Allelopathic Effect of Ecofriendly Botanical Extracts and Application of Vinasse as Alternative Source of Mineral Potassium Fertilizers on Yield and Oil Quality of Caraway Plant

Abstract

A field trial was performed during two consecutive winter seasons of 2017 and 2018 at a private farm located in Kafr El Wekala , Sherbin, El Dakahlia Governorate, Egypt to evaluate the allelopathic effect of garlic and licorice extracts at 0, 1, 2 and 4 % and application of vinasse as organic fertilizer at V1 (50%) and V2 (100%) from the recommended dose of potassium fertilizer on growth of caraway plants, seed measurements, essential oil productivity as well as N, P, K, Ca, Mg and Fe contents of caraway seeds. The obtained results showed that garlic and licorice extracts under both the chemical fertilizer NPK and levels of vinasse possess the positive allopathic effect on growth and the yield of caraway. Vinasse at two levels resulted in significant increments on all studied parameters compared to chemical fertilizer, Furthermore, the plants treated with the high rate of vinasse (100%) in combinations with licorice extracts at 2% in both seasons recorded the maximum means values for growth characters, plant dry weight, seed weight per plant subsequently seed yield per fed. and essential oil production. Moreover, Vinasse (100%) in combinations with garlic extracts at 4%, significantly increased the chemical constituents of caraway seeds compared to the control and other treatments in both seasons. GCM analyses for oil showed that a total of 10 compounds, the main component was carvone which constitutes the maximum percentages in plants treated with vinasse (100%) in combination with garlic foliar application at all levels. The obtained data revealed that the best growth, essential oil and chemical composition were obtained from treated plants with vinasse (100%) from the recommended dose of K in combination with licorice extracts at 2% and garlic extract at 4% which had attained the uppermost values of yield and quality of caraway compared to either control or other treatments. Therefore, we recommend spraying caraway plants with ecofriendly, organic and costless extract of licorice at 2% and replacement of the mineral K fertilizers by vinasse (100%) as an organic potassium source without adverse effects on caraway yield and oil quality.