Relationships between growth indices, dry matter production, and nutrient use efficiency in saffron: Integrative effect of mycorrhizal inoculation and nutrient resources

Abstract

This research is aimed to investigate the interactive effect of arbuscular mycorrhizal (AM) fungus inoculation and nutrient supply through organic and chemical resources on growth indices, nutrition, and dry matter production of saffron. During the 2015-2016 and 2016-2017 growing seasons, saffron plants were grown under field conditions fertilized with compost (COM; 20 Mg ha−1), COM + biochar (COM + B; 10 + 8 Mg ha−1), chemical fertilizers (CF), and unfertilized soil (control), each inoculated (+AM) or non-inoculated (-AM) with AM (Funneliformis mosseae). In accordance with the results, AM-inoculation and fertilization promoted growth indices of saffron which resulted in significant increases in leaf parameters, leaf nitrogen uptake (NU) and phosphorus uptake (PU), leaf dry matter, and corm PU. We further found that integration of AM-inoculation and fertilizer types enhanced corm dry matter (CDM) production most likely by promoting NU and PU, NU and PU efficiencies, and agronomic N- and P-use efficiency, which reached the maximum under COM + AM and CF + AM. In contrast, AM-inoculation had no statistically significant effect on CDM and agronomic N- and P-use efficiency in unfertilized plots mainly due to reduced mycorrhizal inoculation effect (MIE). The analysis of MIE values confirmed that AM inoculation efficiency was considerably reduced over time in unfertilized plots indicating that optimal efficiency of AM can be affected by the nutrient supply system. Generally, depending on the used agronomic pattern, the integrated management of AM along with chemical fertilizers or organic amendments is recommended to enhance the yield potential of saffron farms in semi-arid areas.