ABSTRACT
The frequency and intensity of heatwaves are increasing around the world, causing severe damages to plants, but whether leaf thermal metrics is in line with leaf economic spectrum is still controversial. Here, we measured leaf damage ratio, leaf thermal metrics (tolerance and sensitivity) and economic traits of 131 woody species across five cities along the Yangtze River after a two-month natural extreme temperature event. We found that leaf thermal sensitivity but not thermal tolerance was correlated with leaf damage ratio, and the relationships between leaf thermal metrics and economic traits were weak, indicating that leaf thermal adaptation may be independent from leaf carbon construction. This study suggests a potential indicator for predicting plant survival under heatwaves, urging future research to explore more physiological traits to comprehensively understand plant heat responses and adaptations.
Subject(s)
Acclimatization , Plant Leaves , Plant Leaves/physiology , Temperature , Plants , Heat-Shock ResponseABSTRACT
Previous studies have observed a 2D relationship (i.e. decoupled correlation) between leaf size (LS) and leaf economics as well as a tight correlation between leaf economics and drought tolerance. However, the underlying mechanism maintaining the relationship between LS and drought tolerance remains largely unknown. Here, we measured LS, water potential at 50% loss of hydraulic conductance, hydraulic safety margin and different orders of vein traits across 28 tree species in a subtropical forest in Southern China. We found that LS and drought tolerance were in two independent dimensions (R2 = 0.00, P > 0.05). Primary and secondary vein traits (i.e. vein diameter and density) explained the variation of LS, with R2 ranging from 0.37 to 0.70 (all Ps < 0.01), while minor vein traits accounted for the variation of leaf drought tolerance, with R2 ranging from 0.30 to 0.43 (all Ps < 0.01). Our results provide insight into the 2D relationship between LS and drought tolerance and highlight the importance of vein hierarchy in plant leaf functioning.
Subject(s)
Drought Resistance , Trees , Forests , Plant Leaves , Water , DroughtsABSTRACT
We compared branch and leaf functional traits of Ulmus pumila trees inhabiting different climatic zones (sub-humid, dry sub-humid and semi-arid zones), aiming to investigate the role of trait plasticity and coordination in tree acclimation to different water conditions. The results showed that leaf drought stress of U. pumila increased significantly from sub-humid to semi-arid climatic zones, as indicated by a 66.5% reduction in leaf midday water potential. In the sub-humid zone with less severe drought stress, U. pumila had higher stomatal density, thinner leaves, larger average vessel diameter, pit aperture area and membrane area, which could ensure the higher potential water acquisition. With the increases of drought stress in dry sub-humid and semi-arid zones, leaf mass per area and tissue density increased, and the pit aperture area and membrane area decreased, indicating stronger drought tolerance. Across different climatic zones, the vessel and pit structural characteristics were strongly coordinated, while a trade-off between xylem theoretical hydraulic conductivity and safety index was found. The plastic adjustment and coordinated variation of anatomical, structural and physiological traits may be an important mechanism contributing to the success of U. pumila in different climate zones with contrasting water environments.
Subject(s)
Ulmus , Plant Leaves/physiology , Xylem/physiology , Acclimatization , Trees/physiology , Droughts , Water/physiologyABSTRACT
Seed priming is a widely used technique in crops to obtain uniform germination and high-quality seedlings. In this study, we found a long-term effect of seed priming with gibberellic acid-3 (GA3) on plant growth and production in Leymus chinensis. Seeds were germinated on agar plates containing 0-200 µM GA3, and the germinated seedlings were transplanted to clay planting pots and grown for about one year. The clonal tillers grown from the mother plants were transplanted to field conditions in the second year. Results showed that GA3 treatment significantly increased seed germination rate by 14-27%. GA3 treatment also promoted subsequent plant growth and biomass production, as shown by a significant increase in plant height, tiller number, and fresh and dry weight in both pot (2016) and field (2017) conditions. It is particularly noteworthy that the growth-promoting effect of a single seed treatment with GA3 lasted for at least two years. In particular, GA3 treatment at 50 µM increased aboveground fresh and dry weight by 168.2% and 108.9% in pot-grown conditions, and 64.5% and 126.2% in field-grown conditions, respectively. These results imply a transgenerational transmission mechanism for the GA-priming effect on clonal offspring growth and biomass production in L. chinensis.