Sexual Reproduction Characteristics Of Kengyilia Thoroldiana

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.