Is zakat obligatory on tomatoes, alfalfa, sesame, and wheat straw (hay)?

There is no zakat due on tomatoes and vegetables, unless they are trade goods, in which case zakat is due on their value if it reaches the nisab and a year has passed over it. As for hay, there is no zakat on it. However, sesame is subject to zakat if its grains reach the nisab (653 kilograms), and the zakat is paid from its oil. Some scholars, however, are of the view that no zakat is due on it.