Plantation, Spices & Medicinal Crops

• Correct Answer: $2n = 2x = 26$.
• Elephant foot yam (Amorphophallus paeoniifolius (Dennst.) Nicolson, Araceae) is a diploid tropical tuber crop with a basic chromosome number of $x = 13$, giving a somatic diploid complement of $2n = 2x = 26$.
• Famous non-acrid Indian commercial cultivars include 'Gajendra' and 'Bidhan Kusum'.

• Correct Answer: 10 %.
• On a fresh weight basis, potato tubers contain $78\text{--}80\%$ water, $16\text{--}18\%$ starch, and approximately $2\%$ protein.
• However, on a dry weight basis (total solids $\approx 20\%$), crude protein constitutes $8\text{--}12\%$ (averaging about $10\%$) of the total dry matter.
• Potato protein (patatin) possesses exceptionally high biological value ($73$), comparable to whole egg protein.

• Correct Answer: Allyl propyl disulphide.
• The characteristic pungent aroma and tear-inducing volatile sulfur compounds in onion (Allium cepa) are primarily attributed to allyl propyl disulphide (and the lachrymatory factor thiopropanal S-oxide produced enzymatically via alliinase).
• Other compounds:

  - Quercetin: Flavonoid pigment responsible for the yellow skin colour in onions.
  - Sinigrin: Glucosinolate compound responsible for pungency in mustard and cole crops.
  - Diallyl disulphide: Responsible for pungency in garlic.

• Statement (A) is incorrect: In onion, photoperiod (day length) is the primary decisive environmental trigger for bulb initiation, while temperature merely modulates the rate.
• Statement (B) is incorrect: Low temperature (vernalization chilling at $10\text{--}15^\circ\text{C}$) is the primary requirement for floral bolting in onion, not day length.
• Statement (C) is correct: Long day cultivars (requiring $\gt 14\text{ hours}$ of light) remain purely vegetative and fail to bulb when grown under tropical short days ($10\text{--}12\text{ hours}$).
• Statement (D) is correct: In the Jones and Davis (1944) CGMS system: Male sterile A-line is $S\,msms$, maintainer B-line is $N\,msms$ (normal cytoplasm with homozygous recessive nuclear alleles), and restorer C-line is $N/S\,MsMs$.