Radiation and Water Use Efficiencies of Mycorrhizal Inoculated Hemp Under Water-Deficit Stress

Crop production requires specific management strategies and practices in semiarid areas. This study aimed to evaluate the effect of mycorrhizal inoculation on hemp ( Cannabis sativa L.) grain production and the relationship between water and light inputs in yield improvement. This study was conducted in Shahrekord, Iran, in 2014–2015 using a randomized complete block design with split-plot restriction. Treatments included irrigation regimes with four levels (severe stress, moderate, mild, and well-watered) and mycorrhizal inoculation. Mycorrhizal colonization and grain P content decreased by increasing drought stress, but electrolyte leakage and root/shoot ratio raised. The grain yield was minimum under severe stress despite the effect of mycorrhizae under moderate and especially mild stress levels due to the reduced symbiosis between mycorrhizae and hemp root. According to the results, mycorrhizal inoculation increased water use efficiency (WUE), radiation use efficiency (RUE), and relative water content (RWC), resulting in a yield increase compared to non-inoculated plants. Generally, the positive role of mycorrhizae, especially under mild water stress conditions, improved the efficiency of light consumption and water efficiency, followed by more water supply for hemp production in semiarid environments.