Effects of elevated CO₂ concentration on growth and photosynthesis of Chinese yam under different temperature regimes

Figures & data

Table 1. Effects of elevated CO₂ concentration on the plant growth of Chinese yam and rice.

	Chinese yam			Rice
Treatments	No. of leaves	Vine length	Leaf area	No. of leaves	Shoot length	No. of tillers	Leaf blade area
	(plant^−1)	(cm plant^−1)	(m^2 plant^−1)	(plant^−1)	(cm plant^−1)	(plant^−1)	(m^2 plant^−1)
Summer experiment
AL 24.1 °C^†	107.3 a	230.0 a	0.115 a	13.8 a	102.3 a	28.7 ab	0.295 a
EL 24.1 °C^†	138.7 b (1.29)	343.3 b (1.49)	0.182 b (1.59)	14.4 b (1.04)	103.3 a (1.01)	30.2 a (1.05)	0.299 a (1.01)
AH 29.1 °C^†	37.3 c	111.7 c	0.039 d	14.6 c	114.1 b	24.9 b	0.314 a
EH 29.1 °C^†	57.3 c (1.54)	208.0 a (1.86)	0.067 c (1.71)	14.8 c (1.01)	114.9 b (1.01)	27.5 ab (1.10)	0.323 a (1.03)
ANOVA results
CO2 (C)	***	***	***	***	ns	ns	ns
Temperature (T)	***	***	***	***	***	**	ns
C × T	ns	ns	**	**	ns	ns	ns
Autumn experiment
AL 20.2 °C^†	18.0 a	64.2 a	0.027 a	10.6 a	67.8 a	18.4 ab	0.071 a
EL 20.2 °C^†	24.8 ab (1.38)	71.3 ab (1.11)	0.031 a (1.16)	10.6 a (1.00)	67.8 a (1.00)	19.6 a (1.07)	0.082 a (1.15)
AH 24.9 °C^†	34.7 b	105.7 b	0.057 b	12.0 b	93.3 b	14.6 c	0.109 b
EH 24.9 °C^†	36.8 b (1.06)	111.2 b (1.05)	0.050 b (0.88)	12.3 c (1.02)	96.4 b (1.03)	17.3 b (1.18)	0.140 c (1.29)
ANOVA results
CO2 (C)	ns	ns	ns	*	ns	**	**
Temperature (T)	**	***	***	***	***	***	***
C × T	ns	ns	ns	ns	ns	ns	ns

Notes: Different letters within each plant indicate significant differences at the 5% level (Tukey–Kramer’s test). No. of leaves: Number of leaves, No. of tillers: number of tillers, AL: ambient [CO₂]-low temperature, EL: elevated [CO₂]-low temperature, AH: ambient [CO₂]-high temperature, EH: elevated [CO₂]-high temperature. Numbers in brackets are ratios of values under elevated [CO₂] to those under ambient [CO₂].

^† mean air temperature.

^*** p < 0.001

^** p < 0.01

^* p < 0.05

ns: not significant.

Table 2. Effects of elevated CO₂ concentration on the dry weight of Chinese yam and rice.

	Chinese yam				Rice
Treatments	Leaf DW	Vine DW	Root DW	Tuber DW	Leaf blade DW	Shoot DW	Root DW
	(g plant^−1)	(g plant^−1)	(g plant^−1)	(g plant^−1)	(g plant^−1)	(g plant^−1)	(g plant^−1)
Summer experiment
AL 24.1 °C^†	7.03 a	2.09 a	1.68 a	3.13 ab	15.1 a	48.7 a	12.75 a
EL 24.1 °C^†	11.31 b (1.61)	3.33 b (1.59)	2.33 b (1.38)	4.49 b (1.44)	16.2 a (1.07)	53.5 a (1.10)	13.16 a (1.03)
AH 29.1 °C^†	2.46 c	0.67 c	0.63 c	2.46 a	14.9 a	47.9 a	8.27 b
EH 29.1 °C^†	4.33 d (1.76)	1.11 c (1.67)	1.15 ac (1.83)	3.43 ab (1.40)	15.8 a (1.07)	51.3 a (1.07)	10.80 a (1.31)
ANOVA results
CO2 (C)	***	***	***	*	ns	ns	**
Temperature (T)	***	***	***	ns	ns	ns	***
C × T	**	*	ns	ns	ns	ns	ns
Autumn experiment
AL 20.2 °C^†	1.27 a	0.32 a	0.39 a	3.01 a	3.8 a	8.3 a	2.44 a
EL 20.2 °C^†	1.66 ab (1.31)	0.40 ab (1.25)	0.51 ab (1.30)	3.68 a (1.22)	4.4 a (1.16)	10.4 a (1.25)	2.85 ab (1.17)
AH 24.9 °C^†	2.45 b	0.52 b	0.68 ab	3.93 a	5.6 b	15.1 b	3.18 ab
EH 24.9 °C^†	2.61 b (1.07)	0.57 b (1.08)	0.72 b (1.06)	5.34 b (1.36)	7.6 c (1.36)	20.2 c (1.33)	3.91 b (1.23)
ANOVA results
CO2 (C)	ns	ns	ns	**	***	***	ns
Temperature (T)	***	***	**	***	***	***	**
C × T	ns	ns	ns	ns	*	ns	ns

Notes: Different letters within each plant indicate significant differences at the 5% level (Tukey–Kramer’s test). DW: dry weight, AL: ambient [CO₂]-low temperature, EL: elevated [CO₂]-low temperature, AH: ambient [CO₂]-high temperature, EH: elevated [CO₂]-high temperature. Numbers in brackets are ratios of values under elevated [CO₂] to those under ambient [CO₂].

^† mean air temperature.

^*** p < 0.001

^** p < 0.01

^* p < 0.05

ns: not significant.

Figure 1. Effects of elevated CO₂ concentration on total plant dry weight in Chinese yam and rice.

Notes: Different letters indicate significant differences at the 5% level (Tukey–Kramer’s test). Bars show mean ± SE (n=6), AL: ambient [CO₂]-low temperature, EL: elevated [CO₂]-low temperature, AH: ambient [CO₂]-high temperature, EH: elevated [CO₂]-high temperature. Numbers in brackets are ratios of values under elevated [CO₂] to those under ambient [CO₂]. ^†mean air temperature, ***p<0.001, **p<0.01, *p<0.05, ns: not significant.

Figure 2. Effects of elevated CO₂ concentration on net photosynthetic rates of single leaf in Chinese yam and rice.

Notes: Different letters indicate significant differences at the 5% level (Tukey–Kramer’s test). Bars show means ± SE (n = 2–5), AL: ambient [CO₂]-low temperature, EL: elevated [CO₂]-low temperature, AH: ambient [CO₂]-high temperature, EH: elevated [CO₂]-high temperature, numbers in brackets are ratios of values under elevated [CO₂] to those under ambient [CO₂]. ^†mean air temperature, ***p<0.001, **p<0.01, *p<0.05, ns: not significant.