نوع مقاله : مقالات پژوهشی
عنوان مقاله [English]
Introduction: Gerbera jamesonii is a permanent, herbaceous and chilling-sensitive plant species from the family Asteraceae that is native to hot regions. The species has high color diversity and it is among the top ten cut flowers in the world. Fulvic acids are a family of organic acids, natural compounds, and components of the humus (which is a fraction of soil organic matter). They are similar to humic acids, with differences being the carbon and oxygen contents, acidity degree of polymerization, molecular weight and color. Fulvic acid remains in solution after removal of humic acid from humin by acidification. Fulvic acids are of relatively low molecular mass and less biologically active than humic acids. Among micronutrients, Iron (Fe) is a cofactor for approximately 140 enzymes that catalyze unique biochemical reactions and is an essential element for growth of plants. Lack of iron causes young leaves yellow and photosynthesis activity reduce significantly and consequently biomass reduce. Iron plays many essential roles in plant growth and development, including chlorophyll synthesis, thylakoid synthesis, chloroplast development, contribution in RNA synthesis and improvement the performance of photosystems. Nano-fertilizers can be substituted for conventional fertilizers. Studies showed that the effect of nano-particles on plants can be beneficial (seedling growth and development).
Materials and Methods: In order to investigate the effect of different concentrations of fulvic acid and iron nano chelate on flowering of gerbera as well as flower vase life of gerbera cv. Dune, an experiment was conducted as a factorial based on a completely randomized design with three replications during the years 2016-2017. The medium was included peat moss 65%, perlite 30% and cocopeat 5%. The seedlings of tissue cultured plants were planted into pots (size-20) (volume 7 L, height 19 cm, diameter 24 cm) in hydroponic greenhouse conditions. Day/night temperature regime was set at 20-25/13-16°C and light intensity at 400-500 μmol m-2 s-1. The plants were fed three times a week. The treatments were: fulvic acid at four concentrations of 0 , 50, 100 and 250 mg L-1 as drench and iron nano chelate at 4 concentrations of 0, 1, 2 and 4 gr L-1 as foliar application (15 days intervals for 4 months),. Two weeks after the last treatment, morphological parameters were measured. They were included flower fresh and dry weight, flowering stem length, flower longevity and vase life and the number of days to the appearance of flower buds. Also, the recorded physiological parameters included chlorophyll a, b and total chlorophyll, chlorophyll index and carotenoid.
Results and Discussion: The results of this study showed that, flower dry weight was increased with increasing the concentration of iron nano chelate. The highest flower dry weight )6.43g( was obtained from plants treated with 4 g L-1 iron nano chelate and the lowest one )5.57 g( from control plants, but flower fresh weight was not affected by these treatments. The highest length of flowering stem was observed in treatment of 2 g L-1 iron nano chelate. The lowest time to flowering was obtained from 50 mg L-1 fulvic acid without application of iron nano chelate. The results of means comparisons showed that fulvic acid and iron nano chelate caused to increase flower longevity significantly. The highest flower longevity (19 days) was obtained from 250 mg L-1 fulvic acid and 1 g L-1 iron nano chelate and the lowest mean (12.66 days) was related to control plants. Also, most of treatments caused to increase vase life compared to control. The highest vase life (14.66 days) was observed in 1 g L-1 iron nano chelate without fulvic acid while the lowest mean (6.66 days) was observed in control. Chlorophyll content (chlorophyll a, b and total chlorophyll) and carotenoid content of gerbera increased with increasing concentrations of fulvic acid and iron nano chelate in compared with the control.
Conclusion: According to the results obtained from this research, application of fulvic acid and iron nano chelate have a positive effect on most flowering and biochemical indices. Application of low concentrations of fulvic acid (50 mg L-1) supplemented with iron nano chelate caused to early flowering. Fulvic acid didn’t have any effect on flowering stem length and its application reduced the flower dry weight. While combined application of fulvic acid and iron nano chelate caused to increase flower longevity. Also iron nano chelate caused to increase flowering stem length, vase life and flower dry weight. In most of the biochemical indices, combined treatment of 100 mg L-1 of fulvic acid and 2g L-1 of iron nano chelate had better or favorable result on measured indices compared to the control treatment although the highest concentration of treatments did not have a negative effect and sometimes in some indicators also have more impact. Among these treatments, the concentrations of 100 and 250 mg L-1 fulvic acid and 2 and 4 g L-1 iron nano chelate can be effective for gerbera plant.
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