Influence of irrigation regimes on the performance of groundnut (Arachis hypogaea) under intercropping situation

The system output of groundnut based intercropping system depends on the selected companion crop as well as the frequency with which irrigation is supplied. This initiates a requisite to evaluate the performance of present traditional intercropping systems and thereby optimize the level of irrigation for both the crops under the system.

A two-year field experiment was conducted during the rabi season 2017–2019 at Oilseeds Research Station, Tamil Nadu Agricultural University, Tindivanam, Tamil Nadu, India The experiment was laid out in split plot design with three replications. Main plot comprised of five treatments with four intercrops viz., castor (TMV 5), blackgram (VBN 8), sesame (TMV 7), pearl millet (CO 10) and sole groundnut (TMV 13). The sub plot was assigned with three irrigation regimes based on IW/CPE ratio of 0.50, 0.75 and 1.0.

Groundnut + blackgram combination recorded higher pod yield (6.31 g plant⁻¹), equivalent pod yield (1986 kg ha⁻¹) with increased water use efficiency (5.49 kg ha⁻¹ mm⁻¹) and economic water productivity ('309 ha⁻¹ mm⁻¹) over sole groundnut while other intercropping combinations failed to express. Soil moisture extraction pattern was higher at top layers and decreased with soil depth. More frequent irrigations (IW/CPE 1.0) mismatched with the crop water requirement and resulted in higher consumptive water use (500.8 mm) with moisture extraction pattern from initial layers favouring evaporation losses. At peak growth stage (60 days after sowing) higher light interception was observed in groundnut + pearl millet (41.4%) followed by castor (38.2%) combinations which was the prime reason for decreased yields as groundnut is susceptible to shading. Therefore, groundnut + blackgram combination under rabi season when supplied with six irrigations at twenty days interval (based on IW/CPE 0.50) could significantly increase the productivity and monetary returns from the system.