Abstract
Background: Climate change is expected to increase global irrigation demands, challenging agricultural productivity.
Objectives: To study the influence of irrigation interval and nano-zinc chelate fertilization on soybean [Glycine max (L.) Merr.]. Growth, yield, yield components and quality.
Methods: A field experiment conducted at Qlyasan Research Station, University of Sulaimani, Sulaimaniyah, Iraq, at 2023 growing season, investigated the effects of irrigation intervals and nano-zinc fertilizer on soybean growth and yield. The study employed a split- split plot design with three replications, the treatment (main plot) irrigation intervals (5, 10, and 15 days), three soybean varieties in a subplot (Lee74, Ebba, and Shaimaa), and three nano-zinc fertilizer levels applied as a foliar spray during vegetative growth in the sub-sub plot (0, 200, and 400 µg L-1), using drip irrigation at 3.4 L/h. Temperature was monitored continuously, and actual crop evapotranspiration was measured to assess irrigation efficiency
Results: It was revealed that 5-day irrigation intervals significantly improved plant parameters, including plant height, leaf area index, seed weight, and seed's oil and protein content. Nano-zinc fertilizer application at 400 µgL-1 enhanced root depth, pod weight, and seed's oil, while 200 µg L -1 promoted optimal protein synthesis. The Ebba variety achieved the highest seed yield (1823.75 kg ha -1) under 5-day irrigation with 200 µg L -1 nano-zinc fertilizer. The Lee74 variety produced the highest protein content (34.97%) with 5-day irrigation and 400 µg L-1 Zinc. Both Lee74 and Ebba varieties reached maximum oil content (24.85%) under 5-day irrigation with 400 µg L-1 zinc application. Conclusions: Maximum plant height, leaf area index, pod weight, seed yield, seed's oil, and protein content were enhanced by frequent irrigation intervals. High levels of nano-zinc fertilizers also augmented plant resilience against water stress, enhancing growth parameters and elevating yield components.