## 2 Materials and Methods
### Gas Exchange and Plant Measurements  
The gravimetric soil water content was measured by weighing each pot with an electronic balance before and after irrigation. Canopy evapotranspiration (ET, mm day\({}^{-1}\)) was calculated from the water balance to establish the amount of water to be dispensed during each irrigation.  
Physiological, morphological, and biochemical measurements were conducted seven times for maize plants and eight times for soybean plants (Table 1) during a time span of about 20 days between 11:00 and 14:00 after irrigation. We measured gas exchange of CO\({}_{2}\) and H\({}_{2}\)O at the leaf level with the open photosynthesis system LI-6400 (Li-COR Biosciences Inc., Lincoln, NE, USA). The system maintained the leaf chamber at the ambient temperature, at 400 \(\mu\)mol mol\({}^{-1}\) CO\({}_{2}\) level and constant photosynthetic active radiation (PAR) of 1500 \(\mu\)mol m\({}^{-2}\) s\({}^{-1}\) (saturation point). Gas exchange measurements were conducted on two randomly selected upper leaves, fully matured and light exposed, to obtain parameters such as photosynthetic CO\({}_{2}\) assimilation rate (A, \(\mu\)mol CO\({}_{2}\) m\({}^{-2}\) s\({}^{-1}\)), transpiration rate (T\({}_{r}\), mmol H\({}_{2}\)O m\({}^{-2}\) s\({}^{-1}\)), stomatal conductance (g\({}_{s}\), mol H\({}_{2}\)O m\({}^{-2}\) s\({}^{-1}\)), leaf vapor pressure deficit (VPD\({}_{\text{leaf}}\), KPa), intercellular CO\({}_{2}\) concentration (C\({}_{i}\), \(\mu\)mol CO\({}_{2}\) mol\({}^{-1}\) moist air), and water use efficiency (WUE = A/Tr, \(\mu\)mol CO\({}_{2}\) mmol\({}^{-1}\) H\({}_{2}\)O). We measured absolute chlorophyll concentration (chl, \(\mu\)g cm\({}^{-2}\)) with the SPAD 502 Plus leaf chlorophyll meter (Konica Minolta Sensing  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Date (2018)** & **15-Apr.** & **18-Apr.** & **21-Apr.** & **24-Apr.** & **26-Apr.** & **28-Apr.** & **30-Apr.** & **2-May** & **Samples** \\ \hline \multirow{2}{*}{Soybean} & DAS & 23 & 26 & 29 & 32 & 34 & 36 & 38 & 40 & \\  & DoM & 1 & 4 & 7 & 10 & 12 & 14 & 16 & 18 & 144 \\ \hline \multirow{2}{*}{**Date (2018)**} & **21-Apr.** & **24-Apr.** & **26-Apr.** & **28-Apr.** & **30-Apr.** & **2-May** & **4-May** & **Samples** \\ \hline \multirow{2}{*}{Maize} & DAS & 12 & 15 & 17 & 19 & 21 & 23 & 25 & \\  & DoM & 1 & 4 & 6 & 8 & 10 & 12 & 14 & 126 & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Summary of data acquisition of soybean and maize during 2018. DAS = days after sowing (DAS); DoM = days of measurement. Total of samples is calculated considering the number of replicates, water groups and DoM (For soybean: 6 replicates \(\times\) 3 WHC \(\times\) 8 DoM = 144 samples and for maize: 6 replicates \(\times\) 3 WHC \(\times\) 7 DoM = 126 samples).  
Inc., Sakai, Osaka, Japan) in three randomly and fully expanded top leaves. In each leaf, we took the average of three sampling points distributed over the leaf. Selected leaves for chl measurements were not necessary the same as leaves selected for gas exchange measurements. We manually measured canopy height (h\({}_{\text{c}}\), m) with a meter from the soil surface to the highest point of each plant. h\({}_{\text{c}}\) was used as a proxy for plant growth, as it can be associated to cell enlargement [7, 17]. Gas exchange, chl and h\({}_{\text{c}}\) measurements were averaged per pot.  
Grouping pots by crop and soil water status, we measured leaf area index (LAI) three times with the plant canopy analyzer LAI-2200C (Li-COR Biosciences Inc., Lincoln, NE, USA) on the last day of the experiment (15 June 2018).