Reduced yield & quality
Any nutient that has a significant effect on plant growth and development will naturally affect yield and or quality. NPK is the main source of growth and energy for any crop and so any problems in availability there and it will be seen at harvest. However, the minor nutrients either directly via their roles in important processes such as photosynthesis or indirectly via the effect that some have on the uptake and utilisation of NPK can also dramatically affect both yield and quality. Look at the specific crop and nutrient pages to find out what nutrients are key in your crop.