| dc.description.abstract | Iron (Fe) is a fundamental element involved in various plant metabolic processes. However, when Fe uptake
is excessive, it becomes toxic to the plant and disrupts cellular homeostasis. The aim of this study was to determine
the physiological and biochemical mechanisms underlying tolerance to Fe toxicity in contrasting rice varieties adapted to
African environments. Four varieties (CK801 and Suakoko 8 (tolerant), Supa and IR64 (sensitive)) selected from our
previous work were analysed in more detail, and the first part of this study reports morphological, physiological and
biochemical responses induced by Fe toxicity in these four varieties. Morphological (shoot length, root length, number
of lateral roots), physiological (photosynthesis rate, stomatal conductance, transpiration rate, fluorescence, relative
water content and cell membrane stability) and biochemical (tissue Fe, chlorophyll pigments, soluble sugars, protein
and starch) traits were measured, as appropriate, on both shoot and root tissues and at different time points during the
stress period. Fe toxicity significantly (P 0.05) reduced growth and metabolism of all the four varieties. Tolerant varieties
showed more lateral roots than the sensitive ones, under Fe toxic conditions as well as higher photosynthesis rate,
chlorophyll content and cell membrane stability. Strong dilution of Fe concentration in cells was identified, as one
of the additional tolerance mechanisms used by CK801, whereas Suakoko 8 mainly used strong mobilisation of
carbohydrates at the early stage of the stress period to anticipate metabolite shortage. Traits associated with Fe
toxicity tolerance in this study could be specifically targeted in trait-based breeding programs of superior lowland rice
varieties tolerant of Fe toxicity | en_US |
