水分胁迫对糜子物质生产及光合特性的影响

Effects of water stress on matter production and photosynthesis characteristics of broomcorn millet (Panicum miliaceum L.)

【目的】研究水分胁迫对糜子物质生产及光合特性的影响,为糜子抗旱节水栽培和水分高效利用提供理论依据。【方法】以榆糜2号为材料,采用盆栽试验,以充足供水（占田间最大持水量的65%~70%）为对照,分别在糜子全生育期及拔节前、后进行中度（占田间最大持水量的35%~40%）、重度（占田间最大持水量的15%~20%）水分胁迫,分别于播种后不同时期采样测定干物质、顶三叶叶面积、旗叶光合参数,并在成熟期测定穗部性状和籽粒产量。【结果】（1）与对照相比,全生育期重度及拔节后中度和重度水分胁迫显著降低了糜子成熟期地上部干物质积累量。拔节前水分胁迫增加干物质向叶片和茎的分配,减少向根的分配,但拔节后水分胁迫却减少干物质向穗、叶的分配,增加向根的分配。（2）全生育期和拔节后重度水分胁迫显著降低了糜子穗粒质量,拔节前中度水分胁迫显著增加了穗粒数,其他处理对糜子穗粒质量、穗粒数和千粒质量无显著影响。（3）水分胁迫降低了糜子顶三叶叶面积及旗叶净光合速率,且随着胁迫程度的加剧,降低幅度增大,但恢复供水后,糜子顶三叶叶面积会受激发而继续增大,其净光合速率会逐渐恢复正常。【结论】全生育期和拔节后重度水分胁迫会降低糜子产量、叶面积、地上部干物质积累量和旗叶净光合速率,而拔节前水分亏缺对糜子干物质积累及产量的影响可以通过拔节后恢复水分供应得以补偿。

[Objective] Effects of water stress on dry matter production and photosynthetic characteris- tics of broomcorn millet （Panicum miliaceum L. ） were studied to improve the water saving farming of broomcorn millet and water use efficiency. [Method] Using Yumi 2 as study species, pot experiments were conducted under three water levels： adequate water supply （65%--70% of field capacity,CK）, moderate water stress （35%--40% of field capacity） and severe water stress （15%--20% of field capacity） during the whole growth period, before and after jointing stage, respectively. Dry matter content,area of top three leaves, and photosynthetic parameters of flag leaf were measured after sowing, and spike traits and yield were measured during mature period. [Result] （1） Compared with CK, severe water stress through the whole growth period,and moderate and severe water stress after jointing stage reduced the dry matter accumulation （maturation period） significantly. Water stress before iointing stage increased dry matter allo- cation to leaves and stems while reduced the allocation to roots. Water stress after jointing stage decreased dry matter allocation to spikes and leaves while increased the allocation to roots. （2） Severe water stress for whole growth period and after jointing stage reduced grain weight significantly. Moderate water stress be- fore jointing stage increased the grain number significantly. Other treatments had no significantly effects on grain weight,grain number and 1 000-seeds weight. （3） Water stress reduced leaf area of the top three leav- es and net photosynthetic rate of flag leaf, and the amplitude increased as the increase of the stress level. However, the leaf area increased continually, and the net photosynthetic rate returned to normal gradually after water supply was restored. [Conclusion：] Severe water stress for whole growth period and after joint- ing stage decreased the leaf area,dry matter accumulation,net photosynthetic rate of flag leaf and yield of broomcorn millet, while the losses of dry matter and yield caused by water stress before jointing stage could be compensated by the recovery of water supply after jointing stage.