Evaluation of the growth and yield response of wheat varieties (Triticum aestivum L.) to humic acid

Abstract

In order to increase productivity and improve growth and yield characteristics of wheat, the study was conducted during the autumn season of 2024–2025 with the aim of evaluating the growth and yield response of wheat varieties (Triticum aestivum L.) to the effect of humic acid and grown under semi-arid conditions in Diyala Governorate. The experiment was implemented according to the design of the Randomized Complete Blocks (R.C.B.D) and the factorial experiment system, with two factors: the first factor was three varieties of wheat crop (Baghdad, Buhouth3, Al-Rasheed) and the second factor was spraying with humic acid at two levels (without adding H₀, adding H₁ 2ml.L^-1) with three replications. The results obtained from the study showed the superiority of the Al-Rashid variety in most of the studied traits, which are plant height 76.33 cm, number of effective branches per plant 5.58, spike length 13.25 cm, number of grains per spike 58.83, weight of 1000 grains 44.33 g, yield per plant 8.15 g and biological yield 31.08 g. while the superiority of the Buhouth3 variety in the trait of flag leaf area 24.88 cm² and harvest index 32.49%. As for the second factor, which is spraying with humic acid, the H₁ addition treatment was superior for all studied traits, which are plant height cm, flag leaf area cm², number of effective branches. Plant⁻¹, spike length cm, number of grains. Spike⁻¹, weight of 1000 grains g, yield per plant g, biological yield g and harvest index %, which reached 76.44 cm, 28.11 cm², 4.22, 12.17 cm, 46.33, 43.88 g, 6.05 g, 21.55 g and 28.75% respectively. The interaction between the Rashid variety and humic acid H₁ spraying resulted in a maximum plant height of 82.00 cm, 6.00 effective tillers per plant, a spike length of 15.33 cm, 60.00 grains per spike, a 1000-grain weight of 49.32 g, a yield per plant of 9.51 g, and a biological yield of 32.67 g. The Buhouth3 variety and H₁ humic acid spraying also showed in a larger flag leaf area of ​​30.00 cm² and a harvest index of 37.07%. These results demonstrate the importance of appropriate variety selection as a key factor contributing significantly to improved wheat growth and yield when treated with humic acid.