India's wheat yield revolution in the 1960s was possible primarily due to :-
- Hybrid seeds
- Quantitative trait mutations
- Increased chlorophyll content
- Mutations resulting in plant height reduction
Answer
(4) Mutations resulting in plant height reduction
Solution
As per NCERT, in 1963 several varieties such as Sonalika and Kalyan Sona, which were high yielding and disease resistant, were introduced all over the wheat-growing belt of India; these are semi-dwarf varieties of wheat.
Their semi-dwarf character comes from dwarfing gene mutations (Norin-10 dwarfing genes used by Norman Borlaug); Sharbati Sonora and Pusa Lerma were obtained from Mexican dwarf wheats by gamma-ray treatment.
Short, stiff stems do not lodge (fall over) under heavy fertiliser and irrigation, so more of the plant's resources go into grain.
∴ The wheat yield revolution was possible primarily due to mutations resulting in plant height reduction.
Answer: (4)