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Gamma-and laser-irradiated seeds were grown under drought stress conditions to evaluate the irradiation effects on growth, flowering and some physiological traits of Salvia coccinea plants grown in pots. Pre-sowing gammairradiation at 5, 10, 15, 20 and 25 k.rad or laser irradiation (He-Ne) for 5, 10, 15 and 20 min. exposure time were applied. Soil moisture levels were imposed by irrigating the plants with 100 (control), 80, 60 and 40% of field capacity (F.C.). Results indicated that laser-irradiation was less effective than gamma-irradiation on drought stress. Plants grown under high water stress (40 and 60% F.C.) resulted in significant decreases in all vegetative growth and flowering parameters tested. The decrease in plant growth and flowering quality induced by water deficit was associated with a reduction in leaf relative water content and increases in total phenols, proline and abscisic acid contents in plants. Under water stress, there were significant changes in the activities of the defensive enzymatic system in leaves. The activities of peroxidase and catalase in irradiated plants with gamma or laser were higher at 60% F.C. than in other water stress treatments. In general, it can be concluded that initiated resistance of Salvia coccinea plants under drought stress are enhanced after pre-sowing seed irradiation with gamma at 15-25 k.rad followed by laser for 10 min. exposure time. The most effective combination was gamma-radiation (15-25 k.rad) plus soil moisture content at 80% F.C. This combined treatment protects plants from the deleterious effects of drought. It can tolerate soil water deficit and consume less irrigation water by 30%.

Foliar application effects of salicylic acid (SA) and gibberellic acid (GA 3) were investigated on growth and flowering of Ixora coccinea L. plants. Four concentrations (100, 200, 300 and 400 ppm) of both SA and GA 3 were sprayed in addition to the control (water-sprayed plants). Results indicated that all growth and flowering characteristics of Ixora plants were increased by all concentrations of SA or GA 3 compared to the untreated plants. Concerning salicylic acid, the lowest concentration (100 ppm) produced the highest plants while 200 ppm increased leaf area and shoot/root ratio. Number of leaves and plant pigments (chlorophyll a, b, a+b and carotenoids) were increased at 300ppm concentration. Spraying the plants with 400ppm increased fresh and dry weight of shoots and roots and flower number. GA 3 sprayers at 300 or 400ppm led to a significant increase in most of the characteristics studied in comparison to the untreated plants. The correlation coefficient among most of Ixora vegetative and flowering growth characteristics proved to be significant.

Stem bark aqueous extracts of eight woody plants Brachychiton populneus, Ceiba pentandra, Bombax malabaricum, Chorisia speciosa, Albizia lebbeck, Bauhinia variegata, Kigelia africana and Pinus halepensis were tested for their mutagenic and antimutagenic potential in the Ames test with Salmonella typhimurium strains TA98 and TA100. The aqueous extracts were neither toxic nor mutagenic in S. typhimurium tester strains. All of the tested extracts showed detectable antimutagenic effect towards the direct acting mutagens 2-nitrofluorene (2-NF) in TA98 as well as sodium azide in TA100. The extract from Kigelia africana was the most effective in reducing the mutagenicity caused by the direct mutagen 2-NF in the TA98 with 85.42% inhibition rate. A. lebbeck stem bark extract demonstrated the highest antimutagenic activity reducing the base substitution mutations rate for strain TA100 by 94.66% in pre-incubation assay. The results obtained showed that the stem bark aqueous extracts tested can protect cells against induced gene mutations.

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