write the effct of pesticides on plant ,both short term and long term effect in four five points ....... (no unwanted messages please) .......
Answers
Answer:
The term pesticide covers a wide range of compounds including insecticides, fungicides, herbicides, rodenticides, molluscicides, nematicides, plant growth regulators and others.
Explanation:
Short term Effect.
1) Nitrogen fixation which is required for the growth of higher plants is hindered by pesticides in soil.
2. The insecticides DDT, methyl parathion, and especially pentachlorophenol have been shown to interfere with legume-rhizobium chemical signaling.
3. Reduction of this symbiotic chemical signaling results in reduced nitrogen fixation and thus reduced crop yields.
4. Root nodule formation in these plants saves the world economy $10 billion in synthetic nitrogen fertilizer every year.
5. Contact pesticides are usually sprayed on plants and can kill bees when they crawl over sprayed surfaces
Long term effect.
1. Improving productivity
Tremendous benefits have been derived from the use of pesticides in forestry, public health and the domestic sphere – and, of course, in agriculture, a sector upon which the Indian economy is largely dependent. Food grain production, which stood at a mere 50 million tons in 1948–49, had increased almost fourfold to 198 million tons by the end of 1996–97 from an estimated 169 million hectares of permanently cropped land. This result has been achieved by the use of high-yield varieties of seeds, advanced irrigation technologies and agricultural chemicals.
2. Protection of crop losses/yield reduction
In medium land, rice even under puddle conditions during the critical period warranted an effective and economic weed control practice to prevent reduction in rice yield due to weeds that ranged from 28 to 48%, based on comparisons that included control (weedy) plots (Behera and Singh, 1999). Weeds reduce yield of dry land crops (Behera and Singh, 1999) by 37–79%.
3. Vector disease control
Vector-borne diseases are most effectively tackled by killing the vectors. Insecticides are often the only practical way to control the insects that spread deadly diseases such as malaria, resulting in an estimated 5000 deaths each day
4. Quality of food
In countries of the first world, it has been observed that a diet containing fresh fruit and vegetables far outweigh potential risks from eating very low residues of pesticides in crops.
5. Other areas – transport, sport complex, building
The transport sector makes extensive use of pesticides, particularly herbicides. Herbicides and insecticides are used to maintain the turf on sports pitches, cricket grounds and golf courses. Insecticides protect buildings and other wooden structures from damage by termites and woodboring insects.