Influência do uso da cobertura plástica no microclima de parreirais na região do submédio São Francisco: efeitos na produtividade e rentabilidade econômica.

Abstract

This study aimed to evaluate the influence of the plastic cover film of low density polyethylene (LDPE), 160 mm thick, transparent and width of 3 m, the microclimatic conditions of the vineyards covered in the region Submédio São Francisco - RSMSF, productivity and economic profitability of viticulture table in the region. The research consisted of four experimental stages conducted in vineyards production of table grape varieties Festival and Italy Muscat in Petrolina, Pernambuco (09 ° 06 '14''S, 40 º 29' 52 "W, altitude 360 m) during October 2009 to November 2010. The coverage period occurred only during the ripening and harvesting of the grapes, as traditionally used by local farmers. Was studied three treatments: treatment 1 - no plastic cover canopy (SCob), treatment 2 - plastic cover positioned 50 cm above the canopy (CP50) and treatment 3 - plastic cover positioned 100 cm above the canopy (CP100). Each research plot consisted of seven consecutive useful plants and a row of planting. The microclimatic monitoring was performed by temperature sensors and relative humidity, wind speed and radiative flows, installed in three locations: beneath the canopy at the time of the clusters between the canopy and the plastic cover over the cover and the atmosphere. The sensors were connected to automatic data acquisition CR23X and CR1000, programmed to perform readings every 2 seconds to generate hourly and daily averages and extreme values daily. The results indicated that the plastic cover positioned at 50 cm and 100 cm above the canopy changed the microclimate of the vineyard, increasing the air temperature and relative humidity and reducing wind speed and reducing up to 40% availability of radiation inside. The transmissivity of the plastic cover allowed the passage of 67% of global radiation (Rg), 55% of the ultraviolet (UV), 58% of photosynthetic active radiation (PAR), and 76% of infrared radiation (IR). Between April and May, time of year that occur in the region increased cloudiness and air temperature more gently, the plastic has changed the microclimate of the interior of Italy Muscat grape vineyards, with up to 2 ° C in air temperature , increased relative humidity in relation to the external environment (with the main difference being observed in the canopy CP50, a significant reduction in wind speed, especially on the canopy, and the amount of defect clusters with CP50 in the canopy compared to canopies Scob and CP100. During September and October the physical productivity under the canopy was positively influenced and contributed to a greater availability of radiation when compared to canopy cover CP50. The increased business productivity, whether by reducing the quantity of clusters with defects observed during the April and May in the canopy CP50 or by increased availability of light in September and October period in canopy CP100, was decisive to positive economic return of the activity, making the benefit / cost ratio remained always greater than 1 widening of the margin of safety activity.