1. High Yield: This means the crop produces a large quantity of usable product (fruits, vegetables, grains, etc.) per unit area of land. This is crucial for feeding a growing global population and ensuring food security.

2. Resistance to Pests and Diseases: Crops need to be able to withstand attacks from insects, fungi, bacteria, and viruses that can damage or destroy crops, leading to lower yields and potential economic losses.

These two characteristics are often intertwined, as a crop with high yield may be more susceptible to pests, while a disease-resistant crop may have a lower yield. Biologists use a variety of techniques to breed and select for these characteristics, including traditional breeding methods, genetic engineering, and marker-assisted selection.