Effects of rootzone CO₂ and O₂ levels on seed germination and stolon growth of Cynodon dactylon

Figures & data

Figure 1.  Representation of the micro-lysimeter used for the stolon establishment experiment.

Table I. Total seed germination (%) and T₅₀ (days) of bermudagrass seeds being treated with: 40–20 % [CO₂–O₂], 40–10 % [CO₂–O₂], 40–2.5 % [CO₂–O₂] and [Control]: air.

	Total germination (%)
Gas treatment	21d	T50 (days)
Control	45.5 c	−^†
40–20% [CO2–O2]	70.8 a	3.6 b
40–10% [CO2–O2]	70.6 a	5.8 ab
40–2.5% [CO2–O2]	57.0 b	7.8 a
LSD	10.4	3.6
Means followed by different letters within a column are significantly different at p = 0.05.
†T50 was not calculated due to germination lower than 50%.

Figure 2.  Cumulative clippings dry weight for plants treated with gas mixtures of 40–20%, 40–10%, 40–2.5% [CO₂–O₂], and [Control]: air. Bars represent Fisher's least significance difference (LSD) at p = 0.05.

Table II. Leaf chlorophyll content and relative water content of C. dactylon, when the root system was treated with 40–20% [CO₂–O₂], 40–10% [CO₂–O₂], 40–2.5% [CO₂–O₂], and [Control]: air at 7 DGT and 28 DGT.

	Chla (mg g^−1 FW)		Chlb (mg g^−1 FW)		Chla/b		RWC (%)
Gas Treatment	7d	28d	7d	28d	7d	28d	7d	28d
Control	2.6	2.7	1.1	2.0a^*	2.4	1.4b^*	62.3a	65.9a
40–20% [CO2–O2]	2.7	2.5	1.1	1.8a^*	2.6	1.4b^*	58.9ab	58.3ab
40–10% [CO2–O2]	2.6	2.5	1.0	1.7a^*	2.5	1.5b^*	55.9b	57.8ab
40–2.5% [CO2–O2]	2.6	2.7	1.1	1.1b	2.4	2.4a	57.8b	50.9b
	NS	NS	NS	*	NS	*	*	*
Means followed by different letters within a column are significantly different at p = 0.05. Means of the same line between the two different sampling dates followed by * are significantly different at p = 0.05.
*: Significance at p = 0.05, NS: non-significant at p = 0.05.

Table III. Concentration of soluble sugars in C. dactylon leaves, when the root system was treated with 40–20% [CO₂–O₂], 40–10% [CO₂–O₂], 40–2.5% [CO₂–O₂], and [Control]: air at 7 DGT and 28 DGT.

	Sucrose (mg g^−1 DW)		Glucose (mg g^−1 DW)		Fructose (mg g^−1 DW)
Gas treatment	7d	28d	7d	28d	7d	28d
Control	67.4a	27.2	20.3a	14.3a	11.4a	6.2ab
40–20% [CO2–O2]	52.9b	27.1	16.5b	11.3b	10.3ab	5.6b
40–10% [CO2–O2]	70.9a	26.4	12.4b	11.1b	9.5ab	8.2a
40–2.5% [CO2–O2]	33.3c	25.1	11.7b	10.9b	8.1b	4.5b
	***	NS	***	*	*	*
Means followed by different letters within a column are significantly different at p = 0.05.
*: Significance at p = 0.05, ***: Significance at p = 0.0001, NS: non-significant at p = 0.05.

Figure 3.  Root growth parameters for plants treated with gas mixtures of 40–20%, 40–10%, 40–2.5% [CO₂–O₂], and [Control]: air. Bars represent Fisher's least significance difference at p = 0.05. A: Root Dry Weight, B: Root total length and C: Root total area.

Table IV. Concentration of soluble sugars in C. dactylon roots, when the root system was treated with 40–20% [CO₂–O₂], 40–10% [CO₂–O₂], 40–2.5% [CO₂–O₂], and [Control]: air at 7 DGT and 28 DGT.

	Sucrose (mg g^−1 DW)		Glucose (mg g^−1 DW)		Fructose (mg g^−1 DW)
Gas treatment	7d	28d	7d	28d	7d	28d
Control	9.7b	9.8b	9.2b	9.5b	11.3a	10.2b
40–20% [CO2–O2]	23.5a	58.0a	9.4b	11.7b	11.0a	14.9b
40–10% [CO2–O2]	9.2b	24.7b	18.2a	11.1b	11.0a	9.7b
40–2.5% [CO2–O2]	9.2b	23.9b	20.9a	40.3a	14.1a	24.8a
	***	***	***	***	NS	*
Means followed by different letters within a column are significantly different at p = 0.05.
*: Significance at p = 0.05, ***: Significance at p = 0.0001, NS: non-significant at p = 0.05.