【作者】 王丽娟；

【导师】 李青丰；

【作者基本信息】 内蒙古农业大学 ， 草业科学， 2008， 博士

【摘要】 本文报道了披碱草(Elymus dahuricus)等8种牧草种子的萌发特性和其对高温胁迫的反应。研究了内蒙古呼和浩特地区牧草种子播期的气温及土壤温度的变化节律,以及温度变化对披碱草、老芒麦(Elymu sibiricus)、蒙古冰草(Agropyron mongolicum)和缘毛雀麦(Bromus ciliatus)等4种牧草萌发成苗的影响。对种子的吸水和萌发特性进行了测定。利用水分预调法对种子进行了旨在促进萌发和提高种子抗高温能力的处理。探讨了水分预调处理对种子萌发的影响及水分预调的生理生化基础。研究旨在为确定内蒙古地区牧草适宜的播种时期,及种子播前处理方式提供理论依据。主要研究成果如下:1、对发芽率、死亡率、休眠率、畸形苗率、峰值、日平均发芽率、发芽值、发芽系数、发芽指数、胚芽干重和活力指数这10个种子活力测定指标进行筛选。研究结果表明,发芽率、发芽指数、活力指数、死亡率和休眠率这5个测定指标能够较真实、全面地反映种子活力水平。在不良的环境条件中,死亡率和休眠率是评价种子活力的较好指标。2、供试牧草种子的适宜萌发温度为15～35℃;披碱草、老芒麦、蒙古冰草和缘毛雀麦种子萌发的最适温度分别为25℃、25℃或20/30℃、20/40℃或20/30℃和20/30℃。豌豆种子的发芽能力在恒温15℃和变温20/30℃下较好。毛苕子的最适萌发温度为10/20℃的变温。沙打旺和敖汉苜蓿种子的最适萌发温度为20℃。供试牧草种子在变温环境条件下的萌发表现较好,发芽率、发芽指数和活力指数等各项萌发指标均较高,而休眠率和死亡率均较低。3、通过对内蒙古地区4至8月份的气温及土壤温度的测定和研究,指出牧草种子的适宜播种时期为:在内蒙古呼和浩特地区适宜在5月末到7月初进行播种;呼伦贝尔地区适宜在6月份播种;兴安盟的巴彦胡硕地区和通辽科尔沁地区在5月末播种较好;乌兰察布和鄂尔多斯地区牧草最好在秋季进行播种,但不宜晚于8月初。4、牧草种子在吸水的过程中,吸水速度先快后慢,最后达到吸胀状态,种子进入萌发准备阶段。四种供试牧草种子,蒙古冰草种子的吸水能力最强;披碱草和老芒麦种子相若,居第二;缘毛雀麦种子的吸水能力最弱。5、种子经吸湿未回干处理后,能够提高其发芽速度和发芽率,但对其成苗及幼苗的耐旱性有降低的影响。吸湿回干处理能够显著提高蒙古冰草和缘毛雀麦种子的发芽率;对披碱草、老芒麦种子没有显著影响。在吸湿程度较低的情况下,吸湿回干处理能够提高种子的活力指数,尤其是在吸湿达最大吸水率30%的处理,表现最为显著。种子在吸湿程度较高的情况下,对其发芽率和发芽指数有负面影响。吸湿回干处理能够在一定程度上,提高种子对高温逆境的耐性和抵抗能力。吸湿回干处理能够不同程度地提高种子的出苗率,其有随着吸胀程度的增加而提高的趋势;但处理降低了幼苗的耐旱性(披碱草种子吸湿达最大吸水率的30%处理除外)。湿干循环处理对披碱草、老芒麦、蒙古冰草和缘毛雀麦种子萌发的影响不同,蒙古冰草和缘毛雀麦的二次、三次回干对其种子萌发有降低的影响,其他处理均不显著。种子经过处理后,能够增强种子抵抗高温逆境的能力,披碱草、老芒麦和缘毛雀麦种子二次回干效果最好,蒙古冰草种子一次回干效果最好。6、吸湿回干处理对质膜完整性的恢复有一定的促进作用。能够提高种子脱氢酶和过氧化物酶活性。在吸湿程度较低的情况下,种子脱氢酶活性的提高较显著。披碱草和老芒麦种子在萌发48h种子过氧化物酶活性,各处理均比对照显著提高;蒙古冰草种子在萌发12h时,各处理均显著比对照增高;缘毛雀麦种子在萌发的48h、72h时,其种子吸湿达最大吸水率的30%处理酶活性显著比对照高。更多还原

【Abstract】 This thesis reports the study on germination behaviors and germination tolerance to high temperature of several forage seeds. Changes of ambient temperature and temperatures at different soil layers during sowing season were monitored and effects of temperature regimes on seed germinations of several grasses of Elymus dahuricus, E. sibiricus, Agropyron mongolicum and Bromus ciliatus were investigated. Seed imbibition and germination characters were observed and measurements on seed germination after hydro-conditioning treatments were conducted. Biological and physiological responses of seed germination to the hydro-treatments were probed. The aim of the study is to search for the optimum sowing times based on seed germination requirement and temperature conditions in the sowing season, and to seek the possibility of pre-sowing treatment in improving seed germination performance in order to overcome the difficulties for herbage crop seedling establishment in the Northern China grassland region. Main research results are summarized as follow:1, Ten measurement indexes, i.e., germination percentage, dead seed percentage, dormant seed percentage, abnormal seedling percentage, peak germination percentage, daily germination percentage, final germination rate, germination co-efficiency, germination index, seedling weight and vigour index, are evaluated for their contributions to germination performance. The results showed that germination percentage, germination index, vigour index, dead seed percentage and dormant seed percentage are the most important indicators reflecting seed vigour level. Under unfavourable conditions, dead seed percentage and seed dormancy were the best alternative indicators, which can be used as reliable indexes for evaluating seed vigour when other measurements were not so effective.2, Suitable germination temperature for the tested seeds is in the range of 15-35℃. Optimum germination temperatures for the grasses seeds of E. dahulicum, E. Sibricus, A. mongolicum and B. ciliatus are 25℃, 25℃or 20/30℃, 20/40℃and 20/30℃, respectively. Optimum germination temperatures for the legume seeds of Pisum sativum, Vicia sativa, Astragalus adsurgens and Medicago sativa cv“Aohan”are E. dahulicum, E. Sibricus, A. mongolicum and B. ciliatus are 15℃or 20/30℃, 10/20℃, 20℃and 20℃, respectively. High germination percentage, high germination index and high vigour index were observed under alternative temperatures. In contract, low dormancy percentage and low dead seed percentage were observed under the alternative temperatures.3, Research on ambient and soil temperature changes during the period from April to August indicated that end of May to early July is the most suitable sowing time for the tested species in Hohhot area. Optimum sowing times for Hulunbeer area, Bayanhusu in Xingan League and Kerqin area, Wulanchabu and Erdos areas are in June, end of May, Autumn, respectively. No sowing should be made later than early August.4, In regards to the seed imbibition behavours, tested seeds showed a fast-slow imbibition pattern. Agropyron mongolicum has the strongest imbibition capacity. Elymus species have similar imbibition capacities. Bromus ciliatus has the lowest imbibiton capacity.5, The results of hydro-treatments showed that germination performances, in terms of germination speed and percentage, were enhanced by hydration treatments. However, the treatment reduced the seedling establishment and drought resistances of the seeds. Hydration - dehydration treatments had little effect on germination speeds and percentages of E. dahuricum and E. sibiricus. Low imbibition enhanced germination percentages of A. mongolicum and B. ciliatus High imbibation rates reduce seed germination percentages and seed vigour. Hydration-dehydration treatments enhanced seed vigour levels. Maximum enhancement was found when the seed had a moisture content of 30% of maximum imbibition. Hydration-dehydration treatments enhance seedling emergency rates, but reduce drought resistances of seedlings (except for the seeds of E. sibiricus in 30% of maximum imbibation. Two or three cycles of hydration-dehydration reduce germanition percentages of A. mongolicum and B. ciliatus seeds, but have little effects on other seeds. In summary, hydro-treatments had complicated effects on the seeds under different treatment conditions and seeds of different species had various responses to the treatments. Suitable hydration-dehydration treatments fordiferent seeds are recommended.6, Hydration-dehydration treatment has positive effects on membrane re-organization, enhancing dehydration and peroxide enzyme activities. Under low imbibition conditions, dehydration enzyme activities have been greatly enhanced. Peroxide enzyme activities are enhanced after 48 hours of seed germination for E. dahuricum and E. sibiricus seeds under hydration-dehydration treatments. For A. mongolicum seeds, high peroxide enzyme activity is enhanced at 12 hours after germination. High enzyme activities were found at 48 hours and 72 hours after germination for B. ciliatus with T30 treatments.更多还原