不同氮素形态和水分胁迫对水稻水分吸收及光合特性的影响

Effect of nitrogen form and water stress on photosynthetic characteristics and water uptake in rice

采用PEG模拟水分胁迫、根系烫伤处理和0.5 mmol.L-1HgCl2处理等方法,研究不同质量比(9∶1、5∶5、1∶9)NH4+-N/NO3--N营养对水稻幼苗生长和水分吸收的影响。结果表明:正常水分条件下,NH4+-N/NO3--N比为5∶5处理的水稻生物量最大,水分胁迫条件下,1∶9处理的水稻生物量最大;根系烫伤处理后,正常水分条件下,NH4+-N/NO3--N比为9∶1、5∶5、1∶9处理的水稻吸水量分别降低26.5%、24.1%、36.3%,而水分胁迫条件下,各处理分别降低30.6%、23.9%、21.0%;加HgCl2处理后,正常水分条件下,NH4+-N/NO3--N比为9∶1、5∶5、1∶9处理的水稻吸水量分别降低47.1%、46.3%、31.8%,而在水分胁迫条件下,各处理分别降低46.6%、42.4%、23.5%。正常水分条件下,NH4+-N/NO3--N比为9∶1处理的水稻光合速率最高,5∶5处理的水稻气孔导度、细胞间CO2浓度及蒸腾速率最低;水分胁迫后,9∶1、1∶9处理的水稻气孔导度、细胞间CO2浓度及蒸腾速率比正常水分处理降低,而5∶5处理的水稻气孔导度、细胞间CO2浓度及蒸腾速率较正常水分处理高。

This study aimed at studying the effects of different nitrogen forms and water stress on rice growth and water uptake.Water stress was simulated either by adding PEG,scalding roots,or by inhibiting aquaporin activity with 0.5 mmol·L（-1）HgCl2.NH4＋-N/NO3——N ratios at 9/1,5/5 and 1/9 were used as nitrogen sources.Water uptake of rice through the apoplastic pathway was determined.The results showed,the highest rice biomass was obtained at NH4＋-N/NO3——N ratio of 5/5 under non-water stress conditions,and at a ratio of 1/9 in water stress conditions.As to the scalding root treatments,water uptake of rice decreased by 26.5%,24.1% and 36.3% in the three treatments with NH4＋-N/NO3——N ratio of 9/1,5/5 and 1/9 without water stress,and decreased by 30.6%,23.9%,and 21.0% with water stress,respectively.For the HgCl2 treatments,water uptake decreased by 47.1%,46.3% and 31.8% without water streess and 46.6%,42.4%,and 23.5% with water stress,respectively.Under non-water stress conditions,the highest photosynthetic rate was observed at a NH4＋-N/NO3——N ratio of 9/1,while the lowest stomatic conductance,intercellular CO2 concentration and transpiration rate were found in at a ratio of 5/5,respectively.Under water stress conditions,stomatic conductance,intercellular CO2,and transpiration rate were lower when treated with NH4＋-N/NO3——N ratios at 9/1 and 1/9 but higher at 5/5.