A crop is only as good as its root system

Tops show. Roots decide. They pull water and minerals, send signals that slow or push the shoot, and set how far the plant can ride a dry week.

Deep, uncompacted roots reach cooler, wetter layers. Shallow roots in a pan or a drowned bed make a handsome canopy that collapses at noon.

Build roots at establishment: open the pan, keep air in the hole, do not salt the feeder zone. Physiology here is the job of depth and health — mycorrhizae and compost are other stories.

If the top looks fed and still wilts daily, dig.

In this series

• Ask what cuts sugar production — not which bag to add
• A crop is only as good as its root system
• Maximise yield per drop, not drops per hectare
• Yield falls before the leaf wilts
• Fruit drop is the plant aborting when resources fail
• Architecture: every productive leaf needs light