Root Response of Moso Bamboo (Phyllostachys edulis (Carrière) J. Houz.) Seedlings to Drought with Different Intensities and Durations

Abstract

The root of Moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) develops extremely rapidly at seedling phase and is highly sensitive to water content in soil, but its response patterns and adaptation strategies of its root to drought are little known. The aim of this study was to investigate the response of root morphology and architecture of Moso bamboo to drought at seedling phase and then to explore the drought adaptation strategies of its root. One-year-old potted seedlings of Moso bamboo were planted under three drought treatments (control, moderate drought and severe drought) for three months. Seedling growth, specific root length (SRL), root architecture (fractal dimension (FD), root branching angle (RBA) and root topological index (TI)) and non-structural carbohydrate (NSC) concentrations in roots were measured every month. The results are as follows: (i) The dry weight of root and shoot decreased significantly under drought stress. (ii) The SRL decreased under drought stress in the early duration (the first month), and then increased in the late duration (the third month). Both FD and RBA decreased, while TI and the concentrations of NSCs increased under drought stress. (iii) The NSC concentrations were positively correlated with SRL and TI, but exhibited an inverse relationship to FD and RBA. Our results indicated that Moso bamboo seedlings formed a “steeper, simpler, expensive (low SRL and high TI)” root architecture to adapt to a short-term drought (one month), and formed a “cheaper (high SRL)” root to adapt to a long-term drought (three months). Increase of NSC concentrations supported the root architecture plasticity to some extent.

Drought- and soil substrate-induced variations in root nonstructural carbohydrates result from fine root morphological and anatomical traits of Juglans mandshurica seedlings

“…More recently, Liu et al [ 27 ] applied 13 C isotope labelling technology and found that compared with higher orders, drought promoted the structural growth of lower-order roots by increasing the respiration rate and allocating more photosynthetic carbohydrates, but there is still a lack of more fine-scale differences in the allocation of root NSCs. Yang et al [ 28 ] found that the sensitivity of the root NSC concentration of Phyllostachys edulis seedlings to drought supported the plasticity of root architecture to some extent in allocating more carbon to structure low-cost roots. Our previous study demonstrated that the root morphological traits but not chemical traits, explain the variation in NSC contents induced by drought [ 29 , 30 ].…”

Differential Variation in Non-structural Carbohydrates in Root Branch Orders of Fraxinus mandshurica Rupr. Seedlings Across Different Drought Intensities and Soil Substrates

“…ST stored in the root system can promote root growth and maintain root osmotic potential, ensuring that plants can absorb more water ( Ge et al, 2012 ; Camarero et al, 2016 ). However, previous studies have mostly focused on the overall NSC level of the root system (including coarse roots and fine roots) ( Hoch and Körner, 2003 ; Landhäusser and Lieffers, 2012 ; Hartmann et al, 2013 ; Yang et al, 2021 ), and the response of fine root NSCs with functional root branch orders to drought is rarely considered ( Aubrey and Teskey, 2018 ; Nikolova et al, 2020 ). Fine roots (≤2 mm) are the main organ for water and nutrient absorption, and the most active and sensitive part of the root system ( McCormack et al, 2015 ; Ma et al, 2018 ).…”

“… Zhou et al (2018) based on 128 drought experiments found that the drought increased the specific root length (SRL) of woody plants by 30%, and there was a significant positive correlation between plant–SRL and drought. Although numerous studies have reported the response of root traits (high SRL, low diameter) to drought or water deficit ( Comas et al, 2013 ; Fort et al, 2017 ; Zhou et al, 2018 , 2019 ; Lozano et al, 2020 ; Nikolova et al, 2020 ), few studies have focused on the synergistic changes and relationships between root NSC levels and root traits under stress conditions ( Ji et al, 2020 ; Yang et al, 2021 ). Olmo et al (2014) studied the drought resistance response of 10 woody tree species seedlings and found that SRL increased significantly under drought conditions.…”

“…Indeed, increasing the carbon input per unit produces a larger surface area, length of fine roots, and more fine roots, which could facilitate optimization of the cost-benefit ratio of fine roots ( Eissenstat et al, 2000 ; Ostonen et al, 2007 ). Under drought conditions, thicker roots with transport and storage functions tend to preserve NSCs ( Konôpka et al, 2007 ; Yang et al, 2021 ), whereas thinner roots with absorption functions are severely affected by the drought ( Olmo et al, 2014 ). Yang et al (2021) found that a significant correlation between the root NSC concentration, root architecture, and SRL occurred in Phyllostachys edulis seedlings under drought conditions, indicating that the sensitivity of NSC concentration to drought supported the plasticity of root architecture to a certain extent, and plants could build low-cost roots through more carbon investment.…”

“…Under drought conditions, thicker roots with transport and storage functions tend to preserve NSCs ( Konôpka et al, 2007 ; Yang et al, 2021 ), whereas thinner roots with absorption functions are severely affected by the drought ( Olmo et al, 2014 ). Yang et al (2021) found that a significant correlation between the root NSC concentration, root architecture, and SRL occurred in Phyllostachys edulis seedlings under drought conditions, indicating that the sensitivity of NSC concentration to drought supported the plasticity of root architecture to a certain extent, and plants could build low-cost roots through more carbon investment. In addition, when plants adapt to drought stress, they balance the lack of tissue radial growth by increasing the concentration of NSCs in the growing parts ( Dietze et al, 2014 ; Kannenberg et al, 2018 ).…”