Eustoma Quality is Adversely Affected by Low pH of Root Medium

Abstract

Foliar chlorosis or bleaching, interveinal chlorosis, leaf edge and tip necrosis, a poor root system, and stunted growth of Eustoma grandiflorum (Raf) Shinn seedlings were associated with a medium pH of 5.0 or 5.5 but not when the values ranged from 6.4 to 7.5. The range in medium pH resulting in the best growth of seedings and flowering plants was 6.3 to 6.7. Responses to medium pH were similar, regardless of fertilizer solution pH or cultivar. Eustoma seedling and shoot fresh weights for pH 5.0 and 5.5 were only 23% to 66% of corresponding values for plants grown at pH 6.4. Leaf tissue Zn was extremely high (1050 mg·kg-l dry leaf tissue) at a medium pH of 5.0, but other macro- and micronutrients in leaves were not at abnormal levels.