Question

I have four pure lines of plants - Line 1 - high yielding ; Line 2 - disease resistant; Line 3 - disease resistant , medium yield; Line 4 - High yielding, susceptible to disease. Which combination of these lines will lead to heterosis in the F1 hybrid?

• A. Line 1 and Line 2
• B. Line 3 and Line 4
• C. Line 1 and Line 3
• D. Only A

Answer 1

Answer: (A), (B), (C)

The correct options are
A Line 1 and Line 2
B Line 3 and Line 4
C Line 1 and Line 3

Cross-pollination of different lines will lead to mixing of characters. So, a superior hybrid can be formed by either of the combinations mentioned above. Crossing of Line 1 and Line 2 will most definitely give a superior hybrid with both the desirable traits i.e. high yield and disease resistance. A cross between Line 3 and Line 4 will give rise to a mixed progeny, few of which might have the desirable trait of disease resistance from Line 3 and high yield from Line 4. Similarly, a cross between Line 1 and Line 3 can also lead to appearance of both desirable traits in the progeny.