Introduction

Sweet corn is one of the most valuable vegetables and industrial crops worldwide due to its high sugar content, pleasant flavor, and rich nutritional profile. Global demand for sweet corn has been steadily increasing, driven by urbanization and growing awareness of healthy diets. However, drought stress is the primary limiting factor in arid and semi-arid regions, capable of reducing yield by 30–90%. Developing sustainable strategies to mitigate drought effects is therefore critical. Nano-selenium (nano-Se) acts as a powerful antioxidant, improves osmotic adjustment, and enhances nutrient uptake, while arbuscular mycorrhizal fungi (AMF) significantly increase water and nutrient acquisition through extensive hyphal networks. Although several studies have examined these factors individually, their combined synergistic effects on sweet corn under varying water regimes have remained largely unexplored in Iran. This study was the first in the country to investigate the interaction of foliar nano-Se and Glomus mosseae inoculation on growth, physiological traits, and canned kernel yield of sweet corn under full irrigation and moderate-to-severe drought stress.

Materials and methods

A two-year field experiment (2023 and 2024) was conducted at Yasouj University Research Farm (30°34′N, 51°30′E). The experiment was arranged as a split-plot factorial in a randomized complete block design with three replications. Main plots were three irrigation regimes (100%, 80%, and 60% of crop water requirement calculated from Class A pan evaporation). Sub-plots consisted of eight factorial combinations of four nano-Se levels (0, 15, 30, and 45 mg L⁻¹ applied as foliar spray at the 8-leaf stage, three times, one week apart) and two mycorrhizal treatments (inoculated and non-inoculated with Glomus mosseae at 80 kg ha⁻¹ placed in-furrow beneath seeds). The sweet corn hybrid ‘Royal Sluis’ was planted at 20 cm spacing on 75 cm ridges. Fertilization followed soil test recommendations. Plant height, stem diameter, leaf number, ear characteristics, biological yield, fresh ear yield, canned kernel yield, harvest index, 100-kernel weight, and leaf proline content were measured. Combined analysis of variance was performed using R software; means were separated by LSD test at P ≤ 0.05.

Results and discussion

The three-way interaction (irrigation × nano-selenium × mycorrhiza) was significant for the majority of measured traits. Across all irrigation regimes, the highest performance was consistently recorded in treatments combining 30 and 45 mg L⁻¹ nano-selenium with mycorrhizal inoculation (Glomus mosseae); these two concentrations rarely differed significantly from each other. Under full irrigation (100% water requirement), these combined treatments produced the tallest plants (182.16 and 180.75 cm), thickest stems (28.15 and 28.00 mm), highest leaf number per plant (15.33), longest ears (24.50 and 24.78 cm), highest biological yield (46864 kg ha⁻¹; +25%), highest fresh ear yield (23375 and 23295 kg ha⁻¹; +37.5% and +37%, respectively), and highest canned kernel yield (5693.33 and ~5710 kg ha⁻¹; +39% and +39.1%, respectively). Even under severe drought (60% water requirement), the same treatments significantly mitigated stress effects, increasing plant height by 14–15%, stem diameter by up to 39%, leaf number per plant, ear diameter by up to 20%, ear length by up to 25%, kernels per row by up to 23%, fresh ear yield by 35–35.4%, fresh ear harvest index by up to 20.4%, 100-kernel weight by 31.3–31.8%, and canned kernel yield by 32.4% (reaching ~4500 kg ha⁻¹). Biological yield still rose by 12% compared with the untreated control. The same superior treatments dramatically elevated leaf proline content by up to 70% under severe drought and by up to 130% under non-stress conditions-reflecting enhanced osmotic adjustment and antioxidant protection. These outstanding results stem from the strong synergistic interaction between nano-selenium and Glomus mosseae. Nano-selenium reinforces the antioxidant defense system and sustains photosynthetic efficiency, while mycorrhizal hyphae greatly extend the root absorption zone, improving water and nutrient uptake even under limited soil moisture. Together, they redirect assimilates toward reproductive sinks, ensuring high ear quality and canned kernel yield despite severe water deficit.

Conclusion

Concurrent application of 30 mg L⁻¹ foliar nano-selenium and Glomus mosseae inoculation is a low-cost, sustainable, and highly efficient strategy that can neutralize the negative impacts of severe drought stress and increase canned kernel yield of sweet corn by 32–39%. This technology is strongly recommended for sweet corn production in arid and semi-arid regions of Iran and similar climates worldwide.