Unraveling plant adaptation to single and combined nutrient deficiencies in a dicotyledonous and a monocotyledonous plant species

Nutrient deficiencies considerably limit agricultural production worldwide. However, while single deficiencies are widely studied, combined deficiencies are poorly addressed. Hence, the aim of this paper was to study single and combined deficiencies of iron (Fe) and phosphorus (P) in barley (Hordeum vulgare) and tomato (Solanum lycopersicum). Plants were grown in hydroponics and root exudation was measured over the growing period. At harvest, root morphology and root and shoot ionome was assessed. Shoot-to-root-ratio decreased in both species and in all nutrient deficiencies, besides in-Fe tomato. Barley root growth was enhanced in plants subjected to double deficiency behaving similarly to-P, while tomato reduced root morphology parameters in all treatments. To cope with the nutrient deficiency barley exuded mostly chelants, while tomato relied on organic acids. Moreover, tomato exhibited a slight exudation increase over time not detected in barley. Overall, in none of the species the double deficiency caused a substantial increase in root exudation. Multivariate statistics emphasized that all the treatments were significantly different from each other in tomato, while in barley only-Fe was statistically different from the other treatments. Our findings highlight that the response of the studied plants in double deficiencies is not additive but plant specific.

Automated summary

Nutrient deficiencies have a significant impact on agricultural production globally. However, combined deficiencies of iron (Fe) and phosphorus (P) have been poorly studied. This study investigated the effects of single and combined deficiencies of Fe and P in barley and tomato plants. The results showed that tomato plants exhibited reduced root morphology and ionome in all deficiency treatments, while barley plants displayed enhanced root growth under double deficiency. Multivariate statistics highlighted significant differences in all treatments in tomato plants, while only Fe deficiency was statistically different in barley plants.