Jean-Pierre Privé

Seasonal growth dynamics and carbon allocation of the wild blueberry plant (Vaccinium angustifolium Ait.)

Kaur, J., Percival, D., Hainstock, L. J. and Privé, J.-P. 2012. Seasonal growth dynamics and carbon allocation of the wild blueberry plant ( Vaccinium angustifolium Ait.). Can. J. Plant Sci. 92: 1145-1154. Field studies were conducted at the Wild Blueberry Research Station, Debert, NS, to examine the carbon allocation dynamics within the wild blueberry (Vaccinium angustifolium Ait.). This was achieved with biweekly measurements of dry weight, soluble sugar and starch levels of the rhizomes, roots, stems/leaves and berries of plants in the vegetative (i.e., sprout phase) and cropping phases of production. Non-structural carbohydrate levels were determined using high-performance liquid chromatography (HPLC). Growth parameters included phenology, stem height, dry weights of the above-ground vegetation (stems and leaves), berries, rhizomes and roots. Interestingly, root growth was observed prior to upright shoot emergence and dry weight for rhizome remained higher compared with stems and leaves. The rhizomes acted as a carbohydrate source during stem and root growth. The developing berry crop appeared to be a strong sink for photo-assimilates, as berries were found to import sucrose and convert it to fructose and glucose during maturation, and HPLC studies further confirmed the increasing levels of fructose and glucose. Given the phenology of the wild blueberry, the results exemplify the importance of the rhizomes as a strong carbohydrate source, especially in the early stages of a growing season when the carbohydrate production is limited.

The impact of kaolin clay sprays on leaf gas exchange of Ginger Gold apple trees in New Brunswick

A field trial was conducted over two growing seasons in a Ginger Gold apple orchard in Bouctouche, New Brunswick, Canada to examine the impact of Surround (95% kaolin clay) on leaf gas exchange [net photosynthesis (Pn), stomatal conductance (gs), intercellular CO2 (Ci) and transpiration (E)]. In 2004, a greater rate of Pn and gs was achieved at the higher than at the lower frequency of Surround applications. This was particularly notable at leaf temperatures exceeding 35°C. In 2005, no significant (P ≤ 0.05) differences among leaf residue groupings [Trace (< 0.5 g m-2), Low (0.5 to 2 g m-2), and High (≥ 2 g m-2)] were found for the four leaf gas exchange parameters at leaf temperatures ranging from 25 to 40°C. It would appear that under New Brunswick commercial orchard conditions, the application of Surround favours or has no effect on leaf gas exchange. Key words: Surround, particle film, leaf physiology, photosynthesis, stomatal conductance, intercellular CO2, transpiration

Impact of reflective groundcover on growth, flowering, yield and fruit quality in Gala apples in New Brunswick

Privé, J-P., Russell, L. and LeBlanc, A. 2011. Impact of reflective groundcover on growth, flowering, yield and fruit quality in Gala apples in New Brunswick. Can. J. Plant Sci. 91: 765-772. A 5-yr field study was conducted in New Brunswick, Canada, to assess the impact of a reflective groundcover (ExtendayTM) on Gala (Malus× domestica Borkh.) apple trunk cross-sectional area (TCSA), flowering, yield and fruit quality. Overall, a 25% increase in the total number of fruit per tree was realized with use of the 3-m wide reflective groundcover on the orchard floor between tree rows from full-bloom until 3 wk post-harvest; this translated to 26% greater total yield per tree and 16% greater yield efficiency. No overall effects on fruit quality at harvest were associated with use of the reflective groundcover. Trees with reflective groundcover exhibited a greater yearly percentage increase in TCSA (18.5%) than those without (15.0%); neither flowering nor fruit set was affected in any year. These increases in productivity were mediated by the enhanced canopy light environment provided by the reflective groundcover. The primary economic benefit to be derived from use of the ExtendayTM reflective groundcover in apple production in the Maritime region is through the capacity to produce higher-yielding crops of fruit on larger trees (increased yield efficiency), without compromising fruit quality. This improvement in production efficiency could translate to an increase in 4.5 t ha-1 of marketable fruit in New Brunswick.