Iron uptake and translocation by tomato plants as influenced by root temperature and manganese nutrition.

The uptake of iron (Fe) by VF-36 tomato plants as influenced by root temperature and manganese (Mn) nutrition was studied. Following a 1-week pretreatment period of various levels of Fe and Mn in the nutrient solution in a controlled temperature room, the uptake of (59)Fe from ferric ethylenediamine di(O-hydroxyphenylacetate) (FeEDDHA) at 1 mumole per liter was studied for periods of 1 to 5 days.Both Fe uptake and translocation were enhanced by increases in root temperature. Varied levels of Fe in the pretreatment period led to increased levels of Fe in the plant, which subsequently depressed further accumulation of (59)Fe. The effect of increased root temperature on (59)Fe uptake and translocation was decreased by increases in the level of Fe in the pretreatment cultures. As Mn in the nutrient solution was increased, (59)Fe uptake and translocation were increased to a point and then decreased.The degree of Fe saturation of the plant appeared to be a primary factor in regulating Fe uptake and translocation in the plant. As the Fe saturation of the plant decreased, the uptake of Fe in response to metabolic processes of the plant increased, as evidenced by increased response of absorption to root temperature.