土壤含水量对夏玉米蒸发蒸腾量和光合性能的影响

Effects of soil moisture content on evapotranspiration and photosynthetic performance of summer maize

采用盆栽控水试验,研究了5种土壤水分条件(分别为土壤田间持水量的50%、60%、70%、80%、90%,记为T1~T5)对夏玉米蒸发蒸腾量(ET)及抽雄期光合性能的影响。结果表明:土壤含水量对夏玉米生长过程中的ET、株高、叶面积和光合性能均有显著影响。与T1处理相比较,T2~T5水分处理下的夏玉米主要生育期内ET依次增加了23.66%、39.17%、43.33%和49.84%,呈线性增大的趋势;在夏玉米耗水强度最旺盛的抽雄期,与T1处理相比较,T2~T5处理下的蒸腾速率(T_(r))分别增长了63.74%、75.65%、78.83%和81.77%,气孔导度(G_(s))分别增长了71.97%、82.63%、83.91%和84.87%,二者均随着土壤含水量的增大呈指数函数变化,但土壤含水量超过田间持水量的70%后增幅显著减小;光合速率(P_(n))分别增长了47.51%、60.65%、57.51%和55.87%,P_(n)、株高、叶面积随着土壤含水量的增大呈现抛物线形变化趋势,即先增加后减小的规律,在T3和T4处理水平下达到最大值,依次为28.14μmol·m^(-2)·s^(-1)(T3)、256.5 cm(T4)、628.6 cm^(2)(T3)。从提高夏玉米光合效率和水分生产效率、减少无效蒸发蒸腾耗水的角度考虑,夏玉米抽雄期的土壤含水量控制在田间持水率的80%左右为宜。

The effects of five soil moisture conditions(They were respectively 50%,60%,70%,80%,90%of the field water capacity,recorded as T1~T5)on evapotranspiration(ET)and photosynthetic performance at tasseling stage of summer maize were studied by a potted water control experiment.The results indicated that soil moisture content had significant effects on ET,plant height,leaf area and photosynthetic performance of summer maize.Compared with T1,the ET of summer maize under T2~T5 water treatments increased by 23.66%,39.17%,43.33%and 49.84%during the main growth period,presenting a linear trend of increasing.Compared with T1 treatment,transpiration rate(T_(r))increased by 63.74%,75.65%,78.83%and 81.77%,stomatal conductance(G_(s))increased by 71.97%,82.63%,83.91%and 84.87%,respectively,in T2~T5 treatments at tasseling stage with the strongest water consumption intensity of summer maize.Both changed exponentially with the increase of soil moisture content,but the increase rate decreased significantly when soil moisture content exceeded 70%of field water capacity.Photosynthetic rate(P_(n))increased by 47.51%,60.65%,57.51%and 55.87%,respectively.With the increase of soil moisture content,the growth of P_(n),plant height and leaf area showed a parabolic trend:increased first and then decreased and reached the maximum under T3 and T4 treatments,they were 28.14μmol·m^(-2)·s^(-1)(T3),256.5 cm(T4)and 628.6 cm^(2)(T3)respectively.In conclusion,to improve the photosynthetic efficiency and water production efficiency of summer maize and reduce the water consumption of ineffective evapotranspiration,the soil moisture content should be controlled at about 80%of the water holding rate in the field at tasseling stage of summer maize.