摘要
摘要:为明确碱敏感和耐碱水稻品种幼苗根系响应碱胁迫的生理差异和应对策略，本试验以碱敏感水稻品种‘中花11’和耐碱品种‘宁粳52’为材料，将两种碱性盐（NaHCO₃和Na₂CO₃）按照不同摩尔比混合，设3个碱浓度水平（10 mmol·L^-1、20 mmol·L^-1和30 mmol·L^-1）和3个pH水平（8.65、9.55和10.50），模拟出9种碱胁迫环境，研究碱胁迫对供试水稻幼苗根系生长和相关抗逆生理指标的影响；并用逐步回归分析建立最优回归方程，进而筛选出不同胁迫程度下不同水稻品种响应碱胁迫的关键指标。结果表明：1）碱胁迫条件下‘中花11’的根系生长特征（根系总长度、根系总表面积、根系平均直径、根体积）和根系活力降幅大于‘宁粳52’，根系脂氧合酶（LOX）活性、丙二醛（MDA）含量、活性氧（O₂^·-、H₂O₂）含量均显著高于‘宁粳52’，而根系渗透调节物质[可溶性糖（SS）、可溶性蛋白（SP）和游离脯氨酸（Pro）]含量、抗氧化酶[超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）]活性、还原型抗坏血酸（ASA）和还原型谷胱甘肽（GSH）含量增幅均低于‘宁粳52’。2）在‘中花11’中，20C（碱浓度为20 mmol·L^-1，pH 10.50）处理下根系平均直径、根系活力低于30A（碱浓度为30 mmol·L^-1，pH 8.65）处理，MDA含量、LOX活性、O₂^·-产生速率、H₂O₂含量显著高于30A处理，即高pH低碱浓度对水稻的伤害大于低pH高碱浓度引起的伤害。3）冗余（RDA）分析表明Na⁺和pH的增加与供试水稻各生长指标的升高呈负相关，与抗逆生理指标的升高呈正相关。4）逐步回归分析表明，ASA、SS和H₂O₂含量是‘中花11’响应碱胁迫较为敏感的指标；根系平均直径、根系总表面积、根系活力、Pro、SS、SOD、POD和GSH是‘宁粳52’响应碱胁迫较为敏感的指标。综上，碱浓度和pH胁迫均影响了供试水稻根系生长特征和生理特性，在碱化土壤中栽培水稻需要同时考虑碱分组成和pH的影响，不同水稻品种在抵御碱胁迫时会启动不同的防御策略。
关键词:水稻/
碱胁迫/
pH/
根系/
生长/
生理/
响应策略
Abstract:This study aimed to investigate the physiological differences and coping strategies of the roots of rice varieties with different tolerances to alkali stress. In this experiment, alkali-sensitive rice variety 'Zhonghua 11' and alkali-tolerant rice variety 'Ninggeng 52' were subjected to nine alkali stress using two types of alkaline salts (sodium bicarbonate and sodium carbonate) in three alkali concentration levels (10 mmol·L^-1, 20 mmol·L^-1, and 30 mmol·L^-1) and three pH levels (8.65, 9.55, and 10.50). The effects of alkali stress on the root growth and stress resistance of rice seedlings were examined. Through stepwise regression analysis, the optimal regression equation was established, and the key indices of the response of different rice varieties to alkali stress were screened. The results showed that: 1) the decline of root growth characteristics (total root length, total root surface area, average root diameter, and root volume) and root activity of 'Zhonghua 11' were greater than those of 'Ninggeng 52' (P < 0.05). The lysyl oxidase (LOX), malondialdehyde (MDA), superoxide anion (O₂^·-) producing rate, and hydrogen peroxide (H₂O₂) content in the roots of 'Zhonghua 11' were significantly higher than those of 'Ninggeng 52' (P < 0.05). The content of osmotic adjustment substances[soluble sugar (SS), soluble protein (SP), free proline (Pro)], the activities of antioxidant enzymes[superoxide dismutase (SOD), peroxidase (POD), catalase (CAT)], reduced ascorbic acid (ASA), and reduced glutathione (GSH) in the roots of 'Zhonghua 11' were lower than those of 'Ninggeng 52'. 2) In 'Zhonghua 11', the average root diameter and root activity of the 20C treatment (20 mmol·L^-1, pH 10.50) were lower than those of the 30A treatment (30 mmol·L^-1, pH 8.65). The MDA content, LOX activity, O₂^·- production rate, and H₂O₂ content of the 20C treatment were significantly higher than those of the 30A treatment, and the damage caused by high pH and a low alkali concentration was greater than that of low pH and a high alkali concentration. 3) Redundancy analysis showed that the increase in sodium ions (Na⁺) and pH was negatively correlated with the increased growth indexes and positively correlated with increases in the physiological indexes for the tested rice varieties. 4) Stepwise regression analysis showed that the ASA, SS, and H₂O₂ contents were sensitive indicators of alkali stress in 'Zhonghua 11'. The average root diameter, total root surface area, root activity, Pro content, SS content, SOD activity, POD activity, and GSH content were the sensitive indexes of alkali stress for 'Ninggeng 52'. In summary, alkali and pH stress affected the growth and physiological characteristics of rice roots of rice. The effects of alkali composition and pH must be considered when cultivating rice in alkaline soil, as different rice varieties initiate different defense strategies against different alkali stresses.
Key words:Rice/
Alkali stress/
pH/
Root system/
Growth/
Physiological/
Response strategy



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