硅对NaCl胁迫下甜瓜种子萌发及幼苗生长的影响

为明确硅(silicon,Si)对盐胁迫的缓解作用,以“雪梨一号”和“朗秦银蜜”两个耐盐性不同的甜瓜品种为材料,在125 mmol/L NaCl胁迫下,研究了不同浓度外源Si对甜瓜种子萌发和幼苗生长的影响。结果表明,NaCl胁迫显著抑制了甜瓜种子萌发,0.50~1.00 mmol/L外源Si处理较对照能显著提高种子的发芽率、发芽势、发芽指数、α-淀粉酶活性及吸水率,其中两个品种的种子均以0.75 mmol/L外源Si处理效果最好;NaCl胁迫下,0.25~1.00 mmol/L外源Si处理后,甜瓜幼苗的株高、叶面积、叶绿素含量、地上部分干重和根系干重较对照显著提高,其中“朗秦银蜜”和“雪梨一号”幼苗分别以0.50和0.75 mmol/L外源Si处理效果最好。研究表明,0.25~1.00 mmol/L外源Si能促进NaCl胁迫下种子吸水和α-淀粉酶活性的提高来促进种子萌发,通过提高NaCl胁迫下幼苗叶绿素含量维持较高的光合能力促进幼苗生长,缓解盐胁迫对甜瓜种子和幼苗的伤害,外源Si浓度超过1.25 mmol/L时对盐胁迫没有缓解效应。

Effects of exogenous silicon on melon seed germination and the growth of seedlings under NaCl stress

The effects of exogenous silicon on the growth of melon under salt stress were investigated. Seedlings of two melon cultivars (Xueli No.1 and Longqinyinmi) with different salt tolerance were grown with 125 mmol/L NaCl stress Exposure to 125 mmol/L NaCl stress significantly inhibited melon seed germination. Compared with control, treatments with 0.5-1.0 mmol/L exogenous silicon significantly increased seed germination rate, germination energy, germination index, alpha-amylase activity and water absorption and the treatment with 0.75 mmol/L exogenous silicon performed best. In addition, melon seedlings with 0.25-1.00 mmol/L silicon exposed to 125 mmol/L NaCl had significantly increased plant height, leaf area, chlorophyll content, shoot dry weight and root dry weight, compared to controls. Treatment with 0.50 mmol/L was optimal for Longqinyinmi, while 0.75 mmol/L gave best results for Xueli No.1. These results indicate that exogenous silicon concentration from 0.50 mmol/L to 0.75 mmol/L can promote melon seed germination by enhancing alpha-amylase activity and water absorption, and promote seedling growth by increasing chlorophyll content and photosynthesis capacity under salt stress. When the silicon concentration was more than 1.25 mmol/L, there was no effect on the seed germination and growth of seedlings under salt stress.