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Anti-oxidative defense systems in wheat plants were studied as a function of zinc deficiency in solution culture under glasshouse conditions. Zinc (Zn) deficiency enhanced cyanide-insensitive superoxide dismutase activity significantly, and decreased the activity of cyanide-sensitive superoxide dismutase before the appearance of visible effects of Zn deficiency. The plants with incipient deficiency of Zn also had significantly higher activities of nonspecific peroxidase, ascorbate peroxidase, and glutathione reductase. There was an increase in the concentrations of malondialdehyde, H2O2, dehydroascorbate, glutathione-sulfhydryl, and glutathione-disulphide, and the ratios carotenoids/chlorophyll, dehydroascorbate/ascorbate, and glutathione-sulfhydryl/glutathione-disulphide. As the effects of Zn deficiency became more severe, there was greater accumulation of malondialdehyde and H2O2, and the activities superoxide dismutase, peroxidase, ascorbate peroxidase, and glutathione reductase declined, part...

Maize (Zea mays L.) plants subjected to severe deficiency of boron (0.0026 ppm B) failed to produce tassels with functional flowers. In plants subjected to moderate deficiency of boron (0.013 ppm B), emergence of tassels and anthesis was suppressed and delayed. In a large percentage of boron deficient plants the stamens lacked sporogenous tissue and appeared as staminodes or floral appendages that either lacked or had branched vascular supply. The apparently normal stamens of these plants also failed to dehisce and showed a marked decrease in pollen producing capacity, pollen size and pollen germination. Even in plants that were only marginally deficient in boron (0.066 ppm B), without any foliar symptoms of boron deficiency, pollen grains showed poor germination and changes in enzyme activities. Pollen grains of such plants had low activities of catalase, acid phosphatase, starch phosphorylase and invertase and high activities of ribonuclease and amylase.

Sand culture studies using cauliflower as the test plant revealed changes in water relations of plants subjected to deficiencies of Fe, Cu, Zn and B. While deficiencies of Zn and B caused a decrease in water potential, transpiration rate and water loss, deficiencies of Fe and Cu caused an increase in each of these. Observed changes in water relations have been examined in terms of changes in leaf morphology and metabolism.