Effects of photoselective netting on root growth and development of young grafted orange trees under semi-arid climate

Photoselective netting is well-known for filtering the intercepted solar radiation, therefore affecting light quality. While its effects on above-ground of plants have been well investigated, the root system was neglected. Here, we evaluated the effects of photoselective netting on root growth and plant development. Minirhizotron and ingrowth cores were applied in a field experiment, performed in a 4-year-old orange orchard grown under three different photoselective net treatments (red, pearl, yellow) and an unnetted control treatment. Our observations confirmed the significant positive effect of photoselective nets on tree physiological performance, by increases of photosynthesis rate and vegetative growth. Trees grown in the pearl plot developed evenly distributed root system along the observation tubes while trees in control, red and yellow plots had a major part of roots concentrated at different depth ranges of 60–80, 100–120, and 120–140 cm, respectively. Photoselective nets showed a strong impact on shoot-root interaction and proved equally successful in promoting rapid establishment of young citrus trees. However, at long-term effect, yellow net might outperform because it could enable plants to develop deeper root systems, which will uptake water and nutrients more efficiently in semi-arid areas with sandy soil.