Abstract: The influence of soil drought stress on leaf rolling index (LRI) and its relationship with stomatal conductance (SC), transpiration rate (TR), net photosynthetic rate (Pn) and water use efficiency (WUE) were investigated by using 13 rice ( Oryza sativa L.) varieties differing in drought resistance under the condit ion of artificially-controlled soil water. The drought stress in soil was initiated at effective active tillering stage and ended at booting stage by re-irrig ating. Results showed that there were obvious differences among rice varieties in the initial increasing date, increasing rate and maximum value of LRI. Thirteen rice varieties may be classified into three categories, i.e. sensitive ( e.g. Zhonghan 1), intermediate (e.g. Handao 8) and insensitive (e.g. I APAR 9 ), according to the development of LRI in response to soil drought stress. The LRI increased with the soil water stress for all varieties, but there was dramatic difference among varieties in the relationships between LRI and SC, TR, Pn a nd WUE. With the increase of every one scale in LRI, SC in Zhonghan 1, Handao 8 and IAPAR 9 decreased by 0.26, 0.20 and 0.17 mm/s, respectively, and TR decreased by 0.86, 0.66 and 0.49 mmol/(m² ·s), respectively. The LRI resulting in substantial reduction in Pn was much smaller in Zhonghan 1 than that in IAPAR 9 . It also showed that the moderate LRI increased WUE, and the effect of LRI on WUE could be attributed to the change of both Pn and TR for Zhonghan 1, but for IAPAR, only the change of TR was significantly related.

Key words: rice, variety, leaf rolling index, drought stress, transpiration rate, photosynthetic rate, water use efficiency

摘要： 在人工控制土壤水分条件下，以13个具有不同耐旱性的栽培稻品种（组合）为供试材料，研究了在分蘖盛期土壤断水后随着干旱胁迫的加重叶片卷曲度（LRI）的动态变化及其与蒸腾、光合特性和叶片水分利用的关系。结果表明，不同品种的LRI明显增大的起始日期、明显增大期日均增量和最大值存在着显著差异，并依据叶片卷曲表现可将参试品种划分为敏感型（如中旱1号）、中间型（如旱稻8号）和钝感型（如巴西陆稻）三种类型。随着土壤断水后干旱胁迫的加重，LRI逐渐增大。LRI与气孔导度（SC）、蒸腾速率（TR）和净光合速率（Pn）的关系因品种类型而异；LRI每增加1级，中旱1号、旱稻8号和巴西陆稻的SC分别降低0.26、0.20和0.17 mm/s，TR分别降低0.86、0.66和0.49 mmol/(m2·s)；Pn呈显著下降的叶片卷曲度中旱1号明显小于巴西陆稻。当叶片适度卷曲时，WUE随LRI值的增大而提高，中旱1号LRI的变化同时引起TR和Pn显著改变进而影响WUE，而旱稻8号和巴西陆稻LRI变化对WUE的影响主要系TR改变所致。

关键词: 水稻, 品种, 叶片卷曲度, 干旱胁迫, 蒸腾速率, 光合速率, 水分利用效率