Skill India

Sampling Method collection of soil and plant samples

Objective the major purpose of sampling for nematodes is to estimate the nematodes population for for research advisory and predictive programmes population estimation is also essential for disease diagnosis and management the specific objectives of sampling should be known before the sampling is done this is particularly important for the selection of sampling design type and amount of nematodes required the decision whether to collect soil or root or both for nematode assay is also important this actually depends on the nematode host plant and purpose of sampling polyspecific population that contain both ecto and endoparasitic nematode may require both soil and root sample s for instance to assay ectoparasites only soil is collected the specific time of sampling is also important as nematodes population vary greatly with the season and age of the host plant

Material required

trowel shovel soil auger kr hand hoe polythene bagabel rubber band pencil and knife .

methods of sampling

1. Sampling from field crop s

leave about 1 m peripheral area of the field remove 2 to 3 cm top soil . collect 200 cc soul along with feeder roots up to a depth of 15 to 20 cm subsample collect 10 subsample from one hectare area in a zig zag manner put all the sub sample s in a polythene bag composite sample . label the sample properly and tie it with a rubber band .

2. Sampling from vegetable crop s

selectv6vrows of a field 2 from beginning 2 from each pair of rows in zigzag manner. put all the subsample s in a polythene bag . label and tie the sample s .

3. Sampling from an orchard

Take a sample from a tree up to a depth of 30 to 60 cm feeder root zone collect subsample s from 10 trees randomly frome one hectare area pool all the sub sample s in a polythene bag label and tie the sample.

4. Sampling from a tree

collect 5 sub sample s each from around the trunk and drip line of the tree put all the subsample in a polythene bag and label and tie the sample s.

Labeling samples taken in polythene bag should be labelled with the following details location host crop and stag6of crop variety previous crop date of sampling soil types name of the collector

important precaution s

selective live plants showing

selectvlive plants showing symptom s take sample from the rhizosphere avoid sampling immediately after fertilizer or pesticides application and irrigation or heavy rainfall avoid surface soil pebble and plant debries keep the plant material moist in polythene bags .

Storage of sample

A. Soil sample since plant parasitic nematode are thin walled short lived organism improper handling such as exposure to sun temperature extremes drou6ness or poor storage result s in high mortality rates leading to erroneous information on the nematodes population after collection each sample should be sealed in a plastic bag and stored at a place away from direct sun exposure and preferably at 20 to 25 degree Celsius temperature.

B. Plant Material

To isolate endo or semi endoparasitic nematode part of the plant invaded by the nematode is collected ex. roots bulbs tubers rhizome leaves trunk seeds and fruit s root sample should be gently rinsed in water before storage plant material containing nematodes should be gently rinsed in water before storage plant material containing nematodes should usually be kept cool and moist and examined as soon as possible intact plants remain fresh for longer periods during storage shokts deconposes much faster than root s hence they should be kept in separate polythene bags the plant material should be moistened before packing in poly bags and storesd at 10 to 15 degree Celsius especially in substropical and tropical regions.

extraction of nematodes from soil and plant tissue s following cobbs sieving and decanting technique bearmann funnel technique

objective to extract nematode and cysts from soil sample for identification counting and assessing their population density.

Extraction of nematodes from soil

cobbs decanting and sieving method principlevthe soul particles and nematodes settle at different rates due to differences in Their specific gravity. and different sized nematodes are retained on sieve s of different pore sizes.

Procedurevmix thoroughly the conposite soil sample and take 250 cc in pan add about one litre water and stir well breaking clods clumps. pass the content through a 359vmesh sieve discard ing the filtrate collect the residue left over 350 mesh sieve in a beaker snd label it.vexaminevthe content s o