| When flowers adapted to acid soil were growed in the north where the soil is neutral or alkaline, they may not growth well or even dead because of their growth affected by many nutrition problems. Three reasons maybe lead to those problems. First, the efficiency of microelements in the soil will be lowered by high pH level of the he North soil. Second, too high content of HCO3-caused this. And the last, as the north soil nitrification is stronger, the nitrogen form in the soil is mainly nitrate form, and not suitable to the growth and development of flowers under the acidic conditions in the south. Whether the plants are affected by these is the focus of the study. In this paper, contrast and completely random block design were used in the experiment and Rhododendron hybridum Hort was irrigating by different pH values and high content of HCO3- as well as different forms of nitrogen water or culture. The nutritional status of leaves was analyzed. The results showed that:In several treatments, chlorosis appeared in only the young leaves of pH8.0 treatment after 80 days. The leaves turned green by added iron after 180 days. The content of active iron is 22.52mg/kg in the young leaves, which may be the critical index of chlorosis due to iron deficiency. The average content of active iron & chlorophyll, as well as the catalase activity in the young leaves and mature leaves and the average content of active manganese in the young leaves were significantly higher than that of the average levels of control. Peroxides activity is lower than that of control, but the difference was not significant. The ratio of nitrogen, phosphorus and potassium and the ratio of active iron and iron of added iron are lower than those of the control. The iron/Fe and Ca/Fe of the leaves are lower than those in control. The P/Fe is lower than those in control in young leaves, and the P/Fe is higher than the control in mature leaves. The N/S is higher than that of control in young leaves and lower in mature leaves than that of control. The Fe/Mn is higher than that of control.In several treatment, the growth and the appearance of Rhododendron hybridum Hort with pH5.0 of ammonium is the best. The average content of active iron, active manganese, and chlorophyll are 26.38mg/kg, 40.82mg/kg and 1.59 mg/g, respectively. The activity of catalase and peroxidase are 0.095mg/(g.min) and 0.043U/(g.min), respectively. The average content of Nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, boron, copper and zinc is 31.71 g/kg, 21 g/kg, 9.89 g/kg, 20.22 g/kg, 3.79 g/kg, 2.74 g/kg, 138.75mg/kg, 97.75mg/kg, 60.84mg/kg, 25.02mg/kg, and 53.73mg/kg, respectively. The N: P: K, active iron/Fe, P/Fe, Ca/Fe, N/S, Fe/Mn and Fe/Zn is 1:0.10:0.31, 0.19, 23.64, 145.73, 0.09, 1.42 and 2.58. There is no difference between HCO3- treatment and control of the growth and the appearance of Rhododendron hybridum Hort. The content of active iron and chlorophyll of HCO3- treatment are lower than those in control, but the difference is not significant.The content of active iron and chlorophyll with ammonium is better than with nitrate, with nitrate is better than HCO3- and with pH5.0 is better than pH8.0 treatment.In conclusion, high pH, nitrate and HCO3- are main reason for chlorosis due to iron deficiency and decreasing the content of chlorophyll of in leaves of Rhododendron hybridum Hort. In alkaline soil and water, we can lower the pH value of irrigation water and use of ammonium to improve the situation of chlorosis of iron deficiency. Acid and ammonium of nutrition can increase the effectiveness of iron and chlorophyll content of leaves of Rhododendron hybridum Hort, to prevent the occurrence of chlorosis. The content of active iron is a reliable diagnostic indicator of chlorosis due to iron deficiency in the leaves of Rhododendron hybridum Hort. |
PDF Full Text Request