Nutrient sink limitation constrains growth in two barley species with contrasting growth strategies

Abstract

Mineral nutrients exert important limitations on plant growth. Growth is limited by the nutrient source when it is constrained by nutrient availability and uptake, which may simultaneously limit investment in photosynthetic proteins, leading to carbon source limitation. However, growth may also be limited by nutrient utilization in sink tissue. The relative importance of these processes is contested, with crop and vegetation models typically assuming source limitations of carbon and mineral nutrients (especially nitrogen). This study compared the importance of source and sink limitation on growth in a slower‐growing wild perennial barley ( Hordeum bulbosum ) and a faster‐growing domesticated annual barley ( Hordeum vulgare ), by applying a mineral nutrient treatment and measuring nitrogen uptake, growth, allocation, and carbon partitioning. We found that nitrogen uptake, growth, tillering, shoot allocation, and nitrogen storage were restricted by low nutrient treatments. Multiple lines of evidence suggest that low nutrient levels do not limit growth via carbon acquisition: (a) Carbohydrate storage does not increase at high nutrient levels. (b) Ratio of free amino acids to sucrose increases at high nutrient levels. (c) Shoot allocation increases at high nutrient levels. These data indicate that barley productivity is limited by the capacity for nutrient use in growth. Models must explicitly account for sink processes in order to properly simulate this mineral nutrient limitation of growth.

Source:sink imbalance detected with leaf‐ and canopy‐level spectroscopy in a field‐grown crop

“…In the precision agriculture context, monitoring sink limitation in major crops may be used to inform the timing of fertiliser application to improve the balance between carbon and nitrogen resources in the plant (Basso et al, 2016; Maes & Steppe, 2019; Maresma, Ariza, Martínez, Lloveras, & Martínez‐Casasnovas, 2016). Both carbon and nitrogen can place limits on crop growth, development and yield (Burnett et al, 2016; Burnett, Rogers, Rees, & Osborne, 2018; White et al, 2016), and both source and sink limitations must be addressed for successful breeding of our future crops (Fernie et al, 2020; White et al, 2016).…”

“…Both carbon and nitrogen can place limits on crop growth, development and yield (Burnett et al, 2016;Burnett, Rogers, Rees, & Osborne, 2018;White et al, 2016), and both source and sink limitations must be addressed for successful breeding of our future crops (Fernie et al, 2020;White et al, 2016).…”

Growth and Nutritional Quality of Lemnaceae Viewed Comparatively in an Ecological and Evolutionary Context

“…An example of such an additional factor is a limited mineral nutrient supply [29,73]. The growth of sink tissues is highly sensitive to a shortage of mineral nutrients, especially nitrogen [74]. In terrestrial plants, the combination of elevated CO 2 and/or high light supply with low nitrogen supply exacerbates source-sink imbalance and downregulates the synthesis of photosynthetic protein [75,76], as well as other metabolic processes [61].…”

Revisiting Why Plants Become N Deficient Under Elevated CO2: Importance to Meet N Demand Regardless of the Fed-Form

“…Burnett et al ( 2018 ) compared fast-growing domesticated annual barley with a slow-growing wild perennial relative under different levels of nutrient supply. They found that the perennial barley has a higher amino acid/sucrose ratio than the annual, implying a greater carbon source-limitation in the perennial than the annual barley.…”

“…Despite the LAR-dependent growth in aCO 2 wheat, N supply levels above 0.3 g N kg −1 soil could no longer increase the leaf area with the saturated tiller number (Supplementary Figure 3), thus, exhibiting growth limitation by CO 2 rather than N as eCO 2 further increased the number of tillers and leaf area. Burnett et al (2018) compared fast-growing domesticated annual barley with a slow-growing wild perennial relative under different levels of nutrient supply. They found that the perennial barley has a higher amino acid/sucrose ratio than the annual, implying a greater carbon source-limitation in the perennial than the annual barley.…”