Showing papers by "Manfred Stoll published in 2010"

Some critical issues in environmental physiology of grapevines: future challenges and current limitations

Abstract: The rapidly increasing world population and the scarcity of suitable land for agricultural food production together with a changing climate will ultimately put pressure on grape-producing areas for the use of land and the input of resources. For most grape-producing areas, the predicted developments in climate will be identical to becoming more marginal for quality production and/or to be forced to improve resource management. This will have a pronounced impact on grapevine physiology, biochemistry and ultimately production methods. Research in the entire area of stress physiology, from the gene to the whole plant and vineyard level (including soils) will need to be expanded to aid in the mitigation of arising problems. In this review, we elaborate on some key issues in environmental stress physiology such as efficient water use to illustrate some of the challenges, current limitations and future possibilities of certain experimental techniques and/or data interpretations. Key regulatory mechanisms in the control of stomatal conductance are treated in some detail and several future research directions are outlined. Diverse physiological aspects such as the functional role of aquaporins, the importance of mesophyll conductance in leaf physiology, night-time water use and respiration under environmental constraints are discussed. New developments for improved resource management (mainly water) such as the use of remote sensing and thermal imagery technologies are also reviewed. Specific cases where our experimental systems are limited or where research has been largely discontinued (i.e. stomatal patchiness) are treated and some promising new developments, such as the use of coupled structural functional models to assess for environmental stress effects on a whole-plant or canopy level are outlined. Finally, the status quo and research challenges around the ‘CO2-problem’ are presented, an area which is highly significant for the study of ‘the future’ of the grape and wine industry, but where substantial financial commitment is needed.

Possibilities to reduce the velocity of berry maturation through various leaf area to fruit ratio modifications in Vitis vinifera L. Riesling

Abstract: Le rechauffement climatique observe ces dernieres annees a entraine un avancement de la phenologie de nombreuses cultures. Chez la vigne, tous les stades phenologiques sont affectes, debourrement, floraison ou veraison, avec de serieuses repercussions sur la qualite des raisins et du vin. Les systemes de conduite de la vigne jouent un role non negligeable sur l'activite photosynthetique et le microclimat des grappes. Ainsi, dans l'optique de retarder les processus de maturation, nous avons teste, sur une vigne de Riesling conduite en Espalier, les effets d'une modification du rapport feuille/fruit sur la maturation. Un effeuillage mecanique de la haie foliaire (MDC) et un rognage severe (SSP), correspondant approximativement a la moitie de la hauteur de la haie foliaire des plants temoins, ont ete appliques apres floraison sur la partie du feuillage situee au-dessus de la zone des grappes. Le rapport feuille/fruit etait compris respectivement entre 8 cm 2 g -1 , 14 cm 2 g -1 et 19.5 cm 2 g -1 pour SSP, MDC et le temoin. Les mesures des echanges gazeux effectues a differents stades phenologiques n'ont pas revele d'effets negatifs du rognage severe et de l'effeuillage sur l'activite photosynthetique du feuillage. Cependant, la suppression des jeunes feuilles pour le traitement SSP a significativement affecte le processus de senescence du feuillage. La maturation du raisin a ete fortement influencee par la surface foliaire, et les premiers resultats semblent indiquer qu'une diminution du rapport feuille/fruit influence la maturation de la vendange et la composition des baies.