A field experiment was conducted during the autumn season of 2018 at agricultural research station in Al- Qurna district (80 km north of Basra center). The aim was to study the effect of spraying different concentrations of humic acid (HA) and silicon on the some growth characteristics of maize (Zea mays L.). The experiment was conducted using Three Concentration of humic acid were used 0, 2 and 4 gm L-1, which took the following symbols H0, H1, and H2 respectively and four concentrations of silicon 0, 1, 2 and 3 mML-1 which took the symbols S0, S1, S2 and S3 respectively. A factorial experiment was used in randomized completely block design with four replicates. Maize seeds cv. Fajir1 were planted at 20/7/2018 in a silty loam soil. The results showed that the concentrations of HA differed significantly in all most of the studied characteristics, plant height, leaf area and ear length with an increase by 11.69, 24.89 and 3.49% respectively as compared to the control treatment (H0). The spraying with silicon showed a significant effect. Moreover, the concentration of S3 gave the highest values for plant height, stem diameter, leaf area and ear length. The interaction between HA and silicon showed a significant effect on some of the studied characteristics, the combination of S3×H2 produced the highest values of plant high (174.42 cm) and leaf area (7390.65 cm2).

No abstract

"A study was conducted in Al-Seba Reserve / Basra Governorate to study the effect of nitrogen and potassium fertilization on growth of stevia plants during 2018-2019 agricultural season, in pots. A sandy mixture of soil was used and two factors were studied: the first factor was urea fertilizer with five levels of nitrogen (N0 0, N1100, N2150, N3 200, and N4 250 kg / ha) and the second factor was potassium sulfate with three levels of potassium (K0 0, K1 75 and K3150 kg/h( . The experiment was experimental factor using a complete randomized design (C.R.D) with three replications. The results showed a significant effect of adding nitrogen and potassium fertilizers and there interaction on: plant height, number of branches, leaf area index, and the treatment N3K2 gave the highest yield reached (1.27 tons. h-1), and N4K2 recorded a highest content of Rebaudioside A (53.26 ppm). *Part of Ph.D. thesis of the first author Corresponding author: E-mail(khawla_74@yahoo.com) Al- Muthanna University All rights reserved"