The major factors influencing coffee quality in Ethiopia: The case of wild Arabica coffee (Coffea arabica L.) from its natural habitat of southwest and southeast afromontane rainforests

Coffee quality is a complex trait involving sensory and bean characteristics as well as biochemical contents. The objective of this study was to assess the major factors influencing the quality of wild Arabica coffee (Coffea arabica L.) in the natural coffee forests of southwest and southeast Ethiopia. Results revealed that both natural (soil, aspect, elevation, climate, geographic location) and human factors (cherry harvesting/ handing, theft, forest management) considerably influenced the quality of wild Arabica coffee. The soil factor affected every component of coffee quality (cup quality, bean characteristics and biochemical contents). The cup quality of coffee varied with soil properties, especially with available P and soil texture. The bean size distribution was also affected by soil properties; there was significant positive relationship between soil pH, sand or Mn and the proportion of bold beans (retained on screen 17). Soil organic matter, total N and sand content were inversely correlated with caffeine content, but available P and clay content were positively correlated with caffeine. Increase in elevation led to increase in bean size up to the elevation of about 1600 m above sea level, but thereafter no more increase in bean size (hump-shaped relationship, not monotonic). Bean size increased with increase in longitude, but it decreased with increase in latitude. Cup quality was also significantly influenced by coffee harvesting and handling, but its influence was not noticed on bean size and biochemical contents. Coffee quality is therefore the resultant of an interaction of different natural and human factors prevailing in the respective area.   Key words: Arabica coffee, bean size, biochemical content, cup quality, environment, management/handling.