| Growing plants that are tolerant to seawater irrigation is one of options for exploitation of mudflats along the coast.Pot experiments were carried out to study the effects of nitrogen and phosphorus on the growth and photosynthetic characteristics of Helianthus Tuberosus seedlings under the treatments of different concentration seawater.The results were as follows:(1) Compared with the control,the fresh weights of roots and aerial parts of Helianthus tuberosus seedlings treated with 10% seawater changed slightly,even were higher than the control,whereas decreased with 25% and 50% seawater treatments of the same concentration of nitrogen and phosphorus.Under the same concentration of seawater,the fresh weights of roots and aerial parts increased with the concentration of nitrogen and phosphorus increasing.The trends of dry weight of roots and aerial parts resembled the trends of fresh weight with the same treatments.(2) Compared with the control,the photosynthetic rate,transpiration rate,water use efficiency,stomatal conductance and stomatal limitation treated with 10% seawater changed slightly,while they all decreased with the increase of seawater concentration under the concentration of N1(7.5 mmol/L) and P1(1 mmol/L).The photosynthetic rate,transpiration rate,stomatal conductance and stomatal limitation all increased with the increase of the concentration of nitrogen and phosphorus under the same seawater concentration.The catabatic effect was more significative when the seawater concentration increased.The water use efficiency decreased with the treatments of control and 10% seawater,while it increased with the treatments of 25% and 50% seawater with the concentration of nitrogen and phosphorus increasing.Compared with the control,the internal CO2 concentration treated with 10% seawater under the concentration of N1(7.5 mmol/L) and P1(1 mmol/L)changed slightly.And it increased with seawater concentration increasing.With the concentration of nitrogen and phosphorus increasing,it decreased with the treatments of the same seawater concentration.It was shown that nitrogen and phosphorus could decrease the stress of seawater on the growth and photosynthetic characteristics of Helianthus Tuberosus seedlings. |