Root-zone temperature influences the distribution of Cu and Zn in potato-plant organs

Root-zone temperatures (RZT) in relation to Cu and Zn uptake and tissue accumulation, and to total biomass, in potato plants (Solanum tuberosum L. var. Spunta) were studied. Using five different plastic mulches (no cover, transparent polyethylene, white polyethylene, coextruded white-black polyethylene, and black polyethylene) resulted in significantly different RZT (16, 20, 23, 27, and 30 degrees C, respectively). These RZT significantly influenced Cu and Zn content (concentrated) and the biomass in various potato organs. Root-zone temperature at 20 degrees C resulted in significantly high Cu content in leaflets, and soluble Cu content in leaflets and stems, whereas 23 and 27 degrees C resulted in significantly high Cu content in roots. However, RZT had no effect on Cu content in tubers or stems or on soluble Cu in roots or tubers. The RZT at 20 degrees C resulted in significantly high Zn and soluble Zn in stems, roots, and tubers; whereas, at 27 degrees C Zn and soluble Zn content were significantly highest in leaflets. The most biomass occurred in roots and tubers at 27 degrees C; whereas in leaves and stems, the RZT influence was highly variable. Total accumulation of both Cu forms was affected by RZT at 20 degrees C, with roots and tubers having significantly the least Cu and stems and leaflets having the most. Total accumulation of both Zn forms by RZT in potato organs was highly variable, but tubers consistently accumulated the most.