Scientific papers

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December 05, 2023

Higher latewood to early ratio increases resistance of radial growth to severe droughts in larch

Authors : Xianliang Zhang, Hongyan Liu et Tim Rademacher

ScienceDirect, Volume 912, 20 February 2024.



As drought has caused great losses of tree growth across the world, the mechanism of how trees adapt to drought has been extensively investigated. However, how trees change their late- to earlywood ratio (LER) to adapt to severe drought events remains poorly understood. We used a network of Larix principis-rupprechtii earlywood and latewood width data from 1979 to 2018, covering most of the distribution of planted larch across North China, to investigate how latewood proportion affected trees' resistance to drought. The interactions among LER, minimum temperature, vapor pressure deficit (VPD), growing season length, and their contributions to drought resistant (Rt) were estimated using structural equation models. The results show a significant increase in LER of the juvenile wood throughout the first 15 growth rings after which it stabilizes. The LER decreased significantly with elevation for the juvenile wood. March–May temperature and VPD were the main determinant in the LER of mature wood. The sensitivity of radial growth to droughts was positively changed with LER when LER was below 0.50, but negatively changed with LER when LER is above 0.50. We confirmed that high LER increases resistance of tree growth to severe droughts in L. principis-rupprechtii. Our results highlight that a higher proportion of latewood is formed in dry years, and this high drought sensitivity of LER in turn led to an increased resistance to drought. This combination of reduced radial growth during dry years, while the latewood proportion remains increases maybe an adaptive strategy of larch trees to cope with severe droughts.

June 01, 2022

A metataxonomic analysis of maple sap microbial communities reveals new insights into maple syrup complexity

Authors : Guillaume Quang N'guyen, Cyril Roblet, Luc Lagacé, Marie Filteau

(Front. Syst. Biol., 29 April 2022


Maple syrup, an emblematic food product of Canada is produced from the concentration of sap collected from maple trees during spring. During this season, the trees come out of dormancy, which modifies sap composition. Meanwhile, microorganisms that contaminate sap as it is collected can also modify its composition. As these two factors can impact the quality of maple syrup, we aimed to better understand how microbial communities vary along dormancy release. We estimated the absolute abundance of bacteria and fungi in maple sap along a dormancy release index using high-throughput amplicon sequencing and digital droplet PCR (ddPCR). Several members were identified as indicators of maple sap composition, syrup organoleptic conformity and color, some of which are also hubs in the microbial association networks. We further explored bacterial communities by performing a predictive functional analysis, revealing various metabolic pathways correlated to dormancy release. Finally, we performed an experimental investigation of maple sap carrying capacity and limiting nutrients along dormancy release and found that maple sap composition variation influences its carrying capacity. Taken together, our results indicate that an increase in nitrogen supply in the form of allantoate combined with possible metabolite excretion could lead microbial communities towards different paths. Indeed, we observed a greater heterogeneity during late dormancy release which in turn could explain the variation in maple syrup quality. Further experimental investigation into the contribution of microbial, vegetal, environmental, technological, and processing factors to the final composition of maple syrup will be required to improve our understanding of this complex and flavorful food matrix and to develop quality control strategies.(4080167)

August 17, 2021

Maple syrup production from sap preconcentrated to ultra high °Brix by membrane technology: Composition and properties

Authors: Fadi Ali, Jessica Houde, Carmen Charron, Mustapha Sadiki

(Food Control, Vol. 131, January 2022, 108450).
(Digital Object Identifier (DOI)): 10.1016/j.foodcont.2021.108450.


Maple syrup is produced typically from maple sap concentrated by nanofiltration or reverse osmosis at a moderate °Brix level ranging from 6 to 16 °Brix followed by heat evaporation. Recently, new membrane processes have been developed to concentrate maple sap to ultra-high °Brix reaching up to 40 °Brix. The aim of this study is to evaluate the effect of this ultra-high concentration of sap on the composition, the properties and the cost of corresponding maple syrup. Results showed some differences in chemical composition and properties between syrups produced from low and ultra-high concentration of sap. Syrups produced from ultra-high °Brix concentrated sap had lower concentrations of potassium and polyphenols, a lighter color and distinctive flavor. This was mainly observed when no modification were applied to the heating pattern in the evaporator pans. However, syrups produced by modulation of the heating pattern in the evaporator had color, flavor and taste similar to control syrups. These results demonstrate that syrups with comparable sensory properties can be obtained from low and ultra-high concentrated sap by adjusting the heating time depending on the initial °Brix. The concentration process to ultra high °Brix allows for a concomitant reduction of the production costs and a modulation of syrup quality. (4010119)

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