The SOD enzyme,POD enzyme activity and proline content of leaves of all apple cultivars were higher than the control under iron deficiency treatment,with‘Hirosaki Fuji’having the highest antioxidant enzyme activity and proline content,followed by‘Yanfu 3’,and‘Red Star’having the lowest.The cell membrane permeability and MDA content of‘Red Star’under iron deficiency stress were significantly higher than those of control.While‘Hirosaki Fuji’and‘Yanfu 3’were not significantly different from iron supply treatments respectively.The contents of active iron and total iron in leaves of three apple cultivars under normal iron supply were significantly higher than those of control,and the iron content of‘Hirosaki Fuji’was the highest under ferrous stress,followed by‘Yanfu 3’,and the lowest in‘Red Star’.The results showed that among the three apple rootstocks,‘M9T337’had a high degree of tolerance to iron deficiency stress,followed by‘MM106’,and rootstock‘M26’is sensitive to iron deficiency.The resistance of three apple cultivars grafted on‘M9T337’showed that‘Hirosaki Fuji’had strong utilization ability,followed by‘Yanfu 3’,and‘Red Star’is the worst.