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Principles and practices of the photothermal

adaptability improvement in soya bean

By Zhang Li-xin, Liu Wei, Mesfin Tsegaw, Xu Xin, Qi Yan-ping,
Enoch Sapey, Liu Lu-ping, Wu Ting-ting, Sun Shi and Han Tian-fu

lowering plants can respond to Allard, 1923; Borthwick and Parker 1938, be partially or completely relieved by
the relative length of day and 1939). Leaves are photoperiodic signal the continuous LD treatment in soya
night, a phenomenon defined receptors that perceive light signals to bean (Han et al., 1998b; Wu et al., 2006).
as ‘photoperiodism’ (Garner and regulate the reproductive development It was found that the photoperiodic
F Allard, 1920). Soya bean has been of soya bean (Borthwick and Parker, 1938). response also existed in the post-flowering
used as a model plant for photoperiodism The age effect of leaves on flowering stages (Han et al., 1995, 1996; Han and Wang,
studies because of its sensitivity to induction increases with the development 1996). When the soya bean plants were
photoperiod and rich genetic diversity of young leaves until they reach full subjected to LD treatment after flowering,
(Owen, 1927; Heinze et al., 1942; Hendricks, size (Borthwick and Parker, 1940). the number of seeds increased with
1958; Coulter and Hamner, 1964). Furthermore, its perception of the prolonged time of LD treatment (Morandi
Increasing evidence demonstrates length of dark plays a critical role in the et al., 1988; Han, 1996; Kantolic
that photoperiod affects many aspects photoperiod response (Borthwick and and Slafer, 2005; Jiang et al., 2011).
of soya bean growth and development Parker, 1938; Xu et al., 2015). A short However, the photoperiod-sensitive
such as leaf senescence, pod setting, seed exposure to light during night (night break cultivars resume vegetative growth
filling, shoot and root growth, etiolation, (NB)) inhibits growth and flowering in SD with ‘whole plant reversion’ if the
and stress responses besides flowering plants (Thomas and Vince-Prue, 1997). LD is over their critical photoperiod
and maturity (Han et al., 2006; Covington When the light was applied in the middle (Han et al., 1998b; Jiang et al.,2011).
and Harmer, 2007; James et al., 2008; of a dark period, the effect of NB is the Soya beans are planted in a wide
Song et al., 2015; Nico et al., 2016). On largest in soya bean (Xu et al., 2015). range of latitudes across the world,
the other hand, as a thermophilic crop, The effect of SD treatment can be resulting from the rich diversity of
soya bean growth and development are partially or completely relieved by transient variation in flowering and maturity time,
also susceptible to temperature changes light treatment in the process of the dark whereas strict photoperiod sensitivity
(Setiyono et al., 2007). Therefore, responses period, and the effect of light discontinuity limits individual soya bean cultivars in
to both photoperiod and temperature depends on the light quality of the last a special latitudinal boundary (Cober
affect the growth, development, and light (Parker et al., 1946; Han et al., 2006; and Morrison, 2010; Wong et al., 2013).
yield formation of soya bean cultivars. Wu et al., 2006). Red light (650nm) was Large diversity in latitude preference
Understanding the physiological the most effective in inhibiting flower bud results from variations in flowering
characteristics, and molecular mechanisms differentiation, while far-red light (730nm) genes and quantitative trait loci (QTLs)
of photothermal responses will not only was ineffective (Parker et al., 1946). (Watanabe et al., 2012; Wong et al., 2013).
contribute to thorough know-how of Moreover, when soya bean plants The extended photoperiod of high
the varietal differences in the adaptation are subjected to SD treatment after latitudes is suitable for soya bean cultivars
climatic conditions, but will also emergence for some days and then that are less sensitive or insensitive
provide a theoretical basis and valuable transferred to long-day (LD) treatment, to photoperiod because they flower
guidance for germplasm introduction they can form flowers first and then revert and mature relatively early under such
and the breeding of soya bean and to vegetative growth at the terminal conditions (Upadhyay et al., 1994). Vice
other photothermal sensitive crops. shoot apex (Han et al., 1998b; Washburn versa, soya bean cultivars with different
and Thomas, 2000). This phenomenon is maturity groups (MGs) may have different
Photoperiod response in soya bean called ‘reversion of flowering’ (Battey and photoperiodic responses and thus adapt to
Soya bean is a typical short-day (SD) Lyndon, 1990). Jiang et al. (2011) found different day length conditions or latitudes.
plant, and its flowering and maturity are that the effect of LD was a cumulative
strictly regulated by photoperiod (Garner process and increased with the duration Temperature response in soya bean
and Allard, 1920, 1923, 1933; Wang et al., of LD treatment. As the length of LD Soya bean is a thermophilic crop of which
1956). Floral bud initiation of photoperiod- treatment increased, the apical meristem growth and development are affected
sensitive soya bean cultivars can only be could be reversed to produce vegetative by temperature (Gaynor et al., 2011).
induced by SD treatment (Garner and organs. Therefore, the effect of SD can The ambient temperature of soil greatly

10 June 2020