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Background and aims: Emerging perennial grain crops yield less grain than annual crops, but the economic viability of these perennial systems could be improved if both forage and grain are harvested. However, the belowground consequences of forage removal in perennial grain systems are unknown. This study aimed to determine the effect of the additional harvest of forage biomass on overall plant biomass allocation and labile soil C and N dynamics within a perennial grain dual-use system. Methods: Plant biomass and associated soil samples of a perennial grain [Kernza (Thinopyrum intermedium)] were taken monthly over the first three growing seasons under three harvest regiments: No Cut (0x), Summer Cut (1x), and Summer and Fall Cut (2x). Results: The harvesting of forage biomass significantly increased both above- and belowground biomass. The once and twice forage-harvested treatments averaged 39% and 73% greater root biomass in 2016 and 39% and 49% greater root biomass in 2017 relative to the treatment not harvested for forage. Soil indicators of carbon and nitrogen storage were not affected by forage harvest but mineralizable carbon, an indicator of nutrient cycling, was greater under the forage harvested treatments. Conclusions: The harvest of forage and grain promoted nutrient availability and overall productivity (forage, root and grain biomass) relative to harvesting for grain only. Our findings suggest dual-use management of Kernza can provide a productive and profitable pathway for perennial grain adoption. [ABSTRACT FROM AUTHOR]

The correlation between growth and accumulation of bioactive compounds was investigated in six genotypes of Polygonum multiflorum, grown in vitro, soil-grown (ex vitro), and as adventitious root cultures. Adventitious roots were induced on leaf and root explants from plantlets of the six genotypes grown in vitro. Line PM-06 achieved the highest biomass in vitro (0.91 g plant−1 FW; 0.1 g plant−1 (DW)), whereas line PM-05 produced the highest biomass ex vitro (54.67 g plant−1 FW; 12.93 g plant−1 DW). A comparison of the six lines found that total phenolic content (TPC) and total flavonoid content (TFC) were highest in roots from line PM-01 grown in vitro, but line PM-06 produced the highest levels of bioactive compounds in tubers (99.06 mg g−1 DW TPC; 42.31 mg g−1 DW TFC), which were 2.5-fold, 5.0-fold, and 4.8-fold higher than the highest levels produced by in vitro roots, in vitro shoots, and ex vitro shoots, respectively. Although adventitious root line AR-06 produced the greatest overall biomass (60.12 g L−1 FW; 6.36 g L−1 DW), bioactive content was highest in line AR-01 (50.35 mg g−1 DW TPC; 22.51 mg g−1 TFC). There was a strong correlation between phenolic production in plant roots grown in vitro and adventitious root lines, and plant roots grown ex vitro and adventitious root lines. Adventitious root cultures of P. multiflorum line AR-06 showed great potential for producing phenolic compounds. Such cultures may therefore provide an alternative to naturally grown plants as a potential biomass source for the production of bioactive compounds. [ABSTRACT FROM AUTHOR]

Purpose: Degradation of grassland creates diverse vegetation patch types with plant species with different palatabilities, potentially affecting ecosystem productivity and soil organic carbon (SOC) sequestration. This study investigated variations in SOC densities and carbon/nitrogen/phosphorus (C/N/P) ratios among vegetation patch types in a degraded alpine steppe on the Qinghai-Tibetan Plateau. Materials and methods: We examined soil, shoot and root C, N and P densities, and C/N/P ratios in a growing season for five vegetation patch types dominated by palatable plant species Stipa purpurea, S. purpurea and Poa litwinowiana, and unpalatable plant species Leontopodium nanum, Artemisia nanschanica, and Oxytropis glacialis. Results and discussion: Soil C and N as well as shoot and root densities varied among patch types, but not soil C/N. Patches dominated by unpalatable plant species had a lower SOC density, lower soil and plant N/P ratios, and greater plant nutrient densities than those dominated by palatable plant species. Vegetation patch type strongly influenced nutrient densities and ratios in soil-plant systems, and sampling only areas dominated by palatable plant species may overestimate the C sequestration rate at the ecosystem scale. Conclusions: Even though patch-level plant biomass and nutrient density may increase with increasing degradation, the decrease in palatability and SOC storage at the ecosystem scale would impair grassland sustainability as alpine grassland degradation proceeds. The palatability of plants should thus be considered for improving regional SOC stock estimate in future research. [ABSTRACT FROM AUTHOR]

• This research unveils optimal airflow and nutrients for leafy green production in vertical farms. • Unexpected discovery: minimal airflow rates efficiently support crop production. • A heavier fertilizer recipe with a high calcium rate enhances crop yields. • Results helped in understanding operational differences since seasonal variations were observed in vertical farms. Indoor vertical farming is a potential solution to address the high food production demands generated by the increased global population and urbanization. However, the maximum potential of indoor farms can only be achieved when optimal cropping systems are used. There is a lack of information concerning vertical farms in the Southeast U.S. since this technology is new and in constant development. The objective of our study was to evaluate the effects of airflow rates and nutrient concentrations for lettuce 'Rex' (Lactuca sativa) and spinach 'Lizard' (Spinacia oleracea) production in a deep water culture system inside an indoor vertical farm. We tested four airflow rates (0.4, 0.7, 1.0, and 1.3 m s−1), two fertilizer solution recipes with different nutrient concentrations (Mattson and Resh), and three levels of calcium (Ca) concentration (regular with 90 and 200 mg L−1 Ca for Mattson and Resh, low with 40–50 mg L−1 Ca lower than regular, and high with 40–50 mg L−1 Ca higher than regular). Results showed that a high airflow rate (1.3 m s−1) significantly increased plant water use and solution electrical conductivity (P < 0.01), negatively affected lettuce P, K, and Mg concentrations (P < 0.05) while having no significant effects on spinach growth performance and mineral concentrations. Lettuce and spinach plants grown using the Resh recipe had higher leaf area, yield, shoot, and root biomass than the Mattson recipe. High Ca concentrations in the solution further accelerated these improvements, with additional benefits on increasing tissue Ca concentrations (P < 0.01). No tipburn symptoms were found, indicating no Ca deficiency induced by low Ca availability, and reduced plant transpiration was presented using these airflow rates and solution Ca concentrations. Overall, slow airflow rates (0.4–0.7 m s−1) and a Resh recipe with high Ca concentration can be used for lettuce and spinach production in vertical farms to increase yield. [ABSTRACT FROM AUTHOR]

Rocky regolith layer can restrain plant root growth, which may affect soil water unitization of deep-rooted fruit trees in rocky mountain areas. However, how and to what magnitude the rocky regolith layer shapes root features and thus changes trees' water consumption, remains unclear. Here, we investigated the root features and water uptake strategies of apple trees in three apple orchards with the underlying weakly (WWP), strongly (SWP), and completely (CK) weathered regolith layer within soil profiles, in the hilly areas of Jiaodong Peninsula, China. The results showed that the fine root biomass density (FRBD) of apple trees decreased while the specific root length (SRL) increased with increasing soil depths in the three orchards. The FRBD within the rocky regolith layer only accounted for 3–5% of the total FRBD in the WWP and SWP orchards, which were significantly lower than that in the CK orchard (3.31–5.11% vs. 29.96%) (P < 0.05). The maximum SRL was 76.61 m·g-1 and 72.38 m·g-1 in the WWP and SWP orchards, respectively, being significantly higher than that in the CK orchard (55.26 m·g-1). Both the FRBD and SRL within the rocky regolith layer showed no significant difference between the WWP and SWP, which indicated that it was the presence but not the weathering intensity of the rocky regolith layer shaped apple trees' root features. The MixSIAR model estimated that the water uptake of roots in the rocky regolith layer accounted for an average of 33.14% of the total water uptake in the WWP and SWP orchards. During the fruit expansion period (July-August) with high water consumption, apple trees' water uptake in the rocky regolith layer contributed 41.40% of water consumption in the WWP orchardand 34.77% in the SWP, which can be comparable to that in the corresponding soil depth in the CK orchard (46.70%). This suggested that apple trees may prime root activity to absorb more soil water with decreased root biomass in the rocky regolith layer. Overall, apple trees could utilize 3–5% of root biomass to absorb 33–34% of water consumption in the rocky regolith layer. Our study highlights the specific water use strategies in rocky mountain areas and will benefit the sustainable water management in the orchards in these areas. • The presence of rock regolith reduces apple trees' FRBD but increases their SRL. • The regolith weathering degree does not impact apple trees' root distribution. • Apple trees utilize 5% of root biomass to absorb 34% of water from rock regolith. [ABSTRACT FROM AUTHOR]

This study aims to explore relationships between plant diversity and soil microbial function and the factors that mediate the relationships. Artificial plant communities (1, 2, 4 and 8 species) were established filled with natural and mine tailing soils, respectively. After 12 months, the plant species richness positively affected the soil microbial functional diversity in both soil environments but negatively affected microbial biomass and soil basal respiration in the natural soil. The root biomass positively correlated with the microbial biomass, cultural bacterial activity and soil basal respiration in both soil environments. Moreover, the Di (deviations between observed performances and expected performances from the monoculture performance of each species of mixture) of microbial biomass, cultural bacterial activity and soil basal respiration positively correlated with the Di of root biomass in both soil environments. Consistent with stress-gradient hypothesis, the Dmix (over-function index) of aboveground biomass positively correlated plant species richness in the mine tailing soil. Results suggest that the root biomass production is an important mechanism that affects the effects of plant diversity on soil microbial functions. Different responses of soil microbial function to increasing plant diversity may be due to root biomass production mediated by other factors.

To explore the effects of multi-cutting and sheep excrement on greenhouse gas (GHG) emissions from grassland ecosystems which simulate grazing livestock to a certain extent, spring wheat (Triticum aestivum L., var. Yongliang 15) and common vetch (Vicia sativa L., var. Lanjian 3) were planted in pot experiments in an inland arid region in 2019. Four treatments were conducted with eight replicates: plants without sheep excrement and cutting (CK), plants with multi-cutting (MC), plants with sheep excrement (SE), and plants with multi-cutting and sheep excrement (CE). The results showed that the carbon dioxide (CO2) emission of common vetch with CE significantly was higher than that with MC at the earlier and later branching stages (p < 0.05). That of spring wheat with CE was significantly higher than that with MC at the later tillering stage (p < 0.05). Nitrogen oxide (N2O) emissions of the two forage crops with SE rose significantly more than those with MC at both stages (p < 0.05). Methane (CH4) of both forage crops with SE changed from absorption to emission (p < 0.05). Soil NO3−-N content of both forages significantly increased with SE compared with MC (p < 0.05), while soil NH4+-N content did not change significantly. Sheep excrement changed the CH4 sink into a CH4 source of the soil growing the two forage crops and increased the emissions of CO2 and N2O, whereas multi-cutting significantly reduced the GHG intensity of forage crops mostly by promoting the growth of the two forage crops. Future studies are suggested to identify the spatiotemporal effects of cutting and sheep excrement on GHG emissions to improve the prediction of future climate impacts from grazing activities.

Abstract Elevated nitrogen (N) deposition may exacerbate soil phosphorus (P) limitations in P-deficient subtropical forest ecosystems. However, which abiotic factors predominantly contribute to soil P transformations and how plant roots affect soil P variations after N addition in these ecosystems are unclear. To address these issues, we studied a natural Castanopsis carlesii forest in Fujian, China subjected to 3 years of N addition. Soil P fractions, soil properties, iron (Fe) and aluminum (Al) oxides, root biomass (RB), and root length density (RLD) were investigated. The results showed that N application remarkably increased the concentrations of soil available P but significantly decreased content of soil moderately labile P. The quantities of free Fe and Al (Fe d and Al d) and organic-bound Fe and Al (Fe p and Al p) decreased after N addition. These changes indicated an important relationship between Fe and Al oxides and P fractions, especially Fe p and moderately labile P, suggesting that Fe and Al oxides predominantly influenced soil P fractions in N-enriched plots. Meanwhile, RB and RLD were higher after N addition treatments than control treatment. Positive correlations between RB and RLD and P fractions (available P, labile P, and moderately labile P) indicated that plant roots exert an essential influence on changes in soil P fractions. In conclusion, N addition in subtropical forests significantly influenced soil P fractions, primarily by decreasing Fe and Al oxides and increasing plant root biomass and density. Highlights • Simulated N deposition significantly decreased soil moderately labile P and increased available P in forest soil. • N deposition induced a decline of free Fe and Al (Fe d and Al d) and organic-bound Fe and Al (Fe p and Al p) in forest soil. • Plant root biomass and root length density were increased by nitrogen treatments. [ABSTRACT FROM AUTHOR]

The method of component integration was tested in the course of studies in typical biogeocenoses of the north of Western Siberia. This method as applied for separate horizons made it possible not only to estimate the contribution of different sources to the total efflux of CO2 from soils but also to evaluate the participation of horizons in soil respiration. Root respiration contributed to about 14 ± 3% of the CO2 efflux from the permafrost-affected peat soil (Hemic Cryic Histosol) and to about 29 ± 6% of the CO2 efflux from the tonguing podzol (Glossic Albic Rustic Podzol (Arenic)). Histosol was characterized by a higher storage of total (organic and inorganic) carbon (26 kg C/m2), extractable carbon (Cextr) (32 g C/m2), and microbial carbon (Cmic) (43 g C/m2). Its upper horizon (TO) contained about 50% of the total soil storage of Cmic and 100% of the total storage of roots (up to 300 g/m2). It had the maximum activity of microbiota and contributed to more than 70% of the total efflux of CO2 from the active layer (on average, 35 cm in thickness) of Cryic Histosol. Podzol was characterized by the low storage of total carbon (6 kg C/m2), considerable storage of Cmic (38 g C/m2), and much higher microbial activity. This circumstance, together with a tenfold higher storage of the roots (up to 3000 g C/m2) and favorable temperature regime specified high values of the gross production of CO2 and its emission from the Podzol surface exceeding the corresponding values for the Cryic Histosol by three–five times. The mineral profile of Podzol contributed to about 20% of the total efflux of CO2 from this soil (on average, about 38 cm in thickness). [ABSTRACT FROM AUTHOR]

In temperate forest ecosystems, ectomycorrhizal (EcM) fungi substantially support coniferous trees by nutrients, but importance of EcM for tree nutrition might be lower in nutrient-rich hotspots, such as in wood ant nests. In this study, we focused on differences in EcM morphotype composition between natural nutrient-rich hot spots of various quality (inhabited vs. abandoned wood ant nests) and the surrounding forest floor. In a secondary Norway spruce forest typical for central Europe, we took samples from different belowground parts of five inhabited and five abandoned nests (centre and rim) as well as from the forest floor 20 cm from the nests (run-off zone) and >3 m from the nests (forest soil). The substrates were subjected to analyses of the EcM morphotype composition, moisture and nutrient contents. Wood ant nest substrates had several times increased nutrient contents compared to the forest soil, but there were no significant differences in moisture. Available nutrient contents were higher in inhabited nests than in abandoned nests. The EcM morphotype composition differed between the nest samples and the forest floor samples but not between the inhabited and abandoned nests suggesting that, apart from the level of nutrient enrichment and their availability, moisture is another important factor affecting EcM community composition. [ABSTRACT FROM AUTHOR]

Highlights • FR growth dynamics and architectural traits of four beech provenances were studied. • The aim was to determine if growth is controlled by endogenous or exogenous factors. • Ingrowth soil cores and minirhizotrons were used. • Results show significantly different growth response of the provenance originating from ecologically most distant site. Abstract European beech (Fagus sylvatica L.) is commercially and ecologically important tree species in Central European forests but its intra-specific variability in drought and temperature tolerance might endanger its future distribution in Europe. Beech phenological and growth traits have been studied in large-scale international beech provenance trials, yet the growth and turnover of its fine roots (FR) has not been included among the observations. FR growth dynamics and FR architectural traits of three beech provenances in the international beech provenance trial Straza/Kamenski hrib, established in Slovenia in 1998, and from a natural beech regeneration site growing at its border, were studied from 2007 to 2010. We studied FR biomass using soil cores (SC), root production using ingrowth soil cores (IC), and root longevity using minirhizotrons (MR). Significant differences in FR biomass (live and dead) between the provenance P37 and other provenances were discovered in SC, FR biomass of P37 being significantly higher than FR biomass of latter, which could be connected with overall excellent growth performance of P37 due to favourable environmental conditions at trial. Values of specific root length (SRL) in IC varied significantly among P37 and P54. The turnover rates in IC were at the end of the experiment close to MR results. Median MR-based longevities of FR varied between 625 and 934 days. Survival curve of the slowest growing provenance (considering its aboveground characteristics) was significantly different from the other two, median longevities of the latter being higher. Death of FR, older than two years, occurred most likely in the winter. Our results suggest that there are significant differences in FR longevity among provenances, which might contribute to their adaptation to future environmental conditions. Furthermore, the calculated annual C investment into FR growth per ha differs up to twofold between provenances, contributing to different C dynamics of their future stands. [ABSTRACT FROM AUTHOR]

Highlights • The below-ground biomass and N uptake of annual and perennial crops were determined. • Root biomass was significantly greater in perennial than annual crops. • Root N uptake of perennial was 3–6 times greater than that in annual crops. • Difference in root N uptake by the two crops accounted for difference in NO 3 leaching. Abstract The aim of this study was to determine the importance of below-ground (root) plant biomass and nitrogen (N) uptake with perennial cropping system (PCS) as a mechanism of reducing nitrate leaching. The experimental design was a split plot with main plot being cropping system [annual cropping system (ACS) versus PCS] and subplots being manure treatment [N-based liquid pig manure (LPM), N-based solid pig manure (SPM), and a control with no manure addition (CON)]. The ACS was seeded to barley (Hurdeum vulgare L.) and canola (Brassica napus L.) in the spring of 2014 and 2015, respectively, whereas the PCS was seeded to a mixture of timothy (Phleum protense L.) and orchard (Dactylis glomerata L.) grass in the fall of 2013. LPM and SPM were applied to meet N requirement of each crop in spring of each year. In 2014, above-ground and root biomass were collected at harvest and in 2015, above-ground and root biomass were collected at mid-season. The PCS had significantly greater root biomass and N uptake than ACS in both years. Root biomass in PCS ranged from 5.3–9.7 Mg ha−1 compared to a range of 1.1–1.5 Mg ha−1 in ACS. Consequently, root N uptake in PCS ranged from 43 to 118 kg N ha−1 in both years while that in ACS was 9–20 kg N ha−1. In 2014, PCS had significantly greater above-ground N than ACS, whereas in 2015, PCS had significantly greater above-ground N than ACS in the LPM only. This study shows that the differences in nitrate leaching between the two cropping systems as previously determined from field core lysimeters at the same plots was mainly due to differences in root N uptake (34–98 kg N ha−1) between the cropping systems rather than above-ground N uptake. It is important that studies comparing N losses by ACS and PCS should consider the role of plant root biomass in N recovery. [ABSTRACT FROM AUTHOR]

Highlights • Pinus pinea is economically important in the Mediterranean basin. • Above and belowground biomass equations were developed with 283 harvested trees. • Accuracy of biomass estimates improved for root and high dimension trees. • Biased estimates were observed when using equations outside the geographical range. • Best biomass equations for regional and national biomass inventories. Abstract Accurate estimates of tree biomass are strongly required for forest carbon budget estimates and to understand ecosystem dynamics for a sustainable management. Existing biomass equations for Mediterranean species are scarce, stand- and site-specific and therefore are not suitable for large scale application. In this study, biomass allometric equations were developed for stone pine (Pinus pinea L.), a Mediterranean tree species with relevant ecologic and economic interest. A dataset of 283 harvested trees was compiled with above- and belowground biomass from 16 sites in three countries (Italy, Spain, Portugal) representative of the species’ geographical Mediterranean distribution. A preliminary approach comparing the ordinary least squares method and the mixed model approach was performed in order to evaluate the most appropriate method for nested data in the absence of calibration data. To quantify the sources of error associated with applying biomass equations beyond the geographical range of the data used to develop them, a residual analysis was conducted. The allometric analysis showed low intra-specific variability in aboveground biomass relationships, which was relatively insensitive to the stand and site conditions. Significant differences were found for the crown components (needles and branches), which may be attributed to local geographical adaptation, site conditions and stand management. The root biomass was highly correlated with diameter at breast height irrespective of the geographical origin. Biased estimates were found when using site-specific equations outside the geographical range from where they were developed. The new biomass equations improved the accuracy of biomass estimates, particularly for the aboveground components of higher dimension trees and for the root component, being highly suitable for use in regional and national biomass forest calculations. It is, up to the present, the most complete database of harvested stone pine trees worldwide. [ABSTRACT FROM AUTHOR]

Beside the production of biomass, short rotation coppice (SRC) poplar plantations can also contribute to carbon sequestration in the soil through their below-ground biomass. The present study evaluated the allocation of above and below-ground biomass at the end of the first rotation of four SRC plantations under Mediterranean conditions. The genotypes evaluated are commonly used for biomass plantations, i.e. genotypes ‘AF2’ and ‘I-214’ ( Populus × canadensis Mönch), and ‘Monviso’ ( P. × generosa Henry  × P. nigra L.). No significant differences among genotypes were found with regard to below-ground biomass yield. The root:shoot ratio decreased in line with the growth in shoot basal diameter, with values ranging from 0.15 to 0.26. The accumulation of carbon in the below-ground fraction of the biomass ranged from 0.86 to 0.91 Mg C ha −1  yr −1 , whereas the above-ground carbon accumulation ranged from 3.89 to 6.48 Mg C ha −1  yr −1 . A general as well as a genotype-specific allometric model allowed to accurately predict the below-ground biomass yield using shoot basal diameter as the predictor variable. Both models provide an important tool to quantify the carbon accumulated in the below-ground fraction of the biomass. [ABSTRACT FROM AUTHOR]

Extreme drought is likely to become more frequent and intense as a result of global climate change, which may significantly impact plant root traits and responses (i.e., morphology, production, turnover, and biomass). However, a comprehensive understanding of how drought affects root traits and responses remains elusive. Here, we synthesized data from 128 published studies under field conditions to examine the responses of 17 variables associated with root traits to drought. Our results showed that drought significantly decreased root length and root length density by 38.29% and 11.12%, respectively, but increased root diameter by 3.49%. However, drought significantly increased root:shoot mass ratio and root cortical aerenchyma by 13.54% and 90.7%, respectively. Our results suggest that drought significantly modified root morphological traits and increased root mortality, and the drought‐induced decrease in root biomass was less than shoot biomass, causing higher root:shoot mass ratio. The cascading effects of drought on root traits and responses may need to be incorporated into terrestrial biosphere models to improve prediction of the climate–biosphere feedback. [ABSTRACT FROM AUTHOR]

Plant roots mediate the impacts of environmental change on ecosystems, yet knowledge of root responses to environmental change is limited because few experiments evaluate multiple environmental factors and their interactions. Inferences about root functions are also limited because root length dynamics are rarely measured.Using a 5‐year experiment in a mixed‐grass prairie, we report the responses of root biomass, length and life span to elevated carbon dioxide (CO2), warming, elevated CO2 and warming combined, and irrigation. Root biomass was quantified using soil cores and root length dynamics were assessed using minirhizotrons. By comparing root dynamics with published results for soil resources and above‐ground productivity, we provide mechanistic insights into how climate change might impact grassland ecosystems.In the upper soil layer, 0–15 cm depth, both irrigation and elevated CO2 alone increased total root length by twofold, but irrigation decreased root biomass and elevated CO2 had only small positive effects on root biomass. The large positive effects of irrigation and elevated CO2 alone on total root length were due to increases in both root length production and root life span. The increased total root length and life span under irrigation and elevated CO2 coincided with apparent shifts from water limitation of plant growth to nitrogen limitation. Warming alone had minimal effects on root biomass, length and life span in this shallow soil layer. Warming and elevated CO2 combined increased root biomass and total root length by c. 25%, but total root length in this treatment was lower than expected if the effects of CO2 and warming alone were additive. Treatment effects on total root length and root life span varied with soil depth and root diameter.Synthesis. Sub‐additive effects of CO2 and warming suggest studies of elevated CO2 alone might overestimate the future capacity of grassland root systems to acquire resources. In this mixed‐grass prairie, elevated CO2 with warming stimulated total root length and root life span in deeper soils, likely enhancing plant access to more stable pools of growth‐limiting resources, including water and phosphorus. Thus, these root responses help explain previous observations of higher, and more stable, above‐ground productivity in these projected climate conditions. Sub‐additive effects of CO2 and warming suggest studies of elevated CO2 alone might overestimate the future capacity of grassland root systems to acquire resources. In this mixed‐grass prairie, elevated CO2 with warming stimulated total root length and root life span in deeper soils, likely enhancing plant access to more stable pools of growth‐limiting resources, including water and phosphorus. Thus, these root responses help explain previous observations of higher, and more stable, above‐ground productivity in these projected climate conditions [ABSTRACT FROM AUTHOR]

Introduction of stem-dwarfing genes had a major impact on wheat breeding and production. It is estimated that 70-90% of modern wheats carry one or more such genes. These genes were the cornerstone of the Green Revolution. They solved the lodging problem by reducing stem height, thus allowing a marked increase in mineral fertilizer use. These genes also changed biomass allocation and allowed more carbon assimilates to be stored as grain. With heavy fertilization and irrigation, plants had little use for an extensive and expensive root system for uptake of water and nutrients. However, with climate change and limited water and nutrient sources, there is a need to remodel crops with novel genetic variation available in landraces and old varieties. In this study, we evaluated nine accessions of wheat representing gene pools of parental, early-tall and late-semi-dwarf Green Revolution wheats for root and shoot biomass and grain yield under well-watered conditions in a glasshouse. Significant genotypic variation was found for total root biomass and root distribution in the soil profile as well as for plant height and days to anthesis. Modern wheats have reduced root-system size relative to their predecessors. This may be the effect of the dwarfing genes or an indirect effect of negative selection pressure, but the wheat root system became smaller within the last century. [ABSTRACT FROM AUTHOR]

Aquatic macroinvertebrates have a close relationship with associated floating macrophytes, especially with the roots. The plant root mass is an environment favorable to the development of the macroinvertebrate fauna, supplying both food resources and refuge against predators. The present study aimed to analyze the structure of the macroinvertebrate community associated with the roots of Eichhornia azurea (Sw.) Kunth (Pontederiaceae) in a lake marginal to a tropical river. Sampling was performed quarterly in three stands of E. azurea. One plant specimen was selected from each stand and five root mass samples were collected. The study was carried out in an extremely rainy year, with high rainfall in July, when the river level increased quickly, causing an extreme inundation and an increase in the root biomass of E. azurea. A higher abundance of macroinvertebrates was found in April, around four to five times the total density of the other periods. Taxa richness presented no significant temporal differences. Oligochaeta and Chironomidae were the predominant group of invertebrates in all periods. The extraordinary flood in June-July caused a modification in the macroinvertebrate fauna (an increase in the abundance and a reduction in the taxon richness), and was apparently a controlling factor for the community structure. [ABSTRACT FROM AUTHOR]

Licorice cultivated is one of the most popular herbal medicines, while its quality is unstable. The aim of present study is to investigate the effect of licorice seedling grade standard on improving its quality. One-year-old Glycyrrhiza uralensis seedlings were classified into three grades 1, 2, and 3 by weight per plant. The major root biomass indexes (root fresh weight, root dry weight and taproot diameter) and contents of 7 bioactive components (glycyrrhizin, liquiritin, liquiritin apioside, liquiritigenin, isoliquiritin, isoliquiritin apioside, and isoliquiritigenin) varied in different grades seedlings. Further, the contents of 7 investigated compounds of 3-year-old licorice produced by grade 1 seedlings were 1.5-2 times as much as those produced by grade 2 and 3. Additionally, the contents of liquiritin apioside and isoliquiritin apioside were positively correlated with licorice root biomass. These results indicated that establishing licorice seedling grade standard is an effective way to improve and control its quality. [ABSTRACT FROM AUTHOR]

Root system size is a key trait for improving water and nitrogen uptake efficiency in wheat (Triticum aestivum L.). This study aimed (i) to characterize the root system and shoot traits of five wheat cultivars with apparent differences in root system size; (ii) to evaluate whether the apparent differences in root system size observed at early vegetative stages in a previous semi-hydroponic phenotyping experiment are reflected at later phenological stages in plants grown in soil using large rhizoboxes. The five wheat cultivars were grown in a glasshouse in rhizoboxes filled to 1.0 m with field soil. Phenology and shoot traits were measured and root growth and proliferation were mapped to quantify root length density (RLD), root length per plant, root biomass and specific root length (SRL). Wheat cultivars with large root systems had greater root length, more root biomass and thicker roots, particularly in the top 40 cm, than those with small root systems. Cultivars that reached anthesis later had larger root system sizes than those that reached anthesis earlier. Later anthesis allowed more time for root growth and proliferation. Cultivars with large root systems had 25% more leaf area and biomass than those with small root systems, which presumably reflects high canopy photosynthesis to supply the demand for carbon assimilates to roots. Wheat cultivars with contrasting root system sizes at the onset of tillering (Z2.1) in a semi-hydroponic phenotyping system maintained their size ranking at booting (Z4.5) when grown in soil. Phenology, particularly time to anthesis, was associated with root system size. [ABSTRACT FROM AUTHOR]

Growing catch crops is one of the possible strategies to decrease erosion and nitrogen loss from soil profiles. Biomass yield and root system size have significant impacts on the soil nitrogen content. a three-year field experiment with eight varieties of white mustard (Sinapis alba L.) was established to evaluate the effects of genotype and environment on biomass yield, soil nitrogen content and rooting parameters. Significant effects of genotype were found for root length density (RLD), root surface density (RSD) and specific root length (SRL) in the plow layer (0 - 20 cm) and for root system size (RSS), measured by electrical capacitance method, during three phenological phases. Higher biomass yield in varieties with higher RLD and RSD values during ripening and a larger RSS during flowering were found in dry conditions. Relationship of the root system and biomass yield to nitrate and ammonia nitrogen content varied in different environments. We found a significant relation between the RSS and ammonia nitrogen content in more fertile environment on average over the three years. The nitrate nitrogen content was related to the RLD, RSD and SRL in favorable year at shallow soil depths (0 - 20 cm). [ABSTRACT FROM AUTHOR]

Stream restoration practitioners often rely upon empirical models to quantify annual streambank erosion rates and identify streambank erosion hotspots. Such models are designed to be widely applicable by incorporating readily available field measurements, but they must be calibrated to each hydrophysiographic region and may not reflect the dominant streambank erosion processes in a given region. Here, we present statistical models for streambank erosion using physical and environmental data collected at 53 locations throughout the northern Gulf of Mexico coastal plain. The data include channel geometry, bank characteristics, precipitation, above-ground biomass density, and root density, the latter two surveyed using techniques introduced here. We developed a statistical model selection process using Akaike's Information Criterion (AIC) and repeated cross-validation (CV). Models derived from the literature that were applied a priori were only weak predictors of erosion rate, but AIC-CV model selection identified 3 strong statistical models. The best model according to AIC showed a significant correlation to lateral streambank erosion rates ( R 2  = 0.54) and included the five strongest covariates of our dataset (bank slope, biomass density, curvature index, BEHI, and understory cover). When volumetric erosion rate (m 2 /year) was predicted, the fit of this model increased ( R 2  = 0.65). CV-based selection resulted in a more conservative model with the four strongest covariates and a lower fit ( R 2  = 0.47). The similarity of the AIC and CV models indicates the stability of the two-tier model selection approach, and suggests it has utility for modeling phenomena with many potential variables. Our models also showcase the ability of our biomass survey to quantify root reinforcement of streambanks. Our approach incorporates measurements familiar to the stream restoration community and can be applied throughout the northern Gulf of Mexico coastal plain, a region characterized by low relief fluvial valleys, unconsolidated alluvium and meandering single thread sand bed channels. The approach, which is based on field observations and robust statistical modeling, offers an alternative for stream restoration practitioners to more traditional streambank erosion prediction methods that underperform in the region, and may have applicability elsewhere. [ABSTRACT FROM AUTHOR]

Soils of Mediterranean drylands are characterized by a low fertility and organic matter content because of past land use and disturbances regime. The restoration of these degraded lands faces at the same time problems related to water scarcity and the unpredictability of precipitations with problems with soil physical, chemical, and microbiological properties. Organic amendments may help to improve soil properties and, consequently, enhance planted seedling establishment and performance. In this study, we assessed the C balance of 3 Mediterranean areas planted with Pinus halepensis Mill. seedlings with different treatments of biosolid application. The assessment was conducted at different times after the establishment of treatments and the C dynamics are discussed. We considered 3 biosolid types (air-dried, fresh sludge, and composted sludge) in application doses ranging from 10 to 320 Mg (d.w.) ha-1. We quantified basal area, pine biomass, biomass of spontaneous vegetation, litter, root density, and soil organic matter. All 3 experimental restoration studies improved restoration success in terms of basal area (ranging from 15% to 300%), especially in composted biosolid at 30 Mg (d.w.) ha-1, whereas litter and, especially, root biomass increased with all biosolid treatments and times since application. Soil organic C was higher in application doses above 30 Mg (dry weight) ha-1 due to the organic matter applied with the sludges. The increment in C sequestration rates associated to these restoration treatments ranged between 0.046 and 0.293 kg C m² yr-1. These results confirm the suitability of organic amendments as restoration technique in Mediterranean degraded drylands. [ABSTRACT FROM AUTHOR]

Abstract: Agricultural soil landscapes of hummocky ground moraines are characterized by 3D spatial patterns of soil types that result from profile modifications due to the combined effect of water and tillage erosion. We hypothesize that crops reflect such soil landscape patterns by increased or reduced plant and root growth. Root development may depend on the thickness and vertical sequence of soil horizons as well as on the structural development state of these horizons at different landscape positions. The hypotheses were tested using field data of the root density (RD) and the root lengths (RL) of winter wheat using the minirhizotron technique. We compared data from plots at the CarboZALF‐D site (NE Germany) that are representing a non‐eroded reference soil profile (Albic Luvisol) at a plateau position, a strongly eroded profile at steep slope (Calcaric Regosol), and a depositional profile at the footslope (Anocolluvic Regosol). At each of these plots, three Plexiglas access tubes were installed down to approx. 1.5 m soil depth. Root measurements were carried out during the growing season of winter wheat (September 2014–August 2015) on six dates. The root length density (RLD) and the root biomass density were derived from RD values assuming a mean specific root length of 100 m g−1. Values of RD and RLD were highest for the Anocolluvic Regosol and lowest for the Calcaric Regosol. The maximum root penetration depth was lower in the Anocolluvic Regosol because of a relatively high and fluctuating water table at this landscape position. Results revealed positive relations between below‐ground (root) and above‐ground crop parameters (i.e., leaf area index, plant height, biomass, and yield) for the three soil types. Observed root densities and root lengths in soils at the three landscape positions corroborated the hypothesis that the root system was reflecting erosion‐induced soil profile modifications. Soil landscape position dependent root growth should be considered when attempting to quantify landscape scale water and element balances as well as agricultural productivity. [ABSTRACT FROM AUTHOR]

Tropical secondary forests are important sinks for atmospheric carbon, yet C uptake and accumulation rates are highly uncertain, and the mechanisms poorly understood. We evaluated the recovery of C stocks in four pools (aboveground biomass, litter, roots and topsoil) during dry forest regrowth by combining a space for time replacement (that is, a chronosequence) with a repeated measurements approach (that is, a resampling). We fit nonlinear models to chronosequence data to test whether forest age could explain differences in C stocks across sites, and to changes in aboveground biomass calculated from resampling over two 3-year periods, to test the predictive potential of forest age. We combined data from both approaches into structural equation models (SEM) to assess forest age and tree community attributes (diversity and dominance) as drivers of C stocks and changes in aboveground biomass. Forest age explained differences across sites in C stocks for aboveground biomass, litter and live roots, but not for the remaining pools. Observed C stock changes in aboveground biomass were poorly predicted by forest age. SEM revealed that aboveground biomass C was consistently and positively related to forest age and to the community weighted mean of maximum tree height (Hmax CWM), but not to tree diversity. Observed C stock changes were related only to Hmax CWM, although not consistently across the two 3-year periods. Our results highlight that the chronosequence approach can yield reasonable insights into long-term C accumulation trends, but erroneous estimates of C change over specific time periods. They also show that, in addition to age, dominance by tall statured species, but not tree species diversity, plays a significant role in C accumulation. [ABSTRACT FROM AUTHOR]

Rye is a small-grain cereal with an extensive and well-branched root system that is particularly suitable for grain production in marginal environments where other grain cereals, especially wheat, cannot thrive well. However, no significant genetic gain could be achieved to improve plant height and lodging resistance in the last 30 years in rye. Thus, the relatively low grain-to-straw ratio currently hinders rye from becoming more integrated into cereal crop rotations. Here, we report first results on the effects of the gibberellin-sensitive dwarfing gene Ddw1 on the root system and aboveground traits of rye under field conditions. We assessed root traits of semidwarf and tall genotypes in two field environments at the time of anthesis using soil coring, the core-break method and root scans. Semidwarfs revealed no negative but slightly positive effects on rooting depth, total root length, root length density, and cumulative root length distribution. While plant height was significantly reduced, no increase in harvest index and grain yield was observed in semidwarf prototypes. We conclude that rye does not lose the advantages of its deep and widely branched root system with the introgression of Ddw1 , especially not on marginal sites. • First field evaluation of the effects of the dwarfing gene Ddw1 on the root system in rye. • Root traits of semidwarf and near-isogenic tall genotypes evaluated in two environments. • No negative effect of Ddw1 on rooting depth, root length, and cumulative root length distribution. • Rye does not lose the advantages of its extensive root system with the introgression of Ddw1. [ABSTRACT FROM AUTHOR]