The Effect of Bio-fertilizers on Growth, Grain and Essential Oil Yield of Fennel (Foeniculum vulgare Mill.) under Drought Stress

IntroductionFennel (Foeniculum vulgare Mill.), a plant belonging to the Apiaceae family uses as both food and medicine. Increasing the desired compounds of medicinal plants is possible by cultivation techniques manipulation such as irrigation, fertilization or photo-bioreactor systems. Water deficit stress, permanently or temporary, limits the growth and the distribution of natural vegetation and the performance of cultivated plants more than any other environmental factors. Babaee et al. (2010) stated that water stress decreased plant height, the number of secondary branches, dry and fresh weight, growth and root mass, dry and fresh weight root and length root of Thyme (Thymus vulgaris L.). Bio-fertilizers as an alternative in some cases and in most cases as a complement to chemical fertilizers can help to ensure the sustainability of agricultural production systems. Han et al. (2006) studied the effect of phosphate solubilizing bacteria (PSB), Bacillus megaterium var. phosphaticum and potassium solubilizing bacteria (KSB), Bacillus mucilaginosus in nutrient limited soil planted with pepper and cucumber and stated that Rock P and K applied either alone or in combination did not significantly enhance soil availability of P and K. PSB was a more potent P-solubilizer than KSB, and co-inoculation of PSB and KSB resulted in consistently higher P and K availability than in the control. Rock P with inoculation of PSB increased the availability of P and K, the uptake of N, P and K by shoots and roots, and the growth of both pepper and cucumber. Combined together, rock materials and both bacterial strains consistently increased further mineral availability, uptake and plant growth, suggesting their potential use as fertilizer. The present study was designed to evaluate the effect of bio-fertilizers inoculation and drought stress on quantitative and qualitative characteristics of Marian thistle.
Materials and methodsThis experiment was conducted in a split plot design based on randomized complete block with three replications, at Agricultural Research Station, University of Zabol, during growing season of 2012. Main plots consisted of irrigation with 40, 60, 80 and 100% field capacity and subplots including plant nutrition with no fertilizer (control), nitroxin, super nitroplus and bio-phosphorus. Plant traits such as days to maturity, plant height, the number of main branches, seed yield per plant, seed yield per ha, essential oil percentage, and essential oil yield were measured. For statistical analysis, analysis of variance (ANOVA), Duncan multiple range test (DMRT) and simple correlation analysis were performed using SAS version 9.2 (SAS Institute Inc., Cary, NC, USA).
Results and DiscussionIn this experiment, main effects of drought stress and bio-fertilizer on all studied traits were significant at 1% probability level. Plants irrigated with 80% of field capacity in comparison with other levels, showed a significant increase in number of days to maturity, plant height, the number of main branches and seed yield. Plants grown under bio-phosphorus had maximum value for days to maturity, plant height, the number of main branches and yield followed by nitroxin and super nitroplus. Interaction of water stress and bio-fertilizer had significant effect on days to maturity, plant height, seed yield and essential oil yield, but this effect for the number of main branches and essential oil were not significant. The maximum plant height, days to maturity, seed yield and essential oil yield were achieved from irrigation of 80% of field capacity and bio-phosphorus bio-fertilizer.
ConclusionThe amount of bio-fertilizers due to its role in improving the nutritional conditions of the plant can play an important role in offsetting the harmful effects of drought stress. In addition, the use of bio-fertilizers in terms of humidity limits can be useful to overcome the negative effects of stress.