Different Waterlogging Depths Affect Spatial Distribution of Fine Root Growth for Pinus thunbergii Seedlings

Abstract

The increase of waterlogged environments at forests and urban greenery is of recent concern with the progress of climate change. Under waterlogging, plant roots are exposed to hypoxic conditions, which strongly affect root growth and function. However, its impact is dependent on various factors, such as waterlogging depth. Therefore, our objective is to elucidate effects of different waterlogging depths on Pinus thunbergii Parl., which is widely used for afforestation, especially at coastal forests. We conducted an experiment to examine growth and morphology of fine roots and transpiration using 2-year-old seedlings under three treatments, (1) control (no waterlogging), (2) partial waterlogging (partial-WL, waterlogging depth = 15 cm from the bottom), and (3) full waterlogging (full-WL, waterlogging depth = from the bottom to the soil surface, 26 cm). As a result, fine root growth and transpiration were both significantly decreased at full-WL. However, for partial-WL, fine root growth was significantly increased compared to control and full-WL at the top soil, where it was not waterlogged. Additionally, transpiration which had decreased after 4 weeks of waterlogging showed no significant difference compared to control after 8 weeks of waterlogging. This recovery is to be attributed to the increase in fine root growth at non-waterlogged top soil, which compensated for the damaged roots at the waterlogged bottom soil. In conclusion, this study suggests that P. thunbergii is sensitive to waterlogging; however, it can adapt to waterlogging by plastically changing the distribution of fine root growth.

Assessing the Response of Diverse Sesame Genotypes to Waterlogging Durations at Different Plant Growth Stages

“…With a shortfall in oxygen availability, the processes that depend on oxygen, such as carbon assimilation and photosynthate utilization, are suppressed [13,14]. Moreover, oxygen depletion and rising carbon dioxide concentrations devastatingly impact root growth and disturb the functional relationships between roots and shoots [15][16][17][18]. Additionally, in the waterlogged soil, compounds such as ethylene, manganese, carbon dioxide, and iron concentrations may rise, causing chronic toxicity as well as anaerobic microbial metabolites, which may accumulate [19].…”

Waterlogging and restricted-below ground aeration on photosynthetic performance and root elongation rate of RRIM 600 and RRIT 251 rubber genotypes (Hevea brasiliensis Mull. Arg.)

“…It may help the plants access other areas where O2 is still available. Different depths of waterlogging also affect the spatial distribution of root growth [29]. In the recovery stages, visually, we observed and found that the plant produced new roots rather than growing the existing sources.…”

Unusual late-fall wildfire in a pre-Alpine Fagus sylvatica forest reduced fine roots in the shallower soil layer and shifted very fine-root growth to deeper soil depth

“…Our findings agree with Hart et al 58 , suggesting that different portions of plant organs might respond autonomously to changing local conditions. In particular, as in the case of drought or hypoxic conditions 59 – 61 , the interplay of fine root depth distribution, morphological traits, and branching orders may be a key functional response to stress determining plant survival and growth.…”