Abstract
Land surface temperature over the past decades has shown a faster warming trend during the night than during the day. Extremely low night temperatures have occurred frequently due to the influence of land-sea thermal difference, topography and climate change. This asymmetric night temperature change is expected to affect plant ecophysiology and growth, as the plant carbon consumption processes could be affected more than the assimilation processes because photosynthesis in most plants occurs during the daytime whereas plant respiration occurs throughout the day. The effects of high night temperature (HNT) and low night temperature (LNT) on plant ecophysiological and growing processes and how the effects vary among different plant functional types (PFTs) have not been analyzed extensively. In this meta-analysis, we examined the effect of HNT and LNT on plant physiology and growth across different PFTs and experimental settings. Plant species were grouped according to their photosynthetic pathways (C3, C4, and CAM), growth forms (herbaceous, woody), and economic purposes (crop, non-crop). We found that HNT and LNT both had a negative effect on plant yield, but the effect of HNT on plant yield was primarily related to a reduction in biomass allocation to reproduction organs and the effect of LNT on plant yield was more related to a negative effect on total biomass. Leaf growth was stimulated at HNT and suppressed at LNT. HNT accelerated plants ecophysiological processes, including photosynthesis and dark respiration, while LNT slowed these processes. Overall, the results showed that the effects of night temperature on plant physiology and growth varied between HNT and LNT, among the response variables and PFTs, and depended on the magnitude of temperature change and experimental design. These findings suggest complexities and challenges in seeking general patterns of terrestrial plant growth in HNT and LNT. The PFT specific responses of plants are critical for obtaining credible predictions of the changes in crop production, plant community structure, vegetation dynamics, biodiversity, and ecosystem functioning of terrestrial biomes when asymmetric night temperature change continues.
Highlights
The increased intensity of human activities has been magnifying the climate change and its consequences in recent decades (IPCC, 2013)
high night temperature (HNT) decreased stem diameter and internode length by 1.61%, and 15.97%, which were unchanged by low night temperature (LNT) (Figure 1B)
We found that: (1) the significance and degree of the effect of HNT and LNT and the causes of yield reduction at HNT and LNT were different; (2) there existed significant variations among different plant functional types (PFTs) in responding HNT and LNT; (3) there was an optimal night temperature for important processes of plants physiology and growth; (4) the responses to HNT and LNT appeared dependent of the experimental designs
Summary
The increased intensity of human activities has been magnifying the climate change and its consequences in recent decades (IPCC, 2013). The global temperature is forecasted to continuously increase 1–3.7◦C by the end of the 21st century (IPCC, 2013). Night temperature has increased faster at local (Peng et al, 2004), country (Zhou et al, 2004; Rao et al, 2014), and global scales (Vose et al, 2005). The lowest land nighttime temperature increased about 0.2◦C per decade between 1950 and 1993, which is double the increased highest daytime temperature (IPCC, 2001). Based on the prediction of multimodel ensembles, asymmetric warming between day and night is going to continue in the future (Christensen et al, 2007; Sillmann et al, 2013). Plants in the future will be exposed to warmer nights, which could greatly influence crop yield and vegetation dynamics as well as ecosystem biodiversity, structure and productivity
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