Written by There are as many instructions on what not to sample as there are on what to sample. Plant tissue or plants not to sample are:
- Tissue covered with soil, dust, or residue chemicals.
- Plants damaged by insects, mechanically injured, or diseased.
- Tissue from dead plants or dead tissue.
- Plants under moisture or temperature stress.
- Plants markedly affected by nutritional stress.
- Border-row plants or end-row plants.
- Plants in weed-infested areas.
- Whole plants unless seedlings.
WHAT NOT TO SAMPLE
THE GENERAL RULE
As a general rule, mature leaves exposed to full sunlight just below the growing tip on main branches or stems are usually preferred, taken just prior to or at the time the plants begin their reproductive stage of growth. In some situations, sampling may be necessary at earlier periods in the plant’s growth cycle with the same maturity.
WHAT NOT TO SAMPLE
There are as many instructions on what not to sample as there are on what to sample. Plant tissue or plants not to sample are:
1- Tissue covered with soil, dust, or residue chemicals.
2- Plants damaged by insects, mechanically injured, or diseased.
3- Tissue from dead plants or dead tissue.
4- Plants under moisture or temperature stress.
5- Plants markedly affected by nutritional stress.
6- Border-row plants or end-row plants. 7- Border-row plants or end-row plants.
8- Plants in weed-infested areas.
9- Whole plants unless seedlings.
PLANT SAMPLING TECHNIQUES
Kenworthy (1969), Chapman (1966), Jones et al. (1971, 1973), Reuter and Robinson (1986, 1997), Jones, Wolf, and Mills (1993), and Mills and Jones (1996) have described plant tissue sampling techniques that have been generally accepted. The following is a partial list of recommended sampling procedures taken from these sources:
Suggested sampling procedures for field and vegetable crops, fruits and nuts, and ornamental plants. READ MORE »
STATISTICAL CONSIDERATIONS
Once it has been determined which plant part is to be sampled to represent the plant’s elemental status, the number of plants to sample for adequate representation must be decided. What constitutes an adequate number has been determined to some degree from the results of previous research. Plants growing adjacent to each other can differ considerably in their elemental content. Lilleland and Brown (1943), when studying the phosphorus (P) nutrition of peach (Prunus persica L.) trees, found that the composition of morphologically homologous leaves taken from adjacent trees receiving the same fertilizer treatment differed considerably. This was also the experience that Thomas (1945) found with apple (Malus sylvestris Mill.) trees, and Steyn (1959) with citrus trees and pineapple [Ananas comosus (L.) Merr.] plants. READ MORE »
FIELD SAMPLING PROCEDURES FOR CONDUCTING A PLANT ANALYSIS
J. Benton )ones, Jr.
INTRODUCTION
The validity and usefulness of the determined elemental content of a collected plant tissue sample hinge on an intelligent and realistic approach to the problem of how to obtain a reliable sample. If the sample taken is not representative of the general population, all the careful and costly work put into the subsequent analysis will be wasted because the results will be invalid. To obtain a representativesample from a particular plant species is a complex problem, and expert knowledge is required before it can be attempted. READ MORE »
PRACTICAL USES OF PLANT ANALYSIS
Plant analysis results are used in a number of ways:
1- Determining that an element is essential for plant growth, development, and maturation or some process closely associated with nutrition and growth, such as symbiotic N fixation
2- Verifying the element associated with a phenotypic or apparent nutrient element deficiency or toxicity symptom.
3- Establishing optimum concentrations or critical values for elements associated with optimum or maximum economic yields.
4- Determining availability of soil nutrients and/or availability and recovery of an applied element or elements in fertilizer in crop response experiments.
5- Evaluating and comparing different areas or sites within a production field, orchard, or forest. READ MORE »
INTERPRETATION
Interpretation of the results of plant analysis is very important. Among those that have written on interpretation of results are Goodall and Gregory (1947), Ulrich (1948), Childers (1966), Jones (1967), Chapman (1966; 1967), Reuter and Robinson (1986), Jones et al. (1991), and Mills and Jones (1996) for crops in general; Ulrich and Hills (1990) for sugar beets; Bowen (1990) for sugarcane; Sabbe and Zelinski (1990) for cotton; Westfall et al. (1990) for small grains; Jones et al. (1 990) for corn and sorghum; Frazier et al. (1 967) and Small and Ohlrogge (1973) for soybeans; Geraldson and Tyler (1990) for vegetable crops; Kenworthy (1967, 1973) and Righetti et al. (1990) for fruits and orchards; Kelling and Matocha (1990) for forage crops; and Weetman and Wells (1990) for forests. Bergmann (1992) has presented nutrient ranges for 10 elements for a host of crops. These references can be very helpful for those looking for information on specific crops and can provide insights as to how these authors interpret plant analyses for those crops. READ MORE »
IMPORTANT ASPECTS OF PLANT ANALYSIS
There are a number of important things to keep in mind when using the plant analysis technique. Some of these have been discussed by Ulrich and Hills (1967) and Munson and Nelson (1973, 1990). Critical nutrient element levels have to be established by restricted growth comparisons and correlation studies for each element and for each crop under a variety of conditions. Ulrich (1948) and Smith (1962) reviewed the early developments and uses of plant analyses. Steenbjerg (1951) discussed different yield curves as related to plant nutrient concentrations. Munson and Nelson (1973, 1990) discussed the interrelationships of yield curves, nutrient supplies, and nutrient concentrations, and also related relative yield to the deficient zone, transition zone or critical range, adequate zone or sufficiency range (optimum concentration occurs at or near maximum or optimum economic yield), and excess zone (occurs at nutrient concentrations for which relative or actual yields begin to decrease). It should be noted that for nearly every element above the optimum concentration, there is an adequate zone or sufficiency range, which indicates that most elements can be taken up at levels greater than needed for optimum yield before yields are decreased due to an excess or an imbalance with other elements occurs. Some refer to this as the luxury range (Bergmann, 1992), inferring luxury consumption, which appears to occur for most elements. Examples of the different types of relationships that can be used in studying plant analysis results are shown in Figures 1.1 to 1.3. READ MORE »
SAMPLING AND METHODS OF ANALYSIS
Before a plant analysis result could be used effectively, research had to be conducted to relate elemental concentrations in the plant-to-growth response or yield. Also, it is necessary to determine what part or portion of the crop or forage plant, vine, or tree should be sampled and the time for sampling. Sample timing usually involves some point in the physiological age or stage of development of the crop, the selection being influenced as to whether the plant is an annual or perennial. Specific sampling procedures are given in the next chapter. Plant analyses are usually carried out on prepared samples in a laboratory under controlled conditions (Jones and Case, 1990). Testing of forage samples may be conducted with near infrared spectrometry (NIR) in mobile laboratories. READ MORE »
VISUAL PLANT SYMPTOMS
When an essential element is seriously deficient, photosynthesis or plant metabolic processes are disturbed, and symptoms in terms of the visual appearance of the leaves or decreased growth rate are produced. In addition, crop yield will be seriously decreased unless the deficiency can be corrected. Such visual symptoms are referred to as deficiency symptoms or hunger signs, which can be quite specific in terms of a given essential element (McMurtrey, 1948; Sprague, 1964; Grundon, 1987; Bergmann, 1992; Bennett, 1993). Usually a characteristic chlorosis or necrosis of leaf tissue is produced with a stunting of overall growth. The same is true for toxicity symptoms. As the mineral nutrition of a crop is improved, usually both yield and quality are positively affected. For example, grain may have higher mineral, starch, or protein contents, or plumper kernels. READ MORE »