Plant tolerance to herbivory affect plant growth and also tolerance are water, light, carbon dioxide and soil nutrients. Water and light levels are generally assumed to be positively associated with tolerance (Strauss and Agrawal 1999). However, there are exceptions such as evidence of decreased tolerance in "Madia sativa" with increased water availability (Wise and Abrahamson 2007, Gonzales "et al." 2008). Many studies have found CO levels to decrease tolerance in plants (Lau and Tiffin 2009). Increased nutrient levels are also commonly found to be negatively associated with tolerance (Wise and Abrahamson 2007). There are currently three prominent models that predict how resource levels may
Natural growth promoter the feed of young animals in order to support the endogenous enzyme secretions. Different feed additives may function as stimulator or modulator of immunity processes. Specific cell wall fragments from bacteria or yeasts or sea algae may induce activation of immune cells (e.g. macrophages, lymphocytes). This Article Natural growth promoter Natural growth promoters (NGPs) are feed additives for farm animals. Different categories of feed additives for farm animals are referred to as natural growth promoters (NGPs) or non-antibiotic growth promoters. They are commonly regarded as favorable alternatives to antibiotic growth promoters (AGPs) in livestock production. NGPs include predominantly organic acids,