Pollen grains of rice and wheat lose their viability in ….. Minutes of their release

Pollen grains of rice and wheat lose their viability in ____ Minutes of their release

Pollen grains of rice and wheat lose their viability in ....... minutes of their release

Pollen grains of rice and wheat lose their viability in....... minutes of their release.

Pollen grain is

Pollen grain is

Pollen grain is

How can pollen grains of wheat and rice which tend to lose viability within 30 minutes of their release be made available months later for bredding programmes ?