Department of Plant Sciences

Over the years, research has provided us with a great wealth of information that may be useful when considering the macro- and micronutrient needs of specific plants. The objective of the following presentation is to explore some examples of how we can predict special nutrients needs for certain crops based on their structure and metabolism. For example, all steps in protein synthesis require high potassium concentrations and after proteins are synthesized they require potassium for balancing the negative charges of aspartate and glutamate residues. Therefore, high protein crops generally require more potassium than low protein crops. Cell walls of grasses contain less pectin, and therefore less boron and calcium than those of dicots. Thus, boron and calcium requirements of dicots are higher than those of grasses. Plants with C4 photosynthesis can be grouped into different categories based on enzymes involved in C4 acid decarboxylation in bundle sheath cells. In C4 species that utilize NAD-malic enzyme, the release of CO2 for the Calvin cycle depends on manganese activation. Therefore these NAD-malic enzyme plants have a higher manganese requirement for maximum biomass production and photosynthesis than other C4 plants or C3 plants. Soybean plants dependent on biological nitrogen fixation may also have a higher manganese requirement than many other crop plants based on manganese involvement in the metabolism of their root nodule bacteria, and ureide metabolism in their leaves and developing pods. These are only a few examples of how plant structural and functional differences lead to unique macro- or micronutrient needs that may be critical for maximizing crop production and crop quality.