Uptake and distribution of manganese in oat plants

Summary

In young oat plants, the mainstream of movement of Mn from nutrient solution to shoot may be regarded as passing through a labile fraction of Mn in the roots. It largely bypasses a relatively nonlabile fraction.

Varietal differences in shoot-Mn can be attributed to variations in size and turnover rate of the labile fraction. Variations in pH and temperature of the substrate affect these quantities. But the effects are similar in both varieties, Sun II and Algerian, and, consequently, the varietal difference in shoot-Mn remains unmodified.

Variations in total root-Mn can be largely attributed to variations in the size of the nonlabile fraction. This fraction, unlike the labile Mn, increases much more in plants of Algerian than in plants of Sun II, when the pH is raised or the temperature lowered. Consequently, the varietal difference in total root-Mn is easily disturbed by these substrate variations, and root-Mn can vary without relation to shoot-Mn.

In several other varieties of oats, kinetic compartmentalisation of root-Mn could also be demonstrated. The amounts and proportions of the two forms varied widely between varieties.