Effect of anti-hail nets with different colors on ‘Eva’ apple trees agronomical responses

Abstract

The aim of the current research was to evaluate the impact of ‘Eva’ apple tress cultivation under nets with different colors as opposed to cultivation deprived of net treatment on the attributes related to the vigor of the plant, production and fruit quality. The evaluations were carried out during the 2017/18 and 2018/19 crop growing seasons at commercial production fields located in the municipality of Porto Amazonas, PR. The treatments in study consisted of a control (plants grown with no protecting net), along with plants protected by anti-hail nets of distinct colors such as white, crystal (transparent) and black. The following response variables were assessed herein: length and diameter of the branch, plant height and branch diameter as plant vigor measurements, crop production (kg plant-1) and yield (kg ha-1), and number of fruits per plant as to productive yield of the cropping system, as well as shape (height and diameter) of the fruits, mass, Hue angle, firmness, soluble solids and titratable acidity to test grade or fruit quality. There was no significant effect of protecting nets on both vigor and development of the plants. However, production and yield were consistently more expressive under crystal and white protecting nets throughout the second crop growing season. This demonstrated that ‘Eva’ apple trees were conducive to render as well as or even better than those plants bereft of protecting nets in view of the fact that the former treatments caused the plants to suffer less harmful impacts promoted by hail events, excess of wind, and sun burning disorders. The black anti-hail net resulted in negative outcomes as to coloration of the fruits in conjunction with titratable acidity, making them reddish and acidic and, therefore, less attractive for in natura commercial consumption.

Grey and Black Anti-Hail Nets Ameliorated Apple (Malus × domestica Borkh. cv. Golden Delicious) Physiology under Mediterranean Climate

“…Although the recorded differences in yield were not significantly different (Figure 6), it is possible to infer a positive influence of the nets in apple trees productivity. On the literature, the nets influence in yield is usually contradictory, varying from increase, the absence of influence to a decrease, depending largely on nets colour and environmental conditions [2,6,18,21,22,27]. In the present study, the absence of significant differences, despite the better physiological performance exhibited by the covered trees, can be due to a higher investment of trees in vegetative growth, as a typical shade avoidance response [57].…”

“…GRSP have received increasing attention, for their role in soil aggregate stability, protection from soil erosion, carbon storage, soil fertility improvement, reduction of greenhouse gases emissions and stress tolerance enhamcement [16], still the effects caused by the use of nets on orchard ecosystem need to be further understood. The induced changes in orchard's microclimate can also affect tree physiology, ionome, growth, yield and fruit quality, in a level depending on the local climatic conditions, the degree of shading, the colour and aperture size of the net, the cultivar/rootstock, among others [6,[10][11][12][18][19][20][21][22]. Unfortunately, data currently available on netting influence on trees physiological responses are usually contradictory.…”

“…As nutrient uptake and the subsequent distribution within the plant, change according to plant needs and in response to environmental conditions [26], the influence of nets on nutrient dynamics deserves further attention. The shading influence on yield and/or fruit size also varies largely in response to a range of factors, being the most determinants the net colour and environmental conditions [2,6,9,18,[20][21][22]27].…”