糜子不同品种的光合能力和源库关系类型对产量形成影响的研究

Effects of Photosynthetic Capacity and Source Sink Relationship Types on Yield Formation in Different Broomcorn Millet Varieties

C4糜子(Panicum miliaceum L.)具有较强的抗旱性,在干旱和半干旱地区被广泛种植。不同糜子品种产量形成与其光合作用以及源库关系密切相关。目前关于糜子光合作用和源库关系与其产量变异之间关系的研究仍然缺乏。本研究通过田间试验测定了半干旱地区9个糜子品种的气体交换参数、叶绿素荧光动力学参数、单株叶面积(LA)、干物质量、收获指数(HI)、产量及产量构成因素,研究了不同糜子品种光合作用和源库关系对产量形成的影响。结果表明,高光利用能力(P_(max)较大)的糜子表现出明显的遗传变异,而弱光利用能力(α较小)的糜子则没有。不同品种糜子水分利用效率(WUE和iWUE)与产量表现出显著的正相关性,而单叶净光合速率(Pn)与产量则没有这种相关性,这能够作为糜子品种选育的目标性状。糜子源库关系遗传变异显著,供试品种根据源库关系的差异可以分成源大库小型、源小库大型和源库关系平衡型。具体表现为:源小库大型品种叶光合速率和单株叶面积较低,源限明显,产量较低(如内蒙古红糜子),但光合潜力较大;源大库小型品种虽然叶光合速率和单株叶面积较大,干物质量较大,但HI显著较低,库限明显(如白黍子),产量较低;源库平衡型品种叶光合速率、单株叶面积和HI都较高,具有较好的源库关系,产量明显较高,如靖远中集青糜、宁糜14,而且该类型品种的蒸腾速率和水分利用效率显著高于其他糜子品种。该研究结果将有利于辅助糜子的育种工作。

The broomcorn millet(Panicum miliaceum L.)is widely cultivated in arid and semiarid areas due to better drought tolerance.The yield of different millet cultivars is closely related to photosynthesis and source-sink relationship.Knowledge is still scarce on the relationship between photosynthesis,source-sink relationship and yield in broomcorn millet.A field experi-ment was conducted to measure gas exchange parameters,chlorophyll fluorescence parameters,leaf area per plant,dry matter per plant,harvest index,yield and yield components to examine the response of yield to photosynthesis and source-sink relation-ship in nine broomcorn millet cultivars in semi-arid areas.The results showed that high light utilization ability(Pmax is higher)of millet showed obvious genetic variation,whereas low light utilization ability(αis lower)did not.Water use efficiency(WUE and iWUE)of different cultivars of millet showed significant positive correlation with yield,while net photosynthetic rate per leaf(Pn)had no such correlation with yield,which could be used as a target trait for millet cultivar selection.The genetic varia-tion in source-sink relationship was significant in broomcorn millet,which enabled all the tested cultivars being divided into source-limited cultivars,sink-limited cultivars and cultivars with balanced source-sink relationship.Specifically,source-limited cultivars showed a lower leaf photosynthetic rate and leaf area per plant,resulting in a significant source limitation to yield(i.e.red broomcorn),whereas the photosynthetic potential was higher.Sink-limited cultivars had a higher photosynthesis,leaf area per plant and dry matter per plant,whereas lower harvest index(i.e.white broomcorn),leading to a significant sink limitation in yield for broomcorn millet.The cultivars in a good source-sink relationship had an intermediate photosynthetic rate,leaf area per plant and harvest index,finally resulting in the highest yield,such as Jingyuanzhongjiqing and Ningmei14.They also showed a higher transpiration rate and water use efficiency than other tested cultivars.This study will be beneficial to the breeding of broomcorn millet.