Mean Root Diameter Research Articles

Modern wheat cultivars have greater root nitrogen uptake efficiency than old cultivars

AbstractThe availability of nitrogen (N) contained in crop residues for a following crop may vary with cultivar, depending on root traits and the interaction between roots and soil. We used a pot experiment to investigate the effects of six spring wheat (Triticum aestivum L.) cultivars (three old varieties introduced before mid last century and three modern varieties) and N fertilization on the ability of wheat to acquire N from maize (Zea mays L.) straw added to soil. Wheat was grown in a soil where 15N‐labeled maize straw had been incorporated with or without N fertilization. Higher grain yield in three modern and one old cultivar was ascribed to preferred allocation of photosynthate to aboveground plant parts and from vegetative organs to grains. Root biomass, root length density and root surface area were all smaller in modern than in old cultivars at both anthesis and maturity. Root mean diameter was generally similar between modern and old cultivars at anthesis but was greater in modern than in old cultivars at maturity. There were cultivar differences in N uptake from incorporated maize straw and the other N sources (soil and fertilizer). However, these differences were not related to variation in the measured root parameters among the six cultivars. At anthesis, total N uptake efficiencies by roots (total N uptake per root weight or root length) were greater in modern than in old cultivars within each fertilization level. At maturity, averaged over fertilization levels, the total N uptake efficiencies by roots were 292−336 mg N g−1 roots or 3.2−4.0 mg N m−1 roots for three modern cultivars, in contrast to 132−213 mg N g−1 roots or 0.93−1.6 mg N m−1 roots for three old cultivars. Fertilization enhanced the utilization of N from maize straw by all cultivars, but root N uptake efficiencies were less affected. We concluded that modern spring wheat cultivars had higher root N uptake efficiency than old cultivars.

Effects of Phosphorus Supply on Root Morphology and Phosphorus Uptake in Maize Seedlings under Different Water Regimes

Water deficit and phosphorus (P) deficiency in soil have become the main limiting factors for the production of maize (<i>Zea mays</i> L.), but it still remains unclear how water and P regulate maize root morphology and P uptake. Through an experiment of potted soil culture, this study has set 4 water gradients [35% (W1), 55% (W2), 75% (W3) and 100% (W4)] of field capacity, and two P levels [high P: 205 mg (P)∙kg^-1; low P: 11 mg (P)∙kg^-1] to investigate the coupling effects of water and P on root growth and P uptake in maize seedlings. The results have shown that: (1) Regardless of soil P supply, the shoot dry weight, root dry weight, total root length, and root surface area of maize seedlings shows a trend of increasing first and then decreasing with increasing water supply intensity; the soil available P content also shows similar trend; the root mass ratio and mean root diameter shows a downward trend with the increase of water supply intensity; furthermore, the P content and P accumulation of plants shows a steady increase with the increase of water supply intensity; (2) Water deficit (W1) and excess water supply (W4) is not conducive to root growth and dry matter accumulation in maize. Water deficit (W1) inhibits the acquisition of soil P by maize, while excess water supply (W4) causes extravagant absorption of soil P (W4). Mild water stress (W2) can promote the growth and dry matter accumulation of maize roots and reduce the extravagant absorption of soil P, and adequate water supply (W3) can promote root growth, dry matter accumulation and the absorption of soil P; (3) Phosphorus supply significantly increases the dry weight, root dry weight (except W4), total root length, root surface area, plant P content (except W4) and P accumulation of maize seedlings, but reduces the root mass ratio of maize. It is thus evident that water is a key factor controlling the morphology and accumulation of dry matter in maize roots, and P is a key factor controlling P uptake and soil available P content in corn field. The better coupling between water and P can promote maize root growth and dry matter accumulation, as well as reduce the extravagant absorption of soil P.

Influence of harvest time and agricultural year in yield components of table cassava cultivars

Agricultural year and harvesting season may interfere with yield and post-harvest performance of table cassava cultivars, with consequences for their commercialization and net profit. The objective of this work was to quantify the effects of harvesting season and agricultural year on yield performance of table cassava cultivars and their correlations. Planting was carried out in September in two consecutive years near Londrina city, PR, in a Clay-textured Oxisols red eutrophric. The experiment followed a randomized complete block design (RCBD) with four replications, consisting of seven harvesting times (8, 10, 12, 14, 16, 18 and 20 months after planting) for each agricultural year. The table cassava cultivars used were: Catarina Amarela, Catarina Branca, Mato Grosso, Pretona, IAPAR 19-Pioneira and IAC 576-70. The following agronomic characteristics were evaluated: number of roots per plant, length, diameter and yield of tuberous roots, as well as the following post-harvest characteristics: net yield and peeling time per kg of each cassava genotype. The cultivars, harvesting time and agricultural year affected the yield and post-harvest characteristics. ‘IAPAR 19-Pioneira’ presented a larger number of roots per plant (9.9) and peeling time (224.8 seconds.kg-1), but lower yield % (66.2%) and diameter of tuberous roots (4.0 cm), regardless of harvest time and year of planting. 'Catarina Amarela', 'Catarina Branca', 'IAC 576-70' and 'Pretona' provided higher yields, diameters and reduced peeling times. The root mean diameter is one of the characteristics that can be used as a selection criterion in a table cassava genetic breeding program: the larger the root mean diameter the larger are tuber root yield and percentage of weight of the tradable part of the roots, and the lower is the time of peeling.

Growth-promoting bacteria and arbuscular mycorrhizal fungi differentially benefit tomato and corn depending upon the supplied form of phosphorus.

The ability of plants to take up phosphorus (P) from soil depends on root morphology and root exudates release and can be modulated by beneficial soil microbes. These microbes can solubilize P, affect root elongation and branching, and lead to a higher uptake of P and other nutrients. However, coordination of these mechanisms is unclear, especially the mechanism for changing the available form of P. We aimed to dissect the effects of two different beneficial microbial taxa (plant growth-promoting bacteria (PGPB) and arbuscular mycorrhizal fungi (AMF)) on root morphological traits, plant nutrient content, and growth in tomato and corn fertilized with either Gafsa rock phosphate (RP) or triple superphosphate (TSP), which have contrasting solubility levels. Tomato and corn were grown in pots and inoculated with one of three PGPB species or a mix of two AMF species or were not inoculated. Root traits, botanical fractions, and the contents of various mineral nutrients were measured. TSP stimulated tomato biomass accumulation compared to RP but did not stimulate corn biomass accumulation. PGPB improved the growth of both plant species under RP, with limited differences among the strains, whereas AMF only improved tomato growth under TSP. These differences between microbial systems were explained by a bacterial effect on the total root length but not on the mean root diameter and by the ability of AMF to improve the mineral nutrient content. The effects of PGPB were less dependent on the plant species and on P form than the effects of AMF.These results have implications for the improvement of the early plant growth through the management of beneficial microbes.

Irrigation with magnetically treated saline water influences the growth and photosynthetic capability of Vitis vinifera L. seedlings

Salinity is one of the major environmental stresses that can inhibit plant growth and development and cause physiological and metabolic changes. In this study, a pot experiment was performed involving two-year-old grape seedlings. Three different concentrations of NaCl solutions composed of tap water were used to irrigate the potted grapevine in the presence and absence of a magnetic device. The growth parameters and photosynthesis characteristics were analyzed during the stress treatments under field conditions. The results were as follows: Compared with those of the plants irrigated with non-magnetized saline water (NMSW), the growth of the aboveground parts (growth quantity, internode length, basal diameter, leaf area and leaf number) and the root growth (total root length, surface area, mean diameter, volume and root tip number) of plants irrigated with magnetized saline water (MSW) increased in response to the different treatment solutions, and the biomass of the leaves, stems and roots increased by 2.0 %∼45.0 %. The proportion of material allocated to the leaves and roots increased, and the root/crown ratio increased when exposed to 6.0 g·L−1 NaCl solutions. Compared with those in the plants irrigated with NMSW, the chlorophyll a, chlorophyll b and carotenoid contents in the plants irrigated with MSW increased by 3.0 %∼13.0 %. Moreover, compared with NMSW, MSW led to increases in the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), limiting value of stomata (Ls) and water-use efficiency (WUE), while the intercellular CO2 concentration (Ci) decreased. The ratio of specific activity parameters per unit area exhibited the largest increase (from 12.0 % to 26.0 %), and photosynthetic performance indexes increased by 18.0 %–56.0 %. Generally, the abovementioned results indicate alleviated inhibition of grape growth under irrigation with MSW. Moreover, treatment with MSW reduced the damage of saline water to the photosynthetic mechanism in grapevine, helped maintain the photosynthetic activity in the mesophyll cells, and promoted efficient electron transport between the photosystems, thus promoting the biomass production of the grapevine.

Carbon dioxide and precipitation alter Reaumuria soongorica root morphology by regulating the levels of soluble sugars and phytohormones

Significant increases in the concentration of carbon dioxide (CO2) have been shown to cause changes in precipitation patterns. These changes can severely affect the desert ecosystem. Therefore, it is important to investigate the impacts of CO2 concentration and precipitation on root morphology, so as to better predict the responses of desert ecosystems to the global climate change. For this purpose, we studied Reaumuria soongorica that is a dominant plant in the desert. Open top chambers were used to simulate changes in CO2 concentrations (350 μmol mol−1 and 700 μmol mol−1), to study the effects of 30% reduction in precipitation (W−), natural precipitation (W), 30% increase in precipitation (W+), and to study the synergistic effects of precipitation with CO2 on R. soongorica root morphological characteristics, endogenous hormones, and soluble sugars. Higher CO2 levels caused a significant increase in root length, mean root diameter, root biomass, total root surface area and total root volume regardless of alterations in precipitation; whereas the root–shoot ratio increased only with increased precipitation. Elevated concentrations of CO2 and decreased precipitation significantly increased the contents of fructose, sucrose, glucose and other soluble sugars in the R. soongorica root system. Meanwhile, the two environmental factors showed significantly synergistic effects on R. soongorica root morphology. With elevated concentrations of CO2, R. soongorica roots showed increased levels of endogenous hormones, including abscisic acid (ABA), indole-3-acetic acid (IAA) and gibberellin (GA). The effect of precipitation on hormone levels varied among hormones. IAA and GA levels were increased, regardless of changes in precipitation; ABA decreased with higher precipitation, whereas zeatin (ZT) increased with more precipitation. Correlation analyses indicated a significant correlation between root morphology and the levels of soluble sugars and endogenous hormone, as well as between the level of soluble sugars and the level of endogenous hormones. We conclude that future changes in climate conditions such as CO2 levels and precipitation will synergistically induce the root system of R. soongorica to undergo morphological and physiological alterations.

Nitrogen deposition and decreased precipitation altered nutrient foraging strategies of three temperate trees by affecting root and mycorrhizal traits

Roots of nearly all plants have symbiotic relationships with mycorrhizal fungi. The root-mycorhizosphere serves an important role in both nutrient acquisition required for the plant growth, and soil carbon cycling of terrestrial ecosystems. The identification of root-mycorhizosphere traits that can be linked to nutrient acquisition is quite indispensable, especially for understanding and predicting plants nutrient acquisition strategies and ecosystem processes under climate change. Nonetheless, tree roots and mycorrhizal fungi traits variations are still rarely quantified synchronously in previous studies, which lead to an important knowledge gap in our understanding of how climate change will affect nutrient foraging strategies and soil carbon cycling. Thus, we conducted a decreased precipitation and N addition experiment to simulate climate change scenarios. Traits of root orders and mycorrhizal fungi that related to nutrient foraging were examined under different treatments across three coexisting mycorrhizal temperate tree species. N addition significantly increased individual root length, individual root surface area and mean root diameter in low root orders (the first root order or the first to third root orders), while it decreased or did not change these traits in high root orders (the fourth and fifth root orders). N addition tended to decrease branching intensity in all root orders across all species. Decreased precipitation significantly increased individual root length and individual root surface area of low order roots (the first and second root orders), while decreased or unchanged these traits in others root orders across all species. Specific root length was significantly increased in the first to fifth root orders with decreased precipitation and decreased in the second to fifth root orders with N addition (except Pinus koraiensis). Moreover, N addition significantly decreased total hyphae length, and significantly increased the mean hyphae diameter. Decreased precipitation significantly increased the total hyphae length and the total hyphae surface area compared with the control. Across all species, N addition, decreased precipitation and their interaction led to significantly decreased mycorrhizal colonization. The impacts of N addition and decreased precipitation on mycorrhizal fungi traits also were mediated by tree species. These results indicated that N addition and decreased precipitation significantly changed fine root and mycorrhizal morphological traits, which would alter the below-ground foraging strategies. These results indicate that the variation in root morphology by order under treatments suggests that roots at different branch order positions have different morphological structure and physiological functions. The trait patterns we found support the hypothesis that under climate change, plants attempt to improve resource acquisition.

Phosphorus Efficiency of Winter Canola Cultivars and Rhizosphere Properties in Rhizobox Technique

ABSTRACTProduction of oilseed crops requires balanced fertilization, while environmental problems of applied fertilizers must be considered. We evaluated seven winter canola cultivars (Brassica napus L.) for their relative efficiency to use or acquire phosphorus (P) under deficient and sufficient conditions. Average root mean diameter (RMD), total root length (RL) and root surface area (RA), of plants were measured as well as rhizosphere properties in rhizobox technique. Water-soluble P (WSP) and phosphatase activity of treatments containing plant were higher than control. WSP increased by 2.86 mg kg−1 soil in Gabriela and 2.63 mg kg−1 soil in Elvis at P deficient condition, compared to the control soil. The Olsen extractable P of the treatments decreased compared to control. Variations in total dry weights of cultivars were mainly explained by the differences in P solubilizing bacteria (PSB) population, pH, and phosphatase activity. The responsible mechanism for the P efficient (PE) cultivars can be higher P uptake through larger root and changes in rhizosphere properties.

Trait-based approach for agroecology: contribution of service crop root traits to explain soil aggregate stability in vineyards

The aim of this study was to explore the impact of soil management strategies and the contribution of root traits of plant communities and soil organic carbon (SOC) in explaining soil aggregate stability in vineyards. We measured topsoil aggregate stability, soil properties and root traits of 38 plant communities in an experimental vineyard, previously subjected to different soil management strategies. Then we investigated statistical relations between aggregate stability, root traits and SOC and estimated root trait and SOC contributions to gain insight into aggregate stability. Soil management strategies strongly affected soil aggregate stability, with a negative effect of tillage, even after several years of service crop cover. Among the investigated parameters, soil organic carbon was found to contribute the most to aggregate stability. Root mean diameter and root mass density showed positive correlations with aggregate stability, while specific root length showed a negative correlation with aggregate stability. Soil aggregate stability is the result of complex interactions between soil management strategies, soil properties and plant root traits. Service crops improve aggregate stability, and a trait-based approach could help to identify service crop ideotypes and expand the pool of species of interest for providing services in agroecosystems in relation with the soil physical quality.

Root growth dynamics and yield responses of rice (Oryza sativa L.) under drought—Flood abrupt alternating conditions

Drought and flash flooding are two common water stresses that negatively affect the rice growth and development in South China. Unfortunately, in some cases, rice plants have to experience these two stresses within a short time. A study on root plasticity responses and their relationships with grain yield (GY) in rice under drought–flood abrupt alternating (DFAA) water stresses at jointing–booting stage was conducted in a specially designed experimental pool. The two-year outdoor pot experiment was composed of six DFAA treatments with combinations of different droughts and floods. Three additional treatments, namely, the drought-followed-by-no-flood (DNF), no-drought-followed-by-flood (NDF), and control treatment, were prepared for each of the DFAA treatment. Results showed that responses of root and yield related traits in rice to DFAA were not the additive effect of drought alone and flooding alone and there existed interaction (positive/negative compensation) between them. DFAA increased bleeding intensity (BI) significantly at the end of flooding, but the increases were less than those of DNF. Compared to DNF and NDF, DFAA showed the highest reduction in total root length, root and shoot dry weight, root mean diameter, root surface area (RSA), and root volume at the end of flooding. However, specific root length and RSA/root volume ratio increased. Root/shoot ratio in DFAA and DNF varied from 2016 to 2017, while it was enhanced in NDF in both years. During recovery period, differences in root traits among treatments still existed. The preceding drought weakened the effects of subsequent flooding on GY in rice. The yield losses in DNF, DFAA, and NDF (reduced by 13.0%, 24.9%, and 33.5% on average, respectively) were mainly attributed to a smaller total number of spikelets and thinner filled spikelets. The percentage of filled grains (FG) depended on the degrees of drought and flooding. Rewatering after drought tended to increase FG, while flooding after drought tended to decrease it. Yield-related traits in DFAA were significantly associated with most of root traits at the end of flooding, while these correlations were not significant in DNF and NDF.

Root moisture content influence on root tensile tests of herbaceous plants

Root tensile strength controls root reinforcement, but a range of factors including root moisture and diameter have such a large impact that it is difficult to make predictions. In this study, we measured how variable root moisture content affects the relationship between root diameter and root tensile strength of herbaceous plants. Fresh roots of two herbaceous plants, Heteropappus altaicus and Poa sphondylodes were divided into four groups: (i) saturated in water, (ii) kept fresh, (iii) or dried for 6 h or (iv) 12 h in air. Root diameter and mechanical failure under tension before and after the moisture treatment were measured. Tensile strength and tensile force of both species decreased linearly while mean root diameter increased linearly with increasing root moisture content. Root moisture content has a large impact on the variability of root tensile strength. This emphasizes the need to avoid desiccation during testing. In field impacts of soil water potential on root strength requires further study. We recommend soaking roots in water before testing to decrease this source of error.

The carboxylate-releasing phosphorus-mobilizing strategy can be proxied by foliar manganese concentration in a large set of chickpea germplasm under low phosphorus supply.

Root foraging and root physiology such as exudation of carboxylates into the rhizosphere are important strategies for plant phosphorus (P) acquisition. We used 100 chickpea (Cicer arietinum) genotypes with diverse genetic backgrounds to study the relative roles of root morphology and physiology in P acquisition. Plants were grown in pots in a low-P sterilized river sand supplied with 10μgPg-1 soil as FePO4 , a poorly soluble form of P. There was a large genotypic variation in root morphology (total root length, root surface area, mean root diameter, specific root length and root hair length), and root physiology (rhizosheath pH, carboxylates and acid phosphatase activity). Shoot P content was correlated with total root length, root surface area and total carboxylates per plant, particularly malonate. A positive correlation was found between mature leaf manganese (Mn) concentration and carboxylate amount in rhizosheath relative to root DW. This is the first study to demonstrate that the mature leaf Mn concentration can be used as an easily measurable proxy for the assessment of belowground carboxylate-releasing processes in a range of chickpea genotypes grown under low-P, and therefore offers an important breeding trait, with potential application in other crops.

Copper Toxicity on Photosynthetic Responses and Root Morphology of Hymenaea courbaril L. (Caesalpinioideae)

Copper (Cu) is a micronutrient essential for plant development. However, in excess, it is toxic to plants and may cause various physiological and morphological changes. The study of the growth of plants exposed to excess Cu is important for the development of phytoremediation programs and for understanding the mechanisms involved in the tolerance of this metal. In this context, the objective of this research was to evaluate the effect of excess copper on photosynthetic responses and root morphology of Hymenaea courbaril L. Biometric measurements, gas exchange, root morphology, and Cu content in tissues and indices (TI and TF) were assessed, involving metal content and biomass. Up to a concentration of 200 mg kg−1, Cu favored growth, gas exchange, and root morphology of the plants under study. At a higher concentration (800 mg kg−1) in the soil, it affected plant growth and caused a decrease in photosynthetic rate. Biochemical limitations in photosynthesis were observed, as well as lower maximum net photosynthetic rate (Amax), respiration rate in the dark (Rd), light compensation point (LCP), light saturation point (LSP), and apparent quantum yield (α), when exposed to excess Cu. Root length, surface area, mean diameter, root volume, dry biomass, and specific root length decreased with high Cu concentrations in the soil. Cu was accumulated in the roots as a mechanism of tolerance to the excess of this metal in order to preserve the most metabolically active tissues present in the leaves. At a concentration of 800 mg kg−1, copper also caused inhibition of the root system. Plants of H. courbaril showed tolerance to excess Cu in the soil and can be indicated for the recovery of areas contaminated with this metal.

Two dimensions define the variation of fine root traits across plant communities under the joint influence of ecological succession and annual mowing

Abstract Quantifying the variation in community‐level fine root (&lt;2 mm) traits along ecological gradients or in response to disturbances is essential to unravel the mechanisms of plant community assembly, but available surveys are scarce. Whether fine root traits covary along a one‐dimensional economic spectrum, as previously shown for leaves, is highly debated. We measured six fine root traits at the community level along a 69‐year succession, with or without annual mowing, offering a unique design of two nested disturbances. We examined whether (1) there is variation and covariation in community‐level fine root traits along the succession and in response to mowing and (2) morphological root traits mirrored analogous leaf traits (using previously acquired data). Early‐successional communities were herbaceous‐dominated (48 ± 6% in &lt;10‐year‐old plots) and possessed fine roots with high specific root length (SRL), low root dry matter content (RDMC) and low root carbon concentration (RCC), while later successional communities were dominated by woody species (56 ± 9% in &gt;40‐year‐old plots) and possessed opposite trait values. Root nitrogen concentration (RNC) did not vary across communities along the succession. The trait values at community level were not affected by mowing, except for a reduction in root mass density. We found covariation of fine root traits across communities along two dimensions: the first dimension (60% of total variation) represented changes in root foraging capacity (related to SRL) and resource conservation (related to RDMC, RCC, mean root diameter), whereas the second dimension (17%–20% of the variation) represented variations in RNC, potentially related to root respiration and metabolism. Specific root length and specific leaf area were correlated regardless of the mowing regime, but there was no analogous relationship between leaf dry matter content and RDMC in mown communities, showing a decoupling in the investment in tissue density above‐ and below‐ground. Synthesis. Our study demonstrates coordinated variations of community‐level fine root traits along a succession gradient and provides evidence that fine root traits covaried along two dimensions, regardless of mowing regime. The relationship between leaf dry matter content and root dry matter content observed in unmown communities was modified by mowing, reflecting an uncoupled response to mowing.

Impact of inoculant and foliar fertilization on root system parameters of pea (Pisum sativum l.)

In recent years, sustainable crop development has played a key role in current strategies to improve roots activity, which increase nutrients uptake in pulse crop. Our study presents the relationship between root system morphology, inoculant application with and without foliar fertilization and nitrogen accumulation in soil and plants. Two inoculants: Nitragina and IUNG, foliar fertilizer (Photrel), as well as two pea cultivars were studied in three years (2009–2011) period. The research has shown that bacterial inoculants have signifiant inflence on the selected parameters of pea root systems. Gel inoculant signifiantly increased mean root diameter (0.44 mm), compared to control (0.33 mm), whereas combination of Nitragina inoculant with micronutrient fertilization signifiantly increased root length density (1.05 cm·cm-3), compared to control (0.85 cm·cm-3). Additionally, the bacterial inoculant IUNG has signifiantly decreased the root length density in roots classes between 0.2–0.5 mm in the most humid year. The impact of inoculants on roots parameters was strongly related to weather conditions. In a dry year, a signifiant decrease of mean root diameter, specifi root length and increase of root dry mass were observed. Nitrogen accumulation in seeds signifiantly increased after gel inoculant application. A higher N content was proven in the fodder cultivar, but the edible cultivar was observed to accumulate more N in the seeds, which caused a Nitrogen Harvest index for this plant (80.0%).

Root system architecture in winter varieties of spelt (TriticumspeltaL.)

The objective of the study was determination of the variability of morphometry and comparison of the morphological structure of the root system in winter cultivars of spelt. Four spelt cultivars were used in the study: Frankencorn, Oberkulmer Rotkorn, Schwabenkorn and Ostro. The material for the study originated from a field experiment. The roots were collected using the soil core method to the depth of 30 cm, from the rows and inter-rows, then the roots were separated using a semi-automatic hydropneumatic scrubber. The cleaned roots were manually separated and scanned, obtaining their digital images. Image analysis was performed using the Aphelion computer software. In order to characterize the root system of the spelt cultivars included in the study, values of the following indexes were determined: root dry mass (RDM), root length density (RLD), specific root length (SRL), mean root diameter (MD). Based on the obtained results it was determined that the RDM, MD and RLD indexes in all spelt cultivars attain the highest values in the row, at the depth 0–5 cm.The highest value of the RDM and MD indexes characterized the root system of the Ostro cultivar at the depth 0–5 cm. The Oberkulmerrotkorn spelt cultivar was distinguished among the tested objects by the highest value of the SRL index.

内陆盐沼芦苇根系形态及生物量分配对土壤盐分因子的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 内陆盐沼芦苇根系形态及生物量分配对土壤盐分因子的响应 DOI: 10.5846/stxb201707141283 作者: 作者单位: 西北师范大学地理与环境科学学院，甘肃省湿地资源保护与产业发展工程研究中心,西北师范大学地理与环境科学学院，甘肃省湿地资源保护与产业发展工程研究中心,西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院,西北师范大学地理与环境科学学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（41461013，91125014）；甘肃省生态学重点学科基金项目资助 Response of root morphology and biomass of Phragmites australis to soil salinity in inland salt marsh Author: Affiliation: Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou,Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:根系形态和生物量分配是决定根系吸收能力发挥的重要特征，其对环境限制因子的响应与适应策略一直是研究的热点。然而，有关土壤盐分对植物根系性状的影响还存在许多不确定性。选择兰州秦王川国家湿地公园芦苇群落为研究对象，垂直于沙河河岸从湿地边缘至湿地中心，依次设置3个不同土壤盐分梯度样地（样地I、样地Ⅱ和样地Ⅲ），采用全根挖掘法和Win-RHIZO根系分析仪相结合的方法，研究了芦苇（Phragmites australis）根冠比、根总长度、比根长、根分叉数、根平均直径等形态参数的变化特征。结果表明：随着样地土壤盐分含量的增加，湿地群落的高度、盖度、密度、地上生物量逐渐下降，芦苇的根冠比、根分叉数呈逐渐减小的趋势，比根长、根总长度呈先下降后上升的趋势，而根平均直径呈相反的变化趋势；研究区土壤含盐量总体以中度盐渍化为主，表层土壤盐分呈现强变异性，随土层深度的增加含盐量呈下降趋势，而变异程度有所差异；芦苇根系性状与土壤含盐量的相关性分析可知，土壤含盐量与根总长度和比根长呈极显著相关关系（P < 0.01），与根冠比、根分叉数呈显著相关（P < 0.05），而与根平均直径相关性不显著。内陆盐沼的芦苇表现出敏感植物的特性，通过根系形态的调整和生物量分配策略的改变来适应盐分强变异的土壤环境，体现了逆境胁迫下湿地植物应对多重环境选择压力的生态适应机制。 Abstract:Root morphology and biomass allocation are important features for determining the capacity of root absorption, and the nature of the responses to environmental constraint factors and adaptation strategies have been a hot research topic. However, numerous uncertainties about the effects of soil salinity on the root traits of plants still exist. This study was performed on Phragmites australis community in Qinwangchuan National Wetland Park of Lanzhou. Three different plots with a soil salinity gradient (plot I, Ⅱ, and Ⅲ) were set up from the edge to the center of wetland, which was perpendicular to the bank of the Sha River. The change characteristics of the morphological parameters such as the ratio of root to shoot, total and specific root lengths, root forks, and the average root diameter of P. australis were studied using the combined method of total root excavation along with the Win-RHIZO root analyzer. The results showed that the height, coverage, density, and above-ground biomass of the wetland community decreased gradually with the increase of soil salinity. In addition, the ratio of root to shoot and root forks of P. australis decreased gradually, and the specific and total root lengths of P. australis first decreased and then they subsequently increased whereas the average root diameter showed an opposite trend. The soil salinity was dominated by moderate salinization, and the surface soil salinity showed strong variability. Specifically, the soil salinity of the plots showed a decreasing trend with increasing soil depth, and the variation degree was different. According to the correlation analysis, there was a significant correlation between the soil salinity, total root length, and specific root length (P < 0.01). Furthermore, the soil salinity was significantly correlated with the root/shoot ratio and root forks (P < 0.05), but not the root mean diameter. The P. australis specimens in the inland salt marshes showed the characteristics of sensitive plants. They adapted to the soil environment that had a strong salt variation by modifying their root morphology and changing the biomass allocation strategy. This phenomenon reflected the ecological adaptation mechanism used by wetland plants to cope with multiple environmental selection pressures under adverse stress conditions. 参考文献 相似文献 引证文献

Relationships between specific root length and respiration rate of fine roots across stands and seasons in Chamaecyparis obtusa

Fine root respiration (R r ) is closely linked with fine root morphology, especially with specific root length (SRL), in short-term measurements in some tree species. However, whether these relationships are also valid across different stands and seasons is not yet known. This study aimed to investigate these relationships in the fine roots of Chamaecyparis obtusa. The R r , mean root diameter, and SRL of fine root segments of two C. obtusa stands were determined every three months over two years. We detected significant positive correlations between R r and SRL of fine root segments across the stands over two years. The relationship of R r with SRL was stronger than that with the mean diameter of fine roots. The slopes and intercepts for the R r and SRL relationships did not differ among stands and measurement times. Further, we proposed a simple approach for estimating CO2 flux from fine roots at the stand level based on SRL and confirmed that the ranges of estimated CO2 values were comparable with those of values reported using the conventional approach. The fine root morphology typified by SRL is a key variable in R r of fine roots and CO2 flux at the stand level.

Root traits and their potential links to plant ideotypes to improve drought resistance in common bean

Drought stress limits growth and yield of crops, particularly under smallholder production systems with minimal use of inputs and edaphic limitations such as nitrogen (N) deficiency. The development of genotypes adapted to these conditions through genetic improvement is an important strategy to address this limitation. The identification of morpho-physiological traits associated with drought resistance contributes to increasing the efficiency of breeding programs. A set of 36 bean genotypes belonging to the Middle American gene pool was evaluated. A greenhouse study using soil cylinders was conducted to determine root vigor traits (total root length and fine root production) under drought stress. Two field trials were conducted to determinate grain yield, symbiotic nitrogen fixation (SNF) ability and other shoot traits under drought stress. Field data on grain yield and other shoot traits measured under drought were related with the greenhouse data on root traits under drought conditions to test the relationships between shoot traits and root traits. Response of root vigor to drought stress appeared to be related with ideotypes of water use (water savers and water spenders). The water spender ideotypes presented deeper root system, while the water saver ideotypes showed a relatively shallower root system. Increase in SNF ability under drought stress was associated with greater values of mean root diameter while greater acquisition of N from soil was associated with finer root system. We identified seven common bean lines (SEA 15, NCB 280, SCR 16, SMC 141, BFS 29, BFS 67 and SER 119) that showed greater root vigor under drought stress in the greenhouse and higher values of grain yield under drought stress in the field. These lines could serve as parents for improving drought resistance in common bean.

Impacts of warming on root biomass allocation in alpine steppe on the north Tibetan Plateau

Biomass is an important component of global carbon cycling and is vulnerable to climate change. Previous studies have mainly focused on the responses of aboveground biomass and phenology to warming, while studies of root architecture and of root biomass allocation between coarse and fine roots have been scarcely reported in grassland ecosystems. We conducted an open-top-chamber warming experiment to investigate the effect of potential warming on root biomass and root allocation in alpine steppe on the north Tibetan Plateau. The results showed that Stipa purpurea had significantly higher total root length, root surface area and tips than Carex moocroftii. However, there were no differences in total root volume, mean diameter and forks for the two species. Warming significantly increased total root biomass (27.60%), root biomass at 0–10 cm depth (27.84%) and coarse root biomass (diameter > 0.20 mm, 57.68%) in the growing season (August). However, warming had no significant influence on root biomass in the non-growing season (April). Root biomass showed clear seasonal variations: total root biomass, root biomass at 0–10 cm depth and coarse root biomass significantly increased in the growing season. The increase in total root biomass was due to the enhancement of root biomass at 0–10 cm depth, to which the increase of coarse root biomass made a great contribution. This research is of significance for understanding biomass allocation, carbon cycling and biological adaptability in alpine grassland ecosystems under future climate change.