Question based on paragraph
Students were taken to observe the crop cultivation in a potato farm in Maharashtra. The students observed that the yield of crops in Mr. Shyam's potato farm was more than that in his neighbour Bharat’s potato farm. Mr. Shyam was using a different variety of the crop, which he suggests has been disease-free ever since he planted the seeds. Based on the above passage, answer the given question
Mention two techniques used for the production of such superior varieties of crops.