Response of Corn (Zea mays L.) to Different Planting Dates and Their Impact on Yield and Quality Traits

• Najwa Najm Al-Deen Bassas Salah Hameed Jumaa

  Author

A field experiment was conducted during the 2025 summer growing season at the Field Crops Department Research Station, College of Agriculture, Tikrit University, located in Salah Al-Din province , at coordinates 43.679° East longitude and 34.616° North latitude. The experiment was   Applied using randomized complete block (RCBD)  arranged in split-plot three replications to determine the effect of planting dates on physiological and morphological traits. The main plots included planting dates, while the  sub-plots  included the six genetic combinations (Saginto, ZP, DKC6777, Portiba, Layla, and DKC5911). The following results were obtained: The third planting date (August 1st) was excelled in vegetative and physiological growth traits, yield, and its components. It recorded the highest plant height, highest chlorophyll content, largest cob diameter, highest number of grains . row-1, highest total grain yield, highest biological yield, highest oil percentage, and the longest number of days to physiological maturity, reaching (171.25 cm), (41.35 SPAD), (48.87 mm), (37.32 grains . row⁻¹), (9.49 ton.ha⁻¹), (14.92 ton.ha⁻¹) (5.38%), and (104.50 days), respectively. Meanwhile, the first planting date (June 20th) was characterized by high heat accumulation values, recording (1769.23 K) until male flowering (57.44 days) and (1950.92 K) until female flowering. (59.17 days) and (2691.05 calories) until physiological maturity (104.50 days). In contrast, the second planting date (July 10) was distinguished by its superiority in protein content (9.05%) and ash content (1.14%). Regarding the genotypes, Saginto genotype showed the highest plant height, the highest number of leaves, the highest number of ear rows, the highest number of cob per plant, and the highest yield per plant, which was reflected in achieving the highest biological yield, harvest index, and oil percentage, recording (181.04 cm), (15.66 leaves . plant^-1), (14.82   rows . plant^-1), (1.24), (144.15 g), (13.79 tons ha⁻¹), (62.64%), and (5.71%) respectively. Meanwhile, genotype DKC5911 recorded the highest heat requirement. For male and female flowering and physiological maturity, the temperatures were 1808.96°C, 2004.53°C, and 2562.28°C, respectively. Genotype DKC6777 showed the earliest male and female flowering, recording the shortest number of days to reach 50% of the flowering stage (53.44 days and 55.33 days), while genotype Portiba was distinguished by its early physiological maturity, with the shortest duration (101.67 days). Genotype Layla was distinguished by its high chlorophyll content and high percentage of starch (39.54% SPAD and 30.28%, respectively .

The third date (1 August) and the genotype (Saganto) were distinguished by their excelled in most of the studied traits. This was clearly reflected in the results of the interaction between the genotype and the planting date, as the genotype (Saganto) and the third date (1 August) recorded the highest values ​​in the traits of the yield and its components, including the number of rows of cob, the number of grains .cob-1, the number of grains per cob, and the weight of 500 grains (17.27 rows . cob^-1), (782.40 grains . cob-1), and (145.00 g) respectively. At the first date (June 20), genotype (DKC6777) excelled in early flowering, recording the lowest number of days for male and female flowering (50.00 days) and (52.00 days) respectively. At the third date (August 1), genotype (Porteba) was distinguished by early physiological maturity (97.33 days). At the second date (July 10), genotype (DKC6777) was distinguished by the highest protein percentage (10.34%). At the second date (July 10), genotype (Porteba) was distinguished by the highest ash percentage (1.21%). At the third date (August 1), genotype (Saganto) recorded the highest oil percentage (6.13%), while genotype (Layla) recorded the highest starch percentage (32.91%). The third date (1 August) and the genotype (Saganto) were distinguished by their superiority in most of the studied traits. This was clearly reflected in the results of the interaction between the genotype and the planting date, as the genotype (Saganto) and the third date (1 August) recorded the highest values ​​in the traits of the yield and its components, including the number of rows of the ear, the number of grains .cob-1, the number of grains .cob-1, and the weight of 500 grains (17.27 rows . cob-1), (782.40 grains . cob-1), and (145.00 g) respectively. At the first planting date (June 20), genotype DKC6777 exhibited the earliest flowering, recording the shortest number of days for male and female flowering (50.00 days and 52.00 days, respectively). At the third planting date (August 1), genotype Porteba showed the earliest physiological maturity (97.33 days). At the second planting date (July 10), genotype DKC6777 exhibited the highest protein content (10.34%), while genotype Porteba showed the highest ash content (1.21%). At the third planting date (August 1), genotype Saginto recorded the highest oil content (6.13%), and genotype Layla recorded the highest starch content. (32.91%)

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