What "drought tolerance" actually means on a seed packet

Ask three seed sellers what drought tolerance means and you will get three answers. The label covers at least two genuinely different plant strategies, and confusing them is how farmers end up with the wrong seed for the right reason.

Escape versus endurance

Drought escape means finishing early. An extra early maize such as SAMMAZ 16 from IAR Zaria matures in around 80 days. It does not withstand drought so much as sidestep it, completing grain fill before the rains withdraw. In the Sahel Savanna, where the reliable window is 75 to 90 days, this is often the only workable approach.

Drought endurance means holding on. Varieties selected under managed drought stress, such as IITA's TZE-W DT STR populations, keep filling grain through a mid season dry spell that would abort the ears of a less tolerant variety. This matters where the season is long enough but unreliable in the middle.

The two strategies fail in different ways. An escape variety planted in a long season simply leaves yield on the table. An endurance variety planted where the season is too short will not finish at all.

Why maturity duration is the first question

Before comparing tolerance ratings, compare duration against your season. A variety needing 120 days cannot finish where the rains last 90, regardless of how it is marketed. This is the single most common mismatch, and it gets worse as rainfall becomes less predictable.

What to ask for

• The variety name and the institute that released it, not just "improved seed"
• Days to maturity, and how that compares with your normal season
• Whether the drought claim is about early maturity or about stress tolerance
• Whether the seed is certified, and what germination percentage it is sold at

A seller who cannot answer the first two is not selling you a known variety.