Studies On Changes Of Temperature And Humidity In Rice Field Microclimate Under Different N Applications

Six nitrogen fertilizer models were used to construct different rice populationstructure. Temperature and humidity within and above canopy were consecutivelyrecorded by HOBO. The temperature and humidity within and above canopy werecompared in different growth stages, and the daily changes of temperature andhumidity within and above canopy were also compared. In addition, the daily changesof temperature and humidity within and above canopy in the paddy field werecompared with those of corresponding data in temperature and humidity at the nearbymeteorological. The results are as follows:1. Studies on the change of microclimatic temperature and humidity of rice fieldin day and night showed that: the day and night changes of temperature and relativehumidity within rice canopy were in accordance with those above canopy. Thetemperature were low and relatively stable at night (from 19:00 to 7:00), but high andgreatly changeable during the day (from 7:00 to 19:00).The relative humidity wasclose to saturation at night but relatively small and changeable in the day. Thetemperature in the day above canopy was higher than that within canopy(except forN1),but there was not much difference between the temperature within and abovecanopy at night. The relative humidity above canopy in the day was lower than thatwithin canopy in all treatments, but there was not much difference between therelative humidity within and above canopy at night. Temperature and relativehumidity differences between within and above canopy were closely related to theamount of nitrogen fertilizer applied. The more nitrogen fertilizer was applied, thegreater the difference was. Temperature difference between with the growth of ricewithin and above canopy (except for N1) increased, and the largest difference occuredin the flowering stage, and then it decreased.2. Studies on the daily changes of temperature and humidity in the rice fieldshowed that: during 41-101 days after transplanting, the maximal temperature in theday above canopy was higher than that within canopy (except for N1), and the more amount of nitrogen fertilizer applied, the greater the difference was. The minimalrelative humidity in the day within canopy was higher than that above canopy, and themore amount of nitrogen fertilizer applied, the greater the difference was. During41-81 days after transplanting, there was a highly significant linear correlation in thedaily maximum temperature between within and above canopy. There was no linearcorrelation in daily minimal relative humidity in Treatment N5 between within andabove canopy, but there was a significant linear correlation in Treatment N6 and ahighly significant linear correlation in other N treatments.3. Studies on the daily changes of temperature between the rice field and thenearby meteorological station showed that: during 41-101 days after transplanting, thedaily maximal temperature difference between above canopy in the rice field andmeteorological station was the largest. In N5 and N6, the daily maximal temperaturewithin canopy was lower than that at the station, while the situation was contrary inN1. The relationship of the daily maximal temperature within and above canopy inother treatments to that at the station was determined by the growth stages. During41-81 days after transplanting, there was a highly significant linear correlation intemperature (daily mean, maximal and minimal temperatures) between above canopyand the station, and there was also a highly significant linear correlation in dailymaximal temperature between within canopy and weather station.