**1. Introduction**

Several tools are available to evaluate the nutritional state of plants. Plant analysis is an effi‐ cient one since it uses the plant itself as a nutrient extractor. Thus, it complements soil chem‐ ical analysis and makes it possible to predict nutritional disorders before the appearance of visual symptoms in the plant tissue. However, it is necessary to integrate both techniques, chemical analysis of plants and chemical and physical analysis of soil, besides visual diagno‐ sis to maximize fertilization efficiency in terms of cost and prevention of environmental damage.

Adequate fertilization avoids damage to the environment by reducing soil acids, water eu‐ throphy, pollution of the phreatic zone and area salinization. Furthermore, efficient fertilizer handling is fundamental in any productive system, especially in the recent decades, due to increased cost, scarcity of some nutrient sources and consumer insistence for high quality products.

Precise analytic methods only are not sufficient to an adequate fertilization handling. A competent professional having theoretical and practical experience and knowledge about the various factors involved in the production chain, like interactions "soil-plant-environ‐ ment- handling, is also an absolute requirement.

By plant analysis it is possible, among others, to determine culture nutrient needs and ex‐ portation, identify nutritional deficiencies that produce similar symptoms, evaluate nutri‐ tional states, help in the managing of fertilization programs and diagnose about levels of nutrients in diverse plant organs. Several procedure, direct and indirect, are available to ach‐ ieve these aims. This chapter will emphasize the main methods utilized in the diagnosis of the nutritional state of plants, like chemical foliar analysis, biochemical tests, measurements of leaf green color and visual observation. The linked information in the present chapter

© 2012 de Mello Prado and Caione; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 de Mello Prado and Caione; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

were obtained from an extensive literature review and also were inserted professional expe‐ riences of the authors.

To exclude the factors in Table 1, the professional must know the interactions "plant-envi‐

Plant Analysis

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http://dx.doi.org/10.5772/53388

In this item, sampling criteria will be discussed, in terms of leaf analysis, although it should be emphasized that these principles are also applied in visual diagnosis and indi‐

Sampling is a fundamental step in the outcome of foliar analysis. Poor or inadequate sam‐ pling compromises all available recommendations. Results quality and precision are directly dependent on the procedure. This is a critical step since nutrients concentrations are not the same in all plant parts, and may differ according to age and variety. Foliar analysis results will only be useful and representative of the culture if sampling is correctly performed.

Some criteria are similar to the ones employed in soil sampling and follow basic procedures [3]. **1.** Cultures should be divided in plots not bigger than 10 ha, having uniformity in age, va‐

**2.** In each plot, the indicated leaves from the desired cultures are collected in a zigzag di‐

**3.** Preferably, collections should be made between 7 and 11 AM, more than 24 hours after

**4.** At least 20 leaves must be collected from each plot and mixed before being sent to the

**7.** Samples should be immediately sent to the laboratory. When this is not possible the material must be kept in an isolated container, fitted with a 150w lamp during 72hours,

**8.** Sampling must never be conducted after fertilization or spraying. In these cases, collec‐

**9.** Leaf samples are sent to the Foliar Analysis Laboratory after complying with the rules

**•** damaged or abnormal looking leaves must not be collected unless this is caused by nutri‐

**•** soil-contaminated samples should be avoided and also the ones collected from plants sit‐

**5.** All samples must be packed in clean unused paper bags to avoid contamination.

**6.** Samples are identified by tags corresponding to each plot

tion of samples is made 30 days later to avoid foreign residues.

ronment-soil – farming activity" before proceeding to sampling.

**3. Criteria for plant sampling**

riety, spacing, soil and manipulations.

rect methods.

rection.

a rain

laboratory.

for initial drying.

Additional important details are:

uated close to roads or entrance pathways.

described.

tional problems

Again, it is emphasized that efficient foliar diagnosis includes all procedures starting from correct field sampling to adequate laboratory analysis.
