Microclimate alterations caused by agricultural hail net coverage and effects on apple tree yield in subtropical climate of Southern Brazil

Leosane Cristina Bosco,Homero Bergamaschi,Loana Silveira Cardoso,Pedro Correa Brauner,Viviane Aires De Paula,Gilmar Arduino Bettio Marodin

doi:10.1590/1678-4499.2016459

Abstract

ABSTRACT The use of hail net coverage on plants is an effective measure to mitigate damage caused by hailstorms. In southern Brazil, areas with apple orchards under hail net coverage have increased in recent years. However, little is known about the possible effects on the microclimate and, consequently, on plant growth, crop yield and fruit quality. The hypothesis of this study was that hail net promotes microclimate and yield changes in apple orchards. The objective was to characterize the microclimate and production of apple trees cultivated under hail nets and to consequently generate numeric parameters that can be used in the management of apple orchards and in crop modeling. The study was conducted in commercial orchards growing under hail net and open sky. Continuous measurements of photosynthetically active radiation (PAR), air temperature and humidity, wind speed and rainfall were performed. Production was assessed based on the number and weight of fruits per plant. The hail nets reduced PAR by 32.8% and the wind speed by 30%. In contrast, coverage did not alter the air temperature, humidity or rainfall. The yield of apples tends to be higher under hail net and this is more pronounced when one hailstorm event occur. These results are important for researchers, and apple farmers to establish criteria for decision making regarding the implementation of hail net coverage and to develop appropriate management systems for protecting orchards to ensure and improve fruit production. Overall, the effects of long-term micrometeorological factors are essential to perform modeling of agricultural production.

Highlights

The increased occurrence of extreme weather events due to climate change has heightened the demand for measures that can mitigate losses in agriculture
Of the global solar radiation (Rg) incident on the apple orchards analyzed in this study, 79% corresponded to the net radiation (Rn) available to the orchard under the open sky and 75% to the Rn of the orchard under the anti-hail net
A large amount of cloudiness and rainfall interfered with the incoming solar radiation and, with the photosynthetically active radiation (PAR) intercepted by the hail net

Summary

Introduction

The increased occurrence of extreme weather events due to climate change has heightened the demand for measures that can mitigate losses in agriculture. Hail is considered an extreme event of great destructive potential, for example, a single hailstorm event in an orchard could result in the total loss of fruit production and would damage the trees (Garnaud 1998). The climatic characteristics of such regions may result in increased production and fruit quality, these areas are affected by frequent hailstorms, causing damage to orchards and adversely affecting growers. In Rio Grande do Sul State, Brazil, the highest incidence of hailstorms occurs in regions of higher elevation and continentality, with four or more events per year (Berlato et al 2000)

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Results

Conclusion