Shizue Matsubara

1 Introduction The stimulus–response1 relationship is a fundamental concept in biology, characterizing the extent to which an organism responds to the strength, duration, or dose of a stimulus (Calabrese and Baldwin 2003; Mattson 2008; Pinheiro and Duffull 2009). In plant research, this concept is commonly applied to assess optimal growth conditions or plant resistance to stress (Berry and Bjorkman 1980; Idso and Idso 1994; Lee et al. 2007; Dusenge et al. 2019).

Abstract The rate of net CO2 uptake is proportional to dim light and saturates when the light exceeds the plant assimilation capacity. This simple relationship between constant light and photosynthesis becomes intriguingly complex when the light oscillates. The rates of photosynthesis may differ between the descending and ascending phases of light oscillation.

AET alternative electron transport AL actinic light CET cyclic electron transport Chl chlorophyll ChlF chlorophyll fluorescence Cyt b6/f cytochrome b6f complex Fd Red apparent relative reduction of ferredoxin Fd ferredoxin Fd−m maximum reduction of ferredoxin NDH-like chloroplast NAD(P)H dehydrogenase-like complex NIR near-infrared light NPQ nonphotochemical quenching.