Determination Of Optimum Irrigation Schedule For Summer Maize Based On Water Surface Evaporation Under Different Irrigation Methods

Field experiments were conducted at Farmland Irrigation Research Institute, located in Xinxiang City of Henan Province, China during the two successive seasons of2011and2012between the month of June and September. The objectives of this research were to determine the optimal irrigation scheduling for summer maize, based on water surface evaporation measured with E601pan, under three irrigation methods.In order to investigate the suitability irrigation schedules of summer maize based on pan evaporation (PE) under different irrigation methods, field experiment under the condition of rain shelf was carried out. The three irrigation methods were:Border irrigation (B) Furrow irrigation (F) and Drip irrigation (D) respectively. Each irrigation method consists of three quotas:which were determined by pan evaporation and pan coefficients. There were total of9treatments, and each treatment was replicated3times. Irrigation scheduling for each irrigation method were represented as follows:B:0.75*PE,1.0*PE and1.25*PE; F:0.75*PE,1.0*PE and1.25*PE; D:0.67*PE,0.3*PE and1.5*PE.The results indicated that water consumption of maize under the three irrigation methods, was mainly affected by irrigation schedules. Total water consumption under B was slightly higher than that of F, and was further higher than that of D. Results also indicated that the maximum value of evapotranspiration (ET)(406.6mm and323.1mm) was derived from treatment B3in2011and2012maize growing season, and the minimum ETo occurred in treatment D1(231.4mm) in2011and D2(174.3mm) in2012.Daily ET of D was lower than that of F and B. The methods of Irrigation had great influence on the leaf area index and plant height. Highest grain yield (10235kg hm-2) and100-grain weights (33.5g) were obtained in2012under treatment B1condition, and the lowest grain yield (6175kg hm-2) was derived under D1treatment condition in2011.The differences in grain yield among D1, D3and F2were significant (P≤0.05). In drip irrigation method, there was no significance difference between D2and D3. Differences among the three treatments with B were not significant. For furrow irrigation, grain yield of treatment F3was significantly different (P≤0.05) and greater than F1and F2. However, there was no significance difference in grain yield between Fl and F2. In comparison to2012results, differences in grain yield among D2, D3, B1and F1-F3were significant (P≤0.05). For yield performance, the highest yield occurred with the middle irrigation quota under B, and with maximum and minimum irrigation quota under F and D respectively.Water Use Efficiency (WUE) of summer maize with three irrigation methods ranged from1.54kg m-3to3.23kg m-3. Compared to B; F and D had greater values of WUE. The maximum WUE (3.23kg m3) was obtained from treatment D1. There was no significance difference in WUE of maize among all treatments in both years. It was obvious that WUE decreased with increase irrigation quota under the three irrigation methods, and the WUE under drip irrigation was generally higher that those under the other two irrigation method.Considering the comprehensive yield and WUE for maize production under extreme drought condition, suitable irrigation schedules may be determined as:E601PE, used directly as an irrigation quota for border irrigation and60mm of water for each irrigation; and under drip irrigation,2/3PE was suitable as irrigation quota and20mm of water.