Study on Physiological Characteristics Behind Mitigative Effects of Flooding on Low Temperature-caused Chilling Damage to Direct Seeded Early indica Rice at the Seedling Stage

doi:10.16819/j.1001-7216.2021.0914

Abstract

Abstract:

【Objective】It is important to explore the effects of flooding on the growth of direct seeded early indica rice seedlings under low-temperature stress, and lay a physiological basis for direct seeded rice production and stress-resistant cultivation in South China. 【Method】The cold-tolerant cultivar Xiangzaoxian 6 and cold-sensitive cultivar Zhongjiazao 17 were used as materials in this experiment, and three treatments each lasting three days including low temperature treatment (8ºC), low temperature & flooding treatment (8ºC plus flooding) and ambient temperature as control treatment (25ºC) were designed to analyze the physiological characteristics including agronomic characters, antioxidant enzyme activities, osmotic regulation substances contents, photosynthesis enzyme activities and endogenous hormone contents of rice seedlings. 【Result】 Compared with low temperature (LT), the seedling height, fresh weight, dry weight and T3 (the 3rd leaf from top) leaf length of different cultivars significantly increased after three days at low temperature under flooding (LTF), and the root number, root length, T1 (the first leaf from top) leaf length and T2 (the 2nd leaf from top) leaf length also increased. Flooding could reduce the damage induced by low temperature to the agronomic characters of rice seedlings with the cold-tolerant cultivar Xiangzaoxian 6 less affected as compared with cold-sensitive cultivar Zhongjiazao 17. In addition, compared with LT, LTF significantly decreased the antioxidant enzymes activities (SOD, POD, CAT), soluble protein contents, osmotic regulatory substances contents (MDA, proline) and endogenous growth inhibitory hormone contents, ABA content, whereas increased the content of endogenous growth promoting hormone GA₃ under low temperature; Flooding could alleviate the accumulation of reactive oxygen species (ROS) and the aggravation of membrane lipid peroxidation in plants, and improve the regulation of endogenous hormones in plants. Meanwhile, LT and LTF significantly decreased the contents of chlorophyll and ATP in leaves, resulting in the decrease of photosynthetic enzyme activities (Rubisco, PEPCK); but LTF had lower damage than that of LT, and LTF could play a mitigating role. After the recovery treatment, the physiological activity indexes of rice subjected to LTF were close to the level of CK, whereas the self-response mechanism of cold-tolerant cultivar could reduce the damage caused by low temperature stress. 【Conclusion】 Low temperature treatment affected the growth characteristics and photosynthetic enzyme activity of direct seeded early indica rice seedlings, and increased the antioxidant protective enzyme activity and osmotic regulation potential of leaves, but flooding treatment help to alleviate the physiological damage of leaves caused by low-temperature stress.

Key words: early indica rice, direct seeded rice, low temperature, flooding, physiological characteristics

摘要：

【目的】 探究淹水对低温胁迫下直播早籼稻幼苗生长的影响,为南方稻区直播稻生产与抗逆栽培奠定生理基础。【方法】 以耐冷品种湘早籼6号和冷敏感品种中嘉早17为材料,设置低温处理(8℃)、低温淹水处理(8℃ + 淹水)与常温对照(25℃)3个处理(处理3 d),分析秧苗农艺性状、抗氧化酶活性、渗透调节物质含量、光合酶活性和内源激素含量等生理特性。【结果】 与低温处理相比,低温淹水处理3 d后不同耐性品种的苗高、鲜质量、干质量和顶三叶叶长显著增加,根数、最大根长、剑叶叶长、倒2叶叶长也都有不同程度增加,淹水可减轻低温对水稻秧苗农艺性状的影响;耐冷品种湘早籼6号苗期受到伤害的程度小于冷敏感品种中嘉早17。此外,与低温处理相比,低温淹水处理显著降低叶片抗氧化酶活性(SOD、POD、CAT)、可溶性蛋白、渗透调节物质(MDA、脯氨酸)含量和内源生长抑制类激素(ABA)含量,同时显著增加了内源生长促进类激素(GA₃)含量;低温条件下淹水可减少植物体内活性氧的积累,减轻膜脂过氧化,加强了植物体内源激素的调控作用。同时,低温和低温淹水处理显著降低叶片叶绿素和ATP含量,导致光合酶(Rubisco、PEPCK)活性降低;但低温淹水处理的影响低于低温处理,低温淹水可起到缓解作用。且在恢复处理后,低温淹水处理各生理活性指标更接近对照处理,而与冷敏感性品种相比,耐冷性品种可缓解低温胁迫产生的伤害。【结论】 低温处理影响直播早籼稻秧苗生长特性,降低了秧苗光合酶活性;同时提升叶片抗氧化保护酶活性与渗透调节势,但淹水处理有助于缓解低温胁迫造成的叶片生理伤害。

关键词: 早籼稻, 直播稻, 低温, 淹水, 生理特性

Wenxia WANG, Liming CHEN, Haixia WANG, Youqing LIU, Ziming WU, Yongjun ZENG, Xueming TAN, Xiaohua PAN, Qinghua SHI, Yanhua ZENG. Study on Physiological Characteristics Behind Mitigative Effects of Flooding on Low Temperature-caused Chilling Damage to Direct Seeded Early indica Rice at the Seedling Stage[J]. Chinese Journal OF Rice Science, 2021, 35(2): 166-176.

王文霞, 陈丽明, 王海霞, 刘有清, 吴自明, 曾勇军, 谭雪明, 潘晓华, 石庆华, 曾研华. 淹水缓解直播早籼稻苗期低温冷害的生理特性研究[J]. 中国水稻科学, 2021, 35(2): 166-176.

Figures/Tables 5

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品种 Cultivar	处理 Treatment	苗高 Seedling height /cm	单株根数 Root number per plant	最大根长 Maximum root length /cm	百株鲜质量 Fresh weight per 100 plants/mg	百株干质量 Dry weight per 100 plants/mg	叶长Leaf length / cm
品种 Cultivar	处理 Treatment	苗高 Seedling height /cm	单株根数 Root number per plant	最大根长 Maximum root length /cm	百株鲜质量 Fresh weight per 100 plants/mg	百株干质量 Dry weight per 100 plants/mg	T1	T2	T3
湘早籼6号 XZX6	Pre-T	20.3 d	10.9 e	6.6 d	182.5 f	26.1 f	3.5 d	12.1 c	6.4 d
	LT	19.7 e	10.8 e	6.6 d	206.4 e	30.5 e	2.8 f	11.0 d	5.0 e
	LTF	20.6 d	11.5 de	7.2 c	209.0 d	32.1 cd	3.0 e	12.0 cd	5.8 d
	CK	28.2 b	14.3 b	9.2 b	229.5 a	33.4 b	4.4 b	13.4 b	9.3 b
	Re-LT	22.3 c	12.6 cd	7.5 cd	211.5 c	31.4 de	3.6 d	11.9 cd	7.8 c
	Re-LTF	22.9 c	13.1 c	7.9 c	216.4 b	32.6 bc	3.8 c	13.0 b	8.2 c
	Re-CK	31.4 a	18.0 a	11.4 a	231.2 a	35.4 a	4.9 a	14.9 a	11.0 a
中嘉早17 ZJZ17	Pre-T	23.1 c	10.7 d	5.2 d	175.1 g	25.3 f	3.1 c	9.2 d	9.0 d
	LT	18.9 e	10.7 d	5.3 d	186.0 f	27.2 e	2.4 e	9.3 e	7.1 f
	LTF	19.9 d	11.0 c	5.5 d	212.4 d	32.5 d	2.4 e	9.8 de	8.1 e
	CK	28.4 b	14.1 b	7.9 b	253.5 b	36.4 b	3.7 b	10.6 c	10.5 b
	Re-LT	20.6 d	12.6 bc	6.6 c	194.8 e	33.5 d	2.8 d	10.8 c	9.8 c
	Re-LTF	22.6 c	12.3 bcd	7.0 c	232.0 c	35.1 c	3.0 d	11.3 b	10.0 bc
	Re-CK	33.2 a	17.1 a	10.9 a	278.0 a	40.2 a	4.2 a	12.4 a	12.1 a

品种 Cultivar	处理 Treatment	苗高 Seedling height /cm	单株根数 Root number per plant	最大根长 Maximum root length /cm	百株鲜质量 Fresh weight per 100 plants/mg	百株干质量 Dry weight per 100 plants/mg	叶长Leaf length / cm
品种 Cultivar	处理 Treatment	苗高 Seedling height /cm	单株根数 Root number per plant	最大根长 Maximum root length /cm	百株鲜质量 Fresh weight per 100 plants/mg	百株干质量 Dry weight per 100 plants/mg	T1	T2	T3
湘早籼6号 XZX6	Pre-T	20.3 d	10.9 e	6.6 d	182.5 f	26.1 f	3.5 d	12.1 c	6.4 d
	LT	19.7 e	10.8 e	6.6 d	206.4 e	30.5 e	2.8 f	11.0 d	5.0 e
	LTF	20.6 d	11.5 de	7.2 c	209.0 d	32.1 cd	3.0 e	12.0 cd	5.8 d
	CK	28.2 b	14.3 b	9.2 b	229.5 a	33.4 b	4.4 b	13.4 b	9.3 b
	Re-LT	22.3 c	12.6 cd	7.5 cd	211.5 c	31.4 de	3.6 d	11.9 cd	7.8 c
	Re-LTF	22.9 c	13.1 c	7.9 c	216.4 b	32.6 bc	3.8 c	13.0 b	8.2 c
	Re-CK	31.4 a	18.0 a	11.4 a	231.2 a	35.4 a	4.9 a	14.9 a	11.0 a
中嘉早17 ZJZ17	Pre-T	23.1 c	10.7 d	5.2 d	175.1 g	25.3 f	3.1 c	9.2 d	9.0 d
	LT	18.9 e	10.7 d	5.3 d	186.0 f	27.2 e	2.4 e	9.3 e	7.1 f
	LTF	19.9 d	11.0 c	5.5 d	212.4 d	32.5 d	2.4 e	9.8 de	8.1 e
	CK	28.4 b	14.1 b	7.9 b	253.5 b	36.4 b	3.7 b	10.6 c	10.5 b
	Re-LT	20.6 d	12.6 bc	6.6 c	194.8 e	33.5 d	2.8 d	10.8 c	9.8 c
	Re-LTF	22.6 c	12.3 bcd	7.0 c	232.0 c	35.1 c	3.0 d	11.3 b	10.0 bc
	Re-CK	33.2 a	17.1 a	10.9 a	278.0 a	40.2 a	4.2 a	12.4 a	12.1 a