Crop plants grown in monoculture are
low in yield
free from intraspecific competition
characterized by poor root system
highly prone to pests
Crop plants grown in monoculture, that is, a single crop being cultivated repeatedly in the same field, are highly prone to pests. When the same crop is grown repeatedly in the same field, it attracts the same pests and diseases, which can build up in the soil over time. This increases the risk of pest outbreaks, which can significantly reduce crop yields. In contrast, crop rotation, in which different crops are grown in the same field in a planned sequence, helps to reduce pest and disease buildup by breaking the pest life cycles and reducing their populations. Therefore, option 4 is the correct answer.