Effects Of Different Water Supply Strategies And High Concentrations Of Iron On The Growth And Photosynthetic Characteristics Of Carex Lasiocarpa

Wetlands have important ecosystem services such as saving and regulating water resources,maintaining habitat for rare waterfowl and plants,regulating climate,and so on.The Sanjiang Plain is the largest marsh wetland distribution area in China.The area is rich in water resources,but it faces the following problems:(1)The large areas of wetlands have been reclaimed into arable land,which leads to the contradiction of water using between agriculture and ecology.(2)Natural precipitation can not meet the normal requirement of paddy growth,and groundwater has been mined massively for agricultural irrigation.This situation has seriously affected the growth of wetland plants,and wetlands is facing the threat of degradation;(3)Because groundwater contains a large amount of iron,continuous irrigation of groundwater will form high concentration of iron,which can affect the growth of crops and wetland plants.In this paper,Carex lasiocarpa Ehrh.was studied,which is the dominant species in Sanjiang Plain.Based on the irrigation rule of paddy field,the strategy of compensating water supply for C.lasiocarpa was taken and the high concentration of iron solution of 100 mg / l was inputed at different growth stages.The effects of different treatments on the growth and photosynthetic characteristics of C.lasiocarpa were studied by measuring the plant height,aboveground biomass,chlorophyll content,photosynthetic parameters and iron content in the plant,in order to form a complementary water supply mechanism between the wetlands and the paddy fields,moreover provide a new way of thinking for the restoration management of the Sanjiang plain wetland and water-saving irrigation of paddy fields.This paper draws the following conclusions:1.In the early stage of growth,a small shortage of water(water level 0 cm)was beneficial to the growth of the C.lasiocarpa.C.lasiocarpa grow better after the initial water supply.In the later stage of growth,a small shortage of water(water level 0 cm)and a shorter water supply cycle(15 days)promoted the plant height growth and aboveground biomass accumulation.2.The input of high concentration of iron had a positive effect on the growth of C.lasiocarpa in the early stage,and had a hindrance effect in the later stage.Under the treatment of high concentration iron,the relative water shortage condition is more suitable for the growth of the C.lasiocarpa.3.The photosynthetic rate,transpiration rate and stomatal conductance of C.lasiocarpa under different treatments showed a single peak curve.Chlorophyll content decreased with the passage of time,and the chlorophyll content which under the treatment of high concentration iron was reduced to a greater extent.The photosynthetic rate and stomatal conductance of the treatment of high concentration iron were higher than that of normal water treatment.The late water supply level at 0 cm can promote the effective use of water for plants.4.The content of iron in the leaf sheaths of the C.lasiocarpa was higher than that of the leaves,which was more obvious under the treatment of high concentration iron.Regardless of whether there is iron input,in the late stage of the water supply level of 0 cm fluctuating dry and wet alternating case,the accumulation of iron in the C.lasiocarpa has a certain role in promoting.5.The water level of the seedling was kept at 0 cm,the initial water supply was once(water level 10 cm),and the water level was controlled every 15 days in the later stage to ensure that the water level was above 0 cm.This water supply strategy not only ensure the height and aboveground biomass of C.lasiocarpa in the normal range,but also take into account the watersaving irrigation,it is a better choice.If the content of iron in the water is high,to avoid excessive water supply(the initial water supply 0 cm,the late water supply level 0 cm),the water supply cycle should not be too long(water supply cycle 15 days),to prevent high concentration iron and lack of water from doing harm to the physiological function of the C.lasiocarpa and affecting the normal growth.