多枝柽柳幼苗根系形态及生物量对不同灌溉处理的响应

Response of root morphology and biomass of Tamarix ramosissima seedlings to different water irrigations

多枝柽柳(Tamarix ramosissima)是塔里木河下游荒漠河岸林中的优势灌木,对荒漠河岸植被群落的稳定起着重要作用。该文通过研究多枝柽柳幼苗根系形态对不同灌溉处理的响应,分析人工水分干扰对多枝柽柳幼苗根系生长的影响。实验设计了侧渗分层和地表灌溉两种给水方式和高灌(50L·株–1)、中灌(25L·株–1)、低灌(12.5L·株–1)三个给水水平,并在整个生长季节监测每个植株的生物量及根系形态参数。结果显示:与地表灌溉比较,侧渗分层的灌溉方式显著提高了细根(0.5mm<d<2mm)长、细根表面积和根系生物量,并使根系生长至160cm深度的土层,大于地表灌溉深度(80–100cm);侧渗分层灌溉+高灌的组合促进根系生长的效果最显著(p<0.05);侧渗分层灌溉方式下总细根(d<2mm)的比根长随着给水量的增加显著增大,而地表灌溉下比根长无显著变化;侧渗分层灌溉方式下根冠比总体小于地表灌溉方式,即侧渗分层灌溉使多枝柽柳地上部分发育较好。因此,侧渗分层灌溉方式有显著促进多枝柽柳幼苗在生长早期快速发育的效果。

Aims Deficient water resources in the lower reaches of Tarim River of China impose constraints on the growth and survival of planted seedlings of Tamarix ramosissima. Our objective was to study root morphology and growth of T. ramosissima seedlings to provide suggestions for rehabilitating degraded desert riparian forest. Methods We investigated root growth, biomass production of the seedlings under two irrigation treatments, i.e., layered-side irrigation and above-ground irrigation, and three watering levels, i.e., high water level （W1, 50 L. tree-1）, medium water level （W2, 25 L.tree-1） and low water level （W3, 12.5 L.tree-1）. lmportantfindings Layered side-irrigation significantly increased fine root length （0.5 mm 〈 d 〈 2 ram）, fine root surface area, coarse root biomass （d 〉 2 ram）, below- and above-ground biomass and root depth compared with above-ground irrigation. Root length and biomass with layered side-irrigation and W1 increased significantly （p 〈 0.05）. Total fine root （d 〈 2 mm） specific root length （SRL） with layered side-irrigation increased signifi- cantly with the increase in watering level, and above-ground irrigation caused insignificant differences in the SRL between W1, W2 and W3. The root/shoot ratio （R/S） in the layered side-irrigation treatment was less than that in the above-ground irrigation treatment. Our results suggest that the layered side-irrigation caused more rapid and greater root elongation, as well as root biomass production in T. ramosissima seedlings. This may benefit seedling survival in the early growing stage.