Effects of wartime harvest delay on seed viability and grain mycobiota of maize
Abstract
The full-scale war in Ukraine has caused unprecedented disruptions to agricultural operations, leading to forced delays in maize ( Zea mays L.) harvesting due to severe security risks, logistics constraints, and restricted field access. This study investigates the long-term impact of such delays on the physiological viability and mycobiota of maize grain during the 2025–2026 agricultural season in the north-eastern Forest-Steppe of Ukraine. Maize cobs were subjected to extreme environmental stress, remaining in the field for 148 days post-physiological maturity, experiencing prolonged exposure to harsh autumn–winter conditions, including repetitive freeze–thaw cycles and extended periods of sub-zero temperatures. Despite the retention of satisfactory grain yield (ranging from 4.74 to 5.31 t / ha) and normal physical grain characteristics, such as the 1000-grain weight (189.5–205.5 g), laboratory analysis revealed a complete loss of seed germination capacity (0%). This critical failure in viability suggests a profound disruption of embryonic tissue function and membrane integrity, likely driven by cumulative oxidative stress and dehydration caused by fluctuating environmental conditions. Furthermore, mycological analysis identified a substantial transformation of the grain's microbiological status. The fungal community was dominated by Trichoderma viride (50.0%), Aspergillus flavus (33.3%), and Penicillium sp. (16.7%). Statistical indices confirmed a specific, low-diversity community structure (H = 1.01; J = 0.92), which serves as an indicator of physiological weakening and degradation of the grain’s protective barriers. The findings demonstrate that traditional quality metrics ( typically used to assess marketable grain ) are insufficient for evaluating seed suitability under conditions of prolonged field weathering. Our results suggest that such grain, although appearing physically intact, is biologically compromised and unsuitable for planting material. This study underscores the critical importance of integrating physiological germination tests and comprehensive phytosanitary screening into grain quality assessment protocols, particularly when harvesting is disrupted by large-scale conflicts or extreme climatic events. These insights are essential for ensuring future food security and agricultural resilience in regions affected by env i ronmental and socio-economic crises.References
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