Yield, Quality, and Water Use Efficiencies of Silage Maize Affected by Deficit Irrigation Treatments

The present study was carried out to investigate the effects of different water deficit levels applied through the growing season on silage yield, quality, and water use efficiency (WUE) of main crop silage maize under semi-arid climate conditions during 2014 and 2015. Irrigation treatments were set at 100% (I100), 70% (I70), and 35% (I35) supply of depleted water within a 0-90 cm effective root zone in 7-day intervals. Applied irrigation water quantities in the I100 (control) treatment during the first and second years (in 8 irrigations) were observed as 693 mm and 666 mm, respectively. Plant water consumptions in the control treatment were measured as 770 mm and 738 mm, respectively. Silage yield was 10650 kg da−1 in the first year and 10600 kg da−1 in the second year. The silage yield from the I70 treatment with a 30% water deficit was statistically placed in group (B) following the I100 (control) treatment. Water deficits over 30% resulted in significant decreases in silage yield and quality. The correlation coefficient between ETa and dry matter was identified as (r:0.78) and (r:0.87) in 2014 and 2015, respectively. The correlation coefficient between plant water consumption (ETa) and protein content was (r:0.81) and (r:0.80), and the correlations between ETa and quality parameters were positive and highly significant (p<0.01). Significant linear correlations existed between ETa and kernel yield (Y) (p<0.01). Yield response factor (ky) for the experimental years was calculated as 0.74 and 1.06. Irrigation water use efficiency (IWUE) values varied between 3.80-5.10 kg da−1 mm, and water use efficiency (WUE) values varied between 3.62 and 4.42 kg da−1 mm.