تأثير التسميد المعدني (NPK) وحامض الهيومك والرش بالسيليكون في بعض مؤشرات نمو وحاصل الذرة الصفراء

Effect of Mineral Fertilization (NPK), Humic Acid, and Silicon Spray on Some Growth Indicators and Yield of Maize

A factorial field experiment was conducted using a Randomized Complete Block Design (RCBD) in an agricultural field belonging to Ibn Al-Bitar Vocational Preparatory School/Al-Husainiya District in Karbala Governorate during the spring season (2024 AD) in a clay loam soil. The experiment aimed to study the effect of adding mineral fertilizers (NPK), humic acid, and silicon foliar application on some growth, yield, and quality traits of maize. The experiment included three main factors: The first factor represented mineral fertilizers (N, P, and K) and was added at three levels: the level without fertilization, denoted as M0; the level of addition (150 kg N ha-1, 50 kg P ha-1, and 80 kg K ha-1), denoted as M1; and the level of addition (300 kg N ha-1, 100 kg P ha-1, and 160 kg K ha-1), denoted as M2. The second factor was humic acid at two levels (0 and 40 kg ha-1). The third factor was foliar application of silicon at three concentrations (0, 3, and 6 ml L-1). The results of the study showed the following:
• The soil addition of mineral fertilizers (N, P, and K) showed a significant superiority in many of the study indicators. The addition level (M2) recorded the highest averages. The percentage increase in the studied traits was as follows: nitrogen, phosphorus, and potassium concentration in the plant dry matter (74.59%, 62.89%, and 53.59%) respectively, and in the grains (47.01%, 43.76%, and 71.03%) respectively; plant height (14.54%); number of leaves per plant (9.10%); leaf area (15.42%); stem diameter (15.41%); chlorophyll index in leaves (18.05%); ear length (20.80%); number of rows per ear (23.04%); number of grains per row (13.70%); ear weight (25.68%); weight of (500) grains (5.45%); biological yield (30.69%); grain yield (44.25%); harvest index (10.80%); and oil (13.23%) and protein (47.04%) concentration in grains.
• The addition of humic acid to the soil showed a significant improvement in several study indicators. The addition level (40 kg ha-1) recorded the highest averages, and the percentage increase in the studied traits was as follows: concentration of nitrogen, phosphorus, and potassium in the plant’s dry matter (30.50%, 39.76%, and 21.39%, respectively), and in the grains (21.07%, 28.44%, and 31.82%, respectively), plant height (6.44%), number of leaves per plant (7.84%), leaf area (7.07%), stem diameter (5.25%), chlorophyll index in leaves (8.22%), cob length (11.53%), number of rows per cob (10.76%), number of grains per row (6.86%), cob weight (12.70%), weight of (500) grains (3.78%), biological yield (17.95%), grain yield (26.33%), harvest index (7.24%), and concentration of oil (5.29%) and protein (21.04%) in the grains.
• Foliar spray concentrations of silicon showed a significant improvement in several study indicators. The concentration (6 ml L-1) recorded the highest averages, and the percentage increase in the studied traits was as follows: concentration of nitrogen, phosphorus, and potassium in the plant’s dry matter (17.88%, 21.77%, and 10.08%, respectively), and in the grains (13.40%, 15.84%, and 17.28%, respectively), plant height (4.61%), number of leaves per plant (3.78%), leaf area (2.46%), stem diameter (3.21%), chlorophyll index in leaves (7.71%), cob length (9.80%), number of rows per cob (8.65%), number of grains per row (5.22%), cob weight (7.22%), weight of (500) grains (2.87%), biological yield (12.00%), grain yield (18.39%), harvest index (5.62%), and concentration of oil (3.15%) and protein (13.40%) in the grains.
• The binary interaction between mineral fertilization (N, P, and K) and humic acid, mineral fertilization (N, P, and K) and silicon spraying, and humic acid and silicon spraying, had a significant effect on several study indicators.
• The triple interaction between the study factors showed a significant effect on many indicators. The treatment representing the level of addition (M1) of the mineral fertilizer, (40 Kg ha-1) of humic acid, and spraying with concentration (6 ml L-1) of silicon recorded the highest averages, and the percentage increase in vegetative traits was as follows: plant height (29.07%), leaf area (23.76%), leaf chlorophyll index (37.26%), ear length (59.32%), number of rows per ear (42.90%), number of grains per row (53.55%), ear weight (48.66%), (500) grain weight (15.25%), grain yield (119.37%), harvest index (27.97%), and protein concentration (101.77%) in grains