Study On Causes Of Iron Deficiency And Remediation Technology Of Camphor-tree

Camphor-tree is a large, tall, evergreen broad-leaved tree which is a representative species in subtropical forests. It is widely distributed in southern China. It has high timber value and considered as special economic species. These trees are not only an important component of urban and rural landscape, but also a source of medicine and biochemical raw materials. Camphor-trees are adapted well to slightly acidic, moist fertile soil and intolerant of drought and infertile soil condition. But urban soil is barren and seriously polluted. So, camphor-trees in the urban areas especially coastal urban areas do not get appropriate living conditions, which results widespread severe chlorosis, leading to an enormous economic and ecological losses. Therefore, studying on reasons for chlorosis of camphor-trees may contribute to figure out remedial measueres. In this study, through laboratory research and field surveys, the reasons for chlorosis were ascertained, and effective control measures were figured out. The results were as follows:1) Year-cycle changes in soil and leaf nutrient factors of normal and chlorotic camphor-trees grown in calcareous soil were surveyed on both sides of the 6th road of Hangzhou economic and technological development zone located in the north shore of the Qiantang River. The results indicated that soil pH value,HCO3- and available P contents of chlorotic trees were higher than normal trees, while its available Fe and organic matter contents were lower; leaf P content of chlorotic trees were higher than normal trees, while active Fe, total Fe, N and K contents, SPAD value, peroxidase and catalase activity were lower. The results also showed that soil pH value, HCO3- and available P contents were antagonistic to effective Fe content, while organic matter content were synergy; leaf P content was antagonistic to active Fe content, while the remaining element contents and physiological index activity were synergistic. Among four sampling times, the degree of chlorosis from low to high was August in 2007> June in 2007> March in 2007> October in 2006. The results also showed that the chlorosis from south side of the road was lesser than north side, topsoil quality was worse. Under this circumstances, a new fertilizing method of camphor-trees was recommended as treatment and prevention for camphor-trees chlorosis.2) Effect of different phosphate and bicarbonate concentrations on growth and Fe, Mn and Zn contents of camphor-tree seedlings was studied in sand culture experiment. Through the analysis of growth and Fe, Mn and Zn contents of camphor-tree seedlings, we found that optimal phosphate concentration for the growth of the camphor-tree seedlings was 0.1 mmol L-1, while suitable phosphate concentration for growth ranged from 0.1 mmol L-1 to 1 mmol L-1, the growth that had a certain degree of inhibition was observed when phosphate concentrations exceeded 1 mmol L"1, and this inhibition was very obvious at a concentration of 10 mmol L-1. In case of bicarbonate concentration, the growth was basically unaffected at 10 mmol L-1, while it showed a certain degree of inhibition at 20 mmol L-1 and at a concentration of 30 mmol L-1 this inhibition became quite obvious.3) Correction technology on iron deficiency of camphor-tree seedlings was studied in sand culture experiment in order to screen for the Fe fertilizer, optimal concentration of the Fe fertilizer, material combined with the Fe fertilizer and material optimal concentration of camphor-tree seedlings. Analysis of growth and Fe, Mn and Zn contents of camphor-tree seedlings suggested that the best Fe fertilizer was ammonium ferrous sulfate and the most effective concentration of ammonium ferrous sulfate was 0.2 g in each pot. It also revealed that boric acid was the best material which was applied with ferrous ammonium sulfate and the best concentration of boric acid was 0.5 g in each pot。4) The main leaf and soil factors change and reasons of chlorosis of camphor-trees were studied after applying a slow-releasing compound Fe fertilizer in the coastal region located in the north shore of the Qiantang River. Results indicated that compared to the experimental control, the application of the slow-releasing compound Fe fertilizer could reduce soil pH value, HCO3- and available P contents. Reduction of HCO3- content was the highest followed by available P content and pH value was the lowest; while it increased the remaining element contents, the increment order were organic matter> effective Fe> available K>hydrolysable N>effective Cu>effective Zn>effective Mn. At the same time, leaf P content was reduced and the remaining element contents were increased, the increased order was active Fe> catalase> peroxidase> K> SPAD value> total Fe> N. Again,5 kg and 7.5 kg fertilizer treatment were exerted rapidly, followed by 5 kg fertilizer mixing 25 kg red soil treatment and 7.5 kg fertilizer mixing 25 kg treatment red soil, while 5 kg fertilizer mixing 50 kg red soil treatment and 7.5 kg fertilizer mixing 50kg red soil treatment were highly persistent. In permitting conditions, the more red soil, the better effect. The order of soil pH value, HCO3-, available P and leaf P contents were 5 kg fertilizer>7.5 kg fertilizer,5 kg fertilizer mixing 25 kg red soil>7.5 kg fertilizer mixing 25 kg red soil,5 kg fertilizer mixing 50 kg red soil>7.5 kg fertilizer mixing 50kg red soil, while the remaining element contents were on the contrary. Suitable fertilizer amount was 5-7.5 kg, at appropriate scope, and the more fertilizer, the better effect. Rule of different sampling times were not evident, only soil organic matter and hydrolysable N contents, soil effective Cu and effective Zn contents, leaf active Fe content and SPAD value were unanimous, most of the element contents were high in August. Soil rule of different treatments were stronger, organic matter, hydrolysable N, available K and effective Fe contents, pH value and HCO3- content were consistent; while leaf rule of different treatments were not evident, only active Fe content and catalase activity, SPAD value and N content were the same. The results also showed that soil pH value, HCO3- and available P contents had antagonism with active Fe content, while the remaining element contents showed synergy; and leaf P content was antagonistic to active Fe content, while the remaining element contents were synergistic.5) The changes of nutrient contents in the main leaf of chlorotic camphor-tree were studied after spraying Fe fertilizer in the coastal region located in the north shore of the Qiantang River. Results indicated that leaf P content was CK> FeCl3> FeSO4·7H2O> Iron citrate> FeEDTA> Ammonium ferrous sulfate, but SPAD value, peroxidase and catalase activity, active Fe, total Fe, K, N contents were on the contrary. Compared with the experimental control, all Fe fertilizers reduced leaf P content, but they increased the contents of remaining elements and activity of physiological indexes, the increased order were active Fe> peroxidase> total Fe> K >catalase= N> SPAD value. Rule of different sampling times were evident, SPAD value, catalase and peroxidase activity, N and K contents were unanimous, and it had a growing trend with the sampling time; Rule of different treatments were evident too, SPAD value, catalase and peroxidase activity, active Fe, total Fe, N and K contents were the same. The results also showed that P content was antagonistic to active Fe content, while the remaining element contents and physiological index activity were synergistic.6) The main soil factors were investigated after applying different calcium carbonate concentrations into the Fe fertilizer in red soil. Results indicated that the application of different calcium carbonate concentrations into the Fe fertilizer increased soil pH value, hydrolysable N, available P, readily available K, available Ca and available Mg contents, with the increased order of available Mg>available P>readily available K>available Ca>pH value> hydrolysable N; but other soil factor contents redused in the order of available Fe>available Cu>available Zn>available Mn>organic matter. Rule of soil factor contents were evident in different calcium carbonate concentrations, available Fe, available Mn, available Cu and available Zn contents, available P, available Ca and available Mg contents, readily available K and hydrolysable N contents were the same; the results also showed that pH value, available P, readily available K, available Ca and available Mg contents were antagonistic to available Fe content, while organic matter, hydrolysable N, available Mn, available Cu and available Zn contents were synergistic to available Fe content. Meanwhile, with the increase of calcium carbonate concentration, Fe, Mn and Zn contents of shoot and root of camphor-tree seedlings were reduced; fresh and dry weight of shoot, root and plant, and root shoot ratio of fresh and dry condition were enhanced first and then declined; water contents of shoot, root and plant were reduced first and then raised.