NaCl胁迫对不同耐盐性水稻某些生理特性和光合特性的影响

选取较耐盐的水稻品种‘HH11’、‘JX99’和盐敏感水稻品种‘YSXD’,设置6个土壤NaCl浓度处理(0、1、2、3、4 g/kg),在防雨棚下盆栽并培育至孕穗期,分析NaCl胁迫对不同耐盐性水稻生理生化及光合特性的影响,结果表明:(1)NaCl胁迫抑制水稻的生长,表现为随着NaCl浓度增加,水稻的株高逐渐降低,但在3～4 g/kg土壤含盐量下耐盐水稻的株高显著高于盐敏感水稻品种。(2)耐盐水稻和盐敏感水稻的可溶性总糖对NaCl胁迫的响应差异明显,在1～4 g/kg NaCl胁迫下,盐敏感水稻叶片可溶性总糖显著降低,但是耐盐水稻可溶性总糖大量合成并积累,并且显著高于盐敏感品种。(3)NaCl浓度增加迫使水稻叶片丙二醛不断积累,导致细胞膜透性逐渐增大,但是耐盐水稻丙二醛的积累量较少,细胞膜受盐害程度显著小于盐敏感水稻。(4)NaCl胁迫抑制了水稻光合速率,但不同的NaCl浓度下导致水稻品种光合速率下降的原因各有差异,其中在0～1 g/kg NaCl胁迫下盐敏感水稻光合速率降低是非气孔因素导致的,而在2～4 g/kg NaCl胁迫下是由气孔因素造成的;0～2g/kg盐浓度下耐盐水稻HH11的光合速率降低是非气孔因素导致的,3～4 g/kg盐浓度处理是由气孔因素导致的;气孔因素是0～4 g/kg盐处理耐盐水稻JX99的光合速率降低的主要原因。(5)盐胁迫下耐盐水稻的叶片蒸腾速率显著降低,并且显著低于盐敏感水稻,相反水分利用效率和气孔限制值却明显升高,并且显著高于盐敏感水稻品种,表明盐浓度增加迫使耐盐水稻气孔阻力增大,减少水分的流失,抑制了蒸腾速率,使耐盐水稻叶片保持较高的水势;同时提高了叶片水分利用效率,碳同化效率提高,以满足耐盐水稻正常代谢生理需求,进行正常生命活动。

Effects of NaCl Stress on Some Physiological and Biochemical Indices and Photosynthetic Physiology Characteristics of Rice Cultivars with Different Salt Tolerance

Two salt tolerances rice varieties ‘HH11’, ‘JX99’ and a salt-sensitive rice variety‘YSXD’ were cultured by a pot experiment until booting stage under soil salinity stress of 0, 1, 2, 3, 4 g/kg in a rainproof greenhouse. The study aimed to analyze the effects of NaCl stress on the physiological and biochemical indices and photosynthetic characteristics of rice varieties under salinity stress. Salinity stress inhibited the growth of rice, and the plant height of rice decreased with the increase of NaCl concentration, but the plant height of salt-tolerant rice was significantly higher than that of the salt-sensitive one under soil salt treatments of 3-4 g/kg. The response of soluble total sugars of the two salt-tolerant rice varieties and salt-sensitive rice variety to NaCl stress showed significant differences. The soluble total sugar of the salt-tolerant rice varieties was significantly higher than that of the salt-sensitive rice variety, but that of salt-sensitive rice variety significantly decreased under 1-4 g/kg NaCl concentration. The content of malondialdehyde in the leaves increased with an increase of NaCl concentration, which resulted in increased cell membrane permeability. The content of malondialdehyde in salt-tolerant rice varieties was less than that in salt-sensitive rice variety, and the cell membrane permeability of the salt-tolerant rice varieties was significantly lower than salt-sensitive rice variety. NaCl stress inhibited the photosynthetic rate of rice,but the reasons for the drop of photosynthetic rate caused by different NaCl concentrations were different. The decline of photosynthetic rate in salt-sensitive rice varieties resulted from non-stomatal limitation under 0-1 g/kg NaCl concentration, but which was caused by stomatal limitation under 2-4 g/kg NaCl concentration. The decline of photosynthetic rate in salt-tolerant rice variety HH11 resulted from non-stomatal limitation under 0-2 g/kg NaCl concentration, but which was caused by stomatal limitation under 3-4 g/kg NaCl concentration. Stomatal limitation was the main reason for the drop of photosynthetic rate of salt-tolerant rice variety JX99 under 0-2 g/kg NaCl concentration. Leaf transpiration rate in salt-tolerant rice variety was significantly decreased, and that was significantly lower than that of the salt-sensitive rice variety, but water use efficiency and stomatal limited value were significantly increased and were significantly higher than that of the salt-sensitive rice varieties under salinity stress. The results showed that salt concentration increased stomatal limited value, reduced water loss, inhibited transpiration rate and improved leaf water use efficiency to meet the needs of normal metabolic physiology of salt-tolerant rice varieties to maintain normal life activities.