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Analysis of the effect of seasonal changes on sensitive parameters of LAI based Penman–Monteith evapotranspiration model based on particle swarm algorithm

Duan Hao, He Xin, Zhao Hongli, Jin Xiaohui, Xu Haowei, Wang Rong

Acta Geophysica

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2023

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Vol. 71, no. 2

1033--1043

EN

The existing researches for leaf area index (LAI)-based Penman–Monteith evapotranspiration (ET) model (PML) are mostly carried out at yearly scale and the analysis of effects of seasonal change and different underlying surface conditions on model parameters is scarce. This study emphasizes on the influences of seasonal change and diverse land surface conditions on ET by optimizing the sensitive parameters, namely soil evaporation coefficient f and maximum stomatal conductance gsx, with particle swarm algorithm. This analysis is based on the observations of eight flux stations in China. The model performance is reasonable with a best Pearson r of 0.87. The seasonal calibration results indicate parameters change evidently in different seasons and have obvious spatial heterogeneity. The seasonal calibration method has an obvious effect on improving the ET accuracy in spring, which is mostly influenced by regional temperature and relative humidity. This study further demonstrates the need to dynamically adjust model parameters over time with PML model for evapotranspiration simulations, rather than simply setting these parameters to constants depended on subsurface conditions such as land use type.

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Plant Growth of Curly Kale Under Salinity Stress

Salachna P., Piechocki R., Byczyńska M.

Journal of Ecological Engineering

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2017

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Vol. 18, nr 1

119--124

EN

Ornamental plants growing in urban areas are exposed to soil salinity that negatively affects their quality. Identifying species that retain high ornamental value despite salt stress is therefore of high practical importance. Curly kale (Brassica oleracea L. var. sabellica L.) is an attractive plant with leaves of both edible and ornamental character. The aim of the study was to evaluate a response of ornamental curly kale to different concentrations of NaCl. The study material was ‘Scarlet’ cultivar. The plants were grown in pots in a plastic tunnel. They were irrigated with NaCl solution at the following concentrations: 50, 100, 200, 400, and 800 mM mmol·dm-3. NaCl treatment resulted in a significant increase in pH and electrical conductivity (EC) of the substrate. Salt stress significantly affected plant growth and number, width and length of leaves, and the effects depended on NaCl concentration. Fifteen days after the salt supply ceased, relative chlorophyll content in leaves (SPAD) decreased due to NaCl treatment in a concentration-dependent manner. Treatments with 200, 400, and 800 mmol·dm-3 NaCl reduced stomatal conductance, and the changes were greater on the 5th day following the stress cessation than on the 15th day. Irrigation with a 200, 400, and 800 mmol·dm-3 NaCl solution negatively affected plant bonitation score. The plants treated with 50 i 100 mmol·dm-3 NaCl were not significantly different visual score from the control plants.

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Effect of tropospheric ozone on photosynthetic activity of ozone-resistant and ozone-sensitive test plants (Nicotiana tabacum L., Phaseolus vulgaris L.) in ambient air conditions

Borowiak K.

Polish Journal of Ecology

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2013

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Vol. 61, nr 4

693--703

EN

Ozone-sensitive and -resistant tobacco plants and an ozone-sensitive bean were employed in this experiment. Plants were exposed at two different sites varying in ozone level, within Poznań city and in a remote forestry area. Net photosynthetic rate (PN), stomatal conductance (gs) and intercellular CO2 concentration (Ci) were measured every 7th day until the 28th day of the experiment. The ozone concentrations were higher at the forest site (called here the high ozone site) than in the city (low ozone site). Mean hour ozone concentrations at forest site varied between 34.2–45.5 ppb and 30.2–39.2 ppb, while cumulative ozone concentrations (AOT 40) were 2032 ppb h-1 and 611, respectively. The aim of the study was to compare the results of exposed ozone-sensitive and resistant test plants according to the potential effect of tropospheric ozone on natural vegetation. The experiment revealed the variability between exposure sites and plant species, as well as changes of photosynthetic parameters during the whole experimental season. Common bean assimilation parameters revealed the best correlation with the tropospheric ozone level. Tobacco test plants – ozone-sensitive and -resistant – varied in response to stress factors. There were no statistical differences between exposure sites and plant response. However, both ozone-sensitive and -resistant tobacco plants revealed lower levels of PN at the low ozone site, while ozone-sensitive bean revealed the opposite relation. Moreover, plants revealed gas exchange relations which were not previously observed in fumigation experiments (such as small differences in Ci levels of tobacco plant in the first three weeks). This might be a result of relatively low levels of tropospheric ozone during the experimental period. Hence, it is suggested to continue ambient air investigations to confirm or reject the results of this experiment.