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

Abstract

The plastic-house experiment was carried out at University of Sulaimani, College of Agricultural Sciences during the growing season of 2016-2017 to determine the effect of soil and foliar application of humic acid on yield and yield components of Lettuce (Lactuca sativa L.var Romaine). Four humic acid doses (0) control, (2.5, 3.5 and 4.5) ml/L were sprayed, and soil application of humic acid in four levels, such as (0) control, (1.5, 2.5 and 3.5) ml/L added to the soil. Among the treatments level, highest total yield (47.863t/ha) was obtained with treatment T4 (1.5 ml/L soil application) followed by treatment T1 (2.5 ml/L foliar application). Foliar application of 4.5 ml/L humic acid (T3) recorded significantly highest plant height as compared with control treatment. In addition the highest values of (TSS) were obtained by soil application (T6) at rate 3.5 ml/L. The data showed that there were no significant differences in the amount of the N, P, K and nitrate in the lettuce product.

Keywords: Lettuce, Humic acid, Foliar application, Soil application, Sustainability.