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Kelly T. Morgan, Lincoln Zotarelli, and Michael D. Dukes

measurements that are independent of soil texture, temperature, and salt content. Evapotranspiration measurement The ET term is used to describe the sum of evaporation and plant transpiration from a given land surface to atmosphere, which practically can be

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Krishna S. Nemali and Marc W. van Iersel

Environmental conditions and incorporation of nutrients into the growing medium can affect the fertilizer needs of bedding plants. To evaluate the effects of photosynthetic photon flux (PPF) and starter fertilizer on the fertilizer requirements of subirrigated plants, we grew wax begonias (Begonia semperflorens-cultorum Hort.) under three PPF levels (averaging 4.4, 6.2, and 9.9 mol·m-2·d-1) and four fertilizer concentrations [electrical conductivity (EC) of 0.15, 0.33, 0.86, and 1.4 dS·m-1] in a normal (with starter fertilizer, EC = 2.1 dS·m-1) and heavily leached (with little starter fertilizer, EC = 0.9 dS·m-1) growing medium. Except for shoot dry mass, we did not find any significant interactions between PPF and fertilizer concentration on any of the growth parameters. There was an interactive effect of fertilizer concentration and starter fertilizer on all growth parameters (shoot dry mass, leaf area, plant height, and number of flowers). When the growing medium contained a starter fertilizer, fertilizer concentration had little effect on growth. When the growing medium was leached before transplanting, growth was best with a fertilizer EC of 0.86 or 1.4 dS·m-1. Water-use efficiency (WUE) was calculated from 24-hour carbon exchange and evapotranspiration measurements, and used to estimate the required [N] in the fertilizer solution to achieve a target tissue N concentration of 45 mg·g-1. Increasing PPF increased WUE and the required [N] (from 157 to 203 mg·L-1 at PPF levels of 4.4 and 9.9 mol·m-2·d-1, respectively). The PPF effect on the required [N] appeared to be too small to be of practical significance, since dry mass data did not confirm that plants grown at high light needed higher fertilizer concentrations. Thus, fertilizer concentrations need not be adjusted based on PPF.

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David R. Bryla, Thomas J. Trout, and James E. Ayars

Publication 7217 Howell, T.A. McCormick, R.L. Phene, C.J. 1985 Design and installation of large weighing lysimeters Trans. ASAE 28 106 112 Howell, T.A. Schneider, A.D. Jensen, M.E. 1991 History of lysimeter design and use for evapotranspiration measurements 1

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Xuewen Gong, Shunsheng Wang, Cundong Xu, Hao Zhang, and Jiankun Ge

evapotranspiration into soil evaporation and transpiration using a modified dual crop coefficient model in irrigated maize field with ground-mulching Agr. Water Mgt. 127 85 96 Ding, R.S. Kang, S.Z. Li, F.S. Zhang, Y.Q. Tong, L. 2013b Evapotranspiration measurement

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Tim R. Pannkuk

changes in soil volumetric water content during a 2- to 6-d period soil dry down. Actual evapotranspiration measurements began 24 to 48 h after an irrigation or precipitation event. Reference evapotranspiration was determined for the same 2- to 6-d time

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Jessie M. Godfrey, Louise Ferguson, and Maciej A. Zwieniecki

differences were observed before treatment on DOY 204 ( P = 0.46). Significant differences between the control (higher) and high-salinity treatment (lower) were observed from the first evapotranspiration measurement after treatment began (DOY 216: P < 0

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Jiankun Ge, Linfeng Zhao, Xuewen Gong, Zhiqiang Lai, Seydou Traore, Yanbin Li, Hui Long, and Lei Zhang

-6819.2012.06.022 Liu, B. Cui, Y. Shi, Y. Cai, X. Luo, Y. Zhang, L. 2019b Comparison of evapotranspiration measurements between eddy covariance and lysimeters in paddy fields under alternate wetting and drying irrigation Paddy Water Environ. 17 4 725 739 doi