光是影响植物生长发育重要的环境因子之一。随着全球气候的异常, 水稻生育期内阴雨寡照天气增多, 太阳辐照减少, 弱光会对水稻生长发育产生不利影响。本文综述了国内外有关弱光对水稻营养生长、避阴反应、光合作用特性、产量形成和品质等方面的影响。水稻营养生长的各个方面都受弱光影响, 包括株高、分蘖、根系、叶片及其气孔和叶绿素等的发育。最重要的是弱光通过影响光合作用, 进而影响干物质积累与分配, 从而导致水稻产量和品质降低。光不仅为植物光合作用提供能量, 还是一种信号物质, 植物通过光受体感受光环境包括光质、光强和光向等的变化来调控自身形态建成。遮阴同样能导致弱光。遮阴后, 植物光敏色素感受到环境中红光和远红光比例的变化, 从而引起株高增加、节间伸长、分枝减少和加速开花等一系列反应, 这些称为避阴反应。本文探讨了在弱光对作物生长发育影响的研究中使用不同遮阴材质对光质的影响。目前水稻避阴反应研究较少, 本文讨论了水稻光敏色素基因及拟南芥中鉴定的与光信号相关的转录因子可能在水稻生产中的应用。对水稻在生育期内遇弱光环境时提出了相应的防治对策, 并分析了当前研究中存在的问题和不足, 指出了今后进一步研究的方向。
Light is an important environmental factor for healthy growth and development of plants. Global warming has increased the occurrence of overcast, rainy and low light intensity. Light stress has been known to adversely affect shade tolerance, healthy growth and development of rice. This paper reviewed research progress on the impact of low light stress on photosynthesis, vegetative growth, yield and quality of rice. Several studied noted that low light stress affected every aspect of vegetative growth (plant height, tiller number, root growth, stoma regulation and chlorophyll development), photosynthesis, dry matter accumulation and partition, and yield and quality of rice. Light not only provided energy for photosynthesis but was also a signal for photomorphogenes. Plant light receptors sensed changes in ambient light signal (including light quantity/fluoresce, quality/wavelength, direction and duration) which correspondingly regulated photomorphogens. Shades induced low light stress in crops. Plant phytochromes detected changes of red/far-red light ratio under shade conditions, leading to a series of changes in morphological traits. These so called shade-avoidance syndrome included accelerated elongation of hypocotyls, internodes and petioles, upward leaf movement (hyponasty), and accelerated flowering and apical dominance. However, shade tolerance lacked classical shade-avoidance syndrome. It also increased specific leaf area, photosystem (PSII︰PSI) ratio, reduced chlorophyll a/b ratio and increased physical defense. There was less research on shade-avoidance syndrome and shade tolerance of rice. The review further discussed how different shade materials affected light quality (wavelength), and how shade-avoidance syndrome was reduced by using rice phytochrome genes and light signal-related transcription factor genes identified in Arabidopsis thaliana. Countermeasures were then suggested to relieve low light stress during rice growth. The problems and prospects of future research in this field were also discussed.