Plants roots interact with microbes in beneficial and detrimental ways (Sylvia et al., 1997; Thies and Grossman, 2006). Soil biotas are involved in mineralization of nutrients to be taken up by plants with mineralization efficiency, in part dictated by the microorganism population (Prosser, 2006). Generally there is a balance between beneficial and plant pathogenic microorganisms (Van Elsas et al., 2006). Detrimental microorganisms can be suppressed as a result of competition, parasitism/predation, induced resistance, or antibiosis (Al-Rawahi and Hancock, 1998; De Cal et al., 2000; Metcalf et al., 2004; Thomashow and Weller, 1996; Zaki et al., 1998). Mixes of microorganisms may provide a greater range of protection than a single organism (Michaud et al., 2002).
Rhizosphere bacteria can benefit plant development (Glick, 2004; Kokalis-Burelle et al., 2003; Lucy et al., 2004; Russo, 2006; Schulze and Pöschel, 2004; Shimshick and Herbert, 1979; Zahir et al., 2004; Zehnder et al., 2001). Rhizobia bacteria may interact with mycorrhizal fungi to increase root colonization and increase nutrient content in plants (Gravel et al., 2009; Singh and Adholeya, 2002; Suresh and Bagyaraj, 2002). Russo and Perkins-Veazie (2010) found that when bell pepper (Capsicum annuum L.) was sown into a medium inoculated with mixes of bacteria in the greenhouse, there was little effect on plant development after seedlings were subsequently transplanted to the field.
Peppers are grown in temperate to tropical climates in various soil types and are diverse in plant size and in fruit size and shape. The role of microbes in pepper production needs clarification (Douds and Reider, 2003; Nemec et al., 1996; Russo, 2006). However, it is accepted that plants grown in the field without a diverse soil microbial population would not develop and produce at acceptable levels.
Several microorganism-containing commercial products claim various benefits for plants. It is necessary to assess these products so producers have information to determine whether use of the products is justified. Growing plants under greenhouse conditions allows screening of materials under controlled conditions with results on how cultivars react to various treatments. The project was undertaken to screen soil amendments for effects on growth, development, and some phytonutrient contents of peppers.
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