Why does my cucumber have bitter fruit?

Cucumber bitterness is caused by cucurbitacin compounds, produced under stress. Common triggers in India: irregular watering (soil alternately dry and wet), high temperatures above 35°C, and nitrogen deficiency. Fix: maintain consistent daily watering, mulch the pot heavily, and harvest cucumbers promptly — overripe fruits on the vine signal the plant to produce more cucurbitacin throughout. Peel and discard the bitter stem end before eating.