A Contribution of ICAR National Fellow Project

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Seed Treatment for Field Crops

This plays a crucial role in protecting the emerging seedlings from insect-pests and diseases. It deals under its purview, both products and processes. Specific products and techniques may improve the growing environment for seeds, seedlings and the young plants. Seed treatment ranges from a basic dressing to coating and pelleting. Seed dressing is the most common method of seed treatment and popular amongst our Indian farmers. The seed is dressed with either a dry formulation or wet treated with a slurry or liquid formulation. Recommendations of seed treatment for various crops are offered by Government of India on major cereal crops - rice, wheat, barley; vegetables (potato, tomato, chilli, okra, leguminous and cruciferous crops), pulses (gram, pigeon pea, pea) and others (sugarcane, coriander, sunflower) etc. under its most ambitious programme Total Seed Treatment Campaign 2007 (www.ppqs.gov.in).

(Credit: Total Seed Campaign, 2007, GOI)

Ideal chemical seed treatment

Today, seed treatment has since evolved into a more advanced science. An ideal chemical seed treatment should be highly effective against various pests and diseases must satisfy few requirements, viz.(1) harmless to the seed; (2) stable for relatively longer periods prior planting; (3) offer an uniform coating to seeds, stick well, without giving a dull or unacceptable appearance, or impairing seed flow in planting equipment; (4) relatively inexpensive; and (4) must be registered for intended use (IOWA, 2006). The pesticides used in seed treatments should not affect adversely the seedling or plan growth and development.

Combinatorial Approach

Insecticide seed treatments are often formulated as combinations with other seed protectant pesticides. These may be a combination of two insecticides to provide a broader spectrum of insect control, or a combination of an insecticide and a fungicide. In Good Agricultural Practices (GAP), inclusion of biofertiliser and biofungicide in the seed-treatment also add another dimension to this issue for a holistic approach study.

Target insect – termites and damage propensities

Termites are xylophagus, considered to be a serious pest as it destroys crops and households. Termites are of regular occurrence mostly in tropical and sub-tropical parts of India.

In vitro germination test

Germination testing is considered as one of the most important quality test in evaluating the planting value of a seed lot. The ability of seeds to produce normal seedling and plants later on is measured in terms of germination test. Testing of seeds under field conditions is normally unsatisfactory as the results cannot be reproduced with reliability. Laboratory methods then have been conceived wherein the external factors are controlled to give the most uniform, rapid and complete germination. Testing conditions in the laboratory have been standardized to enable the test results to be reproduced within limits nearly as possible as those determined by random sample variations. The ultimate objective of seed germination testing is to obtain information with respect to the planting value of the seed and to provide result which could be used to compare the value of different seed lots. Germination of a seed lot in a laboratory is the emergence and development of the seedling to a stage where the aspect of its essential structures indicates whether or not it is able to develop further into a satisfactory plant under favourable conditions in soil (ISTA, 2007). These essential structures are awell-developed and intact root system, hypocotyl, plumule and one or two cotyledons according to the species.

Seed vigour is a highly complex subject. At biochemical level it involves energy and biosynthetic metabolism, coordination of cellular activities and transportation and utilization of reserve foods. At germination level, it involves speed and totality of germination, pushing power of seedling etc. (Agrawal, 1995). Vigour indices I and II are based on the seed germination percentage, seedling length and dry weight of the seedlings. Certainly, these indices provide better information on the seedling growth and development.

Seed treatment insecticides

Earlier (before 1980’s) the chlorinated hydrocarbon insecticides like aldrin, dialdrin, BHC and heptachlor were effectively used to control termites in wheat due to their long residual action. But these chemicals leave harmful residues on the food stuffs and are highly hazardous to the human health and non target organisms. As a result of these consequences, the Government of India banned most of the chlorinated hydrocarbon insecticides. It was observed that most of chemical termiticides which is used for seed treatment cause harmful effects on seed germination as well as seedling development. As on today, termiticides like chlorpyriphos, imidacloprid, and fipronil are dominating and are the recommended insecticides with label claims (www.ppq.gov.in), and very few effective management reports are available,   on management of termites through seed treatment with these new chemicals further meager literature is available on compatibility of this termiticides with bio fertilizer and bio fungicide as seed treatment.

Realizing the negative impacts of chemical pesticides, the whole scientific community is addressing the alternative non-chemical means, and selective use of insecticides like low dose to ultra-low dose pesticides, specific pesticidal application means like seed treatments in an attempt to reduce the pesticide-load to the environment.



Last Updated: 27-01-2021

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