Research On Temporal And Spatial Variability Of Leaf Water Use Efficiency In Winter Wheat

To explore the space and temporal distribution of photosynthetic characteristics,transpiration and water use efficiency of leaves.Research of photosynthetic transpiration rate characteristics of leaves in different water treatment and different growth stages,based on the winter wheat as the research object,from October,2015 to June,2017,the field experiment was carried out in the National Center of Efficient Irrigation Engineering and Technology Research-Beijing.The photosynthetic rate and transpiration rate of different parts and leaves were determined by LI-6400 portable photosynthetic apparatus.The main results were as follows:?1?The photosynthetic rate and transpiration rate of different parts of winter wheat leaves were as follows:leaf middle>leaf base>leaf apex.The response of the middle part of the leaf to photosynthetic effective radiation was the most obvious,and the photosynthetic rate and transpiration rate were the least at the tip of the leaf.The photosynthetic rate in leaf base and leaf of leaves under irrigation was higher than that without irrigation.The transpiration rate under different water treatment were as follows:W2>W3>W1>W0.?2?The photosynthetic rate and transpiration rate of canopy leaves in leaf base and leaf middle were shown,middle layer>top layer>bottom layer.The leaf apex was shown,top layer>middle layer>bottom layer.The photosynthetic rate of top leaf under different irrigation varied was shown,W₃>W₂>W₁>W₀,the photosynthetic rate of middle leaf varied as W₂>W₃>W₁>W₀,the variation of photosynthetic rate under different irrigation of bottom layer was small.?3?Appropriate irrigation could promote the leaves better to carry on the photosynthesis and transpiration.However,excessive irrigation reduced the photosynthetic rate,transpiration rate and water use efficiency of winter wheat leaves,T₁?220mm?irrigation was optimal.?4?The water use efficiency of winter wheat leaves varied with different irrigation during the same growth period.The photosynthetic rate and transpiration rate of the canopy leaves at different growth stages were compared as follows:upper layer>middle layer>lower layer.The photosynthetic rate,transpiration rate and water utilization efficiency of each canopy of winter wheat in different growth stages increased with the increase of photosynthetic effective radiation,and the photosynthetic rate and transpiration rate reached the maximum during the grain filling period.?5?The light response curves of different growth periods of leaves and different parts of the leaves and different leaf positions were fitted with the non-rectangular hyperbola model.The results show that the correlation coefficient of the fitting curve of the blade is greater than0.94 under different treatments.The effect of different soil water conditions on the apparent quantum efficiency and the maximum net photosynthetic rate was greater,and the AQE and P_max under T_I treatment were greater than T₀ and T₂.For the different layers,the AQE and R_d were the top layer>middle layer>bottom layer.For the same canopy,the amount of irrigation increased,and the AQE and P_max were also increased,showed as T₂>T₁>T₀.R_d was strongly influenced by leaf age,along with the growth of winter wheat,the Rd showed a trend of decrease after the first increase.The photosynthetic effective radiation response of different canopy in the same water treatment was obvious,and the change of the canopy was gradually decreased.AQE,P_max,and R_d showed a trend of decreasing first and then decreasing as the growth period changed.