弱光和淹水胁迫对青贮玉米根系生理活性、产量和品质的调控研究

Developing silage maize plant area in order to adjust crop cultivation construction is the key strategy for China. Solar total radiation reduction and precipitation increase are the tendency for climate change, which become research focus for maize yield and quality formation regulation. Currently, there are many studies fouced on grain maize root physiological activity, grain yied and quality formation affected by low irradiance and waterlogging, and which the regulation physiological mechanism has been definited. But, if the regulation physiological mechanism for grain maize can be applied to silage maize, which always havest at grain late milk stage or early dough stage, were not definited. There were little researches foucsed on low irradiance stress, waterlogging stress and double stress effect silage maize root physiological activity, grain yied and quality formation, and so the regulation physiological mechanism were not definited. Therefore, the applicant set low irradiance stress, waterlogging stress and double stress from V6 stage to VT stage and form VT stage to harvest stage, in order to study the stress affect on silage maize root morphology, root physiological activity, photosynthate accumulation pattern among stem, leaves and grain, and silage quality, e.g., crude starch contents and varieties , crude protein contents , crude fiber contents and digestibility, ADF and NDF contents, and so on. So, we can build the silage maize and stress responsed model. Inilluminate the physiological mechanism which low irradiance stress, waterlogging stress and double stress effected on silage maize yield and silage quality. The reseults of our study will provide theoretic basis for exploring a new way to regulate silage maize high yield and superior silage quality under low irradiance stress, waterlogging stress and double stress.

发展青贮玉米是调整种植业结构的国家重点战略，太阳总辐射减少与降水量增加的气候变化趋势，成为调控玉米产量和品质形成的研究重点。目前，弱光和淹水胁迫对籽粒玉米根系生理活性、产量和品质形成过程的影响研究较多，其调控生理机制已经明确。但该生理机制在青贮玉米乳熟末期收获、注重青贮品质的情景下是否适用尚不明确；弱光、淹水单一或双重胁迫对青贮玉米根系生理活性、产量和品质形成过程的调控效应缺乏深入研究，调控生理机制并不明确。为此，申请者在穗期和花粒期设置弱光、淹水单一胁迫和双重胁迫情景，研究青贮玉米根系形态、生理学特性、器官间同化物积累规律、青贮品质（粗淀粉、粗蛋白、粗纤维、酸性洗涤纤维、中性洗涤纤维）对胁迫的响应过程，构建青贮玉米对胁迫的响应模型，阐明弱光、淹水单一或双重胁迫对青贮玉米产量和品质形成过程中的调控效应及其生理学机制，为探索弱光和淹水胁迫下青贮玉米产量和品质协同提升的调控新途径提供理论基础。

弱光和淹水胁迫导致青贮玉米在生长发育过程受阻，产量和品质及其茎节抗逆性显著减弱。本研究通过弱光胁迫和淹水胁迫不同抗性青贮玉米品种筛选，得到大京九26和京科青贮301 2个具有典型品种，研究弱光胁迫时期和强度，淹水胁迫时期与持续期对青贮玉米产量和品质、茎节发育与抗逆性和根系活性。研究结果表明，茎节发育关键期（V12-VT期）弱光胁迫导致青贮玉米地上部第3-6节间发育不良，茎节抗倒伏能力降低，在抽雄期至灌浆期均有倒伏风险产量降低49.8%-79.2%，抽雄后弱光胁迫青贮产量降低9.6%~ 34.4%。弱光胁迫导致青贮玉米根系活力降低17.2%~35.1%，胁迫强度增强根系活力降低3.81%~37.81%，进而导致导致青贮玉米品质显著降低，青贮玉米牛奶生产力降低10.6%~25.3%。淹水胁迫后青贮玉米叶面积和叶片SPAD值显著下降，且随淹水持续期的延长降幅越大，进而抑制了干物质积累。淹水胁迫影响茎节发育，淹水导致茎节发育缩短，茎粗变细，抗逆性降低，根系鲜重和干重降低。淹水胁迫可显著降低青贮玉米产量15.31%~58.43%，胁迫时间延长产量将降低更显著。大口期淹水胁迫对青贮玉米品质影响最显著，抽雄期影响次之，小口期淹水影响最小。