臭氧對水稻不同品種葉片為害之比較

Differentiating the Injury of Ozone on Leaves of Different Rice Cultivars

"面對全球環境變遷，對流層臭氧（tropospheric ozone）濃度增加的程度對作物生育所造成的影響是最被關注的空氣污染問題之一，不同於平流層的臭氧層，對流層的臭氧屬於光化污染物（或稱為二次污染物），其形成主要是人為活動（如工業生產及交通運輸等）所產生的臭氧前驅物在陽光照射下經一連串光化反應而產生，這些前驅物包括氮氧化物（NOx）、一氧化碳（CO）、二氧化硫（SO2）及部分揮發性有機物（VOCs）等。因此空氣中臭氧前驅物的濃度、日照強弱及時間、氣溫、空氣濕度等氣候因子都會影響對流層臭氧濃度的高低。臭氧分子會受風向、氣流及氣艇影響而飄移擴散，一旦發生臭氧為害，容易導致跨區域性的大面積作物受害。根據APCEN （Air Pollution Crop Effect Network）評估資料顯示，包括泰國、印尼、菲律賓、緬甸等亞洲地區水稻生產國皆出現可能導致作物受害的臭氧濃度紀錄；環保署空氣品質監測資料顯示，目前臺灣地區的臭氧成為影響污染指標（Pollutant standards Index, PSI）值的天數有逐年增加的趨勢，比較環保署1999年至2010年之10月份中彰雲嘉4縣市空氣品質監測站的臭氧濃度，其平均值也呈逐年上升的趨勢，雲嘉地區尤為明顯回。2010年10月雲林縣元長、褒忠、虎尾、麥寮等地種植之台南14號落花生葉片出現異常受害情形，徵狀主要出現在植株第4-7節葉片上表皮葉脈兩側之葉肉組織，嚴重受害之葉片出現燒焦枯褐，枯褐面積比例達葉片面積之30-85 %，更甚者葉片捲曲落葉，其他受害徵狀包括葉片出現褪色黃化、黃白色細斑及壞疸斑塊等，經鏡檢及模擬燻氣試驗結果顯示，應與臭氧為害有關。雖然目前我國尚無臭氧為害水稻的相關田間報告，但在彰化部分地區種植之水稻葉片所觀察到的紅褐色細斑徵狀可能與臭氧有所關連，由於水稻是我國最重要的糧食作物，本文針對重要的良質米之水稻品種進行臭氧模擬燻氣試驗，評估臭氧對不同品種水稻葉片之為害情形，亦可作為因應臭氧濃度逐漸升高的趨勢下水稻適栽性品種挑選之參考。"

"The increase of tropospheric ozone concentration affecting the yields of numerous crops was noticed during the last decades. In this study, two O3-treated experiments were conducted in open-top chambers to evaluate the ozone sensitivity of rice cultivars. First, fifteen 42-day-old rice cultivars, including 13japonica cultivars and 2 indica cultivars, were exposed to O3 (120.6 ± 22.7 ppb) for 7 h per day for 10 days. Secondly, these fifteen rice cultivars at 56 days old were exposed to O3(134.8 ± 19.4 ppb) for 7 h per day for 10 days. After ozone exposure, visible leaf injury was quantified by recording a leaf bronzing score (LBS) to evaluate the ozone sensitivity of these tested rice cultivars. Results showed that the japonica cultivars, Kaohsiung 145 and Taikeng 11, were the most tolerant, and both the indica cultivars, Taichung Sen 10 and Taichung Sen 17, were the most sensitive to ozone. The shoot dry weights of rice cultivars Taikeng 2, Taikeng 9, and Taikeng 11 were significantly decreased after O3 exposure; however, the root dry weight of Tainung 71 was significantly increased. The resulting visible leaf injuries did not coincide with the results of dry weights in the tested rice cultivars, suggesting that the short-term O3 treatment can induce leaf injuries of rice but it is not the only factor affecting the biomass of rice."