Abstract
To provide references for poplar cultivation in waterlogged prone area of Jianghan Plain of China, the waterlogging tolerance of 15 poplar clones widely cultivated in these areas were evaluated based on their responses to 45-day waterlogging stress followed by 15-day drainage recovery in morphology, growth, biomass accumulation, leaf gas exchange and chlorophyll fluorescence parameters. The results showed that the normal watered seedlings (CK) of the 15 clones grew vigorously during the experiment, and no defoliation and death occurred. For the seedlings under waterlogging treatment (water 10 cm above the soil surface), its morphology changed markedly, including slowing growth, chlorosis and abscission of leaves, development of hypertrophied lenticels and adventitious roots etc. Waterlogging stress significantly inhibited the seedling growth of height and ground diameter, biomass accumulation, as well as leaf gas exchange and chlorophyll fluorescence parameters of the 15 clones with varying degrees. The net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), intercellular CO2 concentration/ environmental CO2 concentration (Ci/Ca), variable fluorescence (Fv), variable fluorescence/ initial fluorescence (Fv/Fo) and PS Ⅱ primary light energy conversion efficiency (Fv/Fm) decreased gradually with the prolonged waterlogging, and reached their bottom on day 45. During the terminal recovery stage, the leaf gas exchange and chlorophyll fluorescence parameters of the most clones increased, but their recovery abilities were significantly different. At the end of the experiment, the highest survival rates (100%) were observed in DHY, HS-1, HS-2, I-72, I-69, I-63 and NL-895, and the lowest (zero) occurred in XYY. Survival rates of the other clones ranged from 33.33% to 83.33%. Both results of cluster analysis and membership function analysis showed that HS-1, I-69, DHY, NL-895 and HS-2 had the strongest waterlogging tolerance, XYY and HBY were the worst, and the other clones were moderate. These results would provide guidance not only for the selection of cultivated varieties in Jianghan Plain, but also for the selection of hybrid parents for waterlogging resistance breeding.
Highlights
Jianghan Plain is located in the central and southern part of Hubei Province of China
At the end of drainage recovery, DHY, Huashi 1’ (HS-1), HS-2, I-72, I-69, I-63 and NL-895 displayed the highest survival rates (100%); XYY owned the lowest survival rate (0%), and that of the other clones ranged from 33.33% to 83.33%
Among the 15 clones, all plants of XYY and some plants of HBY and I-214 died during the waterlogging treatment, and XYY died earliest on day 32
Summary
Jianghan Plain is located in the central and southern part of Hubei Province of China. It is an important part of the plain in the middle and lower reaches of the Yangtze River, and is one of the lowest plains in China with average altitude of around 27 m. Jianghan Plain has a huge area land prone to waterlogging. Poplar (Populus L.) is one of the most important tree species for afforestation in these areas due to its characteristics of strong waterlogging resistance, rapid growth and broad applications. Due to the lack of oxygen supply to roots, plants often present the phenomenon of leaf chlorosis and abscission, root rotting, photosynthetic capacity decline and so on, which leads to slow growth and even death, coupled with a huge loss of wood yield and ecological function (He et al, 2018; Zhao et al, 2019; Yan et al, 2019)
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