Plant Analysis

Plant analysis as a means of understanding plant physiology perhaps started with de Saussure (21). With plant analysis, de Saussure corrected the misunderstanding at the time that the mineral matter of plants had no importance. He showed that the mineral matter in plants came from the soil and not from the air and that little growth of plants occurred if they were grown in distilled water. Through plant analysis, he also demonstrated that plants absorbed minerals in ratios that differed from the proportions existing in solution or in soil and that plants absorbed substances from solution, whether the substances were beneficial to the plants or not.

Plant analysis was one of the means used by scientists in the 1800s to determine the essentiality of chemical elements as plant nutrients (22). Further refinements and applications of plant analysis led to studies of the relationship between crop growth or yield and nutrient concentrations in plants (23–26). Elemental analysis of leaves is commonly used as a basis for crop fertilizer recommendations (27,28).

Plants can be tested for sufficiency of nutrition by analytical tests, which employ quantitative analysis (total or specific components) in laboratories, or by tissue tests (semiquantitative analysis), often applied in the field. With proper means of separation of constituents, quantitative tests may measure nutrients that have been incorporated into plant structures or that are present as soluble constituents in the plant sap. The tissue tests generally deal with soluble constituents.