不同温度条件下土壤颗粒组成对宽叶雀稗种子发芽与幼苗生长的影响

为探讨水土流失区表层土壤砂砾化环境对植物种子萌发及幼苗生长的影响,选取我国南方水土保持良种宽叶雀稗为试验材料,设置4个温度梯度(15、20、25、30 ℃),按不同径级的土壤颗粒组成配制5种不同程度砂砾化的土壤作为种子发芽基质,研究温度和土壤颗粒组成对宽叶雀稗种子萌发和幼苗生长的影响。结果表明:温度和土壤颗粒配比对宽叶雀稗种子发芽与幼苗生长均有显著影响。随着温度升高,宽叶雀稗种子发芽初始时间提前,发芽率稳定所需时间缩短,发芽速率加快;20、25 ℃时,种子发芽率与发芽势较高,地上部与根系生物量较大;20、25、30 ℃时,种子发芽指数、活力指数较高,苗高较高,根长较长;长度根冠比随着温度升高先降后升,25 ℃时最小。宽叶雀稗种子在土壤粗颗粒含量较高(>2 mm:1~2 mm:<1 mm=100%:0%:0%)时,种子发芽率、发芽势、发芽指数、活力指数均为最低;土壤粗细颗粒含量适中(>2 mm:1~2 mm:<1 mm=25%:37.5%:37.5%或50%:25%:25%)时,种子发芽指数、活力指数较高。苗高随着土壤粗颗粒含量的增加逐渐增大,根长、长度根冠比则随土壤粗颗粒比例的增加而降低,幼苗地上部与根系生物量则在土壤粗细颗粒含量适中(>2 mm:1~2 mm:<1 mm=50%:25%:25%或75%:12.5%:12.5%)时较高,说明土壤粗颗粒比例高有利于宽叶雀稗苗高生长,土壤细颗粒比例高有利于根系生长,土壤粗细颗粒比例适中有利于种子发芽及幼苗生物量的积累。

Effects of soil particle composition on seed germination and seedling growth of Paspalum wettsteinii under different temperatures

In order to explore the effects of soil surface texture (sand and fine gravel) on seed germination and seedling growth in regions vulnerable to soil erosion, the effects of temperature and soil particle composition on seed germination and seedling growth of Paspalum wettsteinii were assessed. The study utilized topsoil collected from eroding areas to use as substrate, with 4 different temperatures (15, 20, 25 and 30 ℃) and 5 soil mixtures created by mixing different soil particle composition based on soil particle diameter. The results showed that the temperature and soil particle composition had a significant influence on seed germination and seedling growth of P. wettsteinii. The time to initiation of seed germination after seeding reduced, the duration of seed germination shortened, and the germination rate increased as temperature rose from 15 to 30 ℃. The seed germination rate, germination energy and seedling biomass at 20 and 25 ℃ were higher than other temperatures. The germination index, vigor index and seedling growth at 20, 25, 30 ℃ were significantly higher than that at 15 ℃. The root-shoot ratio of seedlings initially decreased and then increased, but was lowest at 25 ℃. The seed germination indexes were lowest in the soil with the composition of 100% coarse particles and highest in the soil with the composition of 25% or 50% coarse particles. With increasing coarse particles, the seedling shoot height increased, while the root length and root-shoot ratio of growth decreased. The above-ground and root biomass of seedlings were higher in the soil with the composition of 50% or 75% coarse particles. The results indicated that high proportion of coarse-grained soil was beneficial to shoot growth, while harmful to root growth, and the soil with the composition of 25%, 50% or 75% of coarse particles was propitious to seed germination and the accumulation of seedling biomass.