Root or shoot nitrate assimilation in terrestrial vascular plants – does it matter?

Andrews, Mitchell; Raven, John A.

doi:10.1007/s11104-021-05164-9

Cited by 10 publications

(6 citation statements)

References 191 publications

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“…This study revealed that foliar NRA was greater in sugar maple than red maple, whereas belowground, patterns of fine-root NRA of these species were the opposite. As vicinity to sugar and red maple correlates with respective greater and lesser soil N availability at the FEF [14] and respective lesser and greater soil C:N ratio [60], the observed NRA patterns within each species fit the generalized pattern of a greater ratio of root:shoot NRA in soils of lesser N availability with an increase of the importance of shoot NRA in soils of greater N availability [2,61]. This supports a genetically-driven, species-specific response to the soil N environment the species is able to create, rather than a response to external soil nitrate.…”

Section: Red Maple Vs Sugar Maplementioning

confidence: 59%

“…Studies to assess nitrate use often quantify the activity of the initial reducing enzyme in the process of nitrate assimilation, nitrate reductase (NR). However, existing studies are biased towards herbaceous species of economic importance and the Pinaceae [2]. Of the studies conducted on tree species, many were carried out on potted seedlings under greenhouse conditions [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

“…A few studies have quantified nitrate reductase activity (NRA) of mature temperate deciduous trees [6][7][8], and even fewer quantified NRA of herb-layer species in these forests [8]. Findings from these temperate deciduous forests did not fit the generalized pattern of temperate perennial species carrying out most nitrate reduction in the root under low soil nitrate, or that high soil nitrate results in increased shoot NRA [2]. Despite low soil nitrate, five species of northeastern U.S. tree species had greater foliage than root NRA, with foliage NRA unresponsive to N fertilization [7].…”

Section: Introductionmentioning

confidence: 99%

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Role of Tree Species, the Herb Layer and Watershed Characteristics in Nitrate Assimilation in a Central Appalachian Hardwood Forest

2022

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Forest plants that can assimilate nitrate may act as nitrate sink and, consequently, reduce nitrate losses from watershed ecosystems through leaching. This study, conducted at the Fernow Experimental Forest in West Virginia, quantified via nitrogen reductase activity (NRA) the nitrate assimilation of two tree species, red maple and sugar maple, and surrounding common herb-layer species at the tissue (foliage, roots) and plot level. NRA measurements were conducted in summer and spring. Furthermore, NRA was quantified under varying levels of soil nitrate availability due to fertilization, different stages in secondary forest succession, and watershed aspect. This study confirmed that NRA of mature maples does not respond to varying levels of soil nitrate availability. However, some herb-layer species’ NRA did increase with nitrogen fertilization, and it may be greater in spring than in summer. Combined with biomass, the herb layer’s NRA at the plot-level (NRAA) comprised 9 to 41% of the total (tree + herb-layer) foliar NRAA during the growing season. This demonstrates that the herb layer contributes to nitrate assimilation disproportionally to its small biomass in the forest and may provide a vernal dam to nitrate loss not only by its early presence but also by increased spring NRA relative to summer.

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Section: Red Maple Vs Sugar Maplementioning

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Role of Tree Species, the Herb Layer and Watershed Characteristics in Nitrate Assimilation in a Central Appalachian Hardwood Forest

2022

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“…The results of PCA analysis showed that NR leaf and NR root were two major contributors to the differentiation between the clones (Figure 6). The partitioning of nitrate assimilation between shoot and root is plastic and influenced by nitrogen types and availability, plant species, air temperature, air CO 2 and abiotic stress [27]. However, the functional consequences of nitrate assimilation partitioning between shoot and root are still not clear.…”

Section: Discussionmentioning

confidence: 99%

“…Increased NR leaf during drought could be helpful to consume excess photochemical energy and to maintain chloroplast stability (Figure 7). Nitrate assimilation in leaves could also generate higher osmotic potential through nitrate, potassium and malate accumulation to improve leaf expansion, compared with nitrate assimilation in roots [27]. This may explain the alleviation of leaf ecophysiological traits and the growth of the two clones by nitrogen addition under drought.…”

Section: Discussionmentioning

confidence: 99%

Effects of Nitrate Assimilation in Leaves and Roots on Biomass Allocation and Drought Stress Responses in Poplar Seedlings

Wang,

Shang,

Ræbild

et al. 2024

Forests

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Knowledge of tree biomass allocation is fundamental for estimating forest acclimation and carbon stock for global changes in the future. Optimal partitioning theory (OPT) and allometric partitioning theory (APT) are two major patterns of biomass allocation, and occurrences have been tested on taxonomical, ontogenetic, geographic and environmental scales, showing conflicting results and unclear ecophysiological mechanisms. Here, we examine the biomass allocation patterns of two young poplar (Populus) clones varying greatly in drought resistance under different soil water and nitrogen availabilities and the major physiological processes involved in biomass partitioning. We found that Biyu, a drought-sensitive hybrid poplar clone, had significant relations among biomass of leaf, stem and root, showing allometric partitioning. Xiaoye, a drought-tolerant poplar clone native to semi-arid areas, on the contrary, showed tightly regulated biomass allocation following optimal partitioning theory. Biyu had higher nitrate reductase activity in the fine roots, while Xiaoye had higher nitrate reductase activity in the leaves. Biochemical analyses and measurements of fluorescence and gas exchange showed that Xiaoye maintained more stable chloroplast membranes and photosystem electron flow, showing higher water use efficiency and a higher resistance to drought. A nitrogen addition could improve leaf photosynthesis and growth both in Biyu and Xiaoye seedlings under drought conditions. We concluded that the two poplar clones showed different biomass allocation patterns and suggest that the site of nitrate assimilation may play a role in biomass partitioning under varying water and nitrogen availabilities.

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Fertigation frequency is a useful tool for nitrate management in intensive open-field agriculture

Rubio-Asensio,

Intrigliolo

2024

Irrig Sci

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The main source of nitrogen for most cultivated plants is nitrate. Agriculture has overused this nutrient, resulting in serious environmental problems in various parts of the world. The common practice in open intensive horticultural fields with clay-loam soils with a high water retention capacity (e.g., high percentage of clay) is to irrigate two to four times per week. Technically and logistically, this is much easier than one or more irrigation events per day. However, the loss of nutrients and water below the root zone may occur, with the consequent loss of efficiency. In this work, two cultivation cycles in an open-field endive crop were carried out under plastic soil mulching. We compared three fertigation strategies based on different frequencies of fertigation events; low fertigation frequency (LF, two to three fertigation events per week that simulates common farmer practice), medium fertigation frequency (MF, one fertigation event per day), and high fertigation frequency (HF, three fertigation events per day). The three fertigation strategies applied equal water and fertilizers doses per week. The high fertigation frequency increased volumetric water content in the upper soil profile, while the low fertigation frequency in the lower soil profile. The results demonstrated that HF fertigation increases shoot fresh weight (harvest yield) by increasing shoot water content, but did not improve shoot nutrient uptake or nitrogen nutritional status. The important finding, from the environment point of view, is that high and medium fertigation frequencies decreased nitrate concentration in the root influence zone, where it may be prone to leaching due to heavy rain events.

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Root or shoot nitrate assimilation in terrestrial vascular plants – does it matter?

Cited by 10 publications

References 191 publications

Role of Tree Species, the Herb Layer and Watershed Characteristics in Nitrate Assimilation in a Central Appalachian Hardwood Forest

Role of Tree Species, the Herb Layer and Watershed Characteristics in Nitrate Assimilation in a Central Appalachian Hardwood Forest

Effects of Nitrate Assimilation in Leaves and Roots on Biomass Allocation and Drought Stress Responses in Poplar Seedlings

Fertigation frequency is a useful tool for nitrate management in intensive open-field agriculture

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