新疆针茅传播体形态及埋深对种子萌发出苗的影响OA北大核心

Stipa sareptana,a perennial herb of the Poaceae,is an important community constructive and dominant species widely distributed in desert grassland of Xinjiang.This research studied the morphology of the dispersal unit,the function of the awn and the germination and emergence characteristics of S.sareptana seeds.The relationship between the morphology of each part of the dispersal unit and the buried depth was analyzed,and the effects of different burial depths on seed germination and seedling emergence were compared.The results show that:1)The dispersal unit is composed of lemma,palea and caryopsis.The base of the lemma is sharp and hairy with an anchoring capability.The lemma elongates to form an awn,and the elongated body of the awn is typically doubly bent.The length of the awn is 15 times than that of the seed.2)The awn is hygroscopic,and the hygroscopic awn drives a self-burial phenomenon of the dispersal unit.The burial depth achieved is(4.10±0.53)cm.3)Burial depth had a very significant effect on the seed germination percentage and seedling emergence percentage of S.sareptana seeds(P<0.01).The seeds germinated in the depth range of 0-12 cm,and emerged from depths<6 cm.The seed germination percentage and seedling emergence percentage were highest when the burial depth was 1-2 cm.When the burial depth exceeded 2 cm,the seed germination percentage and seedling emergence percentage were negatively correlated with the burial depth.4)The burial depth had a significant effect on the growth and biomass allocation of S.sareptana seedlings(P<0.01).When the buried depth increases,S.sareptana seedlings allocate more biomass to upward growth,thus promoting the growth of shoots above ground.The plasticity of biomass distribution is an important mechanism for S.sareptana to adjust to variation in burial depth.The unique dispersal unit structure of S.sareptana not only enhances the survival of seeds entering the soil,but also greatly improves the success rate of seed germination and subsequent seedling establishment.These seed properties are highly advantageous to the renewal and reproduction of S.sareptana populations.