Influence of Varieties and Seasons upon the Mineral Nutrient Levels, of Coffee Leaves from Puerto Rico

Abstract

Twenty-six young coffee trees grown under shade in an acid upland soil of 2 farms were selected representing 3 varieties and 2 yield-groups. The yield data were recorded for the crop harvested in the fall of 1962 from 15 highyielding and 11 low-yielding trees. Young leaves from each tree were sampled in the late summer of 1961 and in the late winter of 1962. The following 10 essential plant nutrients were determined: N, P, K, Ca, Mg, Mn, Fe, B, Zn, and Cu; as well as 2 nonessential elements, Na and Al. The yield and leaf-composition data were analyzed statistically. The high-yielding trees produced 2.6 times as much coffee as the lowyielding ones, a highly significant difference. There was no significant difference between the mean yields of the varieties. "Highly significant" or "significant" mean differences were obtained in all the essential nutrients except zinc, in the coffee leaves, between varieties; in the nutrients: N, P, K, Ca, Mg, and B, between seasons; and only in Ca and Mg between yield-groups. The acid soil, Alonso clay, is high in exchangeable manganese and in aluminum; the coffee trees used here also contained high Mn and Al in their leaves.