Investigating Yield, Yield Components, Morphological Characteristics and Proline of Different Hybrids of Sweet Corn (Zea mays var. Saccharata) in Different Irrigation Regimes

IntroductionOne of the main challenges in achieving sustainable agriculture is maintaining production under environmental stress. Drought, a prominent geographical feature of our country, is an unavoidable and unchangeable phenomenon. At the same time, the consumption of energy, water, and food resources is increasing rapidly, making it essential to develop strategies to mitigate and reduce its adverse impacts. Sweet corn (Zea mays var. Saccharata), scientifically known as (Zea mays var. Saccharata), is a genetically modified plant of regular corn. This genetic modification causes the accumulation of sugars and soluble polysaccharides in the endosperm of the seed. This plant has special economic importance because all its parts, including the cob, stem, leaves, wood, and husk, are used. Unlike regular corn, this plant is consumed fresh by humans. The most critical stage in terms of water consumption in sweet corn is the flowering stage, from the appearance of silks to the end of cell division in the growing seed endosperm. Stress occurrence at this stage causes a 14% reduction in grain yield. Meanwhile, stress occurrence in later stages, such as cob elongation and seed maturation, results in a 31% and 21% reduction in grain yield, respectively. The aim of this research is to study the response of different sweet corn cultivars to various irrigation regimes through traits such as seed yield, dry weight of 100 seeds, leaf area index, yield components, and proline content.Materials and MethodsTo compare the response of four foreign hybrids and one domestic hybrid cultivar of sweet corn to different irrigation regimes during flowering, an experiment was conducted in a split-plot design based on randomized complete block design with three replications. In this experiment, the irrigation regimes included: a- stopping irrigation until soil moisture depletion reached 15% of available water and then irrigating to field capacity in the root development zone (control: optimal irrigation), b- stopping irrigation until soil moisture depletion reached 35% of available water in the root development zone (mild water deficit stress), c- stopping irrigation until soil moisture depletion reached 55% of available water and then irrigating to field capacity in the root development zone (moderate water deficit stress), d- stopping irrigation until soil moisture depletion reached 75% of available water and then irrigating to field capacity in the root development zone (severe water deficit stress), applied during the reproductive stage in the main plots and sweet corn cultivars (Merit, Honey, Genesis, Chase, and Single cross 403) in the sub-plots.Results and DiscussionThe results showed that the optimal irrigation treatment had the highest grain yield with an average of 5159.6 kg ha-1, while severe water stress had the lowest grain yield with an average of 3429.2 kg ha-1, which was 33% less than the best treatment. Among the studied cultivars, the Genesis cultivar had the highest grain yield. The Honey cultivar showed the lowest grain yield among the studied cultivars, which was 20% less than the best cultivar. Severe water deficit stress had the lowest dry weight of 100 grains, which was 20% less than the optimal irrigation conditions. The highest biological yield were obtained under optimal irrigation conditions and the Honey cultivar. The single cross 403 had the lowest biological yield under severe water deficit stress conditions.ConclusionThe study demonstrated that optimal irrigation significantly enhanced sweet corn yield, leaf area index, and biological yield, while severe water stress substantially reduced these parameters. Among the hybrids, Genesis outperformed others in grain yield, making it the most suitable choice under water-limited conditions. Conversely, the Honey hybrid exhibited the highest proline concentration, indicating better stress tolerance. Overall, the Genesis hybrid is recommended for cultivation in drought-prone areas due to its superior yield.