不同模拟降水量下草地早熟禾根系形态与解剖结构的动态变化

以草地早熟禾为研究对象,采用人工控水模拟降水量的方法,比较对照组(浇水量为小雨组的60%),小雨组(24 h内的降水量小于10 mm)、中雨组(24 h内降水量为10~25 mm)、大雨组(24 h内降水量为25~50 mm)根系形态与解剖结构的差异,以探究不同模拟降水量对草地早熟禾根系发育的影响机制。结果表明,总体上处理组与对照组相比差异较为显著。在试验进程中,中雨组水分条件下草地早熟禾根系生长全程均良好。在根系构型方面,根长、根表面积、根总体积、根平均直径与根分叉数均显著增加,比根长与根干重密度较为稳定,各项根系构型数据均显示草地早熟禾在中雨组的水分处理下生长状况优于其他处理。在根系解剖方面,到生长第50 天时,对照组继续受干旱的影响,根系结构受损,中柱和导管直径显著变小,占根系直径比例减小;小雨组出现轻微干旱情况;中雨组根系解剖结构正常;大雨组出现水淹情况。以上结果表明,中雨组为最适合草地早熟禾生长的水分条件。

Changes in root morphology and anatomical structure of Poa pratensis under different simulated precipitation rates

This research studied the root development of Poa pratensis under four different levels of simulated precipitation. The simulated precipitation treatments were: heavy rain (HR, 25-50 mm precipitation each 24 h), moderate rain (MR, 10-25 mm precipitation each 24 hours), light rain (LR, <10 mm rainfall each 24 h) and control (CK, 60% of the simulated light rain). Treatments were maintained over an experimental period of 24 days. The research aim was to explore the effect of the different simulated precipitation rates on the development of the P. pratensis root system. It was found that the CK treatment was affected by drought and the HR group by flooding, whereas roots of the MR treatment grew well throughout the experiment. In terms of root morphology, root length, root surface area, total root volume, average root diameter and the number of root functions all increased significantly, specific root length and root dry weight density were more stable. Data root system configurations of the various treatments showed that the growth status of P. pratensis in the MR treatment was better than other treatments. In terms of root anatomical structure, by the 50th day, in the CK treatment affected by drought stress, the root structure was damaged, the ratio of cortex to root diameter, diameter of vascular cylinder and xylem duct decreased. Slight drought effects on root anatomical structure were observed in the LR treatment, while the root anatomical structure of the MR and HR treatments was normal. The above results indicate that the moderate rain treatment provided the most suitable water regime for P. pratensis.