Abstract
ABSTRACTFlower opening time (FOT) is important for reproductive success in higher plants. Rice plants exhibit phenotypic plasticity in FOT in response to environmental factors such as temperature. However, the effect of the concentration of atmospheric CO2 ([CO2]) on FOT has not yet been reported. Elevated [CO2] (E-[CO2]) increases the temperature of panicles, which may in turn advance FOT. We investigated the effect of E-[CO2] on FOT in rice using a free-air CO2 enrichment facility where we increased [CO2] by about 200 μmol mol−1 above the ambient level (A-[CO2]). By photographing panicles at 10-min intervals, we determined 10%FOT and 50%FOT (the time of the day in Japan Standard Time when 10% and 50% of the flowers had opened, respectively). E-[CO2] advanced 10%FOT and 50%FOT by 4 and 5 min at the 10% and 5% levels of significance, respectively. Daily mean air temperature (Ta), solar radiation, and vapor-pressure deficit were negatively correlated with 50%FOT. Regression line slopes for Ta versus 10%FOT and 50%FOT were slightly steeper for A-[CO2] than those for E-[CO2]. Our results suggest that the most probable reason why E-[CO2] advanced FOT is an increase in panicle temperature arising from a reduction in leaf stomatal conductance.Abbreviations: 10%FOT: the time of the day in Japan Standard Time when 10% of the flowers had opened; 50%FOT: the time of the day in Japan Standard Time when 50% of the flowers had opened; A-[CO2]: ambient CO2; [CO2]: the concentration of atmospheric carbon dioxide; E-[CO2]: elevated [CO2]; FACE: free-air CO2 enrichment; FOT: flower opening time; JST: Japan Standard Time; RH: relative humidity; Rs: solar radiation; Ta: air temperature; Tp: panicle temperature; VPD: vapor-pressure deficit
Highlights
The success of pollination or fertilization is largely determined by the flower opening time (FOT) in plants and angiosperms are evolved to optimize reproductive success at a minimal cost by optimizing their FOT
E-[CO2] significantly advanced 10%FOT and 50%FOT by 4 and 5 min at the 10% and 5% levels of significance, respectively (Table 3). These results indicate that increasing [CO2] by about 200 μmol mol−1 in the open field advanced FOT, the time difference between E-[CO2] and A-[CO2] was small
We have demonstrated that [CO2] is another meteorological factor affecting FOT
Summary
The success of pollination or fertilization is largely determined by the flower opening time (FOT) in plants and angiosperms are evolved to optimize reproductive success at a minimal cost by optimizing their FOT (van Doorn & van Meeteren, 2003). Rice plants exhibit phenotypic plasticity in FOT in response to environmental factors such as Ta, and prediction of FOT is important when estimating the effects of heat-induced sterility in rice (Julia & Dingkuhn, 2012, 2013; Nguyen et al, 2014; van Oort et al, 2014) and when evaluating the effectiveness of early-morning flowering cultivars, such as those developed by Ishimaru et al (2010), Ishimaru et al, (2012), and Hirabayashi et al (2015). Increased Tp caused by high [CO2] may advance FOT, as it has been reported (Kobayasi et al, 2010) that higher Ta, higher solar radiation (Rs), and lower vapor-pressure deficit (VPD) in the early morning result in earlier FOT which together might affect FOT through their alteration of Tp. It is important to be able to assess and predict the effect of [CO2] on FOT and heat stress on rice in order to evaluate the early-morning flowering cultivars under heat stress conditions combined with E-[CO2]. Our objective in this experiment was to reveal the effect of E-[CO2] on FOT in rice
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
