Effect of foliar organic fertilization on the growth, yield and oil content of Mentha piperita var. citrata

Abstract

This study was carried out to evaluate the response of Mintha piperita var. citrata (Eau de Cologne mint) to foliar fertilization under Egyptian conditions. This study was carried out on Mintha piperita var. citrata (Eau de Cologne mint) at Sekem Experimental field. Fresh, healthy, insect and disease free suckers were transplanted in furrow at a depth of 4-5 cm as per the treatments. Three weeks later after transplanting, the plants were sprayed with aqueous solution of the test nutrient compounds humic acid (0. 2.5 and 5 g L-1) and amino spot (0, 1 and 1.5 mL L-1). The crop was harvested in mid-May (First cutting) and mid-August (Second cutting). Growth and yield characters were measure. The essential oil percentage was determined in both cuts from fresh herb. The essential oil was analyzed by GC/Mass. It can be observed that, humic acid and/or amino spot fertilizer (Algae extract) had a significant effect on growth characters during both cuts. Increasing amino spot doses increased growth characters (plant height, herb fresh and dry weight) at all doses in the two cuts. The results show that there were clear significantly positive trend in increasing growth characters by spraying of humic acid. The interaction effect was significant in both cuts, the highest values of plant height, herb fresh and dry weight (g plant-1) were produced from the treatment sprayed with humic acid at 5 g L-1+amino spot at 1.5 mL L-1, followed by the treatment sprayed with 2.5 g L-1 humic acid+1.5 mL L-1 amino spot at the two cuts. During the 1st cut, humic acid or amino spot fertilizer had a significant effect on essential oil percentage and yield (mL plant-1) while, all treatments produced significant effect on oil percentage and oil yield (mL plant-1) except the interaction treatments, which had no significant effect on essential oil percentage during second cut. Linalool and linalyl acetate were the main constituents of essential oil of this plant. All treatments or cuttings had a pronounced effect on essential oil constituents. Based on the experimental results it is recommended to treat Mintha piperita var. citrata (Eau de Cologne mint) plants with humic acid at 5 g L-1+amino spot at 1.5 mL L-1 to produce high mass production and oil yield.