Hydrogen isotope partitioning during plant growth

The intrinsic rate of natural growth as well as the growth increment of the hydrogen isotopes 1H and 3H in non-exchangeable organically bound states of maize and barley (representatives of C4- and C3-plants) are determined. In contrast to the kinetic isotope effect, the heavy isotope is preferred instead of retarded not only in the growth rate but also in the growth increment. Local accumulation of the heavy hydrogen isotope in exchangeable hydrogen positions during growth and subsequent relocation in non-exchangeable positions can be concluded. Structural hydrogen bonds, which are abundant in carbohydrates, proteins, DNA, etc., have to be taken into account. The usually employed isotope analysis of isolated plants or plant organs cannot reveal these facts.