Maize Root Growth Research Articles

MODELLING MANAGEMENT STRATEGIES TO MITIGATE THE EFFECTS OF ALTERATIONS OF TEMPERATURE AND OF CO2 CONCENTRATION ON MAIZE

Ongoing climate change may affect rainfed maize yield in Brazil, which can be attenuated by some crop management strategies. This work had the objective of evaluating, using computational modeling, management practices with potential to mitigate the effects of changes in temperature and CO 2 concentration on maize yield. The CSM-CERES-Maize model was applied to simulate the mitigating potential of using maize cultivars with 0.3 m, 0.5 m and 0.7 m deep root system, associated with 0 t ha -1 , 2 t ha -1 and 4 t ha -1 of crop residue left on the soil surface. A set of 33 years of daily weather data, along with soil profile data, were used to evaluate the approach in 10 regions of the state of Minas Gerais, Brazil. For most of the regions, the use of mulching and of a maize cultivar with deeper root system was not capable of attenuating the temperature rise. In contrast, any factor limiting root growth of maize to a depth of 0.30 m, causes significant yield drop, even for a scenario of reducing temperature by 3 o C or rising CO 2 concentration. In warmer and drier regions, the positive response of maize to the increase in CO 2 concentration was more pronounced.

A diffusive model of maize root growth in MAIZSIM and its applications in Ridge-Furrow Rainfall Harvesting

The ability to accurately simulate root density and its spatial distribution can enhance our understanding of plant adaption to the soil environment and agricultural water management. “Ridge-Furrow Rainfall Harvest (RFRH)” is a recently proposed management practice, which utilizes a mulched ridge and furrowed soil to increase infiltration and conserve water within soil profiles. However, this management technique has not been extensively assessed for its effects on yield and water use. Two-dimensional (2D) root models are useful tools to assess crop yield and water use in RFRH systems as they can simulate root growth and water uptake. MAIZSIM is a comprehensive mechanistic model of maize (Zea mays L.) growth and yield, which uses a 2D finite element representation for soil physical/chemical processes and root growth. However, MAIZSIM utilizes a simple recursive model based on carbon (C) allocation to simulate root distribution. Therefore, the objectives of this study are to (I) develop and implement a finite element based diffusive root growth model in MAIZSIM with evaluations on model performance; and (II) study the effects of RFRH management on maize yield, water use and root development using MAIZSIM with the new root model. The root model was written into three modules, which (I) allocates total C from plant photosynthesis for root growth based on soil water availability and transpiration demand; (II) assigns new allocated C for root growth to selected spatial locations in soil; and (III) calculates the spatial root distribution as C diffusion. The root model was validated using observed root data from published studies, under the influences of soil bulk density, penetration resistance, and soil water conditions (normal, irrigation and drought). Numerical simulations for RFRH management, compared to a flat soil, demonstrated that, although soil evaporation was decreased, the differences for yields, shoot and root dry mass were small. In conclusion, (I) the newly develop diffusive root model provided an accurate way to simulate maize root growth; (II) despite the positive effects of RFRH management on soil water conservation, its influence on maize yield is relatively small. The diffusive model can be used to evaluate the root growth in response to climate changes or management practices and support integrated agricultural simulators that included soil, crop and environmental components.

Arbuscular mycorrhizal fungi alter root and foliar responses to fissure-induced root damage stress

Ground subsidence caused by coal mining can produce large amounts of surface ground fissures which may damage the surrounding plant roots. Here, a device was used that simulates root damage and we observed the growth of maize roots in real time, the morphological responses of roots and leaves to fissure-induced root damage stress, and the effects of arbuscular mycorrhizal fungi (AMF). Time series of root and leaf growth and hormonal changes in mycorrhizal and control plants with damaged root systems were observed for the first time. Indole-3-acetic acid (IAA) and cytokinin (CTK) levels in roots and leaves decreased significantly one week after ground fissuring. Abscisic acid (ABA) levels increased and the growth of roots and leaves was inhibited. Arbuscular mycorrhizal fungi (AMF) reversed these trends and significantly increased the percentages of root tips and fine roots compared with uninoculated controls. IAA and CTK levels declined significantly in roots and leaves six weeks after ground fissuring but ABA levels remained unchanged. AMF inoculation significantly increased both IAA and CTK levels but decreased ABA levels. The spatial distribution of roots was affected by fissures in addition to the changes in hormones. The negative impacts of ground fissures on maize growth were alleviated by AMF inoculation at harvest with increased shoot and root biomass. The results suggest that the ameliorative effects of AMF on root damage stress may be related to the regulation of hormone levels and an increase in the percentage of fine roots which was conducive to the growth of roots and leaves and increased plant resistance to environmental stress. In addition, analysis of variable distributions shows that the ameliorative effects of AMF were affected by the degree of root damage.

Quaternary ammonium iminofullerenes promote root growth and osmotic-stress tolerance in maize via ROS neutralization and improved energy status

In the present study, the role of quaternary ammonium iminofullerenes (IFQA) on the root growth of plant seedlings was investigated. The root elongation of Arabidopsis and maize exposed to 20 and 50 mg/L of IFQA was promoted under normal and osmotic stress conditions, respectively. In the meantime, the root active absorption area and adenosine triphosphate content in roots of maize seedlings were enhanced by IFQA treatment, however, the contents of hydrogen peroxide (H2O2) and malondialdehyde in roots were down-regulated. IFQA application improved glutathione transferase and glutathione reductase activities and the ratios of glutathione/oxidized glutathione and ascorbic acid/dehydroascorbic acid, and restored the inhibition of root elongation caused by the excess accumulation of H2O2 in roots of maize seedlings under osmotic stress. Furthermore, the expression of 14 proteins involved in cell growth, energy metabolism, and stress response in maize roots was upregulated by two-dimensional electrophoresis combined with mass spectrometry. This analysis revealed that IFQA stimulated the redox pathway to maintain balance levels of reactive oxygen species to ensure normal cell metabolism, promote energy production for root growth, and enhance osmotic-stress tolerance. It provided crucial information to elucidate the mechanism of the root growth of crop seedlings enhanced by water-soluble fullerene-based nanomaterials.

Integrating transcriptome, co-expression and QTL-seq analysis reveals that primary root growth in maize is regulated via flavonoid biosynthesis and auxin signal transduction.

The primary root is critical for early seedling growth and survival. To understand the molecular mechanisms governing primary root development, we performed a dynamic transcriptome analysis of two maize (Zea mays) inbred lines with contrasting primary root length at nine time points over a 12-day period. A total of 18 702 genes were differentially expressed between two lines or different time points. Gene enrichment, phytohormone content determination, and metabolomics analysis showed that auxin biosynthesis and signal transduction, as well as the phenylpropanoid and flavonoid biosynthesis pathways, were associated with root development. Co-expression network analysis revealed that eight modules were associated with lines/stages, as well as primary or lateral root length. In root-related modules, flavonoid metabolism accompanied by auxin biosynthesis and signal transduction constituted a complex gene regulatory network during primary root development. Two candidate genes (rootless concerning crown and seminal roots, rtcs and Zm00001d012781) involved in auxin signaling and flavonoid biosynthesis were identified by co-expression network analysis, QTL-seq and functional annotation. These results increase our understanding of the regulatory network controlling the development of primary and lateral root length, and provide a valuable genetic resource for improvement of root performance in maize.

Spatiotemporal Dynamics of Maize (Zea mays L.) Root Growth and Its Potential Consequences for the Assembly of the Rhizosphere Microbiota.

Numerous studies have shown that plants selectively recruit microbes from the soil to establish a complex, yet stable and quite predictable microbial community on their roots – their “microbiome.” Microbiome assembly is considered as a key process in the self-organization of root systems. A fundamental question for understanding plant-microbe relationships is where a predictable microbiome is formed along the root axis and through which microbial dynamics the stable formation of a microbiome is challenged. Using maize as a model species for which numerous data on dynamic root traits are available, this mini-review aims to give an integrative overview on the dynamic nature of root growth and its consequences for microbiome assembly based on theoretical considerations from microbial community ecology.

Effects of Different Planting Patterns on the Growth and Yield of Maize and Soybean in Northwest China

Aboveground and belowground interactions are crucial in the over-yielding of intercropping systems. However, the relative effects of aboveground and belowground interactions on yields in maize (Zea mays L.) and soybean (Glycine max) intercropping systems are still unclear. Field experiments, including measurements of plant height, soil-plant analysis development (SPAD) value, photosynthetically active radiation (PAR), root length density (RLD), root volume density (RVD), and grain yield, were conducted in 2018-2019 to analyze the advantages and effects of above-ground and belowground inter-species interactions. This study adopted three different planting patterns: mono-cropping maize (MM), mono-cropping soybeans (MS), and maize-soybean intercropping (IM and IS). This study showed that intercropping promotes the growth of maize and makes maize have a better photosynthetic environment, while the growth of intercropping soybeans is inhibited and the photosynthetic environment becomes worse. In the upper layer (0-40 cm) and close to the plants, the root growth and distribution of intercropped maize increased, resulting in greater root length density and volume density, while the root growth and distribution of intercropped soybean decreased, resulting in lower root length density and volume density. The intercropping increased the maize yield by 18.52-19.8%, and reduced the soybean yield by 55.87-57.44%. The results indicated that intercropping improves the competitiveness of maize and reduces the competitiveness of soybeans. The increase in maize yield made up for the loss of soybean yield and led to an overall significant advantage in the maize-soybean intercropping system.

Deficit irrigation drives maize root distribution and soil microbial communities with implications for soil carbon dynamics

AbstractIncreased food demand and water scarcity require the efficient use of agricultural water. Deficit irrigation (DI) can reduce water use with relatively small impacts to crop yield. However, the effects of DI‐associated water stress on root and soil properties remain poorly understood. We examined the impact of water stress via DI on maize (Zea mays L.) root growth, soil microbial community composition, soil aggregation, and soil organic C (SOC) concentrations at two depths (0–20 and 40–60 cm) after 4 yr of treatment implementation. Water stress during the late vegetative stage increased root growth at both soil depths in all stress treatments (significantly at 40–60 cm) but led to lower microbial biomass, assessed using phospholipid fatty acid (PLFA) analysis. Moreover, water stress led to a lower abundance of arbuscular mycorrhizal fungi markers in the drier treatments. After 4 yr of treatment, we did not find significant differences in SOC. However, a trend towards higher SOC and greater root biomass in the driest treatment indicated the potential to build soil C in deeper soil layers with larger root C inputs. Soil aggregation was generally greater in deeper soils (average increase of 24%). Overall, the observations in this study indicate that DI alters root growth and soil microbial community structure with the potential to impact SOC storage and overall agroecosystem function beyond the 4‐yr timeframe considered in this study.

Monitoring of maize root growth on N, P, and K fertilization using rhizotron

Maize roots will show varying growth responses to the type of fertilizer given. The objective of this study was to determine the effect of N, P, and K fertilizers on the growth of maize roots and the function of the relationship between root dry weight and shoot dry weight of maize under rizhotron. The research was conducted in April - June 2019 at the screen house and Plant Laboratory, Politeknik Lamandau in Lamandau Regency. The research was conducted in rizhotron's growth medium which was arranged in a completely randomized design (CRD) with a fertilizer treatment consisting of urea (N = 200 kg ha-1), SP36 (P = 100 kg ha-1), KCl (K = 100 kg ha-1), and control (without fertilizer) with three replications. The results showed that N fertilizer was able to provide better root dry weight growth compared to P and K fertilizer, namely 2.59 g. Root dry weight has a significant effect on plant dry weight gain based on the function of y = 4.10x + 0.06 (R2 = 0.96 **).

Rhizosphere bacteria containing ACC deaminase decrease root ethylene emission and improve maize root growth with localized nutrient supply

AbstractLocalized nutrient supply can enhance maize root proliferation, but also increase root ethylene production. Whether engineering ethylene signalling in the rhizosphere can further enhance root growth and nutrient uptake remains unknown. Here, field and column experiments for maize (Zea mays. L) were designed as different nutrient treatments (broadcast or localized nutrient supply containing ammonium and phosphorus) with or without inoculation with rhizobacterium Variovorax paradoxus 5C‐2 containing the 1‐aminocyclopropane‐1‐carboxylate (ACC) deaminase. Rhizobacterial inoculation increased shoot biomass by 12% and root length density by 50% with localized nutrient supply. Meanwhile, localized nutrient supply increased root ethylene production by 54% compared with broadcast, and rhizobacterial inoculation prevented the increase in root ethylene. Reduced root ethylene production following V. paradoxus 5C‐2 inoculation was highly associated with a greater proportion of fine root proliferation under localized nutrient supply, which may account for the increased nitrogen and phosphorus uptake. Our work sheds light on the understanding of the interactions between root and microbe through taking hormone into consideration to dissect the relationship between below ground and above ground. It is useful to explore the strategy of soil–crop management by introducing rhizosphere microorganisms to regulate plant ethylene signal and then benefit sustainable agriculture.

Effects of solar radiation on root and shoot growth of maize and the quantitative relationship between them

AbstractSolar radiation is an important environmental factor affecting maize (Zea maysL.) root and shoot growth and grain yield. This study was conducted in Qitai and Yinchuan, China, in 2018 and 2019. The maize cultivars of XY335, ZD958, and DH618 and planting densities of 7.5 × 104(D1) and 12 × 104plants ha−1(D2) were adopted under shading levels of 15 (S1), 30 (S2), and 50% (S3) with natural light as the control (CK). The results showed that averaging all shading and density treatments over the 2 yr, shading reduced the grain yields of XY335, ZD958, and DH618 by an average of 40.4, 39.2, and 35.6%, respectively, compared with the CK. The effect of solar radiation on the root dry weight was greater than that on the shoot dry weight, which resulted in a decrease in root/shoot ratio with increasing shading level. The quantitative analysis results showed that for every 1‐MJ m−2decrease in solar radiation, the root dry weight, shoot dry weight, and root/shoot ratio decreased by 0.1938 g m−2, 1.3517 g m−2, and 0.0103 × 10−2, respectively. According to this quantitative relationship, it was helpful to select cultivars and planting density with suitable root characteristics under different solar radiation conditions in different regions. From the aspects of shoot and grain yield, DH618 was more shade resistant, and its root system rapidly adjusted to compensate for shoot growth and yield formation when solar radiation decreased. Such cultivars should be given attention in future production and breeding.

Function analysis of nitrogen-responsive transcription factor ZmNLP5 affecting root growth in maize

<p indent=0mm>Improving nitrogen (N) use efficiency of crops is crucial for minimizing N loss and reducing environmental pollution, which is a requirement for the sustainable agriculture. Our previous study found that the transcription factor ZmNLP5 directly regulated the expression of <italic>ZmNIR1</italic>.<italic>1</italic> and promoted nitrogen uptake and assimilation in maize, however, its underlying regulation mechanism is unclear. Here, we performed further phenotype analysis of <italic>zmnlp5 </italic>and wild type (W22) plants in hydroponic culture on sufficient nitrogen (SN) solution and deficient nitrogen (DN) solution. Compared with WT plants, the root length of <italic>zmnlp5</italic> mutant plants was significantly decreased under DN condition. Compared with upper and middle regions of roots, ZmNLP5 was predominantly expressed in root tip regions. Then, we examined the relationship between root length and nitrite content in root tips under a series of nitrite concentrations. The results showed that there was no significant differences in root length between WT and <italic>zmnlp5</italic> until the nitrite concentration reached <sc>2 mmol L^–1</sc> and higher; however, when the concentration of nitrite was higher than <sc>2 mmol L^–1,</sc> the root length of <italic>zmnlp5</italic> was significantly shorter than WT, and the accumulation of nitrite in the root tips of <italic>zmnlp5</italic> was significantly higher than WT. Interestingly, <italic>zmnlp5 </italic>plants also accumulated significantly more nitrite in the root tips than WT under DN condition. The study showed that the transcription factor ZmNLP5 played an important role in the root growth of maize in response to deficient nitrogen condition, and provided the candidate genes for breeding of maize nitrogen use efficiency in the future.

Evaluation of maize root growth and genome-wide association studies of root traits in response to low nitrogen supply at seedling emergence

Nitrogen (N) deficiency is one of the main factors limiting maize (Zea mays L.) productivity. Genetic improvement of root traits could improve nitrogen use efficiency. An association panel of 461 maize inbred lines was assayed for root growth at seedling emergence under high-nitrate (HN, 5 mmol L−1) and low-nitrate (LN, 0.05 mmol L−1) conditions. Twenty-one root traits and three shoot traits were measured. Under LN conditions, the root-to-shoot ratio, root dry weight, total root length, axial root length, and lateral root length on the primary root were all increased. Under LN conditions, the heritability of the plant traits ranged from 0.43 to 0.82, a range much wider than that of 0.27 to 0.55 observed under HN conditions. The panel was genotyped with 542,796 high-density single-nucleotide polymorphism (SNP) markers. Totally 328 significant SNP markers were identified using either mixed linear model (MLM) or general linear model analysis, with 34 detected by both methods. In the 100-kb intervals flanking these SNP markers, four candidate genes were identified. Under LN conditions, the protoporphyrinogen IX oxidase 2 gene was associated with total root surface area and the DELLA protein-encoding gene was associated with the length of the visible lateral root zone of the primary root. Under HN conditions, a histone deacetylase gene was associated with plant height. Under both LN and HN conditions, the gene encoding MA3 domain-containing protein was associated with the first whorl crown root number. The phenotypic and genetic information from this study may be exploited for genetic improvement of root traits aimed at increasing NUE in maize.

Effects of biochar on waterlogging and the associated change in micro-ecological environment of maize rhizosphere soil in saline-alkali land

Saline-alkali soils of northern China are prone to waterlogging after degradation caused by overuse. The effects of biochar (40 t/ha) were tested relative to the physico-chemical properties of maize rhizosphere soil, the composition and function of the soil bacterial community, and its response to sudden waterlogging. Biochar treatment decreased the pH and bulk density of the soil and increased soil organic carbon (SOC), available nitrogen (AN), and available phosphorus (AP). The relative abundance of bacteria (Proteobacteria, Actinobacteria, Bacteroidetes, and Nitrospirae) also increased, along with the activities of soil enzymes, such as dehydrogenase, β-glucosidase, and alkaline phosphomonoester. The response of soil microbial enzymes to biochar addition was induced by changes in the soil physical properties (pH, soil moisture content, and soil respiration (BR)). Changes in the bacterial community structure were driven by soil nutrients and physical characteristics (AN, AP, SOC, pH, moisture, water-stable aggregate stability rate, BR, and bulk density). After waterlogging, soil with biochar demonstrated high water permeability and improved soil respiration. The relative abundance of soil bacteria and enzyme activities remained higher in the biochar plot than in the no-biochar plot. Biochar maintained the growth and vitality of maize roots in unfavorable environmental conditions, thus ensuring high yields.

Optimized Nitrogen Application Increases Soil Water Extraction by Changing in-Season Maize Root Morphology and Distribution in Rainfed Farmland

The proper promotion of a deep root system is important for maize cultivation to improve water use efficiency in the arid and semi-arid Loess Plateau. Here, a field experiment was conducted to assess the effect of combined controlled release urea and normal urea on root growth and water extraction of maize in dryland fields. Maize in the combined controlled release urea and normal urea treatment had greater root systems compared to those in the normal urea treatment and no N application treatment. Compared to the urea treatment, combined controlled release urea and normal urea advanced the root length density and root weight density in the 0–10 cm soil layer at R1 stage by 30.99% and 45.03% in 2016 and by 20.54% and 19.13% in 2017. The root length density also increased at the dent stage (R5) by 52.05% and 47.75% in 2016 and 2017, and root weight density increased by 19.58% in 2016. Combined controlled release urea and normal urea promoted production of fine roots and root distribution, as well as decreased soil water storage (SWS) in the deep soil layer at the R5 stage. The grain yield was positively correlated with root length density and root weight density in the topsoil layer at the silking stage (R1) and in the whole soil profile at the R5 stage, suggesting that better root system management is helpful for increasing crop grain yield. Therefore, this work demonstrates that combined use of controlled release urea and normal urea to higher crop yields might attribute to increasing water extraction by optimizing in-season maize root morphology and distribution in the rainfed farmland of the Loess Plateau.

Wood biomass fly ash ameliorates acidic, low-nutrient hydromorphic soil & reduces metal accumulation in maize

Biomass-fuelled facilities generate alkaline and mineral-/nutrient-enriched co-product (ash) that has to be appropriately managed, and preferably reused. The assumption that wood biomass fly ash (BFA) could be used in chemical amelioration of soil acidity and fertility was tested by: i) physicochemical characterisation of BFA and ii) bioassay with maize grown in acidic (pHKCl 4.68) hydromorphic soil amended with BFA (0–10% w/w). Scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray diffraction revealed non-homogeneous (ir)regular spherical/porous agglomerated particle morphology and distinctive distribution of Si-/Ca-/K-based minerals, while secondary ion mass spectrometry, for the first time, confirmed their isotopic (six Ca, three Si/Mg and two K isotopes) diversity. BFA addition strongly shifted soil pHKCl (up to 9.1), raised salinity (by > 8.2-fold) and the content of most phytonutrients (up to 5.4-fold); however, BFA amendments at >1.25% restricted the maize root and shoot growth, likely due to alkaline stress as indicated by necrotic/chlorotic symptoms at >5.0% rate. The BFA amendments increased total concentration of metals in soil (without exceeding the levels recognised as contamination); however, phytoextraction of Cd, Zn, Mn, Cu and Mo was significantly supressed (Cd by almost 12-fold), confirming that BFA improved soil-plant metal immobilisation, shifting rhizosphere biogeochemistry towards chemisorption/precipitation reactions. Even though results revealed a strong liming and P–K–Ca–Mg–Zn–Mn–Cu enrichment potential of BFA, to avoid possible negative environmental implications (saline/alkaline stress, metal contamination, adverse effects on soil microbiome), quantitative and qualitative ex ante evaluation of the BFA/soil matrix combinations is essential before application to ameliorate suboptimal (acidic, low-nutrient) or metal-contaminated soils.

Effects of exogenous sulfur on maize (Zea mays L.) growth and Cd accumulation in Cd-contaminated plastic shed soil.

Cadmium (Cd) pollution in plastic shed soils has become increasingly severe, posing a great threat to human health and social stability. Phytoremediation of cadmium pollution is an environmentally friendly and inexpensive remediation method. In this study, maize (Zea mays L.) was selected as the phytoremediation crop by a potted method, and the bioavailability of cadmium was investigated by adding exogenous elemental sulfur. The relationships among the sulfur content, maize growth, cadmium accumulation, and soil parameters were systematically studied. The results showed that, with the supplement of sulfur, the soil pH and activities of soil enzymes (urease, catalase, and sucrase) decreased gradually, and the available heavy metals (Cd, Cr, Zn, and Cu) in soil showed an upward trend. The optimal cadmium enrichment was achieved under T2 by increasing both the biomass of the maize plant and the cadmium concentration in roots and stems. However, T3 and T4 significantly inhibited the growth of maize roots and shoots, leading to a much lower plant biomass compared with that of CK (sulfur-free treatment) and T2. In addition, the cumulative cadmium was not increased because of the low accumulation of cadmium in some parts of the plant. Correlation analyses showed that the sulfur content was negatively correlated with soil pH and maize biomass (P < 0.01), and the cadmium content of whole maize was positively correlated with the dry weight of maize (P < 0.05) and the cadmium content in roots and stems (P < 0.01). In summary, to optimize cadmium phytoremediation of the plastic shed soil, an appropriate concentration of sulfur should be selected in practical applications to ensure that the biomass of the maize is maximized, and the cadmium concentration in different parts of the maize is increased or stabilized.

Identifying key regulatory genes of maize root growth and development by RNA sequencing

Root system architecture (RSA), the spatio-temporal configuration of roots, plays vital roles in maize (Zea mays L.) development and productivity. We sequenced the maize root transcriptome of four key growth and development stages: the 6th leaf stage, the 12th leaf stage, the tasseling stage and the milk-ripe stage. Differentially expressed genes (DEGs) were detected. 81 DEGs involved in plant hormone signal transduction pathway and 26 transcription factor (TF) genes were screened. These DEGs and TFs were predicted to be potential candidate genes during maize root growth and development. Several of these genes are homologous to well-known genes regulating root architecture or development in Arabidopsis or rice, such as, Zm00001d005892 (AtERF109), Zm00001d027925 (AtERF73/HRE1), Zm00001d047017 (AtMYC2, OsMYC2), Zm00001d039245 (AtWRKY6). Identification of these key genes will provide a further understanding of the molecular mechanisms responsible for maize root growth and development, it will be beneficial to increase maize production and improve stress resistance by altering RSA traits in modern breeding.

Organic manure input improves soil water and nutrients use for sustainable maize (Zea mays. L) productivity on the Loess Plateau.

Long-term chemical fertilizer input causes soil organic matter losses, structural compaction, and changes in soil water and nutrient availability, which have been subdued in the most of dry farmland in China. The concept of “more efficiency with less fertilizer input” has been proposed and is urgently needed in current agriculture. Application of chemical fertilizer combined with organic manure (OM) could be a solution for soil protection and sustainable production of dry-land maize (Zea mays. L). Field research over three consecutive years on the Loess Plateau of China was conducted to evaluate the integrated effects of chemical fertilizer strategies and additional OM input on soil nutrients availability and water use in maize. The results showed that, after harvest, soil bulk density decreased significantly with OM application, concomitant with 11.9, 18.7 and 97.8% increases in topsoil total nitrogen, organic matter, and available phosphorus contents, respectively, compared with those under equal chemical NPK input. Water use in the 1.0–1.5 m soil profile was improved, therefore, the soil conditions were better for maize root growth, leaf area and shoot biomass of individual maize plants increased significantly with OM application. Optimized NPK strategies increased grain yield and water use efficiency by 18.5 and 20.6%, respectively, compared to only chemical NP input. Furthermore, additional OM input promoted yield and water use efficiency by 8.9 and 5.8%, respectively. Addition of OM promotes sustainable soil and maize grain productivity as well as friendly soil environmental management of dry land farming.

Maize root biomass and architecture depend on site but not on variety: Consequences for prediction of C inputs and spread in topsoil based on root-to-shoot ratios

Abstract Knowledge about the response of root biomass and root system architecture (RSA) to soil conditions would increase efficiency in selecting high performance crop varieties and predicting the impact of rotations on long-term soil organic matter (SOM) stock. We evaluated the effect of variety and site on maize (Zea mays L.) root growth. Two-dimensional (2D) and 3D techniques were used to quantify changes of RSA. Commercial maize varieties were grown in three sites with typical soil types for maize cultivation in Belgium. We observed that at Merelbeke, above- and belowground biomass and root-to-shoot ratios (R/S) were larger compared to those at Ravels. Both factors interactively influenced an index of biological stability (ISB) based on biochemical quality of the roots. There were also more fine roots at Merelbeke than at Bassevelde and Ravels. Together with a lower ISB value, this suggests that site had an inherent effect on root biochemical quality. We conclude that a strong impact of site exists on both above- and belowground biomass; however, they are not necessarily correlated. With a fixed R/S, predictions of root biomass were misestimated in one half of the cases. This complex response of root phenotyping to varying soil conditions should not be overlooked.