Shade stress on maize seedlings biomass production and photosynthetic traits

Abstract

The responses of two maize (Zea mays L.) cultivars, ‘LY336’ (shade tolerant) and ‘LC803’ (shade sensitive), to shade stress in a pot experiment conducted in the 2015 and 2016 growing seasons were investigated. The impact of 50% shade stress treatment on shoot biomass, photosynthetic parameters, chlorophyll fluorescence, and malondialdehyde (MDA) content was evaluated. The shoot biomass of the two maize hybrids was decreased significantly by shade stress treatment, for shade stress 7 d, the LC803 and LY336 were reduced by 56.7% and 44.4% compared with natural light. Chlorophyll fluorescence parameters of LY336 were not significantly affected by shade stress, whereas those of LC803 were significantly affected, the Fo increased under shade stress; however Fm, FV/FM and ΦPSII were decreased under shade stress. Among photosynthetic parameters measured, net photosynthetic rate (Pn), stomatal conductance (Gs), and transpiration rate were significantly decreased compared with natural light, LY336 and LC803 reduction by 28.0%, 22.2%, 57.7% and 35.5%, 18.9%, 62.4%; however, intercellular CO2 concentration (Ci) was significantly increased, for the two cultivars. Under shade stress for different durations (1, 3, 5, 7 d), Pn, Gs, Ci, and MDA content differed significantly between the two cultivars. Results indicated that different maize genotypes showed different responses to shading. Shade-tolerant genotypes are only weakly affected by shade stress.

Responses of the photosynthetic characteristics of summer maize to shading stress

“…Shading induces a series of physiological and biochemical changes in plant photosynthesis, which leads to reduced leaf growth rate (Li, Luan, et al, 2005; Ren et al, 2016; Schulz et al, 2018; Takayuki & Osamu, 2019; Wang et al, 2009; Yuan et al, 2012; Zhang et al, 2007), changes in carbohydrate metabolism (Chen, Chen, et al, 2020; Takayuki & Osamu, 2019; Zhang et al, 2007), and significantly reduced yield. Previous studies have measured the changes of chlorophyll fluorescence parameters under shading stress by FMS‐2 instruments, such as Fv/Fm (the PSII photochemical efficiency), ΦPSII (the PSII actual photochemical efficiency) and ETR (electron transfer efficiency), indicating that shading stress restricts the electron supply of photosynthetic carbon metabolism (Wang et al, 2017; Yuan et al, 2022; Zhang et al, 2019). As a non‐invasive spectroscopic technique, chlorophyll a fluorescence OJIP transient curve and JIP test parameters can reflect the changes of electron transfer states between the two systems (Govindje, 1995).…”

“…The hypotheses of this research take into the negative interference that shading changed several metabolic processes, including restricted the photosynthetic carbon metabolism (Chen, Chen, et al, 2020; Takayuki & Osamu, 2019; Wang et al, 2017; Yuan et al, 2022; Zhang et al, 2007, 2019). Therefore, on the basis of previous research results, we want to explore the effect of low light stress on dark response from the aspects of electron transport process and stomatal characteristics, and whether the change of photosynthetic pigment content is a strategy to adapt to low light.…”