盐碱胁迫和氮素供给对盐地碱蓬种子发芽与幼苗生长的影响

Effects of saline alkali stress and nitrogen supply on germination and seedling growth of Suaeda salsa

以蒸馏水、珍珠岩、盐碱土为基质,探究了水培、岩培、土培条件下盐碱胁迫和盐氮互作对盐地碱蓬种子发芽与幼苗生长的影响。结果表明,发芽阶段:发芽率随胁迫作用增强呈线性下降规律。含盐量从0.00%增至3.60%,发芽率自89%线性下降至0%,这一规律与所选基质无关。此外,以1.20%含盐量为界,此盐分含量以下,较水培、岩培,土培下各含盐量对应种子平均发芽率降低8.00%;高于此盐分含量,各含盐量对应种子发芽率趋同。说明当含盐量低于1.20%时,基质对种子发芽的影响大于盐分;盐分含量在1.20%基础上继续升高,基质对种子发芽影响甚微,盐分成为主导因素。成苗阶段:成苗率随胁迫作用增强呈先增后减的规律。盐分含量低于1.00%,成苗率随含盐量增加陡增,最高可达70%;盐分含量在1.00%基础上继续升高,成苗率缓慢下降,直至0%。说明一定盐分含量是幼芽保持较高成苗率的必要条件,含盐量升高或降低,盐地碱蓬都可能会被其他物种取代,群落将演替为以地带性植物为主的群落。生长阶段:盐分含量适宜时,氮素输入可有效促进盐地碱蓬生长,盐分过高,促进作用甚微。因此,以盐地碱蓬作为先锋物种改善和修复黄河三角洲盐碱土时,需考虑盐分和养分的交互作用。

The effects of different substrates;distilled water,pearlite and saline-alkali soil and saline-alkali stress on seed germination and seedling growth of Suaeda salsa was investigated.Increasing levels of saline al-kali stress significantly decreased seed germination of S .salsa.Salt content ranging from 0.00%-3.60% re-sulted in germination % falling from 89% to 0% linearly.The seed germination rate in the soil was lower than those in water and perlite by 8.00% when salt content was below 1.20%.Above 1.20% salt germination in different substrates were not different.The effect of substrate on seed germination is more important than sa-linity at salt contents below 1.20%,but salinity controls seed germination at salt contents above 1.20%.Seed-ling emergence increased to a peak value (70%)with the increase of salt content up to 1.00% and then declined gradually to 0% at salt concentrations above 1.00%.It appears that an optimal level of salinity is necessary for S .salsa seedlings to achieve a high survival rate.Salinity plays a dominant role for S .salsa during the growth period from bud to seedling stage and determines the formation of S .salsa community.Higher or lower salini-ty than optimum may result in the replacement of S .salsa by other plant species and consequently changes to zonal vegetation communities.When soil salinity is at an optimal level,nitrogen can effectively promote the growth of S .salsa.Elevated salt supply may hamper nitrogen uptake by S .salsa.The nitrogen required to maintain optimum growth of S .salsa may vary with salinity.Therefore,both salinity and nitrogen should be considered when utilising S .salsa as the pioneer species to restore the severely degraded saline soil in the Yellow River Delta.