As I know that different Environmental or physiological or biogeochemical parameters are responsible for this variations. Is there any other reason for plant secondary metabolites or bioactive compounds content variations ?
The bio-synthetic pathway of the plants is affected by many ecological factors including the temperature, the humidity, type of the soil and nutrients, atmospheric pressure,..etc. In addition the catalytic enzymes may differ.
The secondary metabolites are synthesized as an adaptation in plants. The amount and functional groups present in these compounds varies from place to place.
The temperature, humidity,soil pH, winds, toxicity in environment etc. these.
In our seed oil research we found many time such conditions when an unusual component was not reportend in the prevoius studies but we detected it in our desert specimen and the reverse were also found.
As my openion it is the most important aspect of phytochemical analysis of plants.
Secondary metabolites are the products of metabolism.Naturally it varies due to the different kind of metabolism in different plants.Also environmental factors to be considered.
The possibilities for the synthesis of secondary metabolites are genetically determined. When, how much and what types of them will be synthesized depends on the conditions of the environment. In plants of the same species but growing at different sites a different amount of secondary metabolites will be synthesized. There is a difference in the content of secondary metabolites in plants of the same species depending on the presence or absence of stress. Each geographic location is characterized by a complex of conditions - soil, moisture, temperature, etc. All of this affects the synthesis of secondary metabolites, as they are a means of protection and adaptation to the environment. On the other hand, the phase of development of a particular plant species also matters. Since part of the secondary metabolites are used by plants at different stages of the life cycle - for attracting pollinators, for attracting animals for fruit and seeds spreading, etc., the synthesis of these metabolites will be changed with the phases of plant development.
The secondary metabolites are synthetized from various pathways that depends on varied substrates. This substrates are acquired from Environmental and them are needed for plant defense, basically. If the Environmental changes, the metabolites also changes.
In addition to the very good answers of Mohamad Ali Mustafa Hijazi, Akleshwar Mathur, Yasodha Thirumal, Lyubka Kohleva and Nikkolas Benites, the following consideration: First, the plant has to perform all processes of primary metabolism or has to operate these processes. This is essential for the existence of the plant. Only when these are ensured can secondary metabolism processes take place. Therefore, it is also a question of capacity. The capacity depends on the genetic factors of the plant, but also on the environmental conditions. Whether and how many biotic and abiotic stressors affect the plant and how strong they are. Therefore, it is a question of how much capacity is left for secondary metabolism. There has to be that variability for the plant to survive.
The secondary metabolites or bioactive compounds content varies with different conditions or places. While experimenting with a medicinally important forest tree species Oroxylum indicum, I too found changes in the bioactive compound content when the soil nutrient content and environmental factors altered. During the experiment, I found that the inoculation of plant species with mycorrhiza, fungus and bacteria enhanced the accumulation of Phytochemicals. Metabolic pathways are other important factor responsible for the same.
Yes it is true. One of my research study I was also found that pollution is highly affecting the plant Pigments. Polluted areas has less amount of chlorophyll and carotenoids contents than comparatively less polluted areas. That means Environmental parameters are directly or indirectly affecting in this bioactive compounds contents.