tion of methanol, systematic field experiments were performed with winter wheat (Triticum aestivumL.),
spring barley (Hordeum vulgareL.), and others and the results were unfortunately not unequivocally con-
firmed [126]. More experiments may be required to substantiate the observations, in particular with re-
spect to a possible inhibitory effect on the water requirement and uptake. In any case, water supply is of
course an important parameter in many parts of the world. Of specific interest are experiments on cassava
suggesting that selection of appropriate plants and/or breeding experiments in this direction might be
promising.Manihot esculentashowed effective growth and high yields under conditions of especially ir-
regular rainfall. Under conditions of severe drought, the plants largely maintained their leaf area and were
capable of effective and faster growth following rain in comparison with other crops. The plants had mod-
ified growth periods with photosynthesis essentially taking place in the morning so that the stomata
(which are specifically sensitive to drought in this plant) could be closed during the day, avoiding leaf de-
hydration [127].
VI. CONCLUDING REMARK
We feel that even the few examples and results presented in this chapter make clear that improved knowl-
edge is needed not only of many details but also of basic parameters of the interaction between plant phys-
iology, the environment, and specific chemicals that play a role, e.g., in applied science or in agriculture.
A reintensification of plant physiological investigations might be more than helpful in the understanding
of interrelationships leading to new developments, e.g., in ecological plant protection linked to modern
biochemistry.
ACKNOWLEDGMENTS
The authors wish to express their gratitude to the Alexander von Humboldt-Stiftung (R. A.-B.) and to the
Deutsche Forschungsgemeinschaft (K.P.B.) for generous financial support.
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