The Study Of Silicon Alleviating Manganese Toxicity In Apple Trees

In recent years, a large number of acid fertilizers were applied to farmland seriouly cause the phenomenon soil acidification. The decrease of soil pH greatly accelerated the release of Mn and caused available Mn excess in the soil. The decrease of soil pH caused Mn toxicity to plants and reduced fruit yield and quality that lead to impact on fruit quality and efficient production and land security sustainable development. Si is also useful elements for plant growth and it play an important role in improving the resistance to heavy metal stress on plants. Under field experiments and solution culture condition,'Fuji'apple at full fruit period and Malus hupehensis were selected as materials to explore the effection and the mechanism of that Si alleviate the toxic hazard Mn. The main results were as follows:1. The results indicated that high Mn stress could significantly reduce the content of chlorophyll, the operating quantum efficiency of electron transport, soluble protein content and root activity under high Mn stress. Antioxidant enzyme and IOD activity in leaves of Malus hupensis increased more markedly under high Mn stress. Mn content improved, while Ca, Fe, Mg content reduced in the leave and root of Malus hupensis by high concentrations of Mn. Application of Si significantly increased the leaves of Malus hupensis chlorophyii a, chlorophyii b, carotenoids, net photosynthetic rate(Pn), stomatal conductance(Gs), soluble protein content and the activities of SOD, POD, CAT, APX under high Mn stress. Application of Si also reduced IOD activity and intercellular CO2 concentration(Ci) in leaves of Malus hupensis under high Mn concentration. Mn content in leaves and roots of Malus hupensis reduced, yet Ca, Fe, Mg, Zn and root activity obviously increased and balanced to nutrition in plant by Si.2. Fruit quality of apples decreased in acidified soil. Si could significantly enhance pH to improve fruit soluble solid content,vitamin c and reduce titratable acid content, meanwhile the storage period was prolonged. Silicon is more significantly than the lime treatment. As silicon treatment reduced soil available Mn and Fe. therefore it resulted to decrease the Mn content in different organs of plant with some degree and improve Fe content in plant and acid soil nutrient status.