TITLE:
Responses of Flowering Time to Elevated Carbon Dioxide among Soybean Photoperiod Isolines
AUTHORS:
James A. Bunce, Wilbert Cruz Hilacondo
KEYWORDS:
Carbon Dioxide Concentration, Flowering, Soybean, Photoperiod, Isolines
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.7 No.6,
April
19,
2016
ABSTRACT: Changes in the phenology of flowering in soybeans caused by long-term growth
at elevated CO2 may be important to the responses of seed yield to elevated
CO2. Here we utilized near-isogenic lines of soybeans differing in three
genes influencing photoperiod sensitivity to determine whether these genes affected
the response of flowering time to elevated CO2. Six isolines of Harosoy
63 were grown at ambient (380 μmol?mol-1) and elevated (560 μmol?mol-1)
CO2 concentrations in the field using free-air CO2 enrichment
systems, in air-conditioned glasshouses with natural summer photoperiods, and in
indoor chambers with day lengths of 11, 13, 15, and 17 hours. The effect of CO2 concentration on flowering time varied with genotype, and there was also an interaction
between CO2 and photoperiod in all genotypes, as indicated by ANOVA.
Elevated CO2 accelerated flowering in some cases, and delayed it in other
cases. For all three of the isolines with single dominant genes, elevated CO2 decreased the days to first open flower at the longest photoperiod. At the shortest
photoperiod, elevated CO2 delayed flowering in all but one isoline. The
all-recessive isoline had slower flowering at elevated CO2 at both the
shortest and the longest photoperiods, and also in the field and in the glasshouse.
Delayed flowering at elevated CO2 in the field and glasshouse was associated
with an increased final number of main stem nodes. It is concluded that the E1,
E3, and E4 genes each influenced how the time to first flowering was affected by
CO2 concentration at long photoperiods.