Mechanism associated with nonstructural carbohydrate accumulation in submergence tolerant rice (Oryza sativa L.) cultivars

Figures & data

Figure 1. Survival (%) of rice seedlings after 8 d of complete submergence. Data were the mean of three replications. Vertical bar represents standard deviation.

Table 1. NSC (sugar and starch) content and plant height in different rice cultivars (21-days-old) without submergence (C) and 8 d after submergence (S).

	Sugar (mg g^−1 dry wt)		Starch (mg g^−1 dry wt)		Total NSC (mg g^−1 dry wt)		Plant height (cm)
Variety	C	S	C	S	C	S	C	S
FR 13A	34.8±3.9^b	30.8±0.5^b	26.3±0.4^a	22.1±0.4^a,b	61.1±4.3^a	52.9±0.5^b	31.5±0.4^d	42.3±0.5^b
Khoda	42.3±0.3^a	34.4±1.5^b	23.7±0.4^a	20.1±0.7^b	65.9±0.8^a	54.4±2.3^b	29.7±0.7^d	39.9±0.9^c
Khadara	42.1±3.6^a	36.9±0.5^a,b	24.2±0.7^a	19.9±0.4^b	66.3±1.8^a	56.8±1.1^a,b	32.2±0.4^d	43.7±0.6^b
Kalaputia	36.6±5.1^a,b	31.9±2.1^b	25.9±0.8^a	21.9±0.6^a,b	62.6±4.3^a	53.8±1.6^b	32.2±0.4^d	40.3±1.5^c
Sarala	36.7±4.6^a,b	24.9±0.9^c	13.4±0.5^c	9.7±0.4^d	50.2±4.1^b	34.5±1.2^c	28.6±0.9^e	51.3±1.4^a
IR 42	31.8±0.9^b	21.3±1.2^c	14.2±0.8^c	8.9±0.4^d	45.6±1.5^b	30.4±1.6^c	26.9±0.4^e	52.5±1.3^a
LSD*p<0.05	6.2		3.0		5.5		1.8

Note: Data were presented as mean±standard deviation (n=3); Means in a column with a common letter are not significantly different at LSD*p<0.05.

Table 2. CO₂ photosynthetic rate, chlorophyll content, and maximum photochemical efficiency of PS II (Fv/Fm) in different rice cultivars (21-days-old) without submergence (C) and 8 d after submergence (S).

	CO2 photosynthetic rate (µmol CO2 m^−2 s^−1)		Chlorophyll content (mg g^−1fwt)		Fv/Fm (rel)
Variety	C	S	C	S	C	S
FR 13A	21.4±2.9^a	14.2±1.2^b	1.98±0.18^a	1.28±0.12^b	0.792±0.02^a	0.765±0.01^a
Khoda	20.1±1.7^a	14.8±1.4^b	2.22±0.05^a	1.46±0.10^b	0.794±0.02^a	0.767±0.02^a
Khadara	18.7±0.5^a	13.9±1.1^b	1.98±0.05^a	1.26±0.08^b	0.798±0.02^a	0.772±0.01^a
Kalaputia	21.7±2.5^a	14.8±1.8^b	2.35±0.15^a	1.61±0.09^b	0.787±0.01^a	0.761±0.02^a
Sarala	19.4±3.0^a	8.7±1.2^c	2.49±0.46^a	0.61±0.18^c	0.794±0.01^a	0.702±0.01^b
IR 42	18.7±0.9^a	8.4±0.8^c	1.99±0.31^a	0.59±0.14^c	0.791±0.01^a	0.681±0.01^b
LSD*p<0.05	3.6		0.53		0.031

Note: Data were presented as mean±standard deviation (n=3); Means in a column with a common letter are not significantly different at LSD*p<0.05.

Table 3. Activities of different carbohydrate metabolic enzymes in different rice cultivars (21-days-old) without submergence (C) and 8 d after submergence (S).

	Rubisco		AGPPase		FDPase
Variety	C	S	C	S	C	S
FR 13A	0.796±0.06^a	0.598±0.01^b	0.090±0.012^a	0.074±0.008^a	125.5±0.7^d	87.5±3.5^f
Khoda	0.752±0.08^a	0.569±0.01^b	0.097±0.014^a	0.083±0.007^a	146.0±2.8^c	103.0±4.5^e
Khadara	0.779±0.05^a	0.600±0.02^b	0.051±0.003^b	0.046±0.006^b	156.5±3.1^b	104.5±4.0^e
Kalaputia	0.710±0.07^a	0.582±0.04^b	0.100±0.003^a	0.083±0.001^a	142.0±4.0^c	102.0±2.0^e
Sarala	0.765±0.02^a	0.501±0.03^b	0.027±0.001^c	0.020±0.002^c	168.5±4.2^a	117.5±2.3^d
IR 42	0.796±0.07^a	0.512±0.01^b	0.019±0.001^c	0.012±0.011^c	163.0±2.0^a	120.5±2.1^d
LSD*p<0.05	0.182		0.016		5.9
	SSyn		SPSyn		Invertase
Variety	C	S	C	S	C	S
FR 13A	715±60^a	721±15^a	1164±104^a	755±14^b	337±7^c	350±3^c
Khoda	682±62^a,b	700±14^a	688±33^b	623±13^b	417±17^a	422±10^a
Khadara	427±26^d	512±17^c	853±23^b	700±28^b	284±6^e	326±7^d
Kalaputia	449±66^d	506±14^c	811±103^b	711±13^b	378±9^b	389±10^b
Sarala	806±36^a	717±12^a	806±82^b	691±17^b	402±4^a	409±4^a
IR 42	563±43^c	580±19^c	1052±21^a	735±21^b	355±3^c	379±10^b
LSD*p<0.05	83		169		19

Rubisco (µmol NADH oxidized min⁻¹ mg⁻¹ protein), AGPPase (µmol NAD⁺ reduced min⁻¹ mg⁻¹ protein), FDPase (µg inorganic phosphate released h⁻¹ mg⁻¹ protein), Invertase (µg glucose released h⁻¹ mg⁻¹ protein), SSyn (µmol sucrose released h⁻¹ mg⁻¹ protein), and SPSyn (µmol sucrose released h⁻¹ mg⁻¹ protein).

Note: Data were presented as mean±standard deviation (n=3); Means in a column with a common letter are not significantly different at LSD*p<0.05.

Table 4. Association of sugar, starch, and total NSC contents with different enzymes of carbohydrate metabolism, photosynthetic parameters, elongation (%), and survival (%) in different rice cultivars during vegetative stage.

Parameters	Sugar	Starch	Total NSC
Rubisco	−0.080^ns	−0.179^ns	0.164^ns
AGPPase	0.329*	0.859**	0.756**
FDPase	0.018^ns	−0.826**	−0.541*
Invertase	0.003^ns	−0.290^ns	−0.191^ns
SSyn	−0.171^ns	−0.309^ns	−0.342^ns
SPSyn	−0.331^ns	−0.004^ns	−0.243^ns
Photosynthetic rate	−0.430*	−0.234^ns	−0.083^ns
Chlorophyll content	0.169^ns	−0.272^ns	−0.087^ns
Fv/Fm	−0.495*	−0.032^ns	0.255^ns
Elongation (%)	−0.523**	−0.945**	−0.992**
Survival (%)	0.372*	0.992**	0.870**

ns, nonsignificant; *p<0.05; **p<0.01.