Beans require a fairly narrow temperature range in order to maximise productivity. Yields can be 6t/ha at optimum temperatures of 15-21C.
Above 28oC, pollen viability is decreased resulting in flower bud drop and reduced pod formation. Pods are also more likely to be fibrous, lacking good flavour and texture. Temperatures below 10C result in poor root system development and reduced photosynthesis, potentially halving total yield.
Long term breeding programs for beans could improve climate tolerance:
- There is scope to breed for improved drought tolerance with better root systems.
- In the tropics, French beans (Phaseolus vulgaris) can be replaced by snake beans (Vigna unguiculata) which are more tolerant to high temperature.
- There has already been some breeding for high and low temperature tolerance by the USDA.