Shoot Heterogeneity Effects on Shiraz/Richter 99 Grapevines. III. Leaf Chlorophyll Content

  • H. Cloete Department of Viticulture and Oenology, University of Stellenbosch, Stellenbosch 7600, South Africa CPUT, Private Bag X8, Wellington 7654, South Africa
  • E. Archer Lusan Premium Wines, PO Box 104, Stellenbosch 7599, South Africa
  • V. Novello Dipartimento di Colture Arboree, I 10095 Grugliasco TO, Italy
  • J.J. Hunter ARC Infruitec-Nietvoorbij, Private Bag X5026 Stellenbosch 7599, South Africa Department of Viticulture and Oenology, University of Stellenbosch, Stellenbosch 7600, South Africa

Abstract

In this study, the leaf chlorophyll content of normally developed and underdeveloped shoots was compared in an
attempt to quantify the effect of shoot heterogeneity in a Shiraz/Richter 99 vineyard, located in the Stellenbosch area
of the Western Cape, South Africa. Comparisons are also made between normally developed and underdeveloped
shoots from shaded and well-exposed canopies. No positive correlation was found between the photosynthetic
activity and the chlorophyll concentration of the leaves at five weeks after véraison. Equal amounts of chlorophyll
per cm2 and a non-significant difference in the assimilation rate were calculated for the leaves of normally developed
and underdeveloped shoots. No significant differences were found between the shaded and well-exposed canopies. It
therefore appears that it is the effective surface area per leaf or per shoot rather than the chlorophyll concentration
or activity that may be responsible for any apparent difference in the photosynthetic output of the leaves from
normally developed and underdeveloped shoots in shaded or well-exposed canopies.
Published
2016-12-13
Section
Articles