Secondary metabolites: harvesting short term benefits from arid zone agroforestry systems in India

Long rotation period of trees and complex trading procedures of wood, are major impediments in spread of agroforestry. Thus, alternative for providing early return to farmers along with long term benefits of raising trees on their farmlands are necessary. Generally, ~ 25% of the trees can be used as timber while the other parts viz. bark, leaves, roots, branches etc. have limited use and are often burnt. In process, leakage of C sequestration potential of trees is reduced. But, tree twigs and leaves can be the potential source of bioactive compounds or secondary metabolites especially in arid region. Vegetation in arid regions possesses very special and unique chemicals which help them to adapt to prevailing harsh conditions. Water stress in these vegetation leads to production of high quantity of reactive oxygen species (ROS) which through a series of pathways eventually leads to higher production of certain special secondary compounds. These compounds, in nature improve defense mechanism of trees, but also have immense pharmaceutical, food, cosmeceutical, nutraceutical and agrochemicals value. They are locally used as folklore medicine but their commercial exploitation can provide short term benefits to farmers. Also, unlike bole, which can be exploited only once, these benefits from trees can be exploited many times during their growing period. Therefore, in this article research work on important secondary metabolites produced by major agroforestry systems of arid region of India has been reviewed along with their industrial applications.