Role of potash in crops: Which class of fertilisers chiefly promotes development of plant fibres and enhances sugar accumulation in vegetables and fruits?

Introduction / Context:
Potassium (K) is a primary macronutrient that regulates osmotic balance, enzyme activation, and transport of photosynthates. Its agronomic effects include improved fibre development in crops like cotton and enhanced sugar translocation and accumulation in fruits and vegetables. This question asks which fertiliser class most directly supports those outcomes.

Given Data / Assumptions:

• Nitrogen promotes vegetative growth and chlorophyll formation.
• Phosphorus supports energy transfer (ATP) and root/flowering development.
• Potassium regulates stomatal function, carbohydrate transport, and stress tolerance.

Concept / Approach:
High K availability improves the movement of sugars from leaves to storage tissues, increases turgor for fibre elongation, and supports enzyme systems involved in carbohydrate metabolism. Consequently, potassic fertilisers (e.g., KCl, K2SO4), graded by % K2O equivalent, are recommended to improve fibre quality and sugar content where soil tests indicate K deficiency or crop demand is high.

Step-by-Step Solution:

Verification / Alternative check:
Crop guides for sugarcane, fruit trees, and cotton consistently link adequate K nutrition with higher sugar recovery, better fibre strength/length, and improved stress tolerance.

Why Other Options Are Wrong:

• Nitrogenous: may boost vegetative growth but can dilute sugar concentrations if excessive.
• Phosphatic: important for roots and energy but not the primary lever for fibre/sugar accumulation.
• None/micronutrients only: contradicts well-established K role as a primary driver.

Common Pitfalls:
Overapplying N in pursuit of yield while neglecting K for quality parameters; ignoring soil test K and crop-specific K removal rates.

Final Answer:
Potassic fertilisers (K sources)