Effect of Spraying with Plant Extracts on Quantitative and Qualitative Characteristics, water requirements and Seed Production of the Local Red-Onion Variety

En. Rawaa Marwan Al-babilie
Horticulture Department, General Commission for Scientific Agricultural Research (GCSAR)
Faculty of Agriculture, Damascus University 


The study was conducted in collaboration between College of Agriculture/ Damascus University, and the General Commission for Scientific Agricultural Research. The experiments carried out at the Faculty of Agriculture and in the nursery of Al-Adaway during the period 2012-2015 using the local red onion variety. The objective of the experiments to study the effect of foliar spray with licorice roots, dry bread yeast, and seaweeds extracts on onion growth, quantitative and qualitative characteristics of resulted bulbs, and on growth of mothers bulbs and their production of seeds.

The results of the first experiment showed that most of foliar spray treatments gave superior plants, especially with the highest concentrations of seaweed extracts 15 ml/l, yeast and licorice extracts15 g/l, where the average plant height and leaf area reached 68.65, 70.58, 74.4 cm and 1498.63, 1552.63, 1612.83 cm2. This increased productivity of bulbs 3.49, 3.91, 4.25 kg/m2 that had better quality characteristics, where dry matter content was 21.3, 21.97 and 22.38%, respectively, compared to control (57.49 cm, 819.58 cm2, 2.12 kg/m2, 20.21%). The profitability of the best treatment (licorice root extract 15 g/l) reached 369% with an increase of 69% in comparison with chemically fertilized control plants.

The results of the second experiments indicated important role of spraying treatments in increasing growth and productivity of onion plants when different irrigation levels were applied (100, 75 and 50% of field capacity). Lower irrigation rates decreased growth and production. Mean plant height and bulb weight of untreated plants decreased significantly from 35.33 cm and 50.82 g/bulb, at 100% irrigation level, to become 31.33, 26.33 cm and 38.72, 30.20 g/bulb at 75% and 50% levels, respectively. Foliar spraying treatments reduced the negative impacts of water irrigation shortage. Mean plant height and bulb weight of plants received 50% of field capacity (31.18 cm, 38.72 g/bulb) increased when sprayed with 10 g/l licorice extract to reach values that are almost equal to that of control plants at thelevel of 75% (31.33 cm, 38.72 g/bulb). Similarly, treated plants received 75% irrigation, had comparable values (35.17 cm, 49.37 g/bulb) to that of untreated control plants at the levels of 100 % (35.33 cm, 50.82 g/bulb). Foliar spray with licorice extract 10 g/l at 50% irrigation level, increased leaf content of total chlorophyll, carotenes and proline (36.14 mg/g, 2.800 mg/g, 0.925 mg/100g), respectively, compared to control plants (31.39 mg/g, 1.633 mg/g, and 0.702 mg/100g).  Treatments applied in the third experiment improved vegetative growth (Mean plant height, length of leaf, number of leaves) which reflected positively on flowering indicators, seed production and quality. The average number of flowers increased to 969.60, 948.00 and 895.20 flower/umbel by licorice and yeast treatments (15 g/l)and seaweeds (15 ml/l) compared to 705.40 flower/umbel in control plants. The ratio of flower set significantly increased from 62.67% in the control to 82.50, 84.90 % in 15g/l yeast and licorice treatments. The 15 g/l licorice treatment was superior and gave the best seed yield per area unit (422.70 g/m2) compared to control (217.00 g/m2).

Key words: Local onion, licorice roots, dry yeast, seaweed, productivity, field capacity.