播于土表种子萌发及其幼苗定居研究初探

飞播成功与否，关键问题之一就是适宜飞播种子的选择，不同种子在土壤表面上具有不同的萌发成苗率。为此，以蒙农红豆草（Onobrychis viciifolia cv.Mengnong）、沙打旺（Astragalus adsurgens）、沙鞭（Psammochloa villosa）和沙地雀麦（Bromus ircutensis）种子为试验材料，在25 ℃，土壤含水量20%条件下，对种子在土表上的萌发行为及其幼苗定居进行研究，为选择适宜土表播种的牧草种子提供理论依据。结果表明，1）4种种子中沙鞭全固着型（Ⅰ型）占总发芽种子比例最高（60%），另外3种均约35%； 2）在3种萌发行为中，蒙农红豆草全固着型（Ⅰ型）发芽指数（沙鞭除外）及活力指数较大，且与其他3种种子有明显差异； 3）4种种子幼根生长阶段，除沙打旺外，全固着型（Ⅰ型）的幼根几乎100%进入土壤，且伸入土壤所需时间表现为蒙农红豆草最短，沙地雀麦与沙鞭较长。综合来看，在此条件下，蒙农红豆草种子较大，萌发后幼根可迅速伸入土壤，躲避不利的环境条件，是较为适宜的表播种子。

Seed germination and seedling settlement by sowing seeds on soil surface

It is important to choose appropriate seeds whether aerial seeding is successful because of different germination rates of seeds on the soil surface.In this study,the seed germination of Onobrychis viciifolia cv.mengnong,Astragalus adsurgens,Psammochloa villosa and Bromus ircutensis on the soil surface and their seedling settlement at 25 ℃ and 20% soil moisture was measured to provide the theoretical basis for the selection of suitable grass seeds,which is suitable for sowing on soil surface.This study showed that the germination rates of P.villosa of completely sessile type(Ⅰ type) was the highest(60%) and the others were about 35%;In three germination behavior,germination index and vigor index of O.viciifolia cv.mengnong(Ⅰ type) were higher than that of others and had significantly difference,except P.villosa;Except A.adsurgens,the young root development of four plants of Ⅰ type almost completely inserted into the soil during growth stage,indicating that the O.viciifolia cv.mengnong spent shorter time to insert into the soil than B.ircutensis and P.villosa did.Comprehensive comparison showed that the seeds of O.viciifolia cv.mengnong were bigger than that of others and inserted into the soil quickly when they germinated fast to avoid adverse environmental conditions.This study suggested that O.viciifolia cv.mengnong was suitable for sowing its seeds on soil surface.