Effects of form and level of orthophosphate on growth, uptake and distribution of some elements in maize (Zea mays L.cv.ksc700). Soraya Fattahpour, Kamaladdin Dilmaghani and Hassan Hekmat Shoar*

In this study, the plants of maize (Zea mays L.cv.ksc700) were grown in Hoagland solution containing 1, 3 and 5 mM KH2PO4 or K2HPO4 under controlled conditions. At similar levels of mono and diphosphate, plants supplied with monophosphate have produced higher content of dry matter and characterized with higher total chlorophyll content and longer and well proliferated root system than those treated with similar levels of diphosphate. Plants fed with monophosphate exported more than 50% of the total produced substances toward root system whereas, for the plant supplied with diphosphate, it was less than 20% approximately. In addition, there were a positive and significant correlation between the rate of the uptake and the content of the measured elements such as P, N, Ca+2, Mg+2, K+, Na+ and monophosphate level; however, the same elements except for K+ negatively correlated with diphosphate. In both groups, the major proportion of the absorbed elements was more or less accumulated in leaves in relation to that of other parts of the plants. At the end of experiment, while pH decreased in the root medium supplied with monophosphate, an increase was observed in pH of those containing diphosphate. Differences between means values related to the same parameters in most of the cases were significant at P