in testing 'the crop is evaluated by comparing with the best available cultivar' what does this means?

A cultivar is a plant or a group of plants that is selected for desirable characteristics which can be maintained by propagation. Thus a cultivar possesses all the characteristics that help sustain the quality of the plant and make it suitable for all conditions. The quality of other crops can be evaluated by comparison of their characteristics with the cultivar which is of supreme quality. This would help in knowing whether the crop in question, possesses the traits necessary for it to withstand certain environmental conditions, insect resistance, high yield etc.