Norin-$10$ gene is

In which method are $\Gamma$-rays used?

Consider the following four measures $(1-4)$ that could be taken to successfully grow chickpea in an area where bacterial blight disease is common.
$(1)$ Spray with Bordeaux mixture
$(2)$ Control of the insect vector of the disease pathogen
$(3)$ Use of only disease-free seeds
$(4)$ Use of varieties resistant to the disease
Which two of the above measures can control the disease?

Can gamma rays used for crop improvement programmes prove to be harmful for health? Discuss.

How is a hybrid variety of maize obtained?

Which methods of breeding are important in plant breeding?