Ozone-induced reductions in below-ground biomass: an anatomical approach in potato

[EN] Potato plants were grown in open-top chambers under three ozone concentrations during two complete cropping seasons (93 and 77 d in 2004 and 2005, respectively). The effects of chronic exposure to ozone on leaf anatomy, cell ultrastructure and crop yield were studied. Severe cell damage was found, even at ambient ozone levels, mainly affecting the spongy parenchyma and areas near the stomata. Damage to the cell wall caused loss of cell contact, and loss of turgor pressure due to tonoplast disintegration, contributed to cell collapse. Phloem sieve plates were obstructed by callose accumulation, and damaged mesophyll cells increased their starch stores. Tuber yield fell sharply (24–44%), due to the biggest tubers becoming smaller, which affected commercial yield. These anatomical findings show the mechanisms of ozone effect on assimilate partitioning, and thus crop yield decrease, in potato. Further implications of ozone causing reductions in belowground biomass are also discussed.
The authors thank Prof Secundino del Valle (Valencia University, Spain) for his helpful comments. We are also grateful to Mr Duncan Gates for revising the English style of the text. AAF was supported by a grant from the Generalitat Valenciana's FPI programme (Government of Valencia, Spain).