Optimum lateral spacing for drip-irrigated corn in the Mediterranean Region of Turkey

This study was carried out to determine the effects of different lateral spacings, and the full and deficit irrigation on yield and yield components of maize under the Mediterranean climatic conditions in Adana, Turkey. Experimental site was located at the Research Field of the Agricultural Structures and Irrigation Department (altitude 20 m above sea level, 36 degrees 59 ' N and 35 degrees 18 ' E) on a clay textured soil. Pioneer 3394 hybrid corn variety was used in this study. Irrigation treatments consisted of three different lateral spacings (A(1): 0.70 m, A(2): 1.40 m, and A(3): 2.10 m) and two different water amounts (I-100, I-67). In the I-100 treatment, soil water deficit in the 90 cm soil profile depth was replenished to field capacity. For deficit irrigation treatment I-67, 33% less water was applied as compared to 1100 treatment plots. A 7-day irrigation interval was used in the study. The highest seasonal water use (ET) was determined in the A,1100 treatment as 758 mm; and the lowest ET was found in the plant row 1.05 m away from the drip lateral in the treatment A(3)I(67) (569 mm). Lateral spacings and irrigation levels resulted in significantly different yields. The highest grain yield was obtained in A(2)I(100) treatment with 9790 kg ha(-1), and the lowest yield was found in the plant row 1.05 m away from the drip lateral in A(3)I(67) treatment with 6180 kg ha-1. Yield from the 1.4 m spacing with full irrigation treatment (A(2)I(100)) was significantly higher than in the other two spacings. According to the research results, optimum lateral spacing for corn plant was found to be 1.4 m. Significant second degree polinomial relationships between corn grain yield (Y) versus irrigation water (1) and water use (ET) were found as Y = -0.0037I(2) + 5.835I - 1397.7 (R-2 = 0.62**) and Y = -0.0039ET(2) + 5.926ET - 1365.1 (R-2 = 0.54), respectively. The highest water use efficiency (WUE) was found in A(2)I(100) (1.40 kg m(-3)) and the lowest one was found in the plant row 1.05 m away from the drip lateral in A(3)I(67) (1.09 kg m-3). Thus a lateral spacing of 1.4 m (one drip lateral per two crop rows) was recommended for drip-irrigated corn in the Mediterranean Region under those specific conditions. (c) 2006 Elsevier B.V. All rights reserved.