Herbicides are part of modern agricultural production systems and therefore contribute significantly to the economy of agricultural products. At the same time, herbicides are potent and specific inhibitors of plant metabolism and may therefore be used as valuable tools in basic plant physiological research. A well-known example is the photosynthesis-inhibiting herbicide diuron, known to plant physiologists as DCMU, which has become one of the essentials in modern photosynthesis research. Similarly, knowledge in other areas of plant metabolism may be advanced by the use of herbicides as...