*2.3. Field Measurement*

An automatic weather station (AWS) Vantage Pro2 product of Davis Instruments Corp. Inc., Hayward, CA, USA measured weather parameters such as air temperature, relative humidity, solar radiation and wind speed at 2 m height. The AWS has sensors such as air temperature and relative humidity, solar radiation and wind speed sensors, all connected to ISS (Integrated Suite Sensors) and then stored in the console. For the water level sensor, we used an e-Tape sensor water level where the output was voltage. Thus, we performed the calibration for this sensor. The water level measurement was stored in an Em50 Data Logger, a product of Meter Group Inc., NE Hopkins Ct, Pullman, WA, USA (previously known as Decagon Corp, Inc.). Both the Davis console and Em50 Data Logger were set and stored data within 15-minute time intervals.

We observed morphological characteristics of rice once in three days. In each plot, we measured plant height, tiller and panicles numbers with five replicates. On the harvesting day, we observed and weighed biomass (straw), grain, panicles number and weed in all plots. The grain yield, biomass weight and weed weight were converted to ton/ha. In addition, a single hill was randomly selected to observe root length among the regimes.
