Investigation of the possibility of reducing the effects of low irrigation of lavender (Lavandula officinalis L.) using biofertilizers and phosphorus through changes in some morphological and biochemical characteristics

IntroductionLavender (Lavandula officinalis L.) belonging to the Lamiaceae family is a plant with economic, medicinal and ornamental value. Its essential oil is used as a raw material for many industries, including perfumery, cosmetics, and pharmaceutical industries. Drought stress as a limiting factor reduces growth and productivity in plants. This issue is especially important in arid and semi-arid regions of the world such as Iran. One of the basic solutions to adjust or reduce the effect of water stress in agricultural plants is the use of different types of biological fertilizers. Also, its low diffusion speed in the soil can play an important role in the lack of its ions in the solution in the soil of the root development area. In most agricultural systems, due to the low mobility of phosphorus in the soil, absorption by the plant is low. In order to investigate the effect of biofertilizers and phosphorus on reducing the effects of irrigation deficiency in lavender, an experiment was conducted in the form of split plots in a randomized complete block design with 3 replications at the Research Station of the Faculty of Agriculture, Islamic Azad University of Tabriz in 2019-2020.Materials and methodsExperimental factors including irrigation levels (irrigation after 60, 90 and 120 mm from Class A evaporation pan) as the main factor and inoculation with biofertilizer including four levels (inoculation with Thiobacillus, Pseudomonas and Thiobacillus + Pseudomonas and no inoculation As control) and phosphorus fertilizer levels at two levels (0 and 50 kg ha-1) as a secondary factor. The studied traits included leaf dry weight, flower dry weight, cell membrane leakage rate, relative leaf water content, soluble sugars and proline content, catalase and superoxide dismutase enzymes and peroxidase and MDA. To measure the activity of antioxidant enzymes, leaf samples kept at -80 degrees Celsius were used. The activity of catalase was measured using the method described by (Aebi, 1984; Ezhilmathi, 2007). The measurement of superoxide dismutase (SOD) enzyme was calculated according to the method (Giannopolitis and Ries, 1977) based on enzyme unit per milligram per body weight. The determination of malondialdehyde (MDA) was based on Aston and Sidney's method (Aston and Sidney, 1987). Proline content in the youngest leaf was also determined by the method of Bates et al. (1973). SAS version 8 software was used to analyze the variance of the data, MSTATC version 2 soft