Heterosis requires

In $1963$,several varieties of wheat such as ........ and ......... were introduced to all over India.

Which plant shows resistance to stem borer insects?

In maize,hybrid vigour is exploited by

$G. hirsutum$ is

Which characteristics are present in cotton varieties that do not attract bollworms?
$(i)$ Smooth leaves
$(ii)$ Hairy leaves
$(iii)$ Stem thorns
$(iv)$ Nectar-containing
$(v)$ Low aspartic acid
$(vi)$ Nectar-less