Question

Which of the following is a major parasitic weed in Sorghum?

• A. Cynadon dactylon
• B. Striga asiatica
• C. Cyprus rotundus
• D. Trianthema portulastrum

Hint:

Classification of Parasitic Weeds:
- Total Stem Parasite: Cuscuta (on Lucerne, Niger).
- Partial Stem Parasite: Loranthus (on Mango, plantation trees).
- Total Root Parasite: Orobanche (on Tobacco, Mustard, Solanaceous crops).
- Partial Root Parasite: Striga (on Sorghum, Maize, Sugarcane).

Answer 1

The Correct Option is B

Concept:
Parasitic weeds are specialized flowering plants that attach to the roots or stems of host crops through specialized physiological absorbing organs called haustoria to draw water, nutrients, or photosynthates.
They cause significant yield losses and are categorized into totalpartial stem parasites and totalpartial root parasites.
Sorghum (Jowar), pearl millet, and maize crops are particularly susceptible to root parasitic weeds.

Step 1: Identifying the Specific Parasite of Sorghum:
Striga spp. (commonly called witchweed, including Striga asiatica and Striga hermonthica) is a major obligate/semi-root parasite of sorghum, pearl millet, maize, and sugarcane.
Striga seeds germinate in response to root exudates (strigolactones) released by host roots, penetrate the root cortex via haustoria, and extract moisture and minerals, severely stunting the host crop.

Step 2: Evaluating the Other Weed Options:
- Cynodon dactylon (Bermuda grass): A perennial, non-parasitic monocot weed of the Poaceae family.
- Cyperus rotundus (Purple nutsedge): A perennial, non-parasitic sedge of the Cyperaceae family.
- Trianthema portulastrum (Horse purslane): A succulent, non-parasitic broadleaved annual weed of the Aizoaceae family.

Step 3: Final Answer:
Hence, the major parasitic weed affecting Sorghum is Striga asiatica, which corresponds to option (B).