We carried out the effect of Si levels (0.5, 1.0 and 2.0 mM) on ethylene and salicylic acid (SA) of hydroponically grown rice plants, after 6h, 12h and 24h of Si application. All samples were analyzed after applying wound stress for 30 minutes. In 6 h treatments, 0.5 and 1.0 mM of Si decreased ethylene production by 7% and 9.9% respectively, while elevated level of Si (2 mM) insignificantly affected ethylene production under same conditions. However 0.5 and 1 mM of Si enhanced endogenous SA contents by 2.6% and 17.3% respectively, while 2 mM of Si decreased SA contents by 3% as compared to control. Samples analyzed after 12h of 0.5, 1 mM and 2 mM Si application showed reduction of 11%, 4% and 1.7% respectively, while SA contents increased by 4% and 9.5% in 0.5 and 1 mM Si treatments. Samples analyzed after 24 h of Si treatment showed that 0.5 and 1.0 mM of Si inhibited ethylene production by 12.6% and 18.2% respectively, while 2 mM Si increased ethylene production by 11.9% as compared to control. It was observed that the SA content of rice was almost similar to control in 0.5 mM Si applied treatments, while 1 mM and 2 mM of Si increased SA contents by 6.5% and 6.9% as compared to control. It was concluded that Si alleviates the effect of wounding stress in rice by regulating ethylene and SA production.

The effect of salicylic acid(SA) on antioxidant system and protective mechanisms against UV-B induced oxidative stress was investigated in cucumber(Cucumis sativus L.) leaves. UV-B radiation and SA were applied separately or in combination to first leaves of cucumber seedlings, and dry matter accumulation, lipid peroxidation and activities of antioxidant enzymes were measured in both dose and time-dependant manner. UV-B exposure showed reduced levels of fresh weight and dry matter production, whereas SA treatment significantly increased them. SA noticeably recovered the UV-B induced inhibition of biomass production. UV-B stress also affected lipid peroxidation and antioxidant enzyme defense system. Malondialdehyde(MDA), a product of lipid peroxidation, was greatly increased under UV-B stress, showing a significant enhancement of a secondary metabolites, which may have antioxidative properties in cucumber leaves exposed to UV-B radiation. Combined application of UV-B and SA caused a moderate increase in lipid peroxidation. These results suggest that SA may mediate protection against oxidative stress. UV-B exposure significantly increased SOD, APX, and GR activity compared with untreated control plants. Those plants treated with 1.0 mM SA showed a similar pattern of changes in activities of antioxidant enzymes. SA-mediated induction of antioxidant enzyme activity may involve a protective accumulation of H2O2 against UV-B stress. Moreover, their activities were stimulated with a greater increase by UV-B+SA treatment. The UV-B+SA plants always presented higher values than UV-B and SA plants, considering the adverse effects of UV-B on the antioxidant cell system. ABA and JA, second messengers in signaling in response to stresses, showed similar mode of action in UV-B stress, supporting that they may be important in acquired stress tolerance. Based on these results, it can be suggested that SA may participates in the induction of protective mechanisms involved in tolerance to UV-B induced oxidative stress.

우수한 자생식물자원인 산국의 수량과 유효성분을 높이기 위해 식물생장조절제 ABA와 SA를 처리한 결과를 요약하면 다음과 같다. 1. 꽃의 건물수량은 ABA, SA과 ABA+SA 처리구에서 무처리구보다 증가되었으며, ABA 처리구보다는 SA 처리구가 증수되었다. 2. 무기성분의 함량변화는 SA 처리구가 다른 처리구들에 비하여 질소, 인산, 마그네슘의 함량이 증가하였으나 칼륨의 흡수는 오히려 감소하였다. 3. 아미노산함량은 SA 처리구와 ABA+SA 처리구는 ABA 처리구보다 높았다. 4. 생장조절제처리는 정유함량을 증가시켰으며, 그 반응은 monoterpenoid계 화합물보다는 sesquiterpennoid계 화합물에서 더 민감하였다. 5. Cumambrin A의 함량은 ABA 처리구에서 증가하였고, SA 처리구에서는 차이가 없었다.

Some morphological character were surveyed and PR-proteinases were induced and characterized from Lilium formosanum Wallace endeimc to Cheju island . Its flower characters were similar to those of white trumpet lilies(Lilium longiflorum Thunb) although its flowering period was later than that of white trumpet lilies and it hadd a wide range of variation among individuals. Six PR-proteinases(II-2, III-1, III-2, IV-1, IV-2 and V) were induced from bulbs by 2.5mM salicylic acid and almost excreted into the intercellular spaces. These PR-proteinases were strongly activated by Ca 2+, , whereas they were strongly inhibited by Cu2+ Co2+ and Fe2+ . Three PR proteinases(II-2, IV-1 and IV-2) were strongly inhibited by 1, 10 -phenanthroline, indicating that these enzymes are metallo-proteinases. Three PR-proteinases(III-1, III-2 and V) had a high sensitivity to PMSF and required β-mercaptoethanol for their activities. These results indicate that these proteinases are cysteine proteinases.

ABA and SA showed different effect on stomatal closing on same condition. The addition of 1 mM salicylic acid to fully opened stomata resulted in a significant reductionn of 22 % in stomatal aperture. However, 1 mM ABA reduced 73 % of stomatal aperture. The light absorption spectra of the salicylic acid solution showed that SA was degraded within 1 hour. Therefore, SA solution was resupplied to the detached epidermis every 30 min. during incubation and it was found that even at 10 μM SA induced stomatal closing significantly. Its effect was also greatly pH dependent. The reduction of stomatal aperture caused by 1 mM SA was most effective at lower pH (pH 7.2, 5 %; pH 6.2, 40 %; pH 5.2, 78 %). Therefore, if SA was properly treated to the epidermal strips in the medium, the effects of SA on stomatal closing were similar with those of ABA.