人工模拟降雨格局变化对红砂种子萌发的影响

气候变化改变降雨格局,会影响到种子出苗及幼苗生长,进而影响幼苗的更新动态。为探讨降雨格局变化对典型荒漠植物红砂种子萌发特性的影响,利用环境控制生长箱开展了降雨量和降雨间隔时间的双因素控制实验。结果表明:(1)总降雨量增加30%,红砂种子出苗率和发芽势分别平均提高45.69%、39.86%(P0.05),延长降雨间隔时间单次降雨量达到6mm其效果更明显,出苗率和发芽势达到最大值,分别为68.33%、63.33%,表明6mm降水量是促使红砂萌发的最小降雨阈量。(2)总降雨量增加30%显著提高了种子萌发指数和活力指数(P0.05),与自然总降雨量相比,分别平均提高57.67%、121%。总降雨量减少30%虽降低了萌发指数和活力指数,但与自然总降雨量相比差异不显著(P0.05)。(3)降雨量增加30%延长降雨间隔时间处理加快了红砂的萌发进程,缩短了种子的萌发持续时间,其萌发曲线较陡峭。降雨量减少30%对其种子萌发进程影响不大。该研究得到以下主要结论:1)红砂种子萌发主要受到降雨量的影响,但降雨量效应依赖降雨间隔时间,总降雨量一定降雨间隔延长所形成的单次降雨量增加均提高萌发率,增加了红砂繁殖成功率,对其幼苗更新起促进效应;2)在自然状态及降雨减少的情况下红砂种子具有推迟萌发的特性,使其幼苗在更适宜的环境条件下出现和生长的机会增多,从而提高植物对环境的长期适应性。

Effects of simulated precipitation change on seed germination of Reaumuria soongorica

Seed germination is considered to be the most important and sensitive factor in response to changes in the moisture and heat phases during the natural process of plant regeneration. The northwest arid areas of China are drought areas that are most sensitive to precipitation changes. Reaumuria soongorica, a super-xerophytic shrub, exhibits a strong tolerance to drought, cold, saline-alkali soil, and barren landscapes, and is a long-lived species. Our objective was to investigate how precipitation changes affect the physiological and ecological processes of seeds of R. soongorica to determine the regeneration mechanisms and changes in the patterns of this key species. Seeds of R. soongorica were collected in the fall of 2013 at the Linze Inland River Basin Research Station of the Chinese Academy of Sciences. We set up a growth-chamber experiment with two factors:precipitation quantity (natural precipitation as a control, reduction of 30%, and increase of 30%) and interval (time elapsed between two precipitation events, 5 and 10 days). Germinated seeds were counted daily until the end of germination. The results showed that increasing precipitation (+30%) resulted in a significantly enhanced germination rate and germination potential by an average of 45.69% and 39.86%, respectively, especially when the precipitation interval was extended from 5 to 10 days (a single rainfall reached up to 6 mm). In addition, the germination rate and potential reached their maxima by an average of 68.33% and 63.33%, respectively. Therefore, the rainfall threshold for the germination of R. soongorica was determined to be 6 mm. The germination index and vigor index were significantly increased by an average of 57.67% and 121% (P < 0.05), respectively, with increasing precipitation quantity (+30%). Extension of the precipitation interval under increasing precipitation (+30%) resulted in a reduced germination index and vigor index, but the effect was not statistically significant. Increasing precipitation (+30%) under the extended precipitation interval treatments accelerated the course of germination, and the germination periods were shorter. Reducing the precipitation by 30% had no significant effects on the course of germination. Therefore, seed germination was mainly affected by precipitation quantity, but the effect was dependent on the precipitation interval. Overall, the seed germination percentage increased under a precipitation pattern of increasing precipitation (+30%) with an extended precipitation interval, the breeding success rate and seedling establishment ability were enhanced, and seedling regeneration was promoted. R. soongorica showed characteristics of delayed germination under the condition of natural rainfall and reduced precipitation(-30%), which could increase the seedling emergence and growth of the seedlings under further favorable environmental conditions and improve the long-term adaptability of plants to the environment.