Search Results

You are looking at 1 - 10 of 14 items for

  • Author or Editor: Jean-Pierre Privé x
Clear All Modify Search
Free access

Jean-Pierre Privé and N. Allain

Four primocane fruiting (PP) red raspberry cultivars, `Bogong', `Cascade', `Heritage', and `Dinkum', were grown in exposed or sheltered (50% permeable artificial windbreak) sites fully exposed to prevailing westerly winds. The cultivars were evaluated to determine the effects of wind stress on vegetative and reproductive development and leaf gas exchange during the establishment year. The artificial windbreak resulted in an overall 35% reduction in wind velocity, increased the number of calm days (<5.4 km·h–1) and decreased the incidence of strong breezes (>36 km·h–1). Concurrently, the artificial windbreak did not have much of an effect on altering relative humidity, air or soil temperature. All cultivars responded similarly to wind exposure Plants in exposed sites had reduced leaf areas, internode lengths, leaf, cane, and total above ground dry weights. Leaf gas exchange parameters (Pn, gs and Ci) expressed per unit leaf area did nor differ between treatments for most of the season but the sheltered plants as a whole supported a greater total leaf area and must have fixed a greater amount of carbon than the exposed plants. These larger sheltered plants produced a more extensive fruiting framework and resulted in a 2-fold yield increase. For these reasons, it is highly recommended to shelter raspberry plants from wind in the establishment year.

Full access

Jean-Pierre Privé and M.I.N. Zhang

2,3,5-triphenyl tetrazolium chloride (TTC) staining, electrical conductivity, and electrical impedance (Z) analyses were used to assess freezing injury of `Beautiful Arcade' apple (Malus ×domestica Borkh.) roots taken in late March from either the field or 3C-refrigerated storage (cold-stored). Lethal temperature (LT50) levels using TTC or electrical conductivity occurred at colder temperatures than those found using Z. Techniques varied in their ability to detect changes in cell viability with increasing cold stress. Listed in order of decreasing responsiveness they are electrical impedance (Z), electrical conductivity, and TTC vital staining. With the most sensitive technique, Z, two parameters—extracellular and total tissue electrical resistance—were about five and eight times lower (indicating more injury) for roots from the field than from cold storage. The smaller values obtained from the field roots were probably due to natural in-field freeze-thaw cycling before the controlled cold-stress tests in the laboratory. More importantly, the impedance technique provided more detailed information than TTC or electrical conductivity about how apple roots respond to cold stress and how Z may provide some insight into freeze-thaw history before injury assessment. Although this technique shows potential, future studies are required to render a complete physiological significance to the impedance parameters involved in calculating Z.

Free access

Jean-Pierre Privé and J. Alan Sullivan

Growth rates for two types of tissue-cultured plant stock for `Heritage', `Ruby', and `Redwing' red raspberry (Rubus idaeus L.) were examined. Actively growing plantlets from the greenhouse (G) were compared to cold-treated (CT) plantlets from cold storage. The greatest differences between these two occurred during the first 6 weeks after planting. At 4 weeks, CT plants for all cultivars had longer canes and internodes, sometimes twice that of G plants. Although `Heritage' had greater total plant dry weights following chilling, `Ruby' and `Redwing' had less. Chilling had no effect on `Heritage' root growth but did reduce root dry weight for `Redwing' and `Ruby'. Relative growth rate (RGR) and leaf area ratio (L-AR) were more effective variables for analyzing growth as they considered differences in initial biomass and cane number and provided a better representation of the data during the initial 6 weeks of growth. All cultivars showed a greater total plant RGR and LAR for the CT plants at 6 weeks. During the first 4 weeks, the G plants were more efficient producers of root dry matter while the CT plants were more efficient producers of cane dry matter. By 6 weeks, the G plants had partitioned a greater percentage of their assimilates into cane growth while the leaves, canes, and roots of the CT plants contributed equally to total RGR. No difference in total or individual component RGR was observed after 6 weeks.

Free access

Jean-Pierre Privé, Lindsay Russell and Anita LeBlanc

Kaolin particle films are used as a means of pest control in some commercial apple orchards in the Maritime provinces; however, no studies to date have evaluated the impact of these particle films on leaf gas exchange under the region's growing conditions. Also previously unexplored is the gas exchange response of blackberry leaves to kaolin particle films and the question of whether leaf gas exchange response varies according to the leaf surface of particle film application. A study consisting of an apple field trial and a blackberry greenhouse trial was conducted during the 2005 growing season in Bouctouche, New Brunswick, Canada, with the aims of 1) characterizing the leaf temperature and gas exchange responses [net photosynthesis, stomatal conductance (g s), intercellular CO2, and transpiration] of ‘Ginger Gold’ apple [Malus ×sylvestris (L.) Mill var. domestica (Borkh.) Mansf.] leaves to a kaolin particle film (95% kaolin clay) applied at various leaf residue densities under the province's growing conditions, 2) characterizing the leaf temperature and gas exchange responses of ‘Triple Crown’ blackberry (Rubus L. subgenus Rubus Watson) leaves to treatment of adaxial or abaxial surfaces with the kaolin particle film at various leaf residue densities, and 3) determining whether the gas exchange response of apple and blackberry leaves to the kaolin particle film varies according to leaf temperature. Leaf gas exchange measurements were taken under conditions of ambient CO2, saturated light, moderate (apple) or high (blackberry) relative humidity levels and leaf temperatures ranging from 26 to 39 °C (apple) and 15 to 41 °C (blackberry). When the particle film was applied to both the adaxial and abaxial surfaces of apple leaves at kaolin residue densities of 0.5 to 3.7 g·m−2, leaf temperature was reduced by up to 1.1 °C (P = 0.005) and g s was increased (P = 0.029) relative to leaves with trace (<0.5 g·m−2) levels of kaolin deposits. No other effects of kaolin leaf residue density on apple leaf gas exchange were found, nor were any interactions of leaf temperature × residue level (P > 0.05). When applied to a fixed area on the adaxial or abaxial surfaces of blackberry leaves at kaolin residue densities of 0.5 to 10.8 g·m−2, the particle film did not alter leaf temperature or gas exchange (P > 0.05). No interactions of leaf temperature × residue level or leaf temperature × leaf surface × residue level were found to affect blackberry leaf gas exchange (P > 0.05).

Free access

Jean-Pierre Prive and M.I.N. Zhang

2,3,5-triphenyltetrazolium chloride (TTC) staining and electrical impedance (?) analyses of apple roots (Malus domestica Borkh. `Beautiful Arcade') taken in late March from either the field or from 3C refrigerated storage (cold-stored). LT50 levels using TTC were much lower than those found using electrical impedance. No loss of viability in the roots was detectable using TTC staining until a freeze–thaw stress of –9C whereas? analysis detected changes in cell viability after a freeze–thaw stress of only –3C. With increasing cold stress, two parameters: extracellular electrical resistance (Ro) and time constant?, decreased linearly for cold-stored roots and exponentially for field roots. Impedance analysis also revealed that the values for both extracellular Ro and total tissue electrical resistance (R?) for the field roots were approximately 5 and 8 times lower, respectively, than in the cold-stored roots. It is believed that the smaller Ro and R? values obtained from the field roots were due to natural in-field freeze–thaw cycling prior to the controlled stress tests in the laboratory. Based on the analyses of winter hardiness using the two methods, the impedance technique? provided the physiological information not only about the hardiness level, but also about freeze–thaw history prior to the hardiness assessment.

Free access

Jean-Pierre Privé, J.A. Sullivan and J.T.A. Proctor

`Autumn Bliss', `Heritage' and `Redwing' were grown in a controlled environment setting at three day/night temperature regimes (30/25, 25/20, 20/15C) at either 12 or 16 hour photo periods. Vegetative (height, diameter, node number, leaf area, leaf, cane and root dry weight) and reproductive (precocity, numbers of fruiting laterals, flower number and dry weight) parameters were analyzed. Optimum vegetative growth was obtained when plants were subjected to short photoperiods (12 hrs) and cool (20/15C) or moderate (25/20C) day/night temperatures. Reproductive characteristics were enhanced when grown under long photoperiods (16 hrs) and moderate temperatures. High temperatures (30/25) reduced cane height due to a decrease in internode length with the greatest reduction occurring under long photo periods. Precocity and flowering was enhanced by long photoperiods especially at cool and moderate temperatures. This may have implications for the reproductive potential of these cultivars when grown in north temperate areas where high temperatures are common for most of the summer.

Free access

Jean-Pierre Privé, J.A. Sullivan and J.T.A. Proctor

Leaf removal, cane girdling, and 14C translocation patterns were used to study source-sink relationships of primocane-fruiting (PF) red raspberries. Although the leaves in the reproductive zone were most important for vegetative and reproductive development, compensatory effects between the cane leaves were evident. When 14C translocation was studied in the reproductive portion of the cane, the lateral closest to the 14C-treated leaf was the major sink for carbohydrate from that leaf, independent of leaf position or reproductive development. Thereafter, partitioning to leaves and/or flowers or fruits above the 14C-treated leaf was related to leaf phyllotaxy 75% of the time.

Free access

Andrew R. Jamieson, Kevin R. Sanderson, Jean-Pierre Privé and Roger J.A. Tremblay

Free access

Andrew R. Jamieson, Kevin R. Sanderson, Jean-Pierre Privé and Roger J.A. Tremblay

Free access

Jean-Pierre Privé, J.A. Sullivan, J.T.A. Proctor and O.B. Allen

The influence of genotype x environment interactions on the performance of `Autumn Bliss' `Heritage' and `Redwing' primocane-fruiting (PF) red raspberry (Rubus idaeus L.) cultivars was studied at six sites across Ontario and Quebec during 1989 and 1990. Cultivar × location × year interactions were found for most vegetative and reproductive components analyzed. `Autumn Bliss' had the most consistent performance of the three cultivars in all location/year combinations, while `Redwing' varied greatly between environments. `Heritage' was always the latest-bearing of the three cultivars and failed to achieve its maximum yield potential in many of the northern locations.