弱光胁迫影响玉米产量形成的生理机制及调控效应

Physiological mechanism and regulation effect of low light on maize yield formation

在全球气候变化背景下,生育期内光照不足已成为制约玉米产量提高的主要因素之一,增加了全球粮食生产和营养安全的风险。本文从光合性能、养分吸收特性、籽粒形成与灌浆特性等方面系统总结了弱光胁迫影响玉米产量形成的生理机制。弱光降低了叶片捕光能力,基质和基粒类囊体结构解体,相关酶活性降低,光系统受到损伤,碳同化能力降低,进而抑制根系发育,影响根系形态和功能,不利于养分吸收和代谢。由于营养供应不足,雌、雄穗发育受阻,花粉和花丝的形态功能受到影响,导致小花受精率低,穗粒数降低。弱光条件下,胚乳细胞数量——“库”容量降低,胚乳传递细胞结构和功能受到影响,内源激素平衡被打破,蔗糖-淀粉代谢相关酶活性下降,茎节维管束数目和面积减少,物质转运和转化能力降低,导致淀粉充实状态差,粒重降低。因此,为缓解弱光胁迫对玉米产量形成的影响,亟须创建系统评估耐阴品种的指标,利用现代育种技术加快培育出高光效耐阴新品种,采取增施氮肥、去除顶部叶、喷施生长调节剂和叶面肥等栽培措施提高产量。未来研究需要注重根冠协调,深入探讨弱光胁迫的作用机理,为玉米抗逆增产关键技术的创建提供理论依据。

As for global climate change,insufficient light during the growth periods has become one of the main factors restricting maize yield,increasing the risk of global food production and nutritional security.In this study,based on the previous experiments,we explored the physiological mechanism of low light on maize yield formation from the aspects of photosynthetic performance,nutrient absorption characteristics,grain formation,and filling characteristics.Under low light stress,the light harvesting ability of leaves was reduced,the stromal and grana thylakoids disintegrated,the activities of related enzymes were reduced,the photosystem was damaged,and the carbon assimilation ability was reduced,which further inhibited root development,significantly affected root morphology and function,and was not conducive to nutrient absorption and metabolism.Due to the insufficient nutrition supply,the development of tassel and ear was blocked,the morphological function of pollen and filaments was affected,resulting in low flower fertilization rate and decreased grain number per ear.Low light also reduced the number of endosperm cells—“sink”capacity,the structure and function of the endosperm transfer cells were affected,the endogenous hormonal balance was broken,sucrose,starch metabolism related enzyme activity decreased,internodes vascular bundle number and area reduced,transport and transformation ability were limited,eventualy led to the poor state of starch and the decreased grain weight significantly.Therefore,to alleviate the influence of low light stress on maize yield formation,it is urgent to establish indexes for systematic evaluation of shade tolerance varieties,accelerate the cultivation of new shade-tolerant varieties with high light efficiency by modern technology,and adopt cultivation measures such as increasing nitrogen fertilizer application,removing top leaves,spraying growth regulator and foliar fertilizer to improve maize yield.In the future,more attention should focus on root-shoot coordination and deeply explore the mechanism of low light stress,so as to provide the theoretical basis for the establishment of key techniques of maize resistance to yield increase.