PEG引发紫花苜蓿和沙打旺种子的生理生态效应

Physiological and ecological responses of alfalfa and milkvetch seed to PEG priming

牧草种子田间出苗率低是我国草业生产亟待解决的技术问题。采用较高渗透势和短时间的聚乙二醇引发技术(-0 .6MPa,2 4h) ,研究了引发对紫花苜蓿 (Med icago sativa )和沙打旺 (Astragalus adsurgens)不同质量种子萌发的促进作用及其生理生态效应。结果表明引发可显著 (p<0 .0 5)提高种子的早期发芽率和发芽指数 ,缩短达 3 0 %出苗的天数 ,但对最终发芽率无显著影响。引发效果因植物种、种批质量和萌发条件不同而异 ;其中 ,沙打旺大于紫花苜蓿 ,质量中等或中等偏下种批大于质量高或质量低的种批 ,在低温和干旱逆境条件下萌发大于适宜条件萌发。引发种子的丙二醛含量和水浸电导率极显著 (p<0 .0 1)低于对照 ;引发回干 2 4h种子的水浸电导率与引发种子的相当。引发种子在萌发吸水 0～ 3 0 h的吸水量极显著高于对照 ,在 2 4～ 72

Poor seedling emergence is one of the critical problems in grassland production in China.Osmotic polyethylene glycol (PEG 6000) priming technique (-0.6MPa, 24h) was used to study priming effects on seed germination and their physiological and ecological responses in different quality commercial seed lots of alfalfa (Medicago sativa) and milkvetch (Astragalus adsurgens). Results showed that PEG priming significantly enhanced (p<0.05) early germination and germination index, and reduced time required for 30% seedling germination, but did not influence final germination. The priming effects varied according to species, seed lot and germination conditions. Positive effects were more evident on milkvetch than alfalfa; for instance, with similar medium quality seed lots of the two species, the time during which significantly increased germination occurred was up to 6 days in milkvetch, but only 4 days in alfalfa. The effect on medium quality seed lots (germination of 65%~77% for alfalfa and 58%~75% for milkvetch) was more evident than those on high (germination of 83% for alfalfa and 88% for milkvetch) or low quality (germination of 48% for alfalfa and 36% for milkvetch). In addition, the effect on germination under lower temperature (10℃) or drought conditions (-0.6MPa) germination media was more evident than that in optimum conditions. Malondialdehyde (MDA) content and electrical conductivity of seed soaking leaches (EC) of primed seeds were significantly lower (p<0.01) than those of the control, and the values obtained indicated that MDA and EC of control seed was 3.3 and 3.2 times those of the primed seeds, respectively. The EC of seed re-dried for 24h after priming was equivalent to that of primed seed. Compared to control seed, water uptake rate of primed seed was significantly (p<0.01) increased during early imbibition (0 to 30h), while during the imbibition before 24 and 72h, free sugar and proline contents of primed seeds were significantly increased (p<0.05 for sugar and p<0.01 for proline).