List five main groups of natural plant growth regulators. Writea note on discovery, physiological functions and agricultural/horticultural applications of any one of them.

which is the only one gaseous natural plant growth regulator?

Name three groups of plants that bear archegonia. Briefly describe the life cycle of any one of them.

The deficiencies of micronutrients, not only affects growth of plants but also vital functions such as photosynthetic and mitochondrial electron flow. Among the list given below, Which group of these elements shall effect most, both photosynthetic and mitochondrail electron transport: