No abstract

Biochemically, starch is composed of amylose and amylopectin but can also be defined by its digestibility rates within the human intestinal tract, i.e., rapidly digested (RDS), slowly digested (SDS), or resistant (RS). The relative ratio of these starch components is the main contributor to differences in the glycemic index (GI) of carbohydrate sources. This study evaluated the digestible starch profile of 12 potato genotypes comprising elite breeding lines and commercial varieties in six environments, with the optimal profile defined as low RDS and high SDS. Genotype by environment interaction (GEI) analysis found significant (p = 0.05) genotypic and environmental effects for all digestibility rate components; however, interaction effects were only significant for SDS. Optimal starch profiles were identified for two genotypes, CV96044-3 and Goldrush. The desirable starch profile in these potato cultivars can be exploited in breeding programs for the improvement of starch profile and other important characteristics such as high yields and disease resistance.

. 2008. Genotype by environment interaction effect on yield and quality of potatoes. Can. J. Plant Sci. 88: 1099Á1107. Colour is an important character in the processing of potatoes for French fries. French fry colour is closely associated with sugar content in the tuber. This study examines the stability of yield, sugar content and French fry colour for eight potato cultivars and advanced selections in four environments. Stability was determined using three approaches based on the Eberhart-Russell, Tai and GGE Biplot analyses. The GGE Biplot analysis provided a better characterization of stability than the other two analyses. The most stable and best performing genotypes for both French fry colour and total sugars were Russet Burbank and Umatilla Russet. Cal White had high yield and yield stability but had average stability for poor (dark) French fry colour. The GGE biplot analysis was able to identify megaenvironments and those environments which optimized differentiation between genotypes. Both factors are important for the optimization of resources for testing new genotypes. Stability for quality factors in potato can be as important or more important than yield for some processing uses. In this study, genotypes with stability for sugar content and French fry colour were identified and these may be used as parents in breeding for stability.Key words: Potato, yield stability, quality, French fry Affleck, I., Sullivan, J. A., Tarn, R. et Falk, D. E. 2008. Interaction du ge´notype et de l'environnement, et incidence sur le rendement et la qualite´des pommes de terre. Can. J. Plant Sci. 88: 1099Á1107. La couleur est une importante caracte´ristique pour la transformation des pommes de terre en frites. La couleur des frites est e´troitement lie´e a`la concentration de sucre dans le tubercule. Cette e´tude porte sur la stabilite´du rendement, la teneur en sucre et la couleur des frites de huit cultivars et se´lections avance´es de pomme de terre dans quatre milieux. La stabilite´a e´te´e´tablie de trois fac¸ons d'apre`s les analyses de Eberhart-Russell, de Tai et a`double projection GGE. L'analyse a`double projection GGE caracte´rise mieux la stabiliteq ue les deux autres me´thodes. Les ge´notypes les plus stables et les plus performants en ce qui concerne la couleur des frites et la concentration totale de sucre sont Russet Burbank et Umatilla Russet. Le ge´notype Cal White a un rendement e´levet re`s stable, mais la pie`tre couleur (fonce´e) de ses frites est mode´re´ment stable. L'analyse a`double projection GGE permet d'identifier les me´ga-environnements et les environnements qui optimisent la diffe´renciation des ge´notypes. Ces deux e´le´ments reveˆtent de l'importance si l'on veut optimiser les ressources pour tester de nouveaux ge´notypes. La stabilite´des facteurs de qualite´chez la pomme de terre a parfois autant sinon plus d'importance que le rendement, selon la destination des tubercules en transformation. La pre´sente e´tude identifie les ge´notypes dont la concentration en sucre et la couleur des fri...

Raspberry (Rubus spp.) is an economically important crop with a restricted growing season and very limited fruit shelf-life due to its extreme tenderness. In order to prolong its shelf life, an aqueous composition containing hexanal as the key active ingredient (HC) was applied as a preharvest spray during fruit development. The effects of HC were assessed using physiological, biochemical and anatomical parameters on the treated fruits and compared with the effects of mock inoculation which lacked hexanal. Sugars and acidity did not show a significant change in response to HC treatment, while the pulling force (the tension required to detach the berry from the receptacle) significantly improved in the HC-treated fruits, compared to control. Scanning electron microscope (SEM) analysis revealed a high correlation between the presence of rigid epidermal hairs and a stronger degree of attachment between berries and their receptacle in the HC treated fruits. Further, electron micrographs also showed abnormal crystalline depositions on the epidermal drupelets of the treated berries. Energy Dispersive X-ray Spectroscopy (EDS) analysis showed those crystals to be largely composed of calcium. HC treatment also resulted in the reduction of transcript level of three phospholipase D genes, as well as altered expression pattern of five members of the annexin gene family, and four calmodulin-binding transcription activators. Quantification of PLD activity showed that hexanal inhibited PLD activity in treated berries. The potential crosstalk between hexanal, phospholipase D activity and calcium and this crosstalk’s role in delaying fruit softening and in prolonging storage life of fruits shelf life is discussed.

. 1997. Fruit zone leaf removal influences vegetative, yield, disease, fruit composition, and wine sensory attributes of Vitis vinifera L. 'Optima' and 'Cabernet Franc'. Can. J. Plant Sci. 77: 149-153. The influence of fruit zone leaf removal treatments (0, 50, and 100%) on grapevine canopy structure, incidence of bunch rot (Botrytis cinerea Pers.:Fr.), yield components, fruit and wine composition and wine sensory attributes was studied on Vitis vinifera L. 'Optima' and 'Cabernet franc'. The 50 and 100% leaf removal reduced leaf layer number, percent interior leaves and percent interior clusters. Yield was reduced between 29 and 46%. Severity of bunch rot in Optima and incidence and severity for Cabernet franc were reduced by leaf removal. Leaf removal improved colour, aroma and palatability of both Optima and Cabernet franc wines.