Abstract
Climate change could alter plant aboveground and belowground resource allocation. Compared with shoots, we know much less about how roots, especially root system architecture (RSA) and their interactions, may respond to temperature changes. Such responses could have great influence on species'acquisition of resources and their competition with neighbors. We used a gel-based transparent growth system to in situ observe the responses of RSA and root interactions of three common subtropical plant species seedlings in Asia differing in growth forms (herb, shrub, and tree) under a wide growth temperature range of 18–34°C, including low and supra-optimal temperatures. Results showed that the RSA, especially root depth and root width, of the three species varied significantly in response to increased temperature although the response of their aboveground shoot traits was very similar. Increased temperature was also observed to have little impact on shoot/root resource allocation pattern. The variations in RSA responses among species could lead to both the intensity and direction change of root interactions. Under high temperature, negative root interactions could be intensified and species with larger root size and fast early root expansion had competitive advantages. In summary, our findings indicate that greater root resilience play a key role in plant adapting to high temperature. The varied intensity and direction of root interactions suggest changed temperatures could alter plant competition. Seedlings with larger root size and fast early root expansion may better adapt to warmer climates.
Highlights
Temperature is one of the most important variables that influence plant growth (Gray and Brady, 2016)
This work addresses three questions: (1) Sensitivity of root system architecture (RSA) traits— for inferring plant seedling adaptation to warming climate: Which RSA traits respond sensitively to temperature change and how they change with temperature? (2) Comparisons between root/shoot growth traits in response to increased temperature— for understanding how plant seedlings coordinate root/shoot responses to climate change: Do roots of plant seedlings respond more strongly than shoots to change in temperature? (3) Interspecific root interactions: How does an increase in temperature change the intensity and the direction of root interactions? To answer these questions, we studied RSA traits of three plant species seedlings with different life forms for understanding the responses of root traits to temperature change
At 22/17°C, only 4°C above the fatal low temperature, the root depth and width of C. capsularis reached the largest value, which was significantly larger than that at 30/ 25°C and 34/29°C, whereas there were no significant differences in C. capsularis total root length, surface area and volume among the four temperature treatments (Figures 1A and 2A–E)
Summary
Temperature is one of the most important variables that influence plant growth (Gray and Brady, 2016). The rapid warming projected for the planet and the limited ability of plants to track climate changes mean that species' survivorship under climate change critically depends on their thermal adaptation ability (Zhu et al, 2012; Lambers, 2015; Urban, 2015). This aspect of adaptation has so far been extensively explored through examining the plant growth response to temperature changes The root system architecture (RSA) which towards deploying roots in the soil that optimizes the acquisition of water and nutrient has been thought to be able to minimize the negative impact of temperature changes (de Dorlodot et al, 2007), compared with shoot, few studies have investigated the sensitivity in RSA response to temperature changes, because of the difficulty in direct observation on underground growth (Aidoo et al, 2016)
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