Leaf mineral nutrient remobilization during leaf senescence and modulation by nutrient deficiency

Abstract

Higher plants have to cope with fluctuating mineral resource availability. However, strategies such as stimulation of root growth, increased transporter activities, and nutrient storage and remobilization have been mostly studied for only a few macronutrients. Leaves of cultivated crops (Zea mays, Brassica napus, Pisum sativum, Triticum aestivum, Hordeum vulgare) and tree species (Quercus robur, Populus nigra, Alnus glutinosa) grown under field conditions were harvested regularly during their life span and analyzed to evaluate the net mobilization of 13 nutrients during leaf senescence. While N was remobilized in all plant species with different efficiencies ranging from 40% (maize) to 90% (wheat), other macronutrients (K–P–S–Mg) were mobilized in most species. Ca and Mn, usually considered as having low phloem mobility were remobilized from leaves in wheat and barley. Leaf content of Cu–Mo–Ni–B–Fe–Zn decreased in some species, as a result of remobilization. Overall, wheat, barley and oak appeared to be the most efficient at remobilization while poplar and maize were the least efficient. Further experiments were performed with rapeseed plants subjected to individual nutrient deficiencies. Compared to field conditions, remobilization from leaves was similar (N–S–Cu) or increased by nutrient deficiency (K–P–Mg) while nutrient deficiency had no effect on Mo–Zn–B–Ca–Mn, which seemed to be non-mobile during leaf senescence under field conditions. However, Ca and Mn were largely mobilized from roots (-97 and -86% of their initial root contents, respectively) to shoots. Differences in remobilization between species and between nutrients are then discussed in relation to a range of putative mechanisms.

Soil properties determine the elevational patterns of base cations and micronutrients in the plant–soil system up to the upper limits of trees and shrubs

“…The concentrations of soil base cations and available micronutrients were suggested to be positively and negatively correlated with soil pH, respectively, but both positively correlated with soil organic matter (SOM) concentration (Reisenauer, 1988;Wang et al, 2017). Concentrations of base cation and micronutrient can differ among plant tissues as a result of their slow translocation from the roots to the canopy (van der Heijden et al, 2015), distinct mobility among plant tissues (Warnock, 1970), and occurrence of remobilization during different physiological stages (Maillard et al, 2015). Quantifying base cation and micronutrient concentrations in soils and plant tissues (leaves, roots, shoots, and stems) can help explain the nutritional status and potential deficiencies of micronutrients during plant growth (Richardson, 2004).…”

Contribution of mineral nutrients from source to sink organs in rice under different nitrogen fertilization

“…Potassium uptake by cereals occurs mainly before anthesis, at about 90% for rice, and vegetative organs including leaves, stem, and sheaths contribute nearly 60% of grain K at maturity . The extent of Cu remobilization within plants was species dependent, and showed the lowest remobilization in rice compared with other crops (Barunawati et al 2013;Maillard et al 2015). In the current study, a minor contribution of bracts to grain P, K, and Cu was detected, with contribution rates of 0.99, 3.90, and 3.05%, respectively.…”

“…In soybean and wheat, seed/grain Mg appears to be mobilized from leaves, partially because of its high phloem mobility (Maillard et al 2015). Zinc is also essential for rice plants, and more than half of grain Zn is remobilized from that accumulated and stored in leaf, sheath, and stem before anthesis (Wu et al 2010;Yilmaz et al 2016).…”

“…2. Calcium is less mobile in the phloem, and its continuous accumulation in leaf even after anthesis has been well established (Himelblau and Amasino 2001;Maillard et al 2015). Iron is inefficient for remobilization between vegetative organs and grains, and a study on rice showed that only 4% of total shoot Fe was translocated to grain (Marr et al 1995).…”

“…Iron is inefficient for remobilization between vegetative organs and grains, and a study on rice showed that only 4% of total shoot Fe was translocated to grain (Marr et al 1995). Due to poor phloem mobilization, Mn appears to be an immobile nutrient in leaves of wheat (Pearson and Rengel 1994) and barley (Maillard et al 2015). In the current study, the net accumulation of Ca, Fe, and Mn increased during grain filling, not only in the grains but also for the vegetative organs, in particular the leaves, indicating that leaves are also a sink of these mineral nutrients.…”