Effects Of Different Nitrogen Form And Water Stress On Water Physiology Of Rice (Oryza Sativas L.)

By using the method of nutrient solution culture, simulated water stress by PEG(6000), the effects of different nitrogen form (NO₃^-, NH₄⁺ and NO₃^-/NH₄⁺) and water stress on growth, water uptake and photosynthesis of rice plants at seedling stage were studied. The results showed that:Rice under the supply of ammonium is propitious to fight a drought. Both under non-water stress and water stress, the bio-mass of rice plants were higher under the supply of mixture of nitrate and ammonium or sole supply of ammonium than sole supply of nitrate, respectively. Under non-water stress, the water uptake rate per dry weight of rice plant was the higher under sole supply of nitrate than under the supply of mixture of nitrate and ammonium or sole supply of ammonium. Under water stress, the water uptake rate per dry weight of rice plant was the higher under sole supply of ammonium than under sole supply of nitrate. Either under non-water stress or under water stress, the rice plant supplied with sole ammonium or mixture of nitrate and ammonium had the higher net photosynthetic rate, Stomatal conductance, transpiration rate and concentration of intercellular CO₂.The curve of rice water uptake showed that under non-water stress, the water uptake in daytime was more with sole supply of nitrate than than sole supply of ammonium and the supply of mixture of nitrate and ammonium. And after with PEG water stress, the water uptake reduced rapidly under sole supply of nitrate.The results of killed the root with boiled water to measure the water uptake via apoplast or with HgCl₂ closing the water channel, showed that, under non-water stress the aquaporin activity under sole supply of nitrate was lower than sole supply of ammonium and the supply of mixture of nitrate and ammonium, while water uptake via apoplast was higher. And under water stress the rice water uptake with all the treatment with different nitrogen form gave piority to via water channel. After half an hour with killed the root with boiled water and with HgCl₂ inhibition, the net photosynthetic rate, Stomatal conductance, transpiration rate and concentration of intercellular CO₂ were reduced rapidly with the water uptake reduced and Stomatal closed.In contrast with sole supply of ammonium and supply of mixture of nitrate and ammonium,...