覆膜与滴灌对河套灌区玉米花粒期叶片光合特征的影响

Effects of different mulching and drip irrigation patterns on photosynthetic characteristics of maize leaves in the Hetao Irrigation District,Inner Mongolia,China

光合作用是作物生长发育和产量形成的基础,栽培方式和土壤含水量变化显著影响作物的光合作用.灌浆期和乳熟期是玉米花粒期2个重要阶段,是玉米籽粒形成和干物质积累的关键时期.通过大田试验研究了河套灌区不同覆膜方式与滴灌水平对不同生育时期玉米光合特征及产量的影响.结果表明:灌浆期玉米叶片光合特征在不同处理下无显著差异,乳熟期净光合速率和蒸腾速率在半覆膜(B_2)和全覆膜(Q_2)滴灌水平2(350 mm)处理下均显著高于半覆膜(B_1)和全覆膜(Q_1)滴灌水平1(200 mm),并且B_1和Q_1处理下灌浆期叶片的净光合速率、蒸腾速率、水分利用效率及气孔导度等显著高于乳熟期.不同处理下灌浆期和乳熟期叶片的净光合速率、蒸腾速率,灌浆期的气孔导度以及乳熟期的水分利用效率等在日变化上存在着同步关系,均呈现出倒"U"型的日变化特征,而胞间CO_2浓度则呈现相反的变化趋势.逐步回归分析显示,光合有效辐射、大气温度和空气相对湿度等气象因子是影响玉米叶片光合特征的主要环境因子.此外,B_2和Q_2处理下玉米产量显著高于B_1和Q_1处理(分别增加了29.3%和50.9%),但B_1和Q_1处理间并无显著差异.这表明与覆膜方式相比,滴灌水平对干旱地区玉米产量的影响更大.

Photosynthesis controls crop growth and yield,and differences in planting methods and soil moisture can significantly affect the photosynthetic characteristics of crops.Grain filling stage and milking stage are two important stages of maize from flowering to maturity,which are essential for maize grain formation and dry matter accumulation.The effects of different mulching and drip irrigation patterns on the photosynthetic characteristics and maize yield at grain filling and milking stages were investigated in a field experiment in the Hetao Irrigation District,Inner Mongolia.Maize leaf photosynthesis during the grain filling stage was not significantly different under the different treatments.During the milking stage,photosynthetic and transpiration rates under both partial（B2）and full（Q2） film mulching with drip irrigation level 2（350 mm） were significantly higher than those in both the partial（B1） and full（Q1） film mulching with drip irrigation level 1（200 mm）.Photosynthetic and transpiration rates,water use efficiency and stomatal conductance under the B1 and Q1 treatments were significantly higher in the grain filling stage than in the milking stage.Diurnal variations in photosynthetic and transpiration rates,stomatal conductance and water use efficiency of maize leaves during the grain filling and milking stages were synchronous and showed an upside-down ＂U＂pattern,but the intercellular CO2 concentration showed the opposite pattern.Stepwise regression analysis showed that photosynthetically active radiation,air temperature and relative humidity were the main environmental factors influencing photosynthetic characteristics of maize leaves under the different mulching and drip irrigation treatments.In addition,maize yield was significantly higher under the B2 and the Q2 treatments than under the B1 and Q1（increase of 29.3% and 50.9%,respectively）,but no significant differences were found between the B1 and Q1 treatments,indicating that drip irrigation level affects the yield of maize and its photosynthetic capacity more than mulching mode in arid regions.