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This version is not peer-reviewed
Submitted:
15 November 2024
Posted:
19 November 2024
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With predicted increase in the intervals between rainfall events becoming more apparent, little is known about how short-term (few weeks) drought events influence plant growth and nitrogen (N) uptake after rewetting, and how this legacy effect is modulated by drought intensity and soil amendment. Methods: Soil (50% water holding capacity, WHC) unamended or amended with faba bean residue (C/N 9) was planted with wheat for two weeks. Thereafter, drought was imposed by reducing soil water content to 10% (DEFICIT) or 30% (MILD) WHC and maintained for two weeks (days 0 to 14). Thereafter, soils (deficit and mild) were rewetted to 50% WHC and maintained at this water content for additional two weeks. Control soils were maintained at 50% WHC (OPTIMAL) throughout the experiment. Results: At the end of the dry period, shoot dry weight was about 60% lower in DEFICIT than OPTIMAL. Contrarily, soil available N was higher in DEFICIT (16.65-41.72 mg kg-1) than OPTIMAL (4.57-26.42 mg kg-1). While MBN did not differ with amendment, it was about 80% lower in DEFICIT than OPTIMAL without amendment. During the two-weeks after rewetting (days 15 to 28), shoot dry weight, N concentration and available N changed little without amendment. But in the amended soil particularly in DEFICIT treatments, shoot dry weight nearly doubled, shoot N concentration increased by about 40%, plant N uptake increased by about 70%, and MBN decreased by about 40%. However, shoot dry weight and plant N uptake were still lower than the OPTIMAL. Conclusion: The reduced plant growth, shoot N concentration and plant N uptake induced by a short period of drying (<30% WHC) is not compensated by increased growth and N uptake after rewetting.
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