Olive mill wastewater triggered changes in physiology and nutritional quality of tomato (Lycopersicon esculentum mill) depending on growth substrate.

We have studied the changes in the physiology and nutritional quality of Lycopersicon esculentum exposed to olive mill wastewater (OMW) with regard to cultivation in sand and soil. Tomato plant performance decreased with increasing concentration of OMW to both substrates. Root was more sensitive to OMW than the upper parts of the plants, grown either in sand or in soil for 10 days and 3 months, respectively, probably due to the direct OMW toxicity on roots as compared to other parts. Significant restriction on uptake and translocation of nutrients (K, Na, Fe, Ca and Mg) under OMW application was found. The decrease in the photochemical efficiency of PSII photochemistry in the light adapted state and the big decrease in photochemical quenching, indicate that OMW resulted in diminished reoxidation of Q(A)(-) and started to inactivate the reaction centers of PSII. The OMW supply on soil and sand, resulted in leaf water stress and lesser water use efficiency. Plants treated with high OMW concentration, produced fewer but bigger tomatoes as compared to plants treated with lower OMW concentration. Generally, fruit yield and nutritional value was inhibited under OMW application.

Response of wheat seedlings to ni stress: effects of supplemental calcium.

The effect of excess Ni (1 mM Ni) on wheat plants as well as the role of Ca (1 mM Ni+5000 microM Ca) for amelioration of toxicity and recovery of growth and photosynthesis in Ni-stressed wheat was evaluated. Growth, nutrient status (Ca, Mg, Fe, K, Na), and photosynthesis showed a distinct decrease strictly related to the period of treatment. Calcium ameliorated to a certain extent toxic symptoms of Ni, due to antagonistic action between Ni and Ca ions. Since chlorophyll content and variable fluorescence (Fv) decreased significantly, but Fo did not particularly change, the decrease of t1/2 with increasing duration of Ni exposure indicates negative changes on the acceptor side of PSII, which also may result from diminution of Calvin cycle. The maximum quantum yield for energy trapping was also suppressed. Plant transfer to Hoagland solution+5000 microM Ca caused recovery to plant morphology and physiology. Even in control plants, during recovery period an increased Ca concentration in plant tissues with concomitant increased rates of growth and morphology was observed. Ni concentration in plants exposed to 1 mM Ni+5000 microM Ca was lower than in plants exposed to 1 mM Ni. In all treatments a certain increase of plant nutrients was observed during recovery.

Changes in growth and physiology of tobacco and cotton under Ag exposure and recovery: are they of direct or indirect nature?

Responses of tobacco and cotton seedlings to two chemical forms of Ag at various concentrations were studied. Cotton exhibited higher resistance than tobacco to Ag. The application of 1 &mgr;g L(-1) Ag, as AgI or AgNO(3), induced no toxicity symptoms in the growth and photosynthesis of cotton. However, the corresponding concentration negatively affected the growth and physiology of tobacco. On exposure to higher Ag concentrations (10(3) and 5 x 10(3) &mgr;g L(-1) as AgNO(3)), root growth and concentrations of Ca, Mg, K, and Fe were significantly depressed, whereas concomitant Ag accumulation, especially in roots, was increased in both species. The loss of nutrients and chlorophyll was associated with disturbances in photosynthetic function. Because there was no apparent change in Fv/Fm, there is a possibility that the faster rise time was due to an increase in LHC size to the PSII reaction centers. The decreased Fv/Fo reflects the inactivation of chlorophyll associated with the PSII reaction center. Stomatal conductance was decreased less than the CO(2) assimilation, possibly due to the direct and/or indirect effects of Ag ions on stomatal guard cells. After the plants were transferred from the highest Ag concentration to a nutrient solution, recovery of tobacco, cotton morphology, and physiology were observed.http://link.springer-ny. com/link/service/journals/00244/bibs/37n4p480.html

Physiological and ultrastructural effects of cadmium on wheat (Triticum aestivum L.) leaves.

The effects of a 7-day exposure of 3-day-old wheat plantsto increasing Cd concentrations are described, with special attention beinggiven to chloroplast ultrastructural changes, chlorophyll fluorescenceresponses, chlorophyll and nutrient concentration changes as well as growthchanges of the whole plant. The plants treated with 1 mM Cd showed symptomsof heavy metal toxicity. The root, shoot-leaf length and the root, shoot-leafbiomass progressively decreased with increasing Cd in nutrient solution andin 1 mM of Cd an almost complete inhibition of growth was found. Shoot-leafCd accumulation increased under Cd-treatments, while a Fe, Mg, Ca, and Kdecline in the above ground parts was observed. The growth reduction and theinhibition of chlorophyll content and photosynthesis observed in the upperplant parts seemed principally due to indirect Cd effects on the content ofessential nutrients. Cadmium treatment was shown to damage the structure ofchloroplasts, as manifested by the disturbed shape and the dilation of thethylakoid membranes. These ultrastructural changes suggest that Cd probablyinduced premature senescence.