Application of biofertilizer, organic and inorganic fertilizer and plant growth regulators on dry matter remobilization and grain filling components of barley (Hordeum vulgare L.) under water deficit conditions

Drought stress is one of the most important factors affecting crop yield especially in irrigated agriculture in arid and semiarid regions. Application of some stress modulators (vermicompost, mycorrhiza, putrescine and zinc nanooxide) increases growth, yield and the resistance of plants against various environmental stresses such as drought. However, the effect of these compounds alone has been investigated on modulating the effects of stress, there are fewer reports about their interaction effects. In this experiment, the interaction effects of organic, biological and mineral fertilizers and stress modulators were investigated on the improvement of current photosynthesis, dry matter remobilization process, grain filling components and grain yield of barley under water deficit conditions.

To investigate the interaction effects of some stress modulators (vermicompost, mycorrhiza, zinc nanooxide and putrescine) on the contribution of dry matter remobilization and grain filling components of barley under water deficit stress conditions, a factorial experiment in randomized complete block design with three replications was conducted in research greenhouse of Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran, in 2022. The experimental factors were included irrigation in three levels (full irrigation as control, irrigation withholding at 50% of the heading and 50% of the booting stages, equal to codes 55 and 43 of BBCH scale, as moderate and severe water limitation, respectively), application of biofertilizer, and organic and inorganic fertilizers in four levels (no application of fertilizers as control, application of vermicompost, application of mycorrhiza, combined application of vermicompost and mycorrhiza), and foliar application of putrescine and zinc nanooxide in four levels (foliar application of water as control, foliar application of 0.4 g.L-1 Zn nanooxide, foliar application of 0.8 mM putrescine, combined foliar application of Zn nanooxide and putrescine). Mycorrhiza fungus (mosseae species) was purchased from Zist Fanavar Turan company and according to copany’s protocol, 10 g per kg soil was used. Vermicompost was purchased from Gilda company and according to copany’s protocol, 50 g per kg soil was used. Zinc nanooxide production of China, with an average particle size of less than 30 nm, a specific surface of more than 30 m2.g-1, a Zn content of about 65.21% and a purity of 99%, was purchased from Jahan Kimia company, Urmia, Iran. The barley variety used in the experiment was Nobahar variety, which was cultivated with a plant density of 400 seeds per m2.

The results showed that the combined application of stress modulators (vermicompost, mycorrhizal, Zn nanooxide and putrescine) under irrigation withholding at booting stage conditions decreased dry matter remobilization from shoot and stem (22.32% and 25.65%, respectively) and their contribution in grain yield (52.92% and 56.95%, respectively) compared to the no application of biofertilizers and no foliar application of putrescine and Zn. In contrast, application of stress modulators under irrigation withholding in booting stage conditions increased total chlorophyll (24.91%), current photosynthesis (62.57%), contribution of current photosynthesis in grain yield (30.54%), grain filling rate (6.62%), grain filling period (18.06%), effective grain filling period (27.67%) and grain yield (25.18%) compared to the no application of biofertilizers and no foliar application of putrescine and Zn.

The findings of the current experiment showed that the application of stress modulators (vermicompost, mycorrhizal, Zn nanooxide and putrescine) can increase grain yield of barley under water limitation conditions by improving the current photosynthesis and grain filling components.