Evaluation of Bio-phosphor and HumicAcid on Growth Parameters and Oil Content in Evening Primrose (Oenotherabiennis L.)

Evening primrose (OenotherabiennisL.) is a relatively new and valuable oilseed crop for temperate region. Its oilseed is important because of high levels of unsaturated fatty acids, especially gamma-linolenic acid. Seeds contain 20-30% oil which includes 70% linoleic acid (LA) and 10% gamma linolenic acid (GLA). Oil content in O. biennis is a quantitative trait which controlled by many genes and similar to any other quantitative traits varies with environmental conditionssuch factors as age of seed and growth conditions. Evening primrose oil, especially gamma-linolenic acid, has many therapeutic properties, and it uses as cure for many diseases such as Diabetes, Eczema, inflammation, Cardiovascular, Cancer, Autoimmune diseases, Rheumatoid Arthritis, Depression. Studies on Medicinal Plants in nature and farmlands show that the use of sustainable agriculturae andnatural sources are two suitable methods for producing healthy plants.Additionally, the use of bio-fertilizers lead to maximum yield and quality in these plants. Azizi et al.(6) showed that interactions of vermicompost and plant density had significant effect on oil content, oil density and refractive index of evening primrose oil. The best treatments were also including 2 Kg/m2 of vermicompost,20 plants/ m2in terms of oil production,9 plants/ m2in terms of oil quality and ratio of unsaturated fatty acids to saturated, respectively.
Material and The aim of this research was to determine the effect of humic acid and bio-phosphor application on growth parameters in O. biennis. The experiment was conducted based on randomized complete block design with 8 treatments and three replicates during 2013-2014 growing season, at the experimental farm of the faculty of Agriculture, Ferdowsi University of Mashhad.. Treatments consisted of 4 levels of humic acid (0, 1, 3, 5 ml/L) and 2 levels of bio-phosphor (without bio-phosphor or with bio-phosphor). Liquid form of humic acid was used, which has low percentage of organic matters (16.5%) and applied as foliar spray after stem elongation in three stages with 10 days intervals until flowers stage. The use of bio-phosphor contain three strains of phosphate solubilizing bacteria(Pseudomonas pautida, Bacillus circulans and Bacillus subtilus) withCFU 108 numbers of spores (the number of living cells of each bacteria per milliliter). Analysis of variance was calculated using MSTATC andDuncan's multiple range tests was employed at probability level of 5%.
The results showed thatmaximum plant height (85.59 cm),number of seed per capsules on main shoot (251.17), oil percent (21.75 %) was obtainedby interaction effect between 5 ml/Lhumic acid and without bio-phosphor. Also, seed yield (1080 kg/ha) and oil yield (227 kg/ha) increased byinteraction effect between 3 ml/Lhumic acid and without bio-phosphor. Humic acid had a significant effect on increasing number of lateral branches (26/8), number of capsules on main shoot (117/35), as the highest value of all traits were obtained in 5 ml/L humic acid treatment. The highest number of capsules in lateral branches was observed in bio-phosphor treatment without humic acid. Bio-phosphor application had no significant effect on increasing oil percent. Oil yield was reduced by using of this fertilizer with 1ml/L humic acid treatment but application of 3 and 5 ml/L of humic acid showed no significant difference in comparison to control. Ahmed et al.reported that humic acid is a suspension based on potassium humate, which can be used as a plant growth stimulant in order to increase plant natural resistance against diseases and pests and subsequently increase plant yields. Phosphorus is an important element for cell division, root development and seed formation. Phosphate solubilizing bacteria produce organic acids which increase solubility of phosphorus and make it available for plants. Use of bio-fertilizers not only improves plant structure and activity of beneficial soil microorganisms, also it provides good availability of water and nutrients which finally improve plant yield. It can be said that foliar spray by humic acid stimulates plant growth and increaseevening primrose oil content.
Application of 3 and 5 ml/L of humic acid had the best results on traits andinteraction effect between humic acid and bio-phosphor showed positive effects on all traits except oil percent and oil yield. Generally, humic acid had positive effect on plant growth, oil yield, content and composition. Although, bio-phosphor had good effect on seed yield as a growth trait,its application with humic acid improved this trait.While bio-phosphor had no significant effect on oil content, it can be relative impact on oil composition.