Investigating the effect of cultivation date and biofertilizers on the yield and agronomic characteristics of Ajowan (Carum copticum L.) plants under salt stress

Ajowan is one of the important medicinal plants of the Apiaceae family, whose essential oil is used in the pharmaceutical and cosmetic industries. Soil salinity is considered one of the most important factors limiting the growth of agricultural plants due to the prevention of the absorption of water and nutrients into the plant. Using biofertilizers with plant-growth-promoting bacteria is one of the most effective ways to reduce the toxic effects caused by high salinity in plant growth. Therefore, this study was conducted with the aim of investigating the effect of different planting dates and biofertilizers on seed yield and agronomic indicators of Ajowan medicinal plant under salt stress.

In order to investigate the effect of biofertilizers on seed yield and vegetative parameters of Ajowan medicinal plant in the climatic conditions of Kashmar, two separate experiments were conducted in the field and greenhouse conditions of Kashmar Research Center. A field experiment in the form of a split plot design using two factors, the first factor included planting date in two levels (March 26, April 27), the second factor included biological fertilizer in 8 levels (1) Control 2) Azetobarvar1 3) Phosphate barvar2 4) Petabarvar2 5) Azetobarvar1 + Phosphatebarvar2 6) Azetobarvar1 + Petabarvar2 7) Phosphatebarvar2 + Petabarvar2 8) Azetobarvar1 + Phosphatebarvar2 + Petabarvar2). The second experiment was conducted as a factorial in a completely randomized design in the greenhouse. The investigated factors included biofertilizer at 8 levels (1) Control 2) Azetobarvar1 3) Phosphate barvar2 4) Petabarvar2 5) Azetobarvar1 + Phosphatebarvar2 6) Azetobarvar1 + Petabarvar2 7) Phosphatebarvar2 + Petabarvar2 8) Azetobarvar1 + Phosphatebarvar2 + Petabarvar2), and salinity stress at 3 levels (zero, 4 and 8 dS/m).

The results indicated that salinity stress significantly reduced the traits of germination percentage, root length, seedling length. The use of biological fertilizers in combination had the best effect on these traits compared to the control. Also, in the treatment of no application of biofertilizer and in the condition of salinity stress of 8 dS/m, the above traits had the lowest values. Also, the combined treatment of Azetobarvar1 + Phosphatebarvar2 + Petabarvar2 could significantly improve the crop yield and plant height. The studies showed that the best planting date for plant height, number of sub-branches, number of flowers, Thousand grain weight and Grain yields was obtained on the planting date of March 26 compared to April 27.

In general, it can be stated that the use of combined biological fertilizers in can reduce the destructive effect of salinity stress on the Ajowan medicinal plant and also significantly increase the seed yield in field conditions.