Authors: Sara Serra1,2, Stefano Borghi1, Giverson Mupambi1, Hector Camargo-Alvarez1, Desmond Layne2,3, Tory Schmidt4, Lee Kalcsits1,2, and Stefano Musacchi1,2. Dec 2020
High temperatures, wind, and excessive sunlight can negatively impact yield and fruit quality in semi-arid apple production regions. Netting was originally designed for hail protection, but it can modify the light spectrum and affect fruit quality. Here, pearl, blue, and red photoselective netting (≈20% shading factor) was installed in 2015 over a commercial “Cameron Select®Honeycrisp” orchard. Our research objectives were to (1) describe the light quantity and quality under the colored nets compared to an uncovered control and (2) investigate the effect of Photoselective nets on “Honeycrisp” apple quality for two growing seasons. Light transmittance and scattering for each treatment were measured with a spectroradiometer, and samples for fruit quality analyses were collected at harvest. PAR (photosynthetic active radiation), UV, blue, red, and far-red light were lower underneath all netting treatments compared to an uncovered control. The scattered light was higher under the pearl net compared to other colors, while red and far-red light were lower under the blue net. For two consecutive years, trees grown under the photoselective nets intercepted more incoming light than the uncovered trees with no differences among the three colors. In both years, trees under red and blue nets had more sunburn-free (clean) apples than pearl and control. Red color development for fruit was lower when nets were used. Interestingly, bitter pit incidence was lower underneath red nets for both years. Other than red color development, “Honeycrisp” fruit quality was not appreciably affected by the use of netting. These results highlight the beneficial effect of nets in improving light quality in orchards and mitigating physiological disorders such as bitter pit in “Honeycrisp” apple.
1 Tree Fruit Research and Extension Center, Washington State University, Wenatchee, WA 98801, USA
2 Department of Horticulture, Washington State University, Pullman, WA 99164, USA
3 Currently, Department of Horticulture, Auburn University, Auburn, AL 36849, USA
4 Washington Tree Fruit Research Commission (WTFRC), Washington State University, Wenatchee, WA 98801, USA