【作者】 李长慧；

【导师】 孙启忠；

【作者基本信息】 中国农业科学院 ， 草业科学， 2014， 博士

【摘要】 梭罗草（Kengyilia thoroldiana）主要分布于青藏高原海拔3500-5000m的高寒草原上，具有叶量相对丰富、抗寒、抗旱、耐盐碱的特点，是恢复重建退化高寒草原的首选草种，但是生产中存在结实率低、种子产量低的问题。2010-2013年，在西宁市采用显微观察法、定株观测法、TTC法和仪器分析等方法，对梭罗草幼穗分化、开花习性、花粉活力、柱头可授性、结实特性、生殖分配做了观察和测定，以揭示种群有性繁殖体的形成机理，为提高种子生产提供理论依据。其结果如下：1、生长锥分化始于秋季，至翌年5月底结束，返青后分化的时间短暂。分化过程是一个具有明显特征的连续过程，可分初生期、伸长期、结节期、小穗突起期、颖片突起期、小花突起期、雌雄蕊形成期和抽穗始期8个时期；复穗状花序中上部小穗分化发育最早，然后依次向上、向下进行；每个小穗则是基部先分化,然后向上依次进行；2、单株花期平均为7d，不利于梭罗草的充分授粉。单株花序开花第1d的开花率比较低，平均为6.35%，然后随开花天数的延长而增加，到第4d达到最高值22.56%，然后逐渐下降。种群开花持续时间约为15d。从开花起的1～2d内，小花开放的时间较晚，一般集中在下午的3:00～4:00，以后开花高峰时间为9:00～14:00，夜间没有发现小花开放的现象。小花的闭合时间一般集中在19:00～20:00。在梭罗草的整个花期中，梭罗草开花相对百分率与温度呈正相关关系，与湿度呈负相关。3、早晨花粉活力较低，随着时间的推移，花粉活力逐渐提高，上午11:00达到峰值，直到下午3:00以后逐渐下降。开花第1d花粉活力较低，第2d到第4d是花粉活力的高峰，第4d过后，其活性显著降低。总体来讲，花粉活力较低，均在54%以下。小穗不同部位而花粉活性有所不同，花粉活性由高到低依次为：基部﹥中部﹥上部。梭罗草柱头为柱状，早晨柱头的可授性不是很高，中午前后柱头可授性较早晚稍高一些。开花第1d柱头具有可授性，但是可授性较低；开花2～5d可授性强，然后下降；开花后第9d柱头几乎没有可授性。小穗不同部位柱头的可授性由大到小依次为：基部﹥中部﹥顶部。在套袋的情况下有32%的结实率。小穗不同部位的可育花、不育花和结实率均有所不同，结实率由高到低依次为：基部>中部>顶部。4、生殖枝的生物量分配在花期、乳熟期、蜡熟期、完熟期内呈现先增加后减小的趋势，而根茎的生物量分配与之相反，在蜡熟期至完熟期，增长速度最快。生殖枝的总能量中用于小穗生产的能量分配比例较低，平均只有20.05%。小穗在有性生殖的主要构件中能量、氮素和磷的繁殖分配都显著低于营养枝的茎叶，不利于种籽的形成的；5、穗分化时间短、花期短暂、花粉活力低、柱头可授性低、不育花所占的比例高，小穗的能量、氮、磷繁殖分配低是影响梭罗草结实率的主要因素。更多还原

【Abstract】 Kengyilia thoroldina is mainly distributed in alpine steppe of Qinghai-tibet plateau, whose altitudeis3500-5000m. Kengyilia thoroldiana is tall plant with relatively abundant leaf quantity, cold resistance,drought resistance, salt resistance. It was the preferred variety for recovery and reconstruction of alpinegrassland degradation, but seed maturity rate and seed production is low. During2010to2013,its youngspike differentiation, flowering habit, pollen vitality, stigma pollination, seed maturity degree,reproductive allocation were observed and determinate by microdissection, positioning observation,TTC method and instrument analysis method in Xining City and the principle of population sexualpropagule formation was revealed. The theoretical basis for improving the seed production wasProvided. The results are as follows.1. The growing tip differentiation of Kengyilia thoroldina started in the fall, and ended in late May.Its differentiation time was short after turning green. The spike differentiation of Kengyilia thoroldianawas a consecutive process and presented a series of significant change in morphological characteristics,and this consecutive process could be divided into8stages: primary growth stage, elongation stage,single ridge stage, spikelet protuberances stage, glume protuberances stage, floret differentiation stage,gynoecium and stamen initiation stage, heading stage. During the process of differentiation, on thewhole spike, the middle and upper parts of the spikelet developed first, and then gradually upward anddownward in turn, the basal spikelet developed last. Flowering began from the top of the spikes, andthen continued downward. On the single spikelet, the base part of the floret developed first, thendeveloped from base to top gradually.2. The flowering period of Kengyilia thoroldiana was short, per plant average flowering period is7d, not conducive to adequately pollination. Flowering rate of inflorescence of per plant was low in firstday with an average of6.35%, and then increased with the extension of flowering days. In fourth day,reached to the highest of22.56%, and then gradually declined. The flowering duration of populationswas about15d. Within1~2d from flowering, small flower opened late, generally concentrated in theafternoon from3to4, and then flowering was between9:00and14:00, it was not found that flowersopen at night. The closure time of floret generally focused on between19:00and20:00. In wholeflowering period, relative percentage of flowering was positively correlated with temperature, andnegatively correlated with humidity.3. The pollen vitality of Kengyilia thoroldiana was low in the morning, with the passage of time,the pollen vitality gradually improved, peaked at11:00am, and then gradually declined until after3:00PM. Pollen vitality was low in first day of flowering, the pollen vitality reached peak between2daysand4days, and then significantly reduced. In general, low pollen vitality, were all below54%. Atdifferent positions of the spikelet had different pollen activity, and the pollen activity from high to lowwas: the base＞middle central＞upper central. Thoreau grass stigma was columnar, in the morningpollination of stigma was not very high, around noon pollination was a little higher than in morning and night. In first day of flowering stigma could pollen, but was low. In2~5days of flowering, pollinationwas strong, and then decreased; In9days of flowering, stigma hardly can be pollinated. In thedifferent parts of spikelet, stigma pollination was: the base＞middle central＞upper central. In thecase of a sack, setting rate of seed was32%. In different parts of spikelet, fertile flower, unfertile flowerand seed setting rate were different, and seed setting rate from high to low was: the base> the middle>the upper.4. In flowering, buds, ripening period, full ripeness period, the biomass allocation of reproductivebranches showed a trend from increasing to decreasing. The biomass allocation of root and stem showedthe contrary trend, and from the ripening stage to full ripeness period showed the fastest growing. In thetotal energy of reproductive branches, proportion of energy allocation used in production of spikeletwas lower with an average of only20.05%. Reproductive allocation of energy, nitrogen and phosphorusin organ growth of spikelet were significantly lower than that of stem and leaf of vegetative branches,not conducive to the formation of the seeds.5. Reproductive allocation of energy, nitrogen and phosphorus in organ growth of spikelet weresignificantly lower than that of stem and leaf of vegetative branches, not conducive to the formation ofthe seeds.更多还原