Interclonal and within-tree variation in wood properties of poplar clones

The wood basic density, cellulose content and fiber form were investigated for all sample trees at breast height (1.3 m) in seven poplar clones, and at 0 (butt), 5.6, 9.6, 13.6, 17.6, 19.6 and 21.6 m for clone Nanlin-95 and Nanlin-895, respectively, for providing information on variation patterns of wood density, fiber characteristics and holocellulose content within trees and among clones. The results showed that significant variations about wood density, cellulose content, fiber diameter and the ratio of fiber length to diameter existed among poplar clones examined. Variance analysis indicated that there were significant differences in wood basic density, fiber length, fiber diameter and cellulose content among the growth rings, which had an increasing tendency along the direction from pith to bark. The significant differences also existed in wood basic density, fiber length and fiber diameter at different tree height. The mean wood basic density had a general increase trend with increasing height of trees and the lowest was found at the base, while fiber length and fiber diameter had a general decline pattern with increasing height of trees and the biggest value was observed at the height of 5.6 m. Regression analysis indicated that the relationship between examined wood properties and growth ring number (cambial age), and the relationship between examined wood properties and tree height can be described by polynomial functions.

Genetic variation in growth traits and stem–branch characteristics and their relationships to Eucalyptus clones

Eucalyptus has become an important genus in China because it displays adaptability to a wide range of site conditions and produces pulp wood and veneer on short rotations. The aim of this study was to estimate genetic parameters and relationships and consider impli- cations for development of clonal forestry. We assessed growth traits, stem-branch characteristics, crown diameter and height of fresh branch for 20 Eucalyptus hybrid clones in China measured at the age of 44 months. Analysis of variance showed that there were significant differences in growth traits, height of fresh branch and stem straightness among clones. Significant differences in height, volume, crown diameter, height of fresh branch and branch size among replicates were also recorded. Coefficients of vari- ation ranged from 9.84 to 28.54 % for growth traits, 12.03 to 17.25 % for stem-branch characteristics, 18.26 % for crown diameter and 11.73 % for height of fresh branch. Estimates of repeatabilities for height, diameter at breastheight over bark, volume, crown diameter, height of fresh branch, stem straightness and branch size at clone mean level were 0.86, 0.80, 0.80, 0.54, 0.85, 0.77 and 0.44 respectively. Diameter at breast height over bark and height had strongly positive phenotypic and genotypic correlations with volume, ranging from 0.96 to 1.00. The positive genotypic and phenotypic correlations between growth traits and other studied traits suggested that fast growing clones always had bigger crown diameter, higher height of fresh branch, straighter stems and relatively smaller branches.

Comparative Assessment of the Fatty Acid Profiles of Crude Oils Extracted from Seeds of Selected Tea ( Camellia sinensis L.) Cultivars

Tea seeds resulting from the cultivation of tea in many parts of the world, often regarded as waste, have been found to contain oil of exceptional quality that can be harnessed for use as an oleo-chemical or chemical intermediate. A comparative study was carried out to examine the free fatty acid profiles of crude oils chemically extracted by Soxhlet extraction from tea seeds collected from different cultivars of Kenyan tea. All the tea seeds of the studied tea cultivars yielded oil, though to different extents (p > 0.05) after the 8-hour extraction. The oils were golden yellow in color. The contents of oleic, linoleic and stearic acids in all the crude test oils have no significant difference (p > 0.05) from each other. However, statistically significant differences (p < 0.05) in the linolenic and palmitic acids contents were evident. Based on the current findings, the test tea oils were predominantly constituted of unsaturated fatty acids, oleic acid being the major unsaturated fatty acid, other fatty acids being present in different but smaller proportions.

Influence of Geographical Regions on Catechin and Caffeine Levels in Tea (Camellia sinensis)

This study aimed at investigating the influence of different growing conditions in two regions, Timbilil and Kangaita, on the levels of catechins and caffeine. Fresh leaf samples of 60 clones cultivated in both sites were obtained, processed and assayed for levels of caffeine, total and individual catechins using Reverse Phase High Performance Liquid Chromatography (RP-HPLC). The obtained data was subjected to analysis of variance using GENSTAT-C statistical software. Safe for a few clones in the Kangaita site had significantly higher total and individual catechins than those grown in the Timbilil site. A mean epigallocatechin gallate (EGCG) content of 7.9% was observed for Kangaita clones compared to 6.7% in Timbilil. A similar trend was observed for the rest of the individual catechin fractions with a mean epicatechin gallate (ECG) of 3.3% in Kangaita and 2.5% in Timbilil, a mean epigallocatechin (EGC) of 5.2% in Kangaita compared to 5.0% in Timbilil and a mean epicatechin (EC) content of 1.5% in Kangaita compared to 1.4% in Timbilil. Similarly in the total catechins analyses, clones in Kangaita had a mean value of 18.7% compared to 16.2% observed for the Timbilil site clones. However, the Timbilil site clones had significantly high caffeine contents (mean, 4.2%) compared to the Kangaita site clones (mean, 3.9%) although with a few exceptions. Significant interactions (P < 0.05) between clone and region are also observed, suggesting that levels of these biomolecules are bound to differ with the growing region but the extent of variation will vary depending on the clonal genotype. The observed differences in levels of these biologically important biomolecules among the two regions shows the importance of the underlying conditions on the production of tea.

The clip cage conundrum: Assessing the interplay of confinement method and aphid genotype in fitness studies

Behavior and fitness are important ecological traits frequently measured in insect bioassays.A common method to measure them in soft-bodied herbivorous insects involves confining individuals to plant leaves using clip cages.Although studies have pre-viously highlighted the negative effects of clip cages on leaf physiology,little is known about the impact that using this confinement method has on insect fitness.The responses of different aphid genotypes/clones to different containment methods have not previously been investigated.Here we measured key fitness traits(intrinsic rate of natural increase,mean relative growth rate,time to reach reproductive adulthood and population doubling time)in the potato aphid,Macrosiphum euphorbiae Thomas(Hemiptera:Aphididae),when confined to plants using two methods:(1)clip cages to confine aphids to individual strawberry leaves and(2)a mesh bag to confine aphids to whole strawberry plants.Our study identified a strong negative impact on all the measured aphid fitness traits when using clip cages instead of mesh bags.We also identified genotype-specific differences in response to confinement method,where clip cage confinement differentially affected the fitness of a given aphid genotype compared to the same genotype on whole plants.These results suggest that clip cage use should be carefully considered when experiments seek to quantify insect fitness and that whole plants should be used wherever possible.Given the prevalence of clip cage use in insect bioassays,our results highlight the need for cau-tion when interpreting the existing literature as confinement method significantly impacts aphid fitness depending on their genotype.