by Kalidas Shetty and Dipayan Sarkar; NDSU Plant Science Department

Corn is an important commodity crop of North Dakota and corn industry is a major contributor to the state’s economy. Addressing different production challenges of corn growers to improve overall productivity and profitability is essential for growth and sustainability of corn industry. Corn growers of North Dakota are facing increasing challenges from several abiotic stresses, such as salinity, drought, waterlogging, and heat stress.

Overall, these abiotic stresses have significant detrimental impacts on growth, survival, and productivity of corn and add serious economic burdens to corn growers. Among these abiotic stresses, increasing salinization and related sodic soil is a growing problem for crop production in different pockets of North Dakota. Waterlogging and flooding due to increasing precipitation in combination with high clay soil is a major production challenge especially in the Red River region of North Dakota during spring and early summer.

Performance of Corn Seedlings under Waterlogging Stress

Overall, corn is moderately susceptible to both salinity and waterlogging stress as prolonged exposures to these stresses can lead to loss of productivity or even complete crop failure. Therefore, improving both salinity and waterlogging stress resilience of corn is important for overall improvement of corn production and to reduce the economic risks associated with these abiotic stress pressures. In this context, findings new tools which are safe and compatible for wider field based application is essential to improve abiotic stress resilience in corn. To address such abiotic stress-induced production challenges of corn, new seed treatment based innovation was advanced in our laboratory during past five years with different commodity crops, such as corn, edible dry beans, and barley. In this context, we have developed an exciting metabolically driven strategy to counter abiotic stress-induced metabolic breakdown and failure of seedling emergence under waterlogging and salinity stress using seed treatments with natural bioprocessed elicitors. Two different natural bioprocessed elicitors; Gro-Pro-fermented marine peptide extracts from seaweed and fish byproduct (1 mL/L concentration), and bioprocessed soluble chitosan oligosaccharide (COS- 1 g/L concentration) were targeted and compared with control (no seed treatment). The novelty of such seed priming-based strategy is to provide multiple benefits such as improved seed vigor, better seedling establishment, enhanced photosynthetic activity, adjustments of root and shoot morphology, and stimulation of critical endogenous defense responses that are essential to counter abiotic stress induced metabolic and physiological breakdowns in corn.

Repeated greenhouse-based experiments with 10 corn cultivars were conducted under different soil salinity stress levels (0-1, 3-4, 7-8 ds/M Electrical Conductivity) and under waterlogging stress (1 cm water above the soil level, full saturation, and field capacity for different duration of 7, 10, 15, and 21 days) during last two years. In initial screening study, most corn seeds did not germinate under high soil salinity and constant waterlogging stress. Therefore, for both stress studies, 1 week old corn seedlings were transplanted and subjected under salinity and waterlogging stress. Overall, we have found that most corn cultivars are moderately tolerant to salinity (7 ds/M EC) and waterlogging stress (1 cm water above ground for 21 days). Though most corn plants were survived and recovered from high salinity and waterlogging stress, the root growth, photosynthetic activity, and reproductive growth were significantly impeded by these abiotic stress pressures.  Overall, significant differences in response of different corn cultivars to both salinity and waterlogging stresses were observed. Legacy L-2937 and Rea1b820 performed better under salinity stress, while Dairlyland DS-7294 and Legacy L-2937 had higher waterlogging stress tolerance.

Interestingly, seed priming treatment with marine peptide (Gro-Pro @10mL/L) had significantly improved seedling emergence, root growth and root architecture, photosynthetic activity, and cob formation under both mild salinity and waterlogging stresses and even without the abiotic stress treatments (control). We also observed that such improvement of salinity and waterlogging stress resilience of corn is associated with critical metabolic regulation of endogenous defense responses related to antioxidant enzyme responses of corn. Such endogenous defense responses against abiotic stresses are also closely associated with pathways related to nitrogen uptake and nitrogen utilization efficiency (NUE) in plants due to root morphology changes. Therefore, the aim is to continue research on this exciting seed elicitation strategy for field-based applications to improve abiotic stress resilience, NUE, and overall productivity of corn under salinity and constantly varying waterlogging stress. Overall, the vision is to help corn growers to select appropriate stress resilient cultivars and to advance economically viable seed elicitation strategy to improve abiotic stress resilience, NUE, and associated improvement in fitness and productivity of corn.