• 作者： 楊純明; 陳宗禮; 宋濟民
• 作者服務機構： 國立中興大學糧食作物研究所
• 中文摘要： 本試驗以兩個水稻品種：台中在來一號及OS4為材料，探討葉片水份潛勢與葉片擴散阻力之關係，同時並探求葉片水分潛勢組成份間之關係，以解釋葉片擴散阻力在低水葉片水份潛勢下之反應。 試驗結果顯示供試之品種葉片水份潛勢由-0.7 MPa降至-1.8 MPa時，葉片擴散阻力均顯著增加。由葉片水分潛勢與葉片膨壓潛勢的關係可知品種間有極顯著的差別，二品種之葉片均顯示有部份溶質調節的現象。當膨壓降低至零時之葉片水分潛勢品種間也有顯著的差別。擴散阻力和膨壓間之關係品種間之反應也不一致，台中在來一號一直保持較低的擴散阻力直至膨壓降低至0.3 MPa時，擴散阻力才迅速增加。相反地，OS4在膨壓低於0.7 MPa時，氣孔即開始呈現部份關閉之現象。 由以上資料顯示：僅憑氣孔阻力或溶質調節來做為抗旱評估的標準失之偏頗，若能同時選用二個評估的標準使用則所得的結果將比較可靠。
• 英文摘要： The relationship between leaf diffusive resistance and leaf water potential was evaluated in two rice(Oryze sativa L.) genotypes. The relationship between leaf water potential components was also examinedto help explain the leaf diffusive resistance observations. Leaf diffusive resistances were increased as leafwater potential declined from -0.7 MPa to -1.8 MPa in both genotypes. Genotypic differences were ob-served in the leaf water potential-leaf turgor potential relationships. Concomitant decreases in turgor po-tential were observed with increasing leaf water potentials. However, the rate of decline in turgor potentialwas less than 1.00, indicating the existence of partial osmotic adjustment. Significant difference was appa-rent in the leaf water potential calculated to result in zero turgor potential. The diffusive resistance-turgorpotential relationship was also varied between two genotypes in that genotype Taichung Native 1 maintain-ed low diffusive resistance until turgor potential was 0.3 MPa, at which time resistance changed rapidly. Incontrast, stomatal closure in genotype OS4 was initiated when turgor potential dropped below 0.7 MPa.The present data reveal that the evaluation of drought tolerance basing solely on stomatal resistance orosmotic adjustment must be conducted with caution. Ideally, a program employing both criteria would bebeneficial.
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