Michel Labrecque

High biomass yield achieved by Salix clones in SRIC following two 3-year coppice rotations on abandoned farmland in southern Quebec, Canada

Abstract Two species of willow, Salix discolor and S. viminalis , were planted in 1995 under short-rotation intensive culture on two abandoned farmland sites: sandy site (S1) and clay site (S2). After three seasons of growth the two species were coppiced. In the spring of the first season following coppicing, one dose of composted sludge equivalent to 100 kg of “available” N ha −1 was applied to some plots (T1) while others were left unfertilized (T0). The aims of the experiment were to compare the growth performance and nutrients exported by willow species planted on marginal sites with different soil characteristics and to assess the impact of fertilization with wastewater sludge on yields during a second rotation cycle. Over three seasons, willow height, diameter and aboveground biomass were greater for S. viminalis than for S. discolor on all fertilized plots. The best growth performance of two willows were obtained on the clay site. S. viminalis , planted on the fertilized plots of the clay site, had the highest biomass yield (70.36 tDM ha −1 ) . The application of a dose of wastewater sludge ( 100 kg of “available” N ha −1 ) was not enough to satisfy all nutritional requirements of willows for the period of growth. Over the second rotation the nutrients removed from the soil by willows (in kg per ton of dry mass harvested) were: from 5.3 to 7.5 for N; from 0.6 to 0.9 for P; from 1.8 to 3 for K; from 4.2 to 7.2 for Ca and from 0.4 to 0.7 for Mg.

Randomized controlled trial of prevention of perineal trauma by perineal massage during pregnancy

OBJECTIVEnThe aim of the study was to evaluate the effectiveness of perineal massage during pregnancy for the prevention of perineal trauma at birth.nnnSTUDY DESIGNnPregnant women with (n = 493) and without (n = 1034) a previous vaginal birth from 5 hospitals in the province of Québec, Canada, participated in this single-blind, randomized, controlled trial. All participants received oral and written information on the prevention of perineal trauma. Women in the experimental groups were requested to perform a 10-minute perineal massage daily from the 34th or 35th week of pregnancy until delivery.nnnRESULTSnAmong participants without a previous vaginal birth, 24.3% (100/411) from the perineal massage group and 15.1% (63/417) from the control group were delivered vaginally with an intact perineum, for a 9.2% absolute difference (95% confidence interval 3.8%-14.6%). The incidence of delivery with an intact perineum increased with compliance with regular practice of perineal massage (chi2 for trend 13.2, P = 0.0003). Among women with a previous vaginal birth, 34.9% (82/235) and 32.4% (78/241) in the massage and control groups, respectively, were delivered with an intact perineum, for an absolute difference of 2.5% (95% confidence interval -6.0% to 11.0%). There were no differences between the groups in the frequency of sutured vulvar and vaginal tears, womens sense of control, and satisfaction with the delivery experience.nnnCONCLUSIONnPerineal massage is an effective approach to increasing the chance of delivery with an intact perineum for women with a first vaginal delivery but not for women with a previous vaginal birth.

Effect of wastewater sludge on growth and heavy metal bioaccumulation of two Salix species

Fast-growing tree species, such as willows, can benefit from sludge application. While sludges are good fertilizers, they may contain heavy metals which could reduce productivity and cause environment risks. The aims of the present research were to: i) determine the biomass production of Salix discolor Mühl. and Salix viminalis L. when supplied with various amounts of dried and pelleted sludge and ii) assess the uptake and accumulation of heavy metals. Trials were carried out using unrooted cuttings that were planted in large plastic pots containing sandy soil and grown outdoors for a 20-week period. Five doses of sludge were applied: the equivalents of 0 (T0), 40 (T1), 80 (T2), 120 (T3), 160 (T4) and 200 (T5) kg “available” N ha-1. Trees which received the highest dosage of sludge showed the best growth. Stem biomass was significantly greater for S. viminalis which had received sludge treatments. The relationship between the total biomass yield Y (g) and the rate of fertilization X (equivalent to kg of “available” nitrogen provided per hectare) is linear. Regression equations of predicted biomass production were established as follows: S. discolor, Y=28.36+0.56X and S. viminalis, Y=39.95+0.64X. For both species, the greatest stem biomass per g of N applied was produced with treatment 4 and 5. Amounts of nitrogen per leaf area (N/LA) and per dry leaf mass (N/DL) were higher for S. viminalis. The metal transfer coefficient did not vary between the species but was significantly different for Cd and Zn. Plants were able to absorb Cd and Zn, but were less able to absorb Ni, Hg, Cu, and Pb. It was concluded that the dried and pelleted sludge is a good fertilizer. S. discolor and particularly S. viminalis can be used as filters for the purification of wastewater sludge as well as for biomass production purposes. R F Huettl Section editor

Influence of plantation site and wastewater sludge fertilization on the performance and foliar nutrient status of two willow species grown under SRIC in southern Quebec (Canada)

Abstract Salix discolor Muhl. (Sd) and Salix viminalis L. (Sv) were planted under short-rotation intensive culture (SRIC) on three unirrigated abandoned farmland sites with different drainage conditions, one well-drained (S1) and the other two poorly-drained (S2, S3). One dose of dried and granulated sludge equivalent to 150 (T1) kg of “available” Nxa0ha−1 was applied to some plots in the spring of the second season while others were left unfertilized (T0). The aims of the experiment were (i) to investigate plant response (growth and productivity) to plantation site conditions and sludge application; (ii) study nutrient status by foliar analysis. Over three seasons, growth in height and aboveground biomass were greater for S. viminalis than for S. discolor on all sites. S. viminalis planted on poorly-drained site 2 had the highest biomass yield (45.28xa0txa0ha−1). Both species showed best height and diameter growth on poorly-drained sites. For both species, best performances were obtained on wastewater sludge fertilized plots. Comparative foliar analysis suggested that unfertilized sandy soil (S1) and low foliar nitrogen concentration and content were limiting factors in the performance of the two species. Soil nitrate concentration increased as a result of sludge application. Heavy metal accumulation from sludge does not represent a risk to the environment. It was concluded that S. viminalis had the best productivity on clay sites, and that a moderate dose of dried and pelleted sludge (150xa0kg of “available” Nxa0ha−1) may be a good fertilizer during the establishment of willows in SRIC, and may reduce nitrate leaching.

Growth patterns and biomass productivity of two Salix species grown under short-rotation intensive culture in southern Quebec

Samples of two species of Salix, Salix discolor, which grows naturally in the northern half of North America and S. viminalis, which originated from central Europe, were studied to compare their productivity and their growth patterns under the short-rotation, intensive-culture system (SRIC). The study was conducted in the nursery of the Montreal Botanical Garden on former agricultural land. The plantation was established at a density of 27,000 trees per hectare from unrooted cuttings without any fertilizer or irrigation. Growth parameters were measured at regular intervals during summer of the two first years following planting. At the end of each growing season, after leaf drop, a part of each plot was cut down and the stems and branches were harvested and weighed to evaluate their annual growth rates and their biomass yields. For the first growing season, height growth in both species was greater than 2 m. Although S. viminalis grew more rapidly early in summer, S. discolor grew about three weeks longer and its total height at the end of the growing season was greater than the former. Meanwhile the stem-branch dry weight of S. discolor was similar to the one produced by S. viminalis. Two growing seasons after establishment, the total tree height was about 3.5 m for both species, while the biomass of stems and branches of S. viminalis was weakly superior in comparison to S. discolor and reached very high values-about 27 Mg ha−1 for S. viminalis. The growth patterns and yields of the one-year-old coppice (one-year-cycle) were similar to those recorded at the end of the first year for trees developed directly from cuttings. Both species produced a comparable quantity of sprout biomass. The yield of the trees harvested two years after planting was about twice the total biomass harvested two times, at the end of each growing season, suggesting that a two-year cycle is more productive than a one-year cycle.

Genotype × environment interaction analysis of North American shrub willow yield trials confirms superior performance of triploid hybrids

Development of dedicated bioenergy crop production systems will require accurate yield estimates, which will be important for determining many of the associated environmental and economic impacts of their production. Shrub willow (Salix spp) is being promoted in areas of the USA and Canada due to its adaption to cool climates and wide genetic diversity available for breeding improvement. Willow breeding in North America is in an early stage, and selection of elite genotypes for commercialization will require testing across broad geographic regions to gain an understanding of how shrub willow interacts with the environment. We analyzed a dataset of first‐rotation shrub willow yields of 16 genotypes across 10 trial environments in the USA and Canada for genotype‐by‐environment interactions using the additive main effects and multiplicative interactions (AMMI) model. Mean genotype yields ranged from 5.22 to 8.58 oven‐dry Mg ha−1 yr−1. Analysis of the main effect of genotype showed that one round of breeding improved yields by as much as 20% over check cultivars and that triploid hybrids, most notably Salix viminalis × S. miyabeana, exhibited superior yields. We also found important variability in genotypic response to environments, which suggests specific adaptability could be exploited among 16 genotypes for yield gains. Strong positive correlations were found between environment main effects and AMMI parameters and growing environment temperatures. These findings demonstrate yield improvements are possible in one generation and will be important for developing cultivar recommendations and for future breeding efforts.

Glyphosate-Dependent Inhibition of Photosynthesis in Willow

We studied the physiological mechanisms involved in the deleterious effects of a glyphosate-based herbicide (Factor® 540) on photosynthesis and related physiological processes of willow (Salix miyabeana cultivar SX64) plants. Sixty-day-old plants grown under greenhouse conditions were sprayed with different rates (0, 1.4, 2.1, and 2.8 kg a.e ha-1) of the commercial glyphosate formulated salt Factor® 540. Evaluations were performed at 0, 6, 24, 48, and 72 h after herbicide exposure. We established that the herbicide decreases chlorophyll, carotenoid and plastoquinone contents, and promotes changes in the photosynthetic apparatus leading to decreased photochemistry which results in hydrogen peroxide (H2O2) accumulation. H2O2 accumulation triggers proline production which can be associated with oxidative protection, NADP+ recovery and shikimate pathway stimulation. Ascorbate peroxidase and glutathione peroxidase appeared to be the main peroxidases involved in the H2O2 scavenging. In addition to promoting decreases of the activity of the antioxidant enzymes, the herbicide induced decreases in ascorbate pool. For the first time, a glyphosate-based herbicide mode of action interconnecting its effects on shikimate pathway, photosynthetic process and oxidative events in plants were presented.

Symbiotic association between Salix purpurea L. and Rhizophagus irregularis: modulation of plant responses under copper stress

There are increasing concerns about trace metal levels such as copper (Cu) in industrial sites and the broader environment. Different studies have highlighted the role of mycorrhizal associations in plant tolerance to trace metals, modulating some of the plant metabolic and physiological responses. In this study, we investigated the role of the symbiotic association betweenRhizophagus irregularisandSalix purpureaL. in modulating plant responses under Cu stress. We measured Cu accumulation, oxidative stress-related, photosynthetic-related and hydraulic traits, for non-inoculated (non-arbuscular mycorrhizal fungi) and inoculated saplings exposed to different Cu concentrations. We found thatS. purpureais a suitable option for phytoremediation of Cu, acting as a phytostabilizer of this trace metal in its root system. We observed that the symbiotic association modulates a broad spectrum of metabolic and physiological responses inS. purpureaunder Cu conditions, including (i) a reduction in gas exchange associated with chlorophyll content changes and (ii) the sequestration of Cu into the cell walls, modifying vessels anatomy and impacting leaf specific conductivity (KL) and root hydraulic conductance (LP). UpholdingKLandLPunder Cu stress might be related to a dynamic Aquaporin gene regulation ofPIP1;2along with an up-regulation ofTIP2;2in the roots of inoculatedS. purpurea.

Maximum Annual Potential Yields of Salix miyabeana SX67 in Southern Quebec and Effects of Coppicing and Stool Age

Aboveground biomass yields of short rotation cultures (SRC) of willow can vary substantially depending on site quality. Among others, aboveground biomass yields depend on climatic conditions, soil properties, age of the SRC, and number of harvesting cycles. In this study, we investigated the effects of coppicing on growth variables (i.e., largest basal stem, height, and aboveground biomass) at ten SRC of Salix miyabeana SX67 established on various soils in southern Quebec. More than 1100 shrubs with stool ages varying between 1 and 15xa0years were measured. Strain analysis was carried out to calculate past annual aboveground productivities, and maximum annual yield potential was quantified at each site. Annual growth rates were highly variable and depended on site and coppicing history. To achieve optimal stool development and aboveground yields, two to three growing seasons following coppicing were necessary for sandy and clayey sites, respectively. The delays for reaching maximum yields were shortened when soil cation exchange capacity was dramatically low and were prolonged when soil was physically restricting stool development. This lag influenced the total yield of the first rotation and also modulated the magnitude of the increase of aboveground biomass that is generally observed in the second rotation. To increase yields in southern Quebec, our results suggest that it is preferable to extend the length of the first rotation instead of coppicing at the end of the first growing season after establishment.

Vascularisation de la fleur d'Orontium aquaticum L. (Aracées)

ResumeChez Orontium, les fleurs hermaphrodites possedent 5 ou 6 etamines et 6 tepales. Lovaire supere contient un ovule hemi-anatrope insere sur un placenta basal. Le gynecee dOrontium est generalement tricarpelle. Chaque carpelle comporte un faisceau dorsal et deux faisceaux ventraux. Les neuf faisceaux carpellaires sindividualisent a partir dun anneau horizontal danastomoses situes a la base de la paroi ovarienne. Dans les gynecees bicarpelles, on ne trouve que 5 faisceaux: deux dorsaux, deux ventraux simples et un ventral complexe, resultant de lunion de deux faisceaux ventraux appartenant a des carpelles differents. Ces gynecees sont donc pseudomonomeres mais peu condenses. La fleur dOrontium presente certains points communs avec celle de Calla: ovaire supere uniloculaire, gynecee trimere, organisation vasculaire semblable, placentation basale. Dun autre cote, les gynecees dimeres que lon trouve quelquefois chez Orontium presentent certaines similitudes avec ceux de Lysichitum camtschatckense...