Shade nets effect on canopy light distribution and quality of fruit and spur leaf on apple cv. Fuji

Abstract

The upper region of the Río Negro and Neuquén valley, Argentina (latitude: 38 degrees 55 minutes South) experiences high temperatures and light intensities before the apple harvest. This hinders these fruits turning red and increases the risks of them becoming sunburnt. In the December of two growing seasons (when the fruits were about 43 mm in diameter), still some 80 days before harvest, 15% and 55% density shade nets were placed over "Fuji" apple trees. At harvest time, light distribution was determined at two canopy heights (1 and 3 m) on either side of the trees. Fruiting spurs were examined, and colour, sunburn damage, weight, soluble solid content and flesh firmness of the fruits determined. Specific leaf weight (SLW) was also established. Shade nets notably decreased the amount of photosynthetically active radiation (PAR) available; they also reduced fruit colour (redness), soluble solid content and flesh firmness, and the SLW. The 55% density net decreased fruit sunburn, but no differences were found between the 15% density net and control treatments. Spurs at the bottom of the canopy received less light, and the SLW, as well as the colour and soluble solid content of their fruit, was lower than observed for the higher spurs. The impossibility of exporting fruits damaged by high temperatures and intense solar radiation during ripening requires shade nets be used, their density depending on the conditions experienced.

Photosynthetic efficiency of apples under protected shade nets

“…Orchard shade netting coverage is used for this purpose; it allows decreasing sunlight and temperature of the fruit surface and lessens direct solar radiation transmission (Dussi et al, 2005). Netting color and density significantly affect direct solar radiation transmission.…”

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

“…From an extensive bibliographical review about the use of anti-hail nets in orchards, it has been verified that there are scientific results showing that microclimatic modifications occur in a greater or smaller scale in the canopy of plants and, consequently, these modifications can alter the yield of fruits (Leite et al 2002;Stampar et al 2002;Middleton and Mcwaters 2002;Dussi et al 2005;Iglesias and Alegre 2006;Solomakhin and Blanke 2007;Amarante et al 2011;Bosco et al 2015). The reduction of solar radiation due to the presence of the hail net, for example, triggers modifications in the environment that will determine accumulation of photoassimilates by the plants influencing the yield.…”

“…Since the 1950s, several systems with hail nets have been developed, and their use has proven to be effective as an alternative control of hail. Indeed, there has been an intensification of hail net use in horticulture since 2000 in Brazil (Amarante et al 2011;Leite et al 2002), Australia (Middleton and McWaters 2002), Italy (Corollaro et al 2015), Argentina (Dussi et al 2005), Spain (Iglesias and Alegre 2006), Germany (Solomakhin and Blanke 2007), South Africa (Gindaba and Wand 2007), Slovenia (Jakopic et al 2007), and Israel (Tanny 2009). However, information on the effects of hail protection nets on the orchard microclimate is inconsistent and varies with site conditions, the screens used and orchard management.…”

Radiação, fotossíntese, rendimento e qualidade de frutos em macieiras 'Royal Gala' cobertas com telas antigranizo

“…Considerando-se o total acumulado ao longo do dia, a tela preta ocasionou maior redução na DFFFA (24,8%) do que a tela branca (21,2%), em relação à área descoberta (Figura 1 B) Esses resultados mostram que o sombreamento ocasionado pelas telas aumentou a eficiência fotossintética em baixos valores de DFFFA, caracterizado pelos menores valores de R e , Γ e coeficiente b das equações hiperbólicas ajustadas, mas ocasionou menor A max . A redução da R e , em folhas sombreadas, é uma estratégia importante para a redução do Γ, por aumentar a eficiência de captação e uso da pouca luz disponível em ambiente sombreado (Dussi et al, 2005). Isso ocasiona redução nos valores de A max , em plantas sombreadas pela tela, como resultado da maior limitação imposta pelas reações de carboxilação ao incremento na fotossíntese, em elevados valores de DFFFA, comparativamente às plantas descobertas (Lambers et al, 1998).…”

“…apresentaram a maior área foliar específica (Tabela 1). Esta adaptação foliar ao sombreamento sob tela, em macieiras 'Royal Gala', também contribui para a maior eficiência fotossintética em condições da baixa DFFFA (Dussi et al, 2005).…”