Citrus is a valuable fruit that can be grown in varying climatic conditions. The Mediterranean climate is considered the favorable climate condition for citrus production and presents exceptional fruit quality than in native regions. There are negative impacts of climate change in the main areas of production, which have negative effects on the future of citriculture. Under semi-arid conditions, rising temperature and high solar radiation might reduce growth rate and yield. Shading is considered a common agriculture practice in nurseries and has recently been used in various commercial fruit orchards. This practice has several advantages for citrus trees particularly in arid and semi-arid environments, as it affects orchard micro-climate reducing the high temperature, light intensity, solar radiation, etc. Tree shading improves leaf photosynthetic efficacy, reduces environmental stress, enhances tree growth, increases yield, and improves fruit quality, reducing disease and pest infection. Shading is considered a principal agriculture practice as a part of integrated farm management.
TopIntroduction
There are different challenges facing fruit production, climate change is considered one of the main threats to the sustainability of the productivity of fruit crops, due to influential fluctuations in the behavior of trees, particularly in flowering and fruit set stages, which causes negative effects on tree productivity and fruit quality (Abobatta 2021a).
Multiple phenomena of climate change affect fruit orchards such as rising temperatures, heatwaves, warmer nights in winter, elevated carbon dioxide (CO2) levels, frequent droughts, extreme winds, and increased solar radiation (Bisbis, et al, 2019).
It is well documented that, rising temperature increases evapotranspiration reduces CO2 assimilation and minimizes stomatal conductance through closing stomata, which reduces carbohydrates formation rate, thus reducing tree yield and affecting fruit quality (Jokar, et al, 2021). In addition, high temperature increases the abscission of flowers and fruitlets of citrus trees (Mditshwa, et al, 2019; Syvertsen, et al, 2003).
Currently, there is more attention to using various techniques to alleviate the negative effects of climate change on various crops particularly fruit trees. Shade netting is one of the modern techniques that are used to reduce impacts of climate change on the physiological performance of fruit trees particularly in dry and semi-dried regions (Manja and Aoun 2019; Mahmood, et al, 2018).
Citrus trees are subjected to various environmental stress especially heat stress in the main production (warm subtropical and semi-dried) regions, particularly during summer when temperatures are above 31 0C which affects negatively yield and reduce fruit quality (Tsai, et al, 2013).
Therefore, using protective cultivation or net shading in citrus cultivation have more interesting particularly in dry and semi-dried regions (Figure 1), due to fluctuation in climate conditions, particularly high temperature, increasing solar radiation rate, and hail injuries (Abobatta, 2021b).
Figure 1. Image field to cultivation mandarin under shading net, under Egyptian desert conditions (Photo by Dr. Waleed Abobatta 2010)
Shading system is used to prevent trees from fluctuation in temperature, reduce physiological disorders like sunburn and cracking, reducing birds’ damage, insect infection threats, strong wind, and sandy storms. Furthermore, shading protects newly establish citrus orchards from infection with Asian citrus psyllid and Candidatus Liberibacter asiaticus (Gaire, et al, 2021).
Complete net houses or top screens are considered a partial solution for mitigating impacts of climate change through modification of the local climate around the trees (Prins, 2018). Partial shading can be used to protect the fruits from excessive environmental conditions like excessive solar radiation, strong wind. In addition, could reduce water loss from the fruits, enhance fruit quality like firmness, and may prolong fruit shelf life (Botes 2018).
This work discussed the impact of climate change conditions on citrus orchards and explored the effects of net shading on growth and productivity, various types of net shading in use, the benefits of shading on citrus production. In addition to the effects of net shading on reducing solar radiation in citrus orchards. Furthermore, discussing the most important gaps that must be avoided in future researches.
TopClimate Change Conditions
Under global warming and increase environmental stresses which affect negatively the growth and productivity of various fruit orchards worldwide, there is a need to use new practice management like net shading to enhance environmental conditions which improve tree vigor and yield (Sadka, et al, 2019).