Investigation of the Response of onion (Allium Cepa L.) to continuous deficit irrigation as smart approaches to crop irrigation under Mediterranean conditions

Water is a crucial resource for food production and its scarcity associated with frequent droughts has increased the need for a more efficient use of it along with new irrigation management technologies. This study addressed onion crop responses to continuous deficit irrigation with trigging thresholds of readily available water content. The experiment was conducted on an experimental plot in open field in Morocco. Three water regimes were applied T1 control (100%), T2 (75%) and T3 (50%) of crop evapotranspiration ETc combined with two trigging thresholds (10% and 5%). This is a complete random block device with four repetitions. The measurements concerned the monitoring of vegetative, Eco physiological and yield parameters. The results obtained show that: (i) 100% ETc irrigation at a threshold of 5% of RAW recorded the maximum bulb diameter and weight, thus achieving the best marketable bulb yields. However, in terms of yields, this treatment is not significantly different from the other irrigation regimes with the exception of the irrigated treatment at 50% daily ETc and at a threshold of 10% RAW. The latter recorded the lowest values in terms of production parameters. (ii) For the ecophysiological parameters, significant effects of irrigation dose were observed for proline content, stomatal conductance and leaf temperature, and the effect of the trigging threshold was clearly observed for the moisture content of the leaves. (iii) Water restrictions have minimized the rate of premature run and population density of Thrips tabaci in the onion. (iv) Finally, the best agronomic efficiencies in the use of irrigation water were recorded in treatments with a water restriction of 50%