Root and Shoot Survival and Recovery after Short-term Waterlogging

Aims Intensive precipitation or excess irrigation cause short-term waterlogging, where all or part of the root system is subjected to saturated soil and oxygen deficit. The root system response and subsequent recovery from such short-term waterlogging is not well understood. In this study, we explored the root and shoot growth response to different duration and severity of short-term waterlogging and the subsequent recovery process.

Methods In two experiments, the winter wheat cultivar ‘Hereford’ was subjected to waterlogging for 1, 2, 3 and 4 days at depths of 0, 0.05, 0.15, 0.20 and 0.40 m below soil surface during the tillering stage. Plants were grown in long transparent tube rhizotrons (1and 2 m), which enabled determination of the dynamics of root growth along the tube surface by imaging. Chlorophyll fluorescence was measured to assess the shoot growth response. One week after drainage, ¹⁵N tracer was supplied to determine deep root activity. Three weeks after drainage, plants were harvested to measure the carbohydrate, leaf area, ¹⁵N enrichment, N content and biomass.

Results and discussion Root growth was shown to decrease below the waterlogging depth, while the adventitious root growth increased above. The measurements of chlorophyll fluorescence indicated that maximum quantum yield of photosystem II (Fv/Fm) decreased significantly in the more severe waterlogging treatments. However, the more severe waterlogging treatments had much higher Fv/Fm values and a faster root growth towards the end of the waterlogging and after drainage. After 3 weeks, root and leaf growth had recovered. There were no significant differences of total carbohydrate, N content, leaf area and dry matter among treatments. Deep root growth and N uptake also recovered. In conclusion, roots and shoots seemed to compensate for short-term waterlogging by growing adventitious roots above the waterlogged zone, and increasing photosynthetic parameters and root growth after drainage.