Physiological Responses of Contrasting Rice Genotypes to Salt Stress at Reproductive Stage

doi:10.1016/j.rsci.2019.05.001

Abstract

Abstract:

Salinity is a major abiotic stress affecting plant growth and productivity. Considerable genetic variation is present in rice in response to salt stress, with higher sensitivity during early seedling and reproductive stage. In this study, physiological changes in leaves and developing panicles of rice genotypes (IR686, Sadri, Rc222, CSR28, IR670 and Pokkali) contrasting in salt tolerance at the reproductive stage were evaluated in greenhouse experiment under salt stress. The results showed that IR670 and the tolerant-check Pokkali maintained lower Na⁺/K⁺ ratio, less reduction in chlorophyll concentration, lower malondialdehyde (MDA) production, higher concentrations of reduced ascorbate (reduced AsA), higher proline accumulation and lower percentage reduction in pollen viability than the salt-sensitive genotypes under salt stress. The higher concentration of reduced AsA suggests an efficient ROS-scavenging system. Physiological measurements and pollen viability analysis revealed that Sadri (moderately tolerant at the seedling stage) is sensitive to salt stress at the flowering stage. The findings will be useful in breeding salt tolerant varieties at both seedling and reproductive stages by selecting appropriate genotypes and phenotypes.

Key words: Na⁺/K⁺ ratio, proline, reproductive stage, rice, salinity stress, reduced ascorbate, pollen viability

Elisa B. Gerona Maria, P. Deocampo Marjorie, A. Egdane James, M. Ismail Abdelbagi, L. Dionisio-Sese Maribel. Physiological Responses of Contrasting Rice Genotypes to Salt Stress at Reproductive Stage[J]. Rice Science, 2019, 26(4): 207-219.

Figures/Tables 6

References 80

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Genotype	Shoot dry weight (g)			Pollen viability (%)			Grain yield per plant (g)			Panicle length (cm)			No. of panicles per plant			Percentage of filled grains (%)			Percentage of unfilled grains (%)
	Control	EC10		Control	EC10		Control	EC10		Control	EC10		Control	EC10		Control	EC10		Control	EC10
Rc222	26.15	7.99	93.85		19.07	7.03		2.64	33.70		29.50	5.8		4.1	92.78		14.83	7.22		85.17
IR686	26.07	5.55	87.79		23.50	6.17		1.66	22.80		16.90	6.7		3.1	90.77		13.82	9.23		86.18
Sadri	27.12	5.92	91.31		44.44	6.03		1.02	28.40		17.00	5.3		2.3	89.42		11.56	10.58		88.44
CSR28	28.74	21.36	91.74		82.64	7.14		2.36	27.90		17.30	4.1		3.9	90.23		70.90	9.77		29.10
IR670	32.29	27.21	92.96		84.61	8.07		6.88	23.80		18.50	6.2		5.1	91.12		84.86	8.88		15.14
Pokkali	30.08	25.93	96.06		94.20	7.55		5.48	29.50		20.20	7.8		6.5	90.63		68.77	9.37		31.23
Mean	28.41	15.66	92.28		58.08	7.00		3.34	27.68		19.90	6.0		4.2	90.82		44.13	9.18		55.87
Salinity (S)	2.49***		5.57***			1.66***			1.30***			0.16***			1.97***			2.48***
Genotype (G)	4.70***		9.89***			1.27***			2.49**			0.12**			1.72**			0.83*
S × G	3.84***		1.69***			0.79***			2.46***			0.35***			2.94***			1.74**
EC10, Salt stress condition with electrical conductivity of 10 dS/m. Data are means of three replications; , * and ***, Significance at the 0.05, 0.01 and 0.001 levels by the Fisher’s least significant difference, respectively.

Genotype	Shoot dry weight (g)			Pollen viability (%)			Grain yield per plant (g)			Panicle length (cm)			No. of panicles per plant			Percentage of filled grains (%)			Percentage of unfilled grains (%)
	Control	EC10		Control	EC10		Control	EC10		Control	EC10		Control	EC10		Control	EC10		Control	EC10
Rc222	26.15	7.99	93.85		19.07	7.03		2.64	33.70		29.50	5.8		4.1	92.78		14.83	7.22		85.17
IR686	26.07	5.55	87.79		23.50	6.17		1.66	22.80		16.90	6.7		3.1	90.77		13.82	9.23		86.18
Sadri	27.12	5.92	91.31		44.44	6.03		1.02	28.40		17.00	5.3		2.3	89.42		11.56	10.58		88.44
CSR28	28.74	21.36	91.74		82.64	7.14		2.36	27.90		17.30	4.1		3.9	90.23		70.90	9.77		29.10
IR670	32.29	27.21	92.96		84.61	8.07		6.88	23.80		18.50	6.2		5.1	91.12		84.86	8.88		15.14
Pokkali	30.08	25.93	96.06		94.20	7.55		5.48	29.50		20.20	7.8		6.5	90.63		68.77	9.37		31.23
Mean	28.41	15.66	92.28		58.08	7.00		3.34	27.68		19.90	6.0		4.2	90.82		44.13	9.18		55.87
Salinity (S)	2.49***		5.57***			1.66***			1.30***			0.16***			1.97***			2.48***
Genotype (G)	4.70***		9.89***			1.27***			2.49**			0.12**			1.72**			0.83*
S × G	3.84***		1.69***			0.79***			2.46***			0.35***			2.94***			1.74**
EC10, Salt stress condition with electrical conductivity of 10 dS/m. Data are means of three replications; , * and ***, Significance at the 0.05, 0.01 and 0.001 levels by the Fisher’s least significant difference, respectively.

Genotype	First leaf from the top		Second leaf from the top		Third leaf from the top		First leaf sheath from the top		Second leaf sheath from the top		Third leaf sheath from the top		Panicle main stalk		Branches with spikelets
Genotype	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10
Rc222	52.1	490.9	79.6	540.4	86.8	899.1	78.5	544.2	76.1	848.3	107.1	990.8	31.9	450.8	34.6	415.9
IR686	52.6	579.0	77.0	884.6	92.4	927.9	69.3	649.0	72.1	921.6	100.9	1507.5	34.5	461.4	39.2	428.9
Sadri	35.8	619.2	69.9	711.2	45.9	883.7	51.5	689.3	55.9	865.5	64.8	1031.0	48.4	459.9	45.2	457.2
CSR28	51.3	459.1	78.8	487.4	67.8	547.7	80.2	481.0	80.6	583.3	92.7	669.8	26.1	382.0	18.5	319.6
IR670	22.6	335.4	41.2	400.8	59.6	554.9	41.6	526.2	47.0	557.9	57.3	563.8	24.0	217.1	17.9	207.7
Pokkali	35.2	400.8	50.3	474.4	51.1	490.9	56.2	460.7	53.7	477.9	71.0	480.2	15.6	141.0	14.1	103.8
Mean	41.6	480.7	66.1	583.1	67.3	717.4	62.9	558.4	64.2	709.1	82.3	873.9	31.3	352.0	27.0	322.2
Salinity (S)	70.84***		137.52***		90.17***		75.69***		89.67***		207.71***		64.46***		86.37***
Genotype (G)	122.28*		192.79**		206.21**		138.43**		244.91*		264.09*		101.54**		104.62**
S × G	117.37***		127.19***		90.53***		156.41***		111.45***		297.64***		12.01***		46.87***
EC10, Salt stress condition with electrical conductivity of 10 dS/m.==Data are means of three replications; , * and ***, Significance at the 0.05, 0.01 and 0.001 levels by the Fisher’s least significant difference, respectively.

Genotype	First leaf from the top		Second leaf from the top		Third leaf from the top		First leaf sheath from the top		Second leaf sheath from the top		Third leaf sheath from the top		Panicle main stalk		Branches with spikelets
Genotype	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10
Rc222	52.1	490.9	79.6	540.4	86.8	899.1	78.5	544.2	76.1	848.3	107.1	990.8	31.9	450.8	34.6	415.9
IR686	52.6	579.0	77.0	884.6	92.4	927.9	69.3	649.0	72.1	921.6	100.9	1507.5	34.5	461.4	39.2	428.9
Sadri	35.8	619.2	69.9	711.2	45.9	883.7	51.5	689.3	55.9	865.5	64.8	1031.0	48.4	459.9	45.2	457.2
CSR28	51.3	459.1	78.8	487.4	67.8	547.7	80.2	481.0	80.6	583.3	92.7	669.8	26.1	382.0	18.5	319.6
IR670	22.6	335.4	41.2	400.8	59.6	554.9	41.6	526.2	47.0	557.9	57.3	563.8	24.0	217.1	17.9	207.7
Pokkali	35.2	400.8	50.3	474.4	51.1	490.9	56.2	460.7	53.7	477.9	71.0	480.2	15.6	141.0	14.1	103.8
Mean	41.6	480.7	66.1	583.1	67.3	717.4	62.9	558.4	64.2	709.1	82.3	873.9	31.3	352.0	27.0	322.2
Salinity (S)	70.84***		137.52***		90.17***		75.69***		89.67***		207.71***		64.46***		86.37***
Genotype (G)	122.28*		192.79**		206.21**		138.43**		244.91*		264.09*		101.54**		104.62**
S × G	117.37***		127.19***		90.53***		156.41***		111.45***		297.64***		12.01***		46.87***
EC10, Salt stress condition with electrical conductivity of 10 dS/m.==Data are means of three replications; , * and ***, Significance at the 0.05, 0.01 and 0.001 levels by the Fisher’s least significant difference, respectively.

Genotype	First leaf from the top		Second leaf from the top		Third leaf from the top		First leaf sheath from the top		Second leaf sheath from the top		Third leaf sheath from the top		Panicle main stalk		Branch with spikelets
Genotype	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10	Control	EC10
Rc222	0.11	1.69	0.11	1.84	0.11	2.18	0.12	1.82	0.11	2.00	0.12	2.28	0.10	1.64	0.11	1.51
IR686	0.10	2.30	0.11	2.57	0.11	2.88	0.10	2.49	0.11	2.73	0.11	3.21	0.10	1.72	0.14	1.65
Sadri	0.10	2.38	0.11	2.48	0.10	3.92	0.10	2.81	0.11	3.49	0.10	4.09	0.15	2.02	0.19	2.02
CSR28	0.10	1.02	0.11	1.03	0.10	1.14	0.10	1.14	0.11	1.17	0.10	1.71	0.09	1.01	0.11	0.88
IR670	0.05	0.69	0.05	0.76	0.05	0.82	0.05	0.72	0.05	0.81	0.06	0.86	0.07	0.68	0.07	0.65
Pokkali	0.06	0.66	0.06	0.67	0.06	0.72	0.07	0.66	0.06	0.69	0.07	0.79	0.06	0.64	0.08	0.43
Mean	0.09	1.46	0.09	1.56	0.09	1.94	0.09	1.61	0.09	1.81	0.09	2.16	0.09	1.28	0.12	1.19
Salinity (S)	0.28***		0.58***		0.39***		0.63***		0.57***		0.61***		0.56***		0.28***
Genotype (G)	0.34*		0.33*		0.06**		0.39**		0.33**		0.40**		0.19*		0.32*
S × G	0.38***		0.30***		0.22***		0.76***		0.20***		0.25***		0.10***		0.22***
EC10, Salt stress condition with electrical conductivity of 10 dS/m. Data are means of three replications; , * and ***, Significance at the 0.05, 0.01 and 0.001 levels by the Fisher’s least significant difference, respectively.