Search

Copyright of Canadian Journal of Plant Science is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The objective of this study was to evaluate the effects of pre- and post-veraison cluster thinning on the physicochemical characteristics of Montepulciano and Cabernet Franc grape varieties grown in regions 900 m above sea level (ASL) in Santa Catarina, southern region of Brazil. The experiment was conducted in two commercial vineyards, Montepulciano vineyard located at 28º12'58''S, 50º06'45''W, 1,185 m ASL during the 2007, 2008 and 2009 vintages; and Cabernet Franc vineyard located at 28°15'20"S, 49°56'60"W, 1,284 m ASL, during the 2010 and 2011 vintages. Treatments consisted on cluster thinning at three distinct moments for both varieties: during veraison, about 15 days pre-veraison and 15 days postveraison. For Montepulciano, when cluster thinning is performed post-veraison, there is a reduction in cluster mass and a slight reduction on the acidity of grapes. For Cabernet Franc, when cluster thinning is performed during veraison, there is an increase in total soluble solids of grapes. In general, cluster thinning is recommended two weeks pre- or post-veraison for Montepulciano and Cabernet Franc wine grapes produced in southern Brazilian highlands. [ABSTRACT FROM AUTHOR]

Rural communities depend upon cotton as cash crop for their livelihood. Agro-based industries are depending upon its yield. Our per acre cotton yield is still far behind than the developed countries. Integrated pest management project was launched in Punjab and run by agriculture extension department. Farmer Field Schools were formed at each village level. Present study was designed to evaluate the role of integrated pest management for cotton production technologies by the registered growers of Hasilpur, Punjab. In order to collect this information an interview schedule was prepared and respondents (150 growers of farmer field school) were interviewed personally by the author. The findings revealed 98.7%, 100% and 98% cotton growers were aware of hoeing, leaf curl virus and biological control of insects-pests. Before integrated pest management all the farmers used pesticides haphazardly while 1.3% used after it. 90.7%, 86.7% and 97.3% farmers were aware of economic threshold level of harmful insects, use of pesticides at economic threshold level and clean cotton picking respectively. 94.7% growers adopted thinning of plants, 91.3% knew pest scouting, 87.3% used pesticides after pest scouting while 74% farmers used pesticides both at morning and evening. It was concluded that integrated pest management project enhanced the skills of farmers and resulted in higher yields of quality cotton through reduction of pesticides sprays. [ABSTRACT FROM AUTHOR]

Fifteen stems of jack pine (Pinus banksianaLamb.) of 3 commercial thinned plots (control, moderate, and intensive thinning) and 15 stems of black spruce (Picea mariana(Mill.) B.S.P), both coming from the Abitibi-Témiscamingue region – Canada, were cross-cut into three 2.4 m length sections: bottom, middle, and top logs. Logs were processed with a chipper-canter at three cutting widths (12.7, 19.1, and 25.4 mm), producing chips and a three-faced cant. The middle section of the cant was used to evaluate surface quality across the grain on each face. Roughness and waviness parameters and depth of torn grain were recorded. Knot characteristics were assessed in the three cant faces. Poorer surface quality was found in the lower part compared to the upper part of the cant for both species. At larger cutting widths, jack pine logs coming from a natural stand showed lower surface quality compared to logs from thinned stands. Black spruce waviness increased with the cutting width and stem height. These results were attributed to the increase of forces and vibration when cutting at larger cutting widths, which was worsened by the presence of bigger, more numerous knots at the control plot and in the top logs. Black spruce had deeper torn grain compared to jack pine. Their differences in knot characteristics resulted in a maximum torn grain depth favored by the presence of more knots rather than by bigger knot size. Other knot characteristics, such as the position of the knots in the cant face, the insertion angle of the branch and the distribution of the knots around the log, should be studied to better understand the relationship between torn grain formation and knottiness. [ABSTRACT FROM PUBLISHER]

Red wine grape varieties 'Fetească neagră' and 'Cabernet Sauvignon' were produced in Murfatlar wine region under organic and conventional viticultural systems. For both varieties and viticultural systems, 30% cluster thinning was performed in some variants during summer, at the beginning of veraison. The resulted grapes, harvested in the autumn of 2014, were vinified using the same winemaking protocol and the differences in aromatic profile of the wine samples were assessed by using a GC e-nose from Alpha MOS. The chromatographic peaks were recorded and analysed with Alpha Soft ver. 12.42 and AroChemBase. The discrimination of the samples was based on multivariate DFA statistical analysis. The results showed that 30% cluster thinning did not influence significantly the major wine aroma compounds, only small differences being observed in the DFA diagram for samples with and without cluster thinning. However, the grape variety and the application of organic cultivation technology led to a good discrimination, with a validation score of 92, of the samples on the DFA diagram. An even better discrimination, with a validation score of 96, was observed on wine samples from grapes produced in conventional and organic system when the cluster thinning was disregarded and samples with or without this intervention in the vineyard were included in the same group. These results show that, as far as the aromatic profile is concerned, the wines produced from grapes to which cluster thinning was applied are difficult to differentiate from the controls produced from vines with normal yield, even with a sensitive equipment such as an e-nose. On the other hand, the organic and conventional growing led to wine samples easily differentiated by the electronic nose, suggesting that these differences can also be perceived by consumers. Some of the aroma compounds significant for the discrimination of wines produced from organic or conventional grapes were identified and their expected sensory effect is discussed. [ABSTRACT FROM AUTHOR]

'Feteasca neagră' is a versatile grape variety, with results highly dependent on the cultivation region and viticultural practices. In Murfatlar this variety is cultivated both organically and conventionally, thus providing a good opportunity to study the behaviour of the variety in the two cultivation systems. Furthermore, in both culture systems, in some experimental variants 30% of the grapes from each vine were removed after the cluster formation - a practice often employed with an aim to obtaining a better-quality crop. The grapes harvested in autumn at technological maturity were vinified in 4 variants, in accordance to the viticultural practices applied: organic and conventional cultivation, with or without cluster thinning. In this work the influences of these viticultural practices on the volatile profile of the obtained wines were evaluated by using a flash GC-electronic nose. Although some differences are present when 30% cluster thinning is applied, the main influence in the volatile profile of wines is still induced by the cultivation system, irrespective of the grape reduction practice. The variability among the volatile profiles of the 4 groups of wines is explained in proportion of 85.3% by the cultivation system and only 12.4% by the grape reduction practice. The wines made from conventionally grown grapes display a more complex volatile profile as compared to the wines obtained from organic grapes. [ABSTRACT FROM AUTHOR]

Chemical treatment is a mean to accomplish fruit thinning; although its efficiency depends on the compound used, application time, and dosage. Effect of the chemical hydrogen cyanamide (CH2N2) on the thinning of flowers and fruits of the peach cultivar Coral was assessed in this study. Treatments consisted of five doses of CH2N2 (0, 0.2, 0.4, 0.6, and 0.8%) spray application to the point of run-off, at two stages (50% and 100% flowering). The experiment was conducted in a completely randomized design with six replicates and one plant per plot. The following parameters were assessed: percentage of flowers thinned at 25 days after spraying, percentage of fruits thinned, fruiting index, production per plant, fruit mass, diameter and length, flesh firmness, soluble solids (SS) and titratable acidity (TA). Concentrations of 0.6 and 0.8% CH2N2application at 50% flowering resulted in thinning 84.4 and 84.7% of the flowers and 0.4% CH2N2 at 100% flowering thinned 87.3%, values close to index assessed in manual thinning (88.0%) experiments. The highest production per plant was recorded for treatments with CH2N2 application at 50% flowering, resulting from a high percentage of flowers opening after spraying the chemical thinner. As such, flowers opening late were not affected by the chemical, thereby ensuring a higher fruiting index. Peach yield with 50% CH2N2 was not significantly different from yield observed for manual treatment, and 0.6% spray was reported to be the optimal dosage. Treatment with 0.6% CH2N2 application at 50% flowering was not significantly qualitatively different from manual thinning. CH2N2 application is efficient for the thinning of ‘Coral' peach flowers and fruits. [ABSTRACT FROM AUTHOR]

The self-thinning rule is regarded as one of the most important principles in plantation management. This rule, involving the assumption of a constant slope coefficient, has been universally applied when regulating stand density. In this study, we hypothesized that the slope coefficient can change significantly with changes in site quality. To test this hypothesis, we first grouped forest plots into 5 categories based on site index. Second, we produced the self-thinning line represented by the Reineke function for each of the 5 site categories, selecting fully stocked plots using reduced major axis regression. Third, the slope coefficients for the different categories were tested for significant differences. The results indicated that in general, the slope was significantly different with different site quality. In addition, we observed that the slope of the self-thinning line exhibited a steeper trend for sites of lower quality, which indicated increased self-thinning or reduced self-tolerance. Finally, we concluded that it is imperative to produce specific self-thinning lines for different site quality categories. [ABSTRACT FROM AUTHOR]

The effect of three levels thinning intensity in Gmelina arbórea plantation on tree diameter, heartwood (diameter and percentage), wood density and drying defects (twist, crook, bow and check) was studied. Wood used for this study was obtained from eight-year-old plantations with thinning intensity of 60, 70 and 80% of initial density. Nine trees were selected from each trial. Results showed that tree diameter and wood density were similar in thinning intensity of 70 and 80%, but tree diameter from the plantation with 60% of thinning intensity was lower than plantation of 70 and 80%. Wood density of trees from 60% thinning intensity plantation was higher than 70 and 80%. Heartwood diameter and its percentage were the highest in 80% of thinning intensity. But not difference was found between 60 and 70% in heartwood (diameter and percentage). Finally, drying defects were not affected significantly by thinning intensity. [ABSTRACT FROM AUTHOR]

Bracken ferns are some of the most widespread ferns in the World causing immense problems for land managers, foresters and rangers. Bracken is suspected of causing cancer in Humans due to its content of the carcinogen ptaquiloside. Ingestion of bracken, or food and drinking water contaminated with ptaquiloside may be the cause. The aim of this study was to monitor the content of ptaquiloside in 20 bracken stands from Britain to obtain a better understanding of the ptaquiloside dynamics and to evaluate the environmental implications of using different cutting regimes in bracken management. The ptaquiloside content in fronds ranged between 50 and 5790 μg/g corresponding to a ptaquiloside load in the standing biomass of up to 590 mg/m 2 in mature fronds. Ptaquiloside was also found in the underground rhizome system (11–657 μg/g) and in decaying litter (0.1–5.8 μg/g). The amount of ptaquiloside present in bracken stands at any given time is difficult to predict and did not show any correlations with edaphic growth factors. The content of ptaquiloside turned out to be higher in fronds emerging after cutting compared to uncut fronds. Environmental risk assessment and bracken management must therefore be based on actual and site specific determinations of the ptaquiloside content. Care must be taken to avoid leaching from cut ferns to aquifers and other recipients and appropriate precautionary measures must be taken to protect staff from exposure to bracken dust. [ABSTRACT FROM AUTHOR]

Aims: Two contrasting canopy manipulations were compared to unpruned controls on London plane trees, to determine the effects on canopy regrowth, soil and leaf water relations. Methods: 'Canopy reduction', was achieved by removing the outer 30 % length of all major branches and 'canopy thinning', by removing 30 % of lateral branches arising from major branches. Results: Total canopy leaf areas recovered within two and three years of pruning for the canopy-thinned and reduced trees respectively. Canopy reduction increased mean leaf size, nitrogen concentration, canopy leaf area density and conserved soil moisture for up to 3 years, whereas canopy thinning had no effects. Another experiment compared more severe canopy reduction to unpruned trees. This produced a similar growth response to the previous experiment, but soil moisture was conserved nearer to the trunk. Analysis of C and O signals along with leaf water relations and soil moisture data suggested that lower boundary layer conductance within the canopy-reduced trees restricted tree water use, whereas for the canopy-thinned trees the opposite occurred. Conclusions: Only canopy reduction conserved soil moisture and this was due to a combination of reduced total canopy leaf area and structural changes in canopy architecture. [ABSTRACT FROM AUTHOR]

Thinning treatments to accelerate coastal redwood forest stand development are in wide application, but managers have yet to identify prescriptions that might best promote Sequoia sempervirens (Lamb. ex D. Don) Endl. (redwood) growth. The creation of successful thinning prescriptions would be aided by identifying the underlying mechanisms governing how individual tree growth responds to competitive environments in coastal redwood forests. We created a spatially explicit individual-based model of tree competition and growth parameterized using surveys of upland redwood forests at Redwood National Park, California. We modeled competition for overstory trees (stems ≥ 20 cm stem diameter at breast height, 1.37 m (dbh)) as growth reductions arising from sizes, distances, and species identity of competitor trees. Our model explained up to half of the variation in individual tree growth, suggesting that neighborhood crowding is an important determinant of growth in this forest type. We used our model to simulate the effects of novel thinning prescriptions (e.g., 40% stand basal area removal) for redwood forest restoration, concluding that these treatments could lead to substantial growth releases, particularly for S. sempervirens. The results of this study, along with continued improvements to our model, will help to determine spacing and species composition that best encourage growth. [ABSTRACT FROM AUTHOR]

Highlights: [•] Indian Ocean Tsunami resulted in loss of coastal vegetation in Nicobar Islands. [•] Natural recovery of coastal forest after tsunami was studied. [•] Disturbance in soil substratum had influenced the vegetation recovery. [•] Unaffected soil sites showed faster vegetation recovery than sand deposited sites. [•] Prevalence of self thinning process in the unaffected soil sites. [ABSTRACT FROM AUTHOR]

Commercial thinning represents one of the treatments used in intensive management to increase the growth of the residual stems. Therefore, commercial thinning would decrease the wood mechanical properties, but the negative effects are temporary according to some authors. To our knowledge, no studies have focused on the effects of commercial thinning on wood mechanical properties according to tree social classes. The objective of this study is to verify, at the stem level, ( i) the effect of different commercial thinning intensities on the stem volume increment according to social classes (dominant, codominant, intermediate, and oppressed) and ( ii) the effect of commercial thinning on wood mechanical properties of white spruce ( Picea glauca (Moench) Voss), and ( iii) to determine if these effects on wood mechanical properties varied between social classes. The measurements were made from samples collected in a 32-year-old white spruce plantation that was thinned in 1989. We used stem analysis to measure volume increments, while the mechanical properties were measured on small pieces of wood (10 mm × 10 mm × 150 mm) without defects at dbh. Thinning has a significant positive effect on the stem volume increment for the dominant and codominant trees and no negative effect on the wood density, the modulus of elasticity and modulus of rupture for all thinning intensities and all social classes combined. After thinning (1989-2000), the modulus of elasticity increased by 50% in the dominant and by 70% in the codominant trees. This study allows us to consider the commercial thinning as a silvicultural tool to increase the productivity of white spruce plantations without affecting negatively the wood mechanical properties. Considering our results, we recommend that the intensity of the first commercial thinning should remove 35% of the basal area. [ABSTRACT FROM AUTHOR]

Growth dominance provides a quantitative description of the relative contribution of individual trees to stand growth. Positive dominance occurs when the largest individuals account for a greater proportion of growth period increment than total biomass. Conversely, negative dominance occurs when the smallest trees account for a greater proportion of the growth period increment than of total biomass. This study uses the relatively new concept of growth dominance to examine long-term changes in tree growth patterns in thinned yellow-poplar ( Liriodendron tulipifera L.) in the southern Appalachians. Growth dominance decreased with site index and the interaction between residual relative density and site index but increased with residual relative density and years since thinning. These relationships suggested that discrepancies in growth dominance among varying degrees of residual relative densities, with stands thinned to lower densities displaying negative growth dominance relative to stands receiving less intense thinning treatments, decreased over time. This negative growth dominance indicates that the stand-level growth included a disproportionate increase in growth of nondominant trees. The concept of growth dominance in a management context appears useful for assessing the efficacy of thinning treatments in meeting various management objectives and should be considered a potential tool for quantifying the relative success of management alternatives. [ABSTRACT FROM AUTHOR]

We conducted thinning trials in a 5-year-old Eucalyptus globulus ssp. globulus Labill plantation near Warrenbayne, northeastern Victoria, Australia, where soil salinization and waterlogging are common, and assessed treatment effects on tree growth, water use and survival. Half-hectare plots were thinned from the original density of 1100 stems ha−1 to densities of 800, 600 and 400 stems ha−1, and stem diameter increment, leaf area index, transpiration, canopy interception and depth of tree water source monitored for 21 months. Two drought periods occurred during the study, rainfall was 30% below the long-term average and there was severe mortality in all three plots. Analysis of deuterium abundance in soil and xylem water indicated that the trees accessed water only from the top meter of the soil profile. Transpiration rates were higher in the most heavily thinned plot than in the least thinned plot, which underwent a reduction in basal area during the study. The most heavily thinned plot increased in basal area by 10% during the study. Edge trees had significantly greater diameters than trees from the middle of the plots. [ABSTRACT FROM PUBLISHER]