Leaf Morphological Variation among Paper Birch (Betula papyrifera Marsh.) Genotypes across Canada

Variations in leaf morphological characteristics have been extensively studied at both interand intraspecific levels although not explicitly on paper birch (Betula papyrifera Marsh). Paper birch populations might have considerable genotypic and leaf morphological variations that have allowed them to inhabit wide environmental gradients. In this study, the authors analyzed variations in leaf morphological characteristics in 23 paper birch populations collected across Canada and grown in a greenhouse. Furthermore, they examined whether the variations in leaf morphological characteristics observed were related to the climate of the population’s origin.

The authors measured leaf size (LS), perimeter (P), blade length (BL), petiole length (PL), petiole size (PS), maximum width (MW), position of maximum width (PMW), horizontal width (HW) and vertical length (VL) of the samples. And mean annual and growing season temperature and precipitation data for population’s origin were normalized climate data from years 1971 to 2001.

The results showed there were significant genotypic differences in all leaf morphological characteristics (p < 0.05) measured among the birch populations. Thus, they expected that the morphological variations in birch might be related to natural diversity in birch populations due to environmental differences at habitat origin. Principal component analysis (PCA) reduced thirteen leaf morphological variables to five principal components (PC) explaining 84.74% of the total variance in the original data. PCs accumulated with specific leaf area, petiole and leaf width were positively related to latitudinal, longitudinal, and elevational gradients at the population’s origin. Unpredictably, these PCs were significantly negatively correlated to precipitation and aridity index at the origin. Thus, they analyzed if correlations within leaf morphological characteristics had supported the birch populations to acclimate and produce unpredictable relations with the environment of origin. The results showed that the populations originated in limited precipitation (during growing season) had large leaf width and petiole size but low leaf hairs on adaxial surface.

In conclusion, the findings raised the possibility that intraspecific variation in paper birch might evolve due to genotypic variation and environmentally induced variation in leaf morphological characteristics. Contrary to our expectations, several leaf characteristics were inversely related to environmental gradient of the birch’s origin, which makes it necessary to consider the fact that the greenhouse had different environment than the habitat the populations would normally be exposed to. Furthermore, the leaf characteristics measured may also include phenotypic plasticity of the birch as an acclimation to the environment as in the greenhouse.

Article by Anjala Pyakurel and Jian R. Wang, from Lakehead University Thunder Bay, Thunder Bay, Canada.

Full access: http://mrw.so/RQNuu

Image by Nicholas A. Tonelli, from Flickr-cc.

Identifying Sustainable Practices for Tapping and Sap Collection from Birch Trees

Tapping and collecting sap from birch trees ( Betula , sp.) for the production of beverages and syrup is gaining increased levels of interest. Although the practice of tapping birch trees and collecting sap has been ongoing for millennia across the world, there remain some critical data needed in order to make science-based decisions about the production practices required to optimize yields and ensure sustainable outcomes are achieved in the long-term. In this study, experiments were conducted to determine two pieces of information essential to identify practices necessary to ensure tapping trees for birch sap collection were both sustainable and profitable—the selection of the time to initiate tapping birch trees to obtain maximum yields, and the volume of nonconductive wood (NCW) associated with taphole wounds in birch trees. The yields obtained from various timing treatments varied between sapflow seasons, but indicated that using test tapholes to choose the appropriate ti

阅读全文

Incorporation of High-Altitude Balloon Experiment in High School Science Classrooms

High-altitude balloon is a balloon, filled usually with helium or hydrogen that ascends into an area called “near space” or stratosphere. The most common type of high-altitude balloons are weather balloons. Other purposes include use as a platform for experiments in the upper atmosphere. Modern balloons generally contain electronic equipment such as radio transmitters, cameras, or satellite navigation systems, such as GPS receivers. The mission of the High-Altitude Balloon Experiment (HABE) is to acquire supporting data, validate enabling technologies, and resolve critical acquisition, tracking, and pointing (ATP) and fire control issues in support of future space-based precision pointing experiments. The use of high-altitude balloons offers a relatively low-cost, low-vibration test platform, a recoverable and reusable payload, worldwide launch capability, and a 'near- space' emulation of the future space systems operational scenarios. More recently, several university

阅读全文

Esophageal Carcinogenesis

Read full paper at: http://www.scirp.org/journal/PaperInformation.aspx?PaperID=50380#.VDy9v1fHRK0 Author(s) Naoki Watanabe 1 , Masahito Shimizu 2 , Takahiro Kochi 2 , Yohei Shirakami 2 , Takuji Tanaka 1,3* Affiliation(s) 1 Department of Diagnostic Pathology (DDP) & Research Center of Diagnostic Pathology (RC-DiP), Gifu Municipal Hospital, Gifu, Japan . 2 Department of Internal Medicine/Gastroenterology, Gifu University Graduate School of Medicine, Gifu, Japan . 3 Department of Tumor Pathology, Gifu University Graduate School of Medicine, Gifu, Japan . ABSTRACT Esophageal cancer is the sixth leading cause of cancer death and remains one of the least survivable cancers. Esophageal cancers show wide variations in incidence in different pop

阅读全文

Scientific Research Publishing

搜索此博客