Can irrigation systems alter the critical period for weed control in onion cropping?

Abstract

Weed management is essential in vegetable crops, constituting the main production cost. Cultural control strategies can help minimize weed interference and decrease the critical period for weed control (CPWC) when well implemented. Localized nutrient and water supply may favor crop growth, suppressing weeds, and reducing the CPWC. We hypothesized that the drip system reduces the CPWC compared to the micro-sprinkler system and may be recommended as a cultural control method. To support our hypothesis, the objective was to determine the CPWC in onion cultivated under drip or micro-sprinkler during three cropping seasons. Field experiments were conducted during 2016, 2017, and 2018 to evaluate the effects of drip and micro-sprinkler irrigation had on the CPWC in onion (Allium cepa L.). The coexistence of weed in the onion lifecycle significantly reduced the bulb yield for both irrigation systems. The reduction by weed infestation in relative onion bulb yield for the drip system was 61.8, 80.9, and 97.6% in 2016, 2017, and 2018 seasons, respectively. For micro-sprinkler systems, the reduction was 89.2, 85.2, and 98.6% in the 2016, 2017, and 2018 seasons, respectively. The CPWC varied according to the irrigation system and season. For example, in a drip system, the CPWC was 11, 17, and 74 days for 2016, 2017, and 2018. In the micro-sprinkler system, the CPWC was 18, 53, and 45 days in 2016, 2017, and 2018. The predominant weed community determines the irrigation system (drip or micro-sprinkler) that promotes better cultural weed control and reduction of the CPWC in onion cropping systems.