​Effects of Microbial Fertilizer and Vermicompost Applications on the Yield and Yield Related Parameters of Broad Bean (Vicia faba L.) under Eastern Mediterranean Highland Agroclimatic Conditions

 

The study was carried out in the fields of Siirt University, in Turkey, during 2017 and 2018 growing seasons. Broad bean (Vicia faba L. cv. Salkim) was used as plant material. In the research, vermicompost (Brand was Ekosol, compost of Eisenia foetida species worms; pH was 6.5-8.5; organic matter was 35%, total N was 1.2%) and Rhizobium leguminosarum inoculant were used for fertilization of the crops. Rhizobium leguminosarum bacterium was obtained from “Soil Fertilizer and Water Resources Central Research Institute” (Ankara, Turkey) supplied in a peat media. No chemical fertilizer was applied.
       
Research soils were sampled at a depth of 0-30 cm prior to experiments and analysis were conducted. It was determined that trial area soil was clayey-loam structured, calcareous (1.61%), slightly alkaline (pH 7.6), salt-free (0.08 dS m^-1), weak in organic matter (0.90%), rich in potassium (669 kg ha^-1) and poor in plant available phosphorus content (31.2 kg ha^-1). (classification followed- and available phosphorus or P₂ O₅??
       
The climatic data of the study area is given in Table 1. The average temperature in 2017 and 2018 growth seasons were higher than the long term averages. While the total amount of precipitation received in 2017 was higher than the long-term average, it was lower than the long-term average in 2018.
 

       
The trials were set up with three replications according to the randomized complete block design. Former crop was wheat for the trial field. Marker assisted hand sowings of broad beans was conducted in the first week of March on four rows at each parcel to 5 m long rows, with 30 cm inter-row and 10 cm intra-row spacing. Total 0, 400, 800 and 1200 kg ha^-1 vermicompost were applied at once at pre-sowing stage just before incorporation with harrow and then irrigated with sprinkler. Plant seeds were soaked in water containing sugar at 4% concentration (Ýþler and Coþkan, 2009) and then were treated with Rhizobium leguminosarum bacteria (1 kg of peat culture/50 kg of seed) (Rivas et al., 2009). Plants were grown under rainfed conditions. Weed control was done mechanically.
       
For observation and harvesting, border rows from each edges and 0.5 m from both ends of the plots were cut out. Observations were made on 10 plants selected from the remaining plants in parcels. Parcel harvest was conducted for yield determinations. The plants were harvested in the first week of July when the pods were dried and the grains got hardened. Harvesting and threshing processes were done manually. Plant height, first pod height, number of pods per plant, number of seeds per pod, 100-grain weight, and grain yield were investigated. The data were subjected to variance analysis and differences between the applications were determined by the LSD_(0.05) test via JMP (version 5.0.1) software program.

In the study, effects of the applications and years on all parameters were found statistically significant (p<0.05). The effect of Year x Application interaction on all properties was significant (p<0.05) except grain yield (Table 2 and Table 3).
 

 

       
Effect of precipitation was positive on plant growth. As mentioned by Uçaret_al(2020), plant available nitrogen mineralization in soil increases with increasing rainfall. Vegetative development of the plants (plant height and first pod height) was higher in 2017 compared to drier year 2018. This was similar to results obtained by Soysal and Erman (2020). Instead, the number of pods per plant, the number of seeds per pod, 100 grain weight and grain yield were higher in 2018 compared to 2017. The generative development of the plants was adversely affected in 2017 due to the anthracnose disease inspite of pesticide spraying. In particular, there was a opposite relationship between plant height, first pod height, number of pods per plant, number of seeds per pod, 100-grain weight and grain yield values. Plant heights were between 50.2-61.8 cm, first pod height were between 13.7-16.4 cm, number of pods per plant were between 6.37-8.99, number of seeds per pod was between 3.19-4.44, 100 grain weight was between 122.0-134.8 g and grain yield was between 1768-1907 kg ha^-1. The minimum values for all parameters were obtained from the control application. Maximum values for all parameters were obtained from Rhizobium leguminosarum + 800 kg ha^-1 vermicompost application. However, there was no statistical significant difference between Rhizobium leguminosarum + 800 kg ha^-1 vermicompost and Rhizobium leguminosarum + 1200 kg ha^-1 vermicompost application. These were followed by applications of sole 1200 kg ha^-1 vermicompost, combined application of Rhizobium leguminosarum + 400 kg ha^-1 vermicompost, sole 800 kg ha^-1 vermicompost, sole Rhizobium leguminosarum and sole 400 kg ha^-1 vermicompost applications, respectively. As vermicompost dose increased, plant height, first pod height, pod number per plant, grain per pod, 100-grain weight, and grain yield were also increased. Soil organic matter has a role in increasing microbial activity in the soil. Since Siirt is within the borders of the gene center of the broad bean, naturally, Rhizobium leguminosarum bacteria exist in the soil. However, due to the low organic matter content of Siirt province and trial field soils, it is not possible to make a definite conclusion about the activities of bacteria under producer conditions. Under natural conditions, these bacteria infect plant roots. However, significant increases for all observed parameters by sole bacterial application reveal the requirement of repeated inoculations (Table 2 and Table 3).

Similar to this study, Roy and Singh (2006) reported that co-application of N-fixing bacteria + vermicompost increased grain yields. Also, Singh et al., (2012) observed increase in plant height by vermicompost applications. Bhattachariya and Chandra (2013) and Pezeshkpour et al., (2014) reported increased grain yields by vermicompost application. Kumar et al., (2014) determined increased plant height, pod number per plant, 100-grain weight and grain yield values by vermicompost applications compared to control. Pashaki et al., (2016) stated that microbial fertilizer and vermicompost application increased the number of pods per plant, the number of grains per pod, and the grain yield compared to the control. Similar results were also reported by Mohammadi and Rezaei (2019) for the broad beans at different locations.

As a results of this study, application of 800 kg ha^-1 vermicompost with Rhizobium leguminosarum inoculation and application of 1200 kg ha^-1 vermicompost with Rhizobium leguminosarum inoculation were found superior for higher grain yields in broad bean. As the dose of vermicompost  increased, plant height, first pod height, pod number per plant, number of seed per plant, 100-seed weight, and grain yield were also increased. All parameters were lowest in control. According to the results of this study, for highest grain yield in broad bean cultivation in Siirt province conditions without any chemical fertilizer application, Rhizobium leguminosarum inoculation + 800 to 1200 kg ha^-1 vermicompost application is recommended.