Moderately reducing N input to mitigate heat stress in maize

Area of Science:

• Agricultural Science
• Agronomy
• Climate Science

Background:

• Maize yields are threatened by high temperature stress during critical growth stages.
• Nitrogen fertilizer is commonly used to boost maize production, but its efficacy under heat stress is uncertain.

Purpose of the Study:

• To evaluate the impact of nitrogen fertilizer on maize grain yield under high temperature stress.
• To understand how environmental and management factors influence nitrogen's effect on yield during heat events.

Main Methods:

• A meta-analysis of 1536 comparisons from 113 studies in China over 20 years.
• Data classified into high temperature stress (HT) and no high temperature stress (NHT) groups based on meteorological data.

Main Results:

• Nitrogen's positive effect on maize yield was significantly reduced under high temperature stress.
• Factors influencing nitrogen's effect differed between HT and NHT conditions, with fewer factors significant under HT.
• Nitrogen input showed diminishing returns beyond specific thresholds in both NHT and HT.

Conclusions:

• Optimizing nitrogen management is crucial for maintaining maize yields in a warming climate.
• Reducing nitrogen input by approximately 20% may enhance maize's tolerance to high temperatures during flowering.
• Improving soil characteristics and crop management has limited impact on nitrogen's effectiveness under severe heat stress.