. 1997. Long-term effects of burn-pruning on lowbush blueberry (Vaccinium angustifolium Ait.) production. Can. J. Plant Sci. 77: 421-425. Burning is a pruning technique used to improve productivity of lowbush blueberry fields. Growers, however, are concerned that continuing and frequent burning might reduce production and eventually destroy blueberry fields. To assess the effect of long-term spring burn-pruning on blueberry production and the surface organic layer, 2-, 3-and 4-yr burning cycles were studied for 24 yr on a previously unfertilized natural stand of lowbush blueberry. Mean annual yield (averaged over burn and crop years) decreased with increases in the interval between burning due to decreased production in the second and third crop years following burning. Yield in the third crop year was similar to that from the unburned check plots. There was no significant yield decrease between the first 12 yr (period 1) and the second 12 yr (period 2) of production for the 2-yr cycle, but there were declines for the 3-and 4-yr cycles due mainly to lower yields in the second crop. Lower second-crop yields in the second period was attributed to damage by the blueberry leaftier (Croesia curvalana Kft.). Mean annual ripe fruit yields for the 2-, 3-and 4-yr cycles and unburned check were 473, 458, 335 and 109 kg ha -1 , respectively, in period 1 and 478, 340, 277 and 38 kg ha -1 , respectively, in period 2. Burning did not decrease the depth of the surface organic layer. Les producteurs s'inquiètent cependant de ce que des brûlages répétés et fréquents pourraient réduire la production des bleuetières, voire même entraîner leur destruction. Pour évaluer les effets à long terme de la taille par brûlage au printemps sur la production des bleuets et sur la couche organique du sol, nous avons étudié pendant 24 ans des cycles de brûlage biennaux, triennaux et quadriennaux sur une bleuetière naturelle auparavant non fertilisée. Le rendement annuel moyen (année de brûlage et année de production confondues) diminuait à mesure qu'on prolongeait l'intervalle entre les brûlages, en raison de la chute des rendements observés dans les deuxième et troisième années après le brûlage. Dans la troisième année de production, le rendement était descendu au même niveau que celui des parcelles témoins sans brûlage. Dans le cycle de deux ans, on ne notait pas de baisses significatives de rendement entre les 12 premières (période 1) et les 12 dernières années (période 2), mais il y en avaient dans les cycles de 3 et 4 ans, surtout à cause du rendement moindre dans la deuxième année de production. Ces chutes étaient attribuées à la lieuse de l'airelle, (Croesia curvalana Kft.). Le rendement annuel moyen en fruits mûrs dans les cycles de brûlage de 2, 3 et 4 ans et dans les parcelles témoins non brûlées étai, respectivement, de 473, 458, 335 et 109 kg ha -1 dans la période 1 et de 478, 340, 277 et 38 kg ha -1 dans la période 2. Le brûlage ne diminuait pas la profondeur de la couche organique superficielle du sol.

. 2008. Effect of long-term burn-pruning on the flora in a lowbush blueberry (Vaccinium angustifolium Ait.) stand. Can. J. Plant Sci. 88: 351Á362. The effect of burn-pruning on the flora in a natural stand of lowbush blueberry was studied over a 24-yr period in Newfoundland and Labrador, Canada. Treatments were: not burned and burn-pruned every 2nd, 3rd, or 4th year. A vegetative survey was conducted before burning and periodically in succeeding years. Following statistical analyses, species were grouped according to their response to burning, as follows: those not significantly affected; those eliminated or whose frequency of occurrence was reduced; and those whose occurrence was increased. Initially, burning virtually eliminated Juniperus communis var. depressa, Empetrum nigrum, Cladina rangiferina, Lycopodium clavatum and Pleurozium schreberi, reduced the frequency of occurrence of nine species by 6 to 69%, and increased 13 others by 1 to 2050%. With burning, Polytrichum commune and Fragaria virginiana ssp. glauca, in particular, increased very early in the study to become two of the most prevalent species. Also, except for some initial effects of burning, the lowbush blueberry and some initially prevalent species (Festuca filiformis, Maianthemum canadense, Danthonia spicata, Cornus canadensis and Luzula multiflora var. acadiensis) remained among the most dominant species. Of the species studied, only seven each of those increased or decreased by burning were affected by the burnpruning cycle. In both groups, the greatest increases or decreases in the frequency of occurrence were obtained with the 2-yr burn-pruning cycle. Ils ont groupe´les espe`ces comme suit, selon leur re´action au traitement en recourant a`des me´thodes d'analyse statistique : plantes peu touche´es; plantes supprime´es ou moins abondantes; plantes plus abondantes. Au de´part, les bruˆlis ont virtuellement e´limine´Juniperus communis var. depressa, Empetrum nigrum, Cladina rangiferina, Lycopodium clavatum et Pleurozium schreberi, diminue´la fre´quence de neuf autres espe`ces de 6 a`69 % et accru l'abondance de 13 autres de 1 a`2 050 %. Apre`s les bruˆlis, Polytrichum commune et Fragaria virginiana ssp. glauca ont vu leur population augmenter tre`s rapidement au de´but de l'e´tude pour devenir deux des espe`ces les plus courantes. Outre certains effets initiaux attribuables aux bruˆlis, le bleuet nain et quelques espe`ces de´ja`abondantes (Festuca filiformis, Maianthemum canadense, Danthonia spicata, Cornus canadensis et Luzula multiflora var. acadiensis) ont continue´de figurer parmi les espe`ces dominantes. Sur les espe`ces examine´es, sept seulement des groupes dont les bruˆlis accroissaient ou re´duisaient la population ont e´te´affecte´es par le cycle d'e´lagage et de bruˆlis. Dans ces deux groupes, la plus forte hausse ou baisse d'abondance se produit avec le cycle d'e´lagage-bruˆlis de deux ans.

ABSTRACT

No abstract

The performance of nine double-cut and three single-cut red clover (Trifolium pratense L.) cultivars was studied at five locations in Atlantic Canada. The single-cut clovers survived relatively well at all locations while the double-cut clovers did not survive well at one location during the first winter. An analysis of data for total dry-matter yield from five environments, i.e., location-year combinations, showed that the single-cut clovers outyielded the double-cut clovers in Newfoundland but yielded lower at the other locations. Among the double-cut cultivars, Florex, Lakeland, Tapiopoly, and Violetta were found to be desirable cultivars because they had a high mean yield and did not yield lower than the population average at any of the five environments. A large cultivar-environment interaction variance was detected for the double-cut cultivars; therefore, at least 15 test environments are required in future trials in order to detect a yield difference of 6% by multiple comparison procedures.Key words: Trifolium pratense L., stability