NaCl胁迫对马唐种子萌发及幼苗生理特性的影响

旨在明确NaCl胁迫对马唐种子萌发及生理特性的影响，为直播稻田马唐适生区域的预测及综合治理提供参考。以马唐种子为材料，采用0、10、30、60、100、150和300 mmol·L^-1 NaCl溶液进行培养，测定马唐种子各萌发指标，并对幼苗生物量及马唐体内叶绿素含量（chlorophyll）、丙二醛含量（malondialde-hyde, MDA）、根系活力（root activity）、超氧化物歧化酶活力（superoxide dismutase, SOD）及过氧化物酶活力（peroxidase, POD）进行比较。结果显示：随着NaCl浓度升高，马唐种子萌发率、相对萌发率、萌发势、萌发指数及胚根和胚芽长度均呈持续下降趋势，而相对盐害率逐渐增强，浓度达300 mmol·L^-1时种子停止萌发；当NaCl浓度为60 mmol·L^-1时，马唐的胚根和胚芽长均达对照水平。马唐幼苗鲜质量随NaCl溶液浓度升高基本呈下降趋势，幼苗干质量较对照无明显差异（P < 0.05）。幼苗的叶绿素含量随NaCl浓度升高逐渐降低；当NaCl浓度为60 mmol·L^-1时，马唐根系活力、SOD活力与对照相比均增加；MDA含量受NaCl胁迫后较对照升高，在NaCl浓度为300 mmol·L^-1时较对照显著增加（P < 0.05）。研究结果显示马唐萌发对NaCl胁迫的适应范围较宽，幼苗具有较强的耐盐能力。

Effects of NaCl stress on seed germination and seedling physiological characteristics of Digitaria sanguinalis

The purpose of this paper is to clarify the effects of NaCl stress on seed germination and physiological characteristics of Digitaria sanguinalis, and to predict and comprehensively manage the suitable area of D. sanguinalis in direct seeding rice fields. The seeds of D. sanguinalis were cultured in 0, 10, 30, 60, 100, 150 and 300 mmol·L^-1 NaCl solution, the germination indexes of D. sanguinalis seeds were determined, and the seedling biomass, chlorophyll content, malondialde-hyde (MDA) content, root activity, superoxide dismutase (SOD) activity and peroxidase (POD) activity were compared. The results showed that with the increase of NaCl concentration, the seed germination rate, relative germination rate, germination potential, germination index, radicle and germ length showed a continuous downward trend, and the relative salt injury index increased gradually. When the concentration reached 300 mmol·L^-1, the seed stopped germination; when NaCl concentration was 60 mmol·L^-1, the radicle and germ length of D. sanguinalis reached the control level. The fresh quality of seedlings decreased with the increase of NaCl concentration, and there was no significant difference in dry quality of seedlings compared with the control (P<0.05). The chlorophyll content of the seedlings gradually decreased with the increase of NaCl concentration. At NaCl concentration of 60 mmol·L^-1, the root activity and SOD activity increased compared with the control. MDA content increased under NaCl treatment compared with the untreated control, and it increased significantly when NaCl concentration was 300 mmol·L^-1 (P<0.05). The results indicated that the germination of D. sanguinalis has a wide range of adaptation to NaCl stress, and the seedlings have strong salt tolerance.