Foliar and soil fertilization of humic acid affect productivity and quality of tomato

Abstract

Abstract The objective of the study was to determine the effect of foliar and soil fertilization with humic acid (HA) on quality, growth and yield of tomato under greenhouse conditions in 2004 and 2005. Tomato plants were treated with soil and foliar HA applications at different concentrations (0 ml/l, 10 ml/l and 20 ml/l). Three weeks after planting HA was sprayed four times during the vegetation period at 10-day intervals. Furthermore, 0, 10 and 20 ml/l HA solutions were applied as a drench to the plant root area four times during the vegetation period at 10-day intervals three weeks after planting. HA treatments had no effect on pH and titratable acidity (TA) of tomato. Total soluble solids (TSS) increased with both foliar and soil HA treatments. Foliar 20 ml/l HA application resulted in the highest ascorbic acid (AA) content. Foliar applications of HA led to higher leaf and stem dry matter contents than the control. Both foliar and soil HA treatments positively affected fruit characteristics including fruit diameter, fruit height, mean fruit weight and fruit number per plant. Similarly, HA treatments increased the early yield of tomato compared to control. The yield of tomato was significantly influenced by soil and foliar HA applications. The highest yield occurred in foliar 20 ml/l HA treatment. The study shows that 20 ml/l concentration of HA sprays could be successfully used to obtain better growth and yield in tomato.