Suzan A. Sayed

Effects of lead and kinetin on the growth, and some physiological components of safflower

Pollution of the root environment with excess of Pb retarded shoot growth, decreased chlorophyll (Chl) content and reduced Chl stability (CSI) to heat. Plants growing in Pb polluted soil accumulated much more free amino acids and less soluble sugars than the control plants. Stability of leaf membranes to heat (51 °C) or dehydration stresses (40% polyethylene glycol, 6000) decreased in response to Pb pollution where the membranes of leaf discs excised from Pb-treated plants were damaged more than those taken from plants growing in Pb free soil. Supplying kinetin ameliorated the deleterious effects of Pb pollution on the parameters tested. Kinetin-treated plants had higher Chl, soluble sugars content and produced more biomass in their shoots. Also, kinetin increased leaf membrane stability especially in Pb-treated plants, effectively protected chlorophyll degradation by heat and increased Chl a and b stability index; the most effective concentration was 10 mg L−1. The effects of Pb and kinetin as well as their interaction (Pb × Kin) on the parameters tested were statistically significant. Applied kinetin had a dominant role (as indicated by η2) in affecting shoot growth, soluble sugars, Chl a and b contents, stability of leaf membranes to dehydration stress as well as the Chl stability index. Pb had a dominant role on total free amino acids (TAA) and leaf relative water content (RWC). The interaction between Kin × Pb influenced the stability of leaf membranes to heat stress in a major way.

Effects of shoot and root application of thiamin on salt-stressed sunflower plants

Plants of sunflower (Helianthus annuus L. cv Giza2) were salt-stressed with a combination of NaCl and CaCl2 inconcentrations having different osmotic potentials (ψs from 0 to −1.0MPa) and were treated with 5 and 10mg L−1 of thiamin either sprayed on the shoot orapplied to the root. The membranes of leaf discs from salt-stressed plantsappeared to be less stable (more injured) under heat(51 °C) and drought (40% polyethylene glycol6000) stresses than control plants. Salinity slowed the rate of growth (lengthand dry mass production), lowered leaf relative water content (RWC) and leafandroot water potential (ψw), decreased the contents of chlorophyll (Chl),soluble sugars (SS) and the K+/Na+ ratio butenhanced total free amino acids (TAA), Na+,Ca2+and Cl− accumulation in the shoot and root system. Root orshoot application of thiamin reduced membrane injury by either heat ordehydration stress, lowered leaf ψw, improved uptake of K+,and increased leaf RWC, Chl, SS, TAA contents and dry mass production. Theeffects of salinity (ψs), thiamin (Thi.) and their interaction(ψs × Thi) on the parameters tested were significant.Salinity was dominant (as indicated by η2 values) in affectingthe contents of Ca2+, Cl−, TAA and membranestability to heat and leaf ψw. The role of thiamin was dominant forNa+, K+ and SS contents and the contribution ofinteraction was dominant for growth parameters, Chl. and root ψw.

Effects of silicon on Zea mays plants exposed to water and oxygen deficiency

Effects of shoot and root supplementation with silicon on the response of Zea mays L. plants to matric water potential (Ψm) and oxygen deficiency (waterlogging) stresses were studied. The soil water limitation (Ψm) and oxygen deprivation significantly reduced shoot dry weight, chlorophyll (Chl) content, ascorbic acid content, as well as leaf relative water content. Both soil drying and waterlogging caused a significant increase in the leaf membrane injury by heat (51°C) and dehydration (40% PEG) stresses. The levels of lipid peroxidation (POL) and hydrogen peroxide (H2O2) content were increased by excess soil drying and oxygen deficiency. Supplementary silicon at 1.0 mM significantly increased Chl content and improved water status. Concentrations of H2O2, MDA, and proline and leaf membrane injury were significantly reduced by Si application. The reverse helds true for ascorbic acid. The results of this study indicate that application of silicon might improve growth attributes, effectively mitigate the adverse effect of drought and waterlogging, and increase tolerance of maize plants. The silicon-induced improvement of drought and anoxia tolerance was associated with the increase in oxidative defense abilities.

Impacts of boron application on maize plants growing under flooded and unflooded conditions

Plants of maize (Zea mays L.) were waterlogged for 7 d and irrigated (root application) or sprayed (foliar application) with 0, 1, 3 and 6 mg dm-3 of boron. The stability of leaf membranes was assessed by determining leakage of electrolytes from leaf discs exposed to heat (51 °C) and dehydration (40 % PEG). Leaf membranes were more stable to heat than to dehydration. The membranes of waterlogged plants were more injured than those of control plants. Waterlogging reduced contents of dry mass, chlorophyll, soluble proteins, total free amino acids and soluble sugars and leaf relative water content (RWC). Application of boron increased the stability of leaf membranes, chlorophyll, soluble sugars, soluble proteins, amino acids contents, leaf RWC and dry mass accumulation. Foliar boron application was more effective. Application of boron alleviated the deleterious effect of waterlogging.

Kinetics of corrosion inhibition of aluminum in acidic media by water-soluble natural polymeric chondroitin-4-sulfate as anionic polyelectrolyte inhibitor

Corrosion inhibition of aluminum (Al) in hydrochloric acid by anionic polyelectrolyte chondroitin-4-sulfate (CS) polysaccharide has been studied using both gasometrical and weight-loss techniques. The results drawn from these two techniques are comparable and exhibit negligible differences. The inhibition efficiency was found to increase with increasing the inhibitor concentration and decreased with increasing temperature. The inhibition action of CS on Al metal surface was found to obey both of Langmuir and Freundlich isotherms. The factors affecting the corrosion rates such as the concentration and geometrical structure of the inhibitor, concentration of the corrosive medium, and the temperature were examined. The kinetic parameters were evaluated and a suitable corrosion mechanism consistent with the results obtained is discussed.