The theoretical limit to plant productivity

Area of Science:

• Ecology
• Plant Physiology
• Agricultural Science

Background:

• Increasing global demand for plant biomass for food, fuel, and fiber necessitates accurate estimation of production potential.
• Net primary production (NPP) quantifies annual biomass increment but current models may underestimate potential yields from managed landscapes.

Purpose of the Study:

• To reassess the theoretical maximum net primary production (NPP) of managed landscapes.
• To identify limitations and potentials for increasing crop yields, particularly for bioenergy crops with low nitrogen requirements.

Main Methods:

• Utilized a light-use efficiency model to estimate an upper-envelope NPP.
• Calculated theoretical maximum NPP based on solar radiation conversion efficiency, unconstrained by resource limitations.
• Re-evaluated NPP estimates considering water availability as a limiting factor.

Main Results:

• Theoretical maximum NPP approached 200 tC ha(-1) yr(-1) at point locations, orders of magnitude higher than current ecosystems.
• Water limitation reduced the upper-envelope NPP estimate by over 50% across 91% of the global land area.
• Observed high conversion efficiencies in some plants suggest potential for yield increases without altering photosynthesis mechanisms, especially for low-nitrogen crops.

Conclusions:

• Current models may underestimate potential biomass production, particularly for specialized crops.
• Realizing significantly higher crop yields is feasible by leveraging high photosynthetic efficiencies, especially in low-nitrogen varieties.
• Improvements in water use efficiency are critical for achieving enhanced crop yields globally.