Shade coffee in Hawai‘i – Exploring some aspects of quality, growth, yield, and nutrition

In a harsh (Kunia) and an ideal (Kona) growing region of Hawai‘i, sun grown Coffea arabica L. was compared to coffee shaded with varying degrees of black and aluminized shade cloth, macadamia trees, and a novel, spray-on shade composed mostly of kaolin. Shading did not appreciably affect organoleptic quality. Shading resulted in statistically different yields in the macadamia (16% of sun) and kaolin (199% of sun) treatments in the second year compared to full sun treatments in their respective locations, although a negative, linear trend was observed with increased shading. The lack of significant differences in yields between the shade cloth and sun treatments was likely a result of large yield variation among replicates. Bean sizes differed little between shade treatments and the percentage of defects and broken beans were generally not significantly different among the treatments in Kunia. Kona bean sizes and characteristics were not different. Shading reduced surface leaf temperatures and increased specific leaf area but generally did not affect lateral nodal growth. Leaf nutrient concentration differed between treatments.

Research highlights► Shade does not affect the organoleptic quality of quality. ► Kaolin can double yields of coffee. ► Shading with shade cloth and macadamia trees seems to depress coffee yields. ► Shading coffee affects leaf nutrient content, increases specific leaf area and reduces leaf temperature.