Characteristics of Maize Roots under Subsurface Drip Irrigation through Various Oxygen Treatment

Abstract

In Korea, irrigation technology using subsurface drip irrigation (SDI) is new in agriculture system. Many limitations of SDI are not well known. SDI can damage crops from overwatering. To address this weakness, it is important to improve and test the applicability of the SDI with air injection (oxygation). Therefore we investigated soil oxygen (O2) and carbon dioxide (CO2), root characteristics and yield of maize using two conditions of soil moisture regime: field capacity (FC) × 100% and 120%. Maize was planted, and then air was injected by compressor and venturi. In the field, irrigation was controlled by a controller connected to soil moisture sensors. Soil moisture sensors were measured at 20 cm below soil surface. Soil O2 and CO2 were measured at 10 and 30 cm below soil surface before and after oxygation. Root activity was measured from tip of roots. Root volume and dry weight were measured. Post-harvest, number and weight of maize ears were surveyed as well. As a result, soil oxygen values increased by 59% in the compressor treatment and by 34% in the venture treatment. However, soil CO2values did not depend on the oxygation. In all soil moisture treatments, the activity of oxygated roots was greater than that of the control, and root activity was increased by 152%. Root volume and dry weight were also greater than those in the control. No significant effect of soil moisture was found on the number and weight of ears of maize. The average ear weight of maize in the FC 100% soil moisture treatment was 1,292 kg 10a-1 in the oxygation and 1,278 kg 10a-1 in the control. In addition, no effect of oxygation was observed on number and weight of ears. The average ear weight of maize in the FC 120% soil moisture treatment was 1,229 kg 10a-1 in the oxygation and 960 kg 10a-1 in the control. Maize yield was 28% greater in the oxygation treatment than that in the control. The yield of maize grown in the control field showed a tendency to decrease as the soil moisture content increased. At FC 120% soil moisture, the ear weight of control maize was reduced by 25% compared to FC 100% soil moisture. These results reflected that the oxygation process had a great effect on the root growth even in humid conditions, which was expected to have a positive effect on the maize plants planted above-ground.Root activity, dry weight and volume of corn as a result of soil moisture and oxygation; Soil moisture treatments (field capacity × 100%, field capacity × 120%), Oxygation treatments (compressor, venturi), Control (no air was injected). Soil moisture regime Oxygation treatment Root activity (µg g-1 h-1) Root dry weight (g) Root volume (cm3) 100% of field capacity Compressor 50.1 ± 1.69 b† 49.5 ± 19.25 a 269 ± 83.8 a Venturi 67.8 ± 3.25 a 44.6 ± 10.17 a 224 ± 34.9 a Control 32.2 ± 2.08 c 12.5 ± 5.55 b 59 ± 43.8 b 120% of field capacity Compressor 50.8 ± 1.07 a 42.4 ± 0.74 ab 225 ± 5.0 b Venturi 39.2 ± 1.54 b 73.7 ± 25.75 a 326 ± 56.6 a Control 35.8 ± 1.52 c 14.6 ± 9.81 b 60 ± 48.2 c †a, b and c represent significant difference level at 95%.