International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines.
J Plant Physiol. 2010 Sep 1;167(13):1066-75. doi: 10.1016/j.jplph.2010.03.003. Epub 2010 Apr 13.
Leaf growth is one of the first physiological processes affected by changes in plant water status under drought. A decrease in leaf expansion rate usually precedes any reduction in stomatal conductance or photosynthesis. Changes in leaf size and stomatal opening are potential adaptive mechanisms, which may help avoid drought by reducing transpiration rate, and can be used to improve rice genotypes in water-saving cultivation. The indica rice cultivar IR64 and four of its near-isogenic lines (NILs; BC(3)-derived lines) unique for leaf size traits, YTK 124 (long leaves), YTK 127 (broad leaves), YTK 205 (short leaves) and YTK 214 (narrow leaves), were compared in this study for changes in leaf growth and its water status. The plants were subjected to two soil water regimes, well-watered and progressive soil drying measured by the fraction of transpirable soil water (FTSW). Applied drought reduced leaf number, total leaf area, specific leaf area, plant biomass, tiller number, plant height, stomatal conductance, amount of water transpired, leaf relative water content, and leaf water potential more in IR64 and the NILs than in the respective controls; nonetheless, transpiration efficiency (TE) was slightly higher under drought than in the well-watered controls. NILs with broader leaves had higher biomass (and its individual components), less stomatal conductance, and higher TE under drought than NILs with narrow and shorter leaves. Under drought, leaf number was positively correlated with tiller number and plant height; nonetheless, root weight and total biomass, water transpired and TE, and plant height and TE were positively correlated with each other. However, a negative correlation was observed between stomatal conductance and the FTSW threshold at which normalized transpiration started to decline during soil drying. Overall, the IR64-derived lines with broader leaves performed better than NILs with narrow and short leaves under drought.
叶片生长是植物在干旱条件下,受到水分状态变化影响的最早的生理过程之一。叶片扩展速度的下降通常先于气孔导度或光合作用的降低。叶片大小和气孔开度的变化是潜在的适应机制,可通过降低蒸腾速率来帮助避免干旱,并可用于在节水栽培中改良水稻基因型。本研究比较了籼稻品种 IR64 及其 4 个近等基因系(BC(3)衍生系)在叶片大小性状上的差异,即 YTK 124(长叶)、YTK 127(阔叶)、YTK 205(短叶)和 YTK 214(窄叶),在叶片生长及其水分状况方面的变化。将这些植株置于两种土壤水分条件下进行处理,即充分供水和通过可蒸腾土壤水分分数(FTSW)进行的渐进土壤干燥。与各自的对照相比,干旱处理减少了叶片数量、总叶面积、比叶面积、植株生物量、分蘖数、株高、气孔导度、蒸腾量、叶片相对含水量和叶片水势,但干旱下的蒸腾效率(TE)略高于充分供水对照。在干旱条件下,与窄叶和短叶的近等基因系相比,阔叶近等基因系具有更高的生物量(及其各个组成部分)、较低的气孔导度和较高的 TE。在干旱条件下,叶片数量与分蘖数和株高呈正相关;然而,根重和总生物量、蒸腾量和 TE、株高和 TE 彼此之间呈正相关。然而,在土壤干燥过程中,归一化蒸腾开始下降时,气孔导度与 FTSW 阈值呈负相关。总体而言,在干旱条件下,具有较宽叶片的 IR64 衍生系比具有窄叶和短叶的近等基因系表现更好。