Investigating the effect of biofertilizers on improving the absorption of nutrients,growth and yield of hazelnut (Corylus avellana L.) trees in Eshkavrat area of Rudsar city in Gilan province

Background and Objectives: In the past decades, due to the use of chemical fertilizers, there were many environmental effects, including water and soil pollution and problems related to the health of humans and other living organisms. The policy of sustainable agriculture and sustainable development of agriculture led experts to get more help from living organisms in the soil in order to meet the plant's nutritional needs. Many studies are carried out in order to sustain hazelnut farming and increase productivity. Work aimed at improving soil performance often considers soil physical and chemical properties, but biological properties are equally important and often neglected. One of the new solutions in sustainable agriculture in order to reduce the negative effects of biological and environmental stresses is the use of beneficial soil microorganisms as biological fertilizers. Biological methods are one of the most useful and environmentally friendly methods for improving the growth and nutrition of plants in harsh environmental conditions. Microorganisms present in biofertilizers in different ways such as production of plant hormones such as auxins, cytokinins, gibberellins, prevention of ethylene production, biofixation of nitrogen, dissolution of mineral phosphates, mineralization of organic phosphates and other food elements, as well Dealing with plant pathogens by producing siderophores, making antibiotics, enzymes or fungicidal compounds and competing with harmful microorganisms in the soil improve the growth and performance of plants and their product quality. Biofertilizers are less expensive and do not cause environmental pollution. Gilan province, having more than 19,000 hectares of hazelnut orchards, with the traditional nature of the orchards, the lack of use of modern methods of agricultural operations, including nutrition, are the main factors of low yield and have recently faced the problem dieback of branches. One of the new solutions in sustainable agriculture is to evaluate the performance of plants under stressful conditions, using beneficial soil microorganisms as biological fertilizers to reduce the damage caused by environmental stress. Biological methods are one of the very useful and environmentally friendly methods to improve the growth and nutrition of plants in stressful conditions.Materials and Methods: In order to investigate the combined effect of chemical fertilizers, Pseudomonas bacteria (PGPR) and Trichoderma fungi on some morpho-physiological traits of orchards with red rot in two experimental orchards of Rudsar city on hazelnut trees in a randomized complete block design with five Treatment and three repetitions (each treatment and each repetition including three trees) were carried out in the two crop years of 1401-1400. The treatments include: T1- control (gardener custom) T2- soil consumption of 20 kilograms of animal manure for each tree + chemical fertilizer recommendation based on the priority of the feeding plan T3- (T2+ growth-improving bacteria) T4- (T2+ Trichoderma mushroom) T5- (T2+ combination of Trichoderma fungi and growth-improving bacteria). Trichoderma fungus will be equal in population (6x107) per gram and Pseudomonas fluorescens bacterium (5x108) per gram, which was obtained as a growth stimulant from Soil and Water Research Institute of Iran. In order to inoculate trees with Trichoderma fungus and Pseudomonas bacteria, it was used under each tree by mixing with animal manure and manure.Results: According to the results of the variance analysis of the data related to the concentration of macro and micro elements in the first year, the effect of chemical fertilizers and the use of trichoderma fungi and growth-stimulating bacteria on the concentration of nitrogen, potassium, zinc, manganese, calcium and magnesium elements in the leaves of hazelnut trees with dieback It is not significant, but the effect of these fungi, bacteria and chemical fertilizers on the concentration of phosphorus and iron elements in the leaves of hazelnut trees is significant at the level of five percent. The results showed that the fifth treatment (combination of chemical fertilizer, organic matter and the use of Trichoderma fungus and Pseudomonas bacteria) had the most positive effects on the studied traits. These biological factors increased the absorption of nutrients, phosphorus, nitrogen, iron and copper by 68.33, 28.13, 172.48 and 146.33% respectively in hazelnut trees, which led to an increase in greenness and reduction of leaf necrosis in orchards. The integrated use of chemical and biological fertilizers, especially in combination, had an effective role in removing the slowness and stopping the growth and improving the dieback of the branches. This treatment caused a significant increase in vegetative parameters such as leaf width (39.53%), length of branch heads (80.21%), chlorophyll index (100.70%) and yield (28.57%) of hazelnut trees.Conclusion: The results showed that T4 and T5 treatments had the most effects on the studied traits, and the use of Trichoderma fungi and growth-improving bacteria together played a more effective role in significantly increasing vegetative parameters such as leaf width, leaf weight, branch length, They had chlorophyll index as well as performance characteristics such as fruit length, fruit width, fruit weight and total yield. These biological factors improved the absorption of nutrients such as phosphorus, copper and iron by hazelnut trees. Therefore, the combined use of Trichoderma fungus and growth-improving bacteria along with organic matter and chemical nutrients were recommended for hazelnut trees with dieback in the region.