Question

Given below are two statements: Statement (I): Bio-fumigation for the management of plant-parasitic nematodes is done by using brassicaceous plants. Statement (II): Bio-fumigation for the management of plant-parasitic nematodes is done by using graminaceous plants. In light of the above statements, choose the most appropriate answer from the options given below.

• A. Both Statement (I) and Statement (II) are true.
• B. Both Statement (I) and Statement (II) are false.
• C. Statement (I) is true but Statement (II) is false.
• D. Statement (I) is false but Statement (II) is true.

Hint:

Bio-fumigation is biochemically defined by the "Glucosinolate-Isothiocyanate" pathway, which is unique to brassicaceous plants like Indian mustard (Brassica juncea).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Bio-fumigation is an organic pest management practice where volatile, toxic chemicals are released into the soil during the decomposition of organic matter.
These natural compounds act as fumigants, suppressing soil-borne pests, pathogens, and plant-parasitic nematodes.

Step 2: Detailed Explanation:
Let us evaluate both statements:
Statement (I):
Plants in the family Brassicaceae (such as mustard, radish, and rapeseed) produce secondary metabolites called glucosinolates.
When these plants are chopped and incorporated into moist soil, the enzyme myrosinase breaks down the glucosinolates.
This reaction releases volatile, biologically active compounds called isothiocyanates (ITCs).
ITCs are highly toxic to many soil-borne pests, including plant-parasitic nematodes like root-knot and cyst nematodes.
This process is the classic definition of bio-fumigation.
Thus, Statement I is true.
Statement (II):
Graminaceous plants (grasses in the family Poaceae, such as oats, wheat, and rye) are often used as cover crops or green manures to improve soil structure and organic matter.
However, they do not contain glucosinolates and do not undergo the biochemical reactions that produce isothiocyanate fumigants.
While some sorghum species contain cyanogenic glycosides (like dhurrin) that can release hydrogen cyanide, the term "bio-fumigation" is scientifically and historically defined by the use of glucosinolate-containing brassicaceous crops.
Thus, Statement II is false in this context.

Step 3: Final Answer:
Statement I is true, and Statement II is false.
This corresponds to Option 3.