Fenologia e acúmulo térmico em videiras viníferas na região da Fronteira Oeste do Rio Grande do Sul

Abstract

Resumo -O objetivo deste trabalho foi avaliar a exigência térmica, obtida por diferentes métodos de cálculo, para caracterizar a fenologia das videiras (Vitis vinifera) 'Cabernet Sauvignon', ' Tannat Phenology and thermal accumulation in grapevines in the Fronteira Oeste region of Rio Grande do Sul, BrazilAbstract -The objective of this work was to evaluate the thermal requirement, obtained by different thermal time calculation methods, to characterize the grapevine (Vitis vinifera) phenology of 'Cabernet Sauvignon', 'Tannat', 'Ruby Cabernet', and 'Merlot' grown in the Fronteira Oeste region, of the state of Rio Grande do Sul, Brazil. The phenological development was followed for five seasons -2005/2006 to 2009/2010. Minimum and maximum air temperatures were recorded daily, and the following eight thermal time methods were tested: M1.1, M1.2, and M1.3, which use only the down threshold temperature (10°C); M2.1 and M2.2, which also consider 25°C as the optimum temperature for development; and M3.1, M3.2, and M3.3, which, besides using the prior temperatures, consider 35°C as the upper threshold temperature of development. These methods were compared using the standard error (SE) estimates of accumulated heat. The SNK test was used to compare the thermal requirement between cultivars. M3.3 was the method that best simulated 'Tannat' and 'Merlot' development (1,823.1 and 1,780.8 degree-day respectively). However, the least deviation was obtained in 'Cabernet Sauvignon' and 'Ruby Cabernet' using the M3.1 method (1,958.9 and 1,944.8 degreeday respectively). Methods employing the three cardinal temperatures showed greater accuracy. 'Tannat' and 'Merlot' are the cultivars that show the lowest thermal requirement to complete the cycle.

Cycle, productivity and must chemical characteristics of varieties of white wine grape

“…Grape varieties are characterized by their high sensitivity to biological adversities [21] and the great influence from environmental conditions on physiology and productive behavior [22]. Several factors that affect its phenology ought to be identified in each and every producing region [23].…”

Plastochron index of 'Cabernet Sauvignon' and 'Chardonnay' grapevines in Fronteira Oeste, in the state of Rio Grande do Sul, Brazil

“…The M3.3 method, developed by Tomazetti et al (2015), was used to determine the daily thermal sum (dTS, ºC day). This approach uses base (Tb), optimum (To), and upper (Tu) cardinal temperatures for plant growth, according to the following conditions: dTS = [(Tmax -Tb)0.5] ×1 day, when Tm<To and Tmin<Tb; dTS = (0) ×1 day, when Tmax<Tb; dTS = (Tm -Tb) ×1 day, when Tm<To and Tmin>Tb; dTS = {(To -Tb) × [(Tu -Tm)/(Tu -To)]} ×1 day, when Tm>To and Tmax<Tu; dTS = {(Tu -To)×[(Tu -Tm)/ (Tu -To)]} ×1 day, when Tm>To and Tmax>Tu, being that if Tmax>Tu, then Tmax=Tu.…”

“…In Rio Grande do Sul, the largest grape production is located in Serra Gaúcha (Mandelli et al, 2003;Mello, 2013); however, new areas within the state are standing out in the national scenario, such as Serra do Sudeste, Campanha, and Fronteira Oeste Radünz et al, 2015;Tomazetti et al, 2015). Local climate conditions are key factors for the development of grapevines, as well as for the choice of the production system to be adopted (Bem et al, 2015).…”

“…High-quality crops are affected by radiant energy, air temperature, and rainfall, for example (Liu & Heins, 2002), and thermal energy is the main responsible for vegetative growth and development, besides playing a crucial role on the phenological behavior of grapevines (Greer & Weedon, 2013). In this context, studying the responses to soil and climatic conditions has great importance (Tomazetti et al, 2015) since the main classes of grape sugars, i.e., glucose and fructose, are synthesized by photosynthesis in leaves (Miele & Rizzon, 2013).…”

“…The phenological performance of grapevine varieties due to climatic conditions can be analyzed by thermal need in terms of degree-days, which is a realistic measure from the biological point of view (Roberto et al, 2005;Brixner et al, 2010;Radünz et al, 2015;Tomazetti et al, 2015). However, an even more attractive way to identify vegetative development as affected by climatic conditions is through the plastochron index (PI), measured in ºC day per node.…”