Effect of Some Organic and Chemical Fertilizers on Morphological and Biochemical Factors of Fenugreek (Trigonella foenum-graecum L.)

Any improvement in agricultural system that results in higher production should reduce the negative environmental impact of agriculture and enhance the sustainability of the system. Seaweed extracts (SWE) are known to cause many beneficial effects on plants as they contain growth promoting hormones, trace elements, vitamins and amino acids. Humic acid plays a vital role in soil fertility and its application increases the plant growth and nutrient uptake. The present study was undertaken to investigate the effect of SWE, humic acid and chemical fertilizers on the morphological and biochemical characteristics of Trigonella foenum-graecum L.
Material and The experiment was carried out in 2016 at the Agricultural Research Greenhouse at Imam Khomeini International University, Qazvin, Iran. The experiment was based on a completely randomized design with four treatments including: SWE, humic acid, chemical fertilizers and control and 7 replications. The pots were filled with 5kg of farm soil, which was evenly mixed with recommended level of chemical fertilizers (N; 0.08, P; 0.06 and K; 0.1 g/kg soil) for chemical fertilizer treatment. Seeds were sown at a depth of 1.5 cm in each pot. Seedlings were thinned to five plants per pot 10 days after emergence. In 4 leaves, appearance stage, SWE and humic acid treatments were applied as a foliar spray every 14 days, for three times before harvesting. Growth parameters were measured in correct time. The biochemical constituent pigments such as chlorophylls and carotenoids and also total ascorbic acid in leaf were estimated in control and treated plants using standard methods. Dried seeds of Fenugreekwere subjected to hydro distillation for 3h using a Clevenger-type apparatus to produce oil and essential oil percentage was measured.
In relation to the mean comparisons, the maximum shoot length and the highest number of pods per plant was obtained in plants receiving SWE and NPK. Maximum plant fresh and dry weights were observed in plants received SWE. All fertilizer treatments increased the number of seeds per pod but there were no significant differences between the treatments. The highest chlorophyll b, total chlorophyll contents, total carotenoids, ascorbic aicd and essential oil percent were obtained in plants that received SWE.
Foliar application of seaweed extract fertilizer on fenugreek plants significantly increased all the examined growth parameters of the plants compared to the control. These results agree with previous studies where growth and plant vigor of dill, coriander and fenugreek plants were enhanced by seaweed extracted treatment. Seaweed extracts create equilibrium in growth as a result of the present auxins which will increase vitamins and hormones produced in the treated plants. Results showed that treatments had a significant effect on total chlorophyll, chlorophyll 'a' and 'b', total carotenoids and essential oil content of fenugreek. Seaweed extracts contain cytokinins as well which induce the physiological activities and increase the total chlorophyll, carotenoids and ascorbic acid in the plant.