Research On Growthand Water Use Efficiency Of Winter Wheat Under Different Irrigation Depths

This experiment was conducted by the way of different irrigation depths with artificially controlling soil moisture profile distribution, and ultimately increase production and the water-saving effect through regulating root growth and spatial distribution and accumulating and allocating above-ground biomass.Using soil column farming methods in Shanxi Conservancy Technical College training base,there were four processing: surface irrigation（T1）, irrigation depth of 60% root distribution（T2）, irrigation depth of 75% root distribution（T3）, irrigation depth of90% root distribution（T4）. Photosynthetic characteristics, Agronomic traits, root zone soil moisture and other factors of winter wheat were considered.Then the output between water consumption and water use efficiency difference were compared.Finally the the optimum irrigation depth was analyzed and concluded, so as to provide reference for increasing crop water use efficiency, develop water-saving agriculture.The main results are:（1） From the photosynthetic physiological characteristics view, deep watering made chlorophyll content slightly increase during the jointing-filling stage,with significant differences between treatments;Under different irrigation depth conditions,winter wheat net photosynthetic rate, transpiration rate and stomatal conductance appeared "M" type bimodal curve, there being an obvious "midday depression",while CO2 concentration appeared "W" shaped bimodal curve,and deep irrigation nap phenomenon was obviously better than surface irrigation; In different growth period,the index value increases with the depth of irrigation; At jointing-filling stage,WUEi showed: T4_WUEi>T3_WUEi>T2_WUEi>T1WUEiand T3_WUEi>T2_WUEi>T4_WUEi>T1_WUEi at filling-maturity.（2） From the point of view agronomic traits, with the increase of irrigation depth,plant gradually increased height and leaf area index showed a decreasing trend after the first increases,but too large irrigation depth would effect the growth of plant height later leading to leaf area index fell faster; Deep irrigation affected greatly dry matter accumulation of winter wheat, operation and distribution, especially the leaf dry weight; Reasonable irrigation depths could significantly increase the wheat harvest index and production; Comparing to surface irrigation, plants under deep irrigation increase their production mainly by increasing column spike, single grain weight and grain number.（3） For the root zone soil moisture,under different irrigation depths conditions,soil moisture of each amplitude in 0-160 cm of the root zone soil dynamic changed obviously, and with depth greater, dynamic changes of soil moisture would moreobvious, especially after irrigation or rainfall; Under surface irrigation conditions, soil moisture increment with increasing soil depth after growth irrigation was "<" type distribution;Under different irrigation depths conditions, they were ">" shape distributions after regreening irrigation.The following topsoil was "3" type bimodal curve after heading irrigation.And they were "S" shape distributions after filling irrigation,and the greater of the irrigation depth, the more obvious of incremental performance.（4） On water consumption characteristics and water use efficiency, deep irrigation increased the consumption of rainfall and irrigation water, reducing the soil water consumption; From heading to grain filling period, the amount of water and water mold coefficients of T3 treatment were larger during the jointing-filling stage and the filling to maturity;Irrigation depths and yield or irrigation depths and water use efficiency all showed parabola of opening downward of increasing first and then decreasing with increasing of irrigation depths;water use efficiency and yield of surface irrigation were the lowest. Water use efficiency and irrigation water use efficiency of T2 and T3 with the irrigation depths of 150 mm and 188 mm performed better.Therefore,irrigation depth of 75% root distribution is the best treatment to save water and increase yield under the experimental conditions.