Correlation and path analysis of Tobacco (Nicotiana tabacum L.) yield vs root traits and relative water content as affected by Azotobacter, mycorrhizal symbiosis and biochar application under dry-land farming conditions

The global approach in agriculture is to reduce the use of chemical fertilizers and the supply of nutrients from available sources which are environmentally friendly. In order to evaluate the feasibility of tobacco products without chemical fertilizer inputs, this research was carried out as a factorial experiment based on a 38282 randomized complete block design which included biochar applied at three levels (0, 4, and 8 t ha(-1)), mycorrhiza, and Azotobacter at two levels (with and without application) with four replications. According to the results, 4 t ha(-1) biochar increased the dry yield by 22%, the relative water content by 6%, and the root length by 41% compared to the zero level. However, there was no statistically significant difference between the 4 and 8 t ha(-1) application of biochar with regard to most traits. The application of mycorrhiza improved the leaf area index as well as the tobacco root length. Azotobacter significantly increased the root length and nicotine content. The tobacco yield in rain-fed conditions is lower than usual, therefore the combined use of biochar and these biofertilizers may be considered as a viable solution. With increasing interest in the use of environmentally friendly sources of fertilizers and in terms of economic considerations, the use of 4 t ha(-1) of biochar along with mycorrhiza and Azotobacter achieved an acceptable yield.