Photosynthetic light response curves in relation to illumination of adaxial and abaxial surfaces of sun and shade leaves of Vitis vinifera L.

The photosynthetic light response of adaxial (upper) and abaxial (lower) surfaces of sun- and shade-adapted leaves of cv. Grechetto/SO 4 was investigated. Vines were exposed to long-term shade by mounting a black polypropylene cover (40 % light transmittance) over the vines for 6 consecutive years. The mean leaf blade inclination varied from 81.4degrees(sun-exposed) to 15.4degrees (shaded) enabling a high light reception. At light saturation, the maximum rate of photosynthesis of sun and shade leaves were similar if the adaxial or the abaxial leaf surface or both sides were irradiated simultaneously. At lower photon flux density (PFD), the adaxial surface consistently fixed more CO2 than the abaxial surface in both leaf types. At PFD below saturation, simultaneous illumination of both leaf surfaces led to an increase of the rate of net photosynthesis (Pn) as compared to illumination of only one surface with the same PFD. Bilateral illumination increased the apparent quantum yield and the convexity coefficient (bending rate of the photosynthetic light response curve) as compared to irradiation of only one side of the blade, whereas the light compensation and saturation points were significantly lower. The possible significance of simultaneous irradiation of both leaf surfaces at low PFD on Pn is discussed

Traditional and innovative summer pruning techniques for vineyard management

This review paper highlights physiological and vine performance effects of widely adopted summer pruning operations such as leaf removal, shoot trimming and positioning and cluster thinning. Leaf removal is addressed either under its traditional configuration, i.e. removing in dense canopies some or all leaves around clusters usually pre-veraison to improve fruit microclimate and facilitate spraying and early (pre-flowering) defoliation primarily aimed at inducing looser clusters via a concurrent reduction of fruit-set and berry size. Time consuming and still non mechanisable cluster thinning is evaluated primarily in terms of response variability vs. season and intensity with emphasis on lack of significant reduction of final yield per vine in thinned treatments when large crop compensation occurs. Variability of expected final grape composition improvements in thinned vines is also discussed based on the actual vine balance when the operation is performed. Although fully mechanisable, shoot trimming is still a debated choice in terms of timing and severity. While severe (i.e. fewer than six or seven main leaves retained) and late (i.e. several weeks after bloom) cuts should possibly be avoided, the effects of shoot trimming on final grape composition is discussed as a function of seasonal changes in leaf area development, demography, fraction of lateral leaves from the total and leaf to fruit ratio. It is indicated that, for vertically shoot-positioned trellises, if the support trellising is correctly designed and vine vigour is balanced, timing and severity of trimming are dictated by the vine “itself” rather than by grower choices. Overall, this review underscores the importance of leading the vineyard to a “natural” control of vegetative growth, which would minimise the need for an extensive use of summer pruning. In other words, such vineyard operations should be viewed not just as something the growers “have to do”, instead as specific tools used to achieve targeted final grape composition

Unmanned Aerial Vehicle (UAV)-based remote sensing to monitor grapevine leaf stripe disease within a vineyard affected by esca complex

Foliar symptoms of grapevine leaf stripe disease (GLSD, a disease within the esca complex) are linked to drastic alteration of photosynthetic function and activation of defense responses in affected grapevines several days before the appearance of the first visible symptoms on leaves. The present study suggests a methodology to investigate the relationships between high-resolution multispectral images (0.05 m/pixel) acquired using an Unmanned Aerial Vehicle (UAV), and GLSD foliar symptoms monitored by ground surveys. This approach showed high correlation between Normalized Differential Vegetation Index (NDVI) acquired by the UAV and GLSD symptoms, and discrimination between symptomatic from asymptomatic plants. High-resolution multispectral images were acquired during June and July of 2012 and 2013, in an experimental vineyard heavily affected by GLSD, located in Tuscany (Italy), where vines had been surveyed and mapped since 2003. Each vine was located with a global positioning system, and classified for appearance of foliar symptoms and disease severity at weekly intervals from the beginning of each season. Remote sensing and ground observation data were analyzed to promptly identify the early stages of disease, even before visual detection. This work suggests an innovative methodology for quantitative and qualitative analysis of spatial distribution of symptomatic plants. The system may also be used for exploring the physiological bases of GLSD, and predicting the onset of this disease.

Intensidades da poda seca e do desbaste de cacho na composição da uva Cabernet Sauvignon.

A pesquisa foi realizada durante quatro anos, num vinhedo de Cabernet Sauvignon (Vitis vinifera L.), em Bento Gonçalves-RS. O objetivo foi determinar o efeito das intensidades da poda seca e do desbaste de cacho em variáveis relacionadas aos componentes de produção da videira e à composição do mosto de uva. Os tratamentos consistiram em dois níveis de poda seca - curta e longa - e quatro de desbaste de cacho (%) - 0; 25; 50 e 75 -; com cinco repetições. O delineamento experimental foi o em blocos casualizados, com os tratamentos em parcelas subdivididas. Os resultados mostram que a poda seca e o desbaste de cacho tiveram efeito altamente significativo na produtividade do vinhedo que, na média dos quatro anos, variou de 10.971 kg/ha ? poda curta, 75% de desbaste ? a 32.819 kg/ha ? poda longa, 0% de desbaste. Houve, também, efeito significativo na produtividade por gema, peso de ramos podados por gema e por hectare, área foliar/peso fresco do fruto e produtividade/peso de ramos podados. Entretanto, o efeito nas variáveis relacionadas a açúcar e acidez do mosto da uva foi pouco expressivo. O componente 1 da análise de componentes principais discriminou o tratamento poda curta a 75% de desbaste de cacho dos tratamentos poda longa-0% de desbaste e poda longa-25% de desbaste

Potential of a multiparametric optical sensor for determining in situ the maturity components of red and white vitis vinifera wine grapes

A non-destructive fluorescence-based technique for evaluating Vitis vinifera L. grape maturity using a portable sensor (Multiplex ®) is presented. It provides indices of anthocyanins and chlorophyll in Cabernet Sauvignon, Merlot and Sangiovese red grapes and of flavonols and chlorophyll in Vermentino white grapes. The good exponential relationship between the anthocyanin index and the actual anthocyanin content determined by wet chemistry was used to estimate grape anthocyanins from in field sensor data during ripening. Marked differences were found in the kinetics and the amount of anthocyanins between cultivars and between seasons. A sensor-driven mapping of the anthocyanin content in the grapes, expressed as g/kg fresh weight, was performed on a 7-ha vineyard planted with Sangiovese. In the Vermentino, the flavonol index was favorably correlated to the actual content of berry skin flavonols determined by means of HPLC analysis of skin extracts. It was used to make a non-destructive estimate of the evolution in the flavonol concentration in grape berry samplings. The chlorophyll index was inversely correlated in linear manner to the total soluble solids (°Brix): it could, therefore, be used as a new index of technological maturity. The fluorescence sensor (Multiplex) possesses a high potential for representing an important innovative tool for controlling grape maturity in precision viticulture

Colour assessment outcomes – a new approach to grading the severity of color vision loss

INTRODUCTION: Recent studies have shown that a significant percentage of subjects with anomalous, congenital trichromacy can perform the suprathreshold, colour-related tasks encountered in many occupations with the same accuracy as normal trichromats. In the absence of detailed, occupation-specific studies, an alternative approach is to make use of new findings and the statistical outcomes of past practices that have been considered safe to produce graded, justifiable categories of colour vision that can be enforced. METHODS: We analyzed traditional color assessment outcomes and measured severity of colour vision loss using the CAD test in 1363 subjects (336 normals, 705 deutan, 319 protan and 3 tritan). The severity of colour vision loss was measured in each subject and statistical, pass / fail outcomes established for each of the most commonly used, conventional colour assessment tests and protocols. RESULTS: The correlation between the number of Ishihara (IH) test plates subjects fail and the severity of RG colour vision loss was very poor. The 38 plates IH test has high sensitivity when no errors are allowed (i.e., only 0.71% deutans and 0.63% protans pass). Protocols based on zero errors are uncommon since 18.15% of normal trichromats fail. The most common protocols employ either the 24 or the 14 plates editions with two or less errors. These protocols pass almost all normal trichromats, but the deutans and some protans that also pass (when two or less errors are allowed) can be severely deficient. This is simply because the most challenging plates have not been included in the 24 and 14 plates editions. As a result, normals no longer fail, but the deutans and protans that pass have more severe loss of colour vision since they fail less challenging plates. The severity of colour vision loss was measured in each subject and statistical, pass / fail outcomes established for each of the most commonly used, conventional colour assessment tests and protocols. DISCUSSION: Historical evidence and new findings that relate severity of loss to the effective use of colour signals in a number of tasks provide the basis for a new colour grading system based on six categories. A single colour assessment test is needed to establish the applicant’s Colour Vision category which can range from ‘supernormal’ (CV0), for the most stringent, colour-demanding tasks, to ‘severe colour deficiency’, when red / green colour vision is either absent or extremely weak (CV5)

Increasing the source/sink ratio in Vitis vinifera (cv Sangiovese) induces extensive transcriptome reprogramming and modifies berry ripening

<p>Abstract</p> <p>Background</p> <p>Cluster thinning is an agronomic practice in which a proportion of berry clusters are removed from the vine to increase the source/sink ratio and improve the quality of the remaining berries. Until now no transcriptomic data have been reported describing the mechanisms that underlie the agronomic and biochemical effects of thinning.</p> <p>Results</p> <p>We profiled the transcriptome of <it>Vitis vinifera </it>cv. Sangiovese berries before and after thinning at veraison using a genome-wide microarray representing all grapevine genes listed in the latest V1 gene prediction. Thinning increased the source/sink ratio from 0.6 to 1.2 m²leaf area per kg of berries and boosted the sugar and anthocyanin content at harvest. Extensive transcriptome remodeling was observed in thinned vines 2 weeks after thinning and at ripening. This included the enhanced modulation of genes that are normally regulated during berry development and the induction of a large set of genes that are not usually expressed.</p> <p>Conclusion</p> <p>Cluster thinning has a profound effect on several important cellular processes and metabolic pathways including carbohydrate metabolism and the synthesis and transport of secondary products. The integrated agronomic, biochemical and transcriptomic data revealed that the positive impact of cluster thinning on final berry composition reflects a much more complex outcome than simply enhancing the normal ripening process.</p