Effect of FE level and solution culture PH on severity of chlorosis and elemental content of apple seedlings

The development of chlorosis and subsequent growth of apple seedlings grown in solution cultures containing various levels of Fe under a range of solution pH regimes were examined. Initial solution pHs were 5.5, 6.5 and 7.8 respectively, with Fe levels of 0.0, 0.13 and 1.3 ppm in a 3x3 factorial arrangement. Leaf chlorosis increased with a decrease in Fe levels and with higher solution pH. Nutrient solutions were changed weekly and during each weekly cycle solution pH levels were monitored. Independent of Fe level, the lower the initial solution pH the greater the change in solution pH during each weekly cycle. Decreasing solution Fe levels decreased both leaf and root Fe concentrations but both parameters were relatively unaffected by solution pH suggesting a solution pH by Fe supply interaction at the root surface.