Evaluation and physiological traits of hazelnut seedlings inoculated with Trichoderma harzianum Rifai fungus in field conditions.

The use of growth-promoting microorganisms is considered one of the biological methods to increase the yield of plants and reduce the consumption of chemical fertilizers. Based on this, in order to study of the effectiveness of Trichoderma harzanium on some leaf vegetative traits and physiological characteristics of hazelnut seedlings, a factorial experiment was conducted in the form of a randomized complete block design in field conditions. The investigated factors include the seedling origin in three levels (Fandoglou, Makesh, and Makidi) and fungi inoculation in two levels (T. harzanium and control) with three replications of 25 at a distance of 3 × 3 m, in the marginal agricultural lands. Ardabil hazelnut forest was planted. The results after four years showed that the inoculated seedlings of all three origins were superior in terms of all the investigated characteristics compared to the control (uninoculated) seedlings. The highest amount of investigated traits belonged to the seedlings of Fandglou origin. So that in these seedlings, the leaf area and specific leaf area are 40.9 and 21.3% respectively, and the physiological characteristics including photosynthesis, stomatal conductance, chlorophyll, and water use efficiency are 66.8, 65, 40.8 and 146.5% respectively, increased compared to control seedlings. Finally, it can be concluded that the planting of hazelnut seedlings inoculated with T. harzanium will be more successful.

Extended Abstract

Introduction and Objective: Hazelnut (Corylus avellana L.) is considered one of the most prominent species of Ardabil Fandoghlou forest in. This species is ecologically and economically important and is one of the most valuable medicinal plants in traditional medicine and pharmaceutical industries. Unfortunately, in recent years, conversion of use, livestock grazing, fire and cutting of trees have been effective factors in the destruction of this valuable forest. Considering the ecological and economic importance of the hazelnut species, it is very important to restore the habitats of this species through seedlings. On the other hand, the success of planting depends a lot on the establishment and survival of planted seedlings (Spehbadi, 2019), which chemical fertilizers are used most of the time. The use of these fertilizers has had adverse effects on the soil ecosystem, and in addition to destroying beneficial soil microorganisms and the poor growth of seedlings, it has resulted in several adverse effects on the environment and human health. The use of growth-promoting microorganisms is considered one of the biological methods to increase the yield of plants and reduce the consumption of chemical fertilizers. Trichoderma spp. have been known as plant growth promoter besides its primary function as pathogen inhibitor. This research was conducted with the aim of the effect of T. harzianum on of physiological properties of hazelnut seedlings in field conditions.

Material and Methods: At the beginning of May 2016, in Ardabil Hazelnut Nursery, the soil around the roots of potted hazelnut seedlings, produced from the three sources of Fandoglou (Ardabil Hazelnut Forest), Makesh (Guilan) and Makidi (Arasbaran) with T. harzianum were inoculated. Then, in November 2017, the one-year-old hazelnut seedlings were transferred to the area adjacent to the nursery located in lands of the forest edge with an area of 4050 m2. Then they were planted in factorial arrangement in a randomized complete block design (with the two factors mentioned above including three seed sources and T. harzianum inoculation and no inoculation or control in three replications). The number of seedlings in each replication was 25 (450 seedlings in total), which were planted a distance of 3 × 3 m in rain-fed conditions. The characteristics of leaf area, specific leaf area and physiological properties including leaf area, specific leaf area, photosynthesis rate, stomatal conductance, transpiration rate, water use efficiency (WUE) and chlorophyll content were measured. For this purpose, in each treatment, three seedlings were randomly selected and measurements were taken on the fourth and fifth healthy and fully grown mature leaves from the tip of the plant using a photosynthesis meter on a sunny day (mid-September) and it was done in the open air under natural conditions of temperature, light and relative air humidity between 9:30 and 11:30 while the constant leaf temperature was between 20 and 25 o C.

Results: After four years, all measured properties were significantly affected by fungal inoculation. Inoculated seedlings from all three origins displayed higher values for all investigated traits compared to controls. The highest of leaf area (22.4 cm2), specific leaf area (119.2 cm2 g-1), photosynthesis rate (18.45 µmol Co2 m2 s-1), stomatal conductance (0.198 mmol m2 s-1), transpiration rate (mmol H20 m2 s-1), water consumption efficiency (7.69 µmol Co2 mol H2o -1) and chlorophyll content increased by (26.49 %) were obtained from Seedlings of Fandoglou origin inoculated with T. harzianum in compared to the control (non- inoculated seedlings). The lowest of leaf area (12.4 cm2), specific leaf area (85.5 cm2 g-1), photosynthesis rate (8.01 µmol Co2 m2 s-1), stomatal conductance (0.101 mmol m2 s-1), water consumption efficiency (2.41 µmol Co2 mol H2o -1) and chlorophyll content increased by (14.15 %) were observed from Seedlings (non- inoculated) of control with origin of Makidi.



Conclusion: The present study showed that the hazelnut seedlings of the origin of Fandoghlou under the influence of T. harzianum inoculation were superior in terms of the studied traits in comparison to the two origins of Makseh and Makidi. Therefore, for the production of healthy and strong hazelnut seedlings in the nursery, the origin of the Fandoghlou can be used. An important point in inoculation of seedlings with T. harzianum fungus was the increase in the water use efficiency (WUE) of of hazelnut seedlings with the origin of Fandoghlou up 150% compared to the control seedlings. So, it can be concluded that by increasing the rate of photosynthesis rate and reducing transpiration rate, inoculated seedlings increase the efficiency of water use and can have more vegetatative growth and suitable physiological traits in reforestation or create of hazelnut gardens in the prone lands of Fandoghlou forest.



Keywords: Arasbaran, Corylus avellana, Stomatal conductance, Specific leaf area.