Eutrophication and development, pollution from septic systems and sewers, sewage sludge spreading, and other human-related activities increase the flow of both inorganic nutrients and organic substances into ecosystems. Elevated levels of atmospheric compounds of nitrogen can increase nitrogen availability. Phosphorus is often regarded as the main culprit in cases of eutrophication in lakes subjected to "point source" pollution from sewage pipes. The concentration of algae and the trophic state of lakes correspond well to phosphorus levels in water. Studies conducted in the Experimental Lakes Area in Ontario have shown a relationship between the addition of phosphorus and the rate of eutrophication.
Epigenetics of plant growth and development premise in plants. In hybrids, lack of proper regulatory action, such as silencing by methylation, leads to uninhibited genes. If the gene is involved in growth, such as photosynthesis, the plant will experience increased vitality (Ni et al. 2008). The results heterosis can be seen in traits such as increased fruit yield, earlier ripening, and heat tolerance. Heterosis has been shown to provide increased general growth and fruit yield in tomato plants (Xiaodong). Epigenetics of plant growth and development Plants depend on epigenetic processes for proper function. Epigenetics has been defined as "the study of changes in gene function that