Effects of Organic and Chemical Fertilizers on some Quantitative Traits and Anthocyanin of Roselle under Zabol conditions

Roselle (Hibiscus sabdariffa L.) belongs to the Malvaceae family, and is an annual or biennial plant that cultivated in tropical and subtropical regions for its stem fibers, eatable calyces, leaves and grains. Roselle is resistant to relatively high temperatures throughout the growing and fruiting times. Continuous use of chemical fertilizers destroys the soil ecological balance, reduces soil fertility and groundwater pollution is caused. In contrast, organic fertilizers are very safe for human health and the environment. It is made by recycling organic material as plant and animals waste, and food scraps in a controlled process. Of the organic fertilizers can be noted to compost, vermicompost, cattle manure andhumic acid. The study was carried out in order to sustainable agriculture. The aim of this study was to investigate the effects of organic and chemical fertilizers on some quantitative traits and anthocyanin of roselle.
The experiment was performed in complete randomized block design with ten treatments and four replications in research field of agricultural faculty, university of zabol. The treatments included T1: control, T2: NPK in a ratio of 2:1:1 (300 kg ha-1), T3: cattle manure (20 t ha-1), T4: compost (10 t ha-1), T5: vermicompost (5 t ha-1), T6: humic acid foliar in a ratio of 1.5 per thousands, T7: 50% of T2 and T6 , T8: 50% of T3 and T6, T9: 50% of T4 and T6 and T10: 50% of the T5 and T6.
Five plants were chosen and an average of five plants was calculated as the single plant for measuring of variables that included the height, number of branches, stem diameter, shoot fresh weight, number of fruits per plant, fruit weight, number of seeds per plant, fresh and dry weights of sepals, inflorescence length, length and diameter of fruit. Method of Wagner has been used for the anthocyanin measurement.
Results of this research showed that the application of different fertilizers increased the height, number of branches and stem diameter per plant in different stages of growth. Mean comparison showed that there were significant differences between the treatments and control in most traits, so that the maximum height, number of branches and stem diameter belonged to the treatment of organic and chemical fertilizer with humic acid (T8, T9 and T10). The highest number of fruits and seed yield per plant (41/98%) was obtained from the T9 treatment compared to the control. This result was corresponded with the results of other researchers in the roselle.
The result showed that inflorescence length, length and diameter of fruit had the highest values by using the cattle manure humic acid (T8); and so measured characters had the lowest values in control treatment. Effect of different fertilizer treatments on fruit fresh weight, fresh and dry weights of sepals had statistically significant differences. The highest and the lowest values of fruit fresh weight, fresh and dry weights of sepals were obtained from T9 treatment (compost humic acid) and control treatment, respectively.
Compost improves conditions for the plant growth. Humic acid stimulates the growth hormone and increases the absorption of nutrients by plant. So, with these reasons it seems that higher growth features and further calyx yield were achieved by applying compost humic acid than other treatments.
The effect of treatments organic and chemical fertilizers with humic acid on the amount of anthocyanin was higher compared with using them separately. Compost, vermicompost and cattle manure fertilizers are containing humic acid substances and humic acid (phenolic compound derivatives) is a precursor for the synthesis of anthocyanidin (flavonoid structure), therefore they correlated with the increasing anthocyanin in treatments organic fertilizers and chemical with humic acid.
The results showed that all applied fertilizers treatments improved growth features, further calyx yield and anthocyanin amount, than the situation of non-use of fertilizer. Nevertheless, the effect of the treatments organic fertilizers with humic acid on vegetative growth, fruit and sepals yield and anthocyanin content per sepals was higher compared with using them separately and using chemical fertilizers.
Therefore, to achieve maximum vegetative growth, fruit and sepals yield and anthocyanin content per sepals using treatments of organic fertilizers with humic acid were better than other fertilizer treatments in this research. Therefore, it seems that, in terms of sustainable production and the environmental protection of roselle, applications of organic fertilizers may be viable alternatives to chemical fertilizers.