Influence of Foliar and Soil application of Humic Acid on Growth and Yield of Lettuce

The plastic-house experiment was carried out at University of Sulaimani, College ofAgricultural Sciences during the growing season of 2016-2017 to determine the effect of soiland foliar application of humic acid on yield and yield components of Lettuce (Lactuca sativaL.var Romaine). Four humic acid concentrations (ml.L-1) were sprayed, and soil applicationof humic acid in four levels that were soil addtions. The design of experiments was aRandomized Complete Block (RCBD) with three replications. The seeds were planted inOctober 2016; moreover, the lettuce seedlings were transplanted in Novrmber 2016 to theexperimental area. The results referred to the highest total yield (47.863t.ha-1) was obtainedwith treatment T4 followed by treatment T1. Foliar application of 4.5 ml.L-1humic acid (T3)recorded significantly highest plant height as compared with control treatment. In addition thehighest values of (TSS) were obtained by soil application (T6) at rate 3.5 ml/L. The datashowed that there were no significant differences in the amount of the N, P, K and nitrate inthe lettuce product.