High yielding dwarf genes from Taiwan in rice are

From which species was resistance against $Phytophthora$ in potato obtained?

Which one of the following agents is used to induce mutation in higher plants?

Which one of the following is an improved variety of maize?

The conventional method of breeding for resistance includes:
$I$. Screening the germplasm for resistant sources
$II$. Hybridization of selected parents
$III$. Selection and evaluation of the hybrids
$IV$. Testing and release of new varieties
Choose the correct option.

Who developed the semi-dwarf wheat varieties?