Root textural quality in ashwagandha (Withania somnifera) as influenced by crop growth periods and morphotypes

Ashwagandha (Withania somnifera) is a commercially important medicinal crop and roots are the main portion of the plant used therapeutically. The root textural quality determined by high starch-fiber ratio fetches premium price for the produce. Influence of morphological variants and crop growth intervals on accumulation of starch and crude fiber in roots was studied to assess morphotypical differences and to determine the right harvest stage for high root yield with better physical quality. The morphotypes showed similar trend for dry root yield, whereas differences were observed for starch and crude fiber accumulation. The pattern of starch and fiber accumulation varied with different crop growth periods. In general, crude fiber content increased with the crop duration, whereas starch content and starch-fiber ratio followed a trend of decrease-increase-decrease as influenced by different phenophases. Discussions on suitable harvest stage based on dry root yield and starch-fiber ratio are made.     

Rooting systems of oilseed and pulse crops. II: Vertical distribution patterns across the soil profile

Root distribution patterns in the soil profile are the important determinant of the ability of a crop to acquire water and nutrients for growth. This study was to determine the root distribution patterns of selected oilseeds and pulses that are widely adapted in semiarid northern Great Plains. We hypothesized that root distribution patterns differed between oilseed, pulse, and cereal crops, and that the magnitude of the difference was influenced by water availability. A field experiment was conducted in 2006 and 2007 near Swift Current (50°15′N, 107°44′W), Saskatchewan, Canada. Three oilseeds [canola (Brassica napus L.), flax (Linum usitatissimum L.), mustard (Brassica juncea L.)], three pulses [chickpea (Cicer arietinum L.), field pea (Pisum sativum L.), lentil (Lens culinaris)], and spring wheat (Triticum aestivum L.) were hand-planted in lysimeters of 15 cm in diameter and 100 cm in length which were pushed into soil with a hydraulic system. Crops were evaluated under low- (natural rainfall) and high- (rainfall + irrigation) water conditions. Vertical distribution of root systems was determined at the late-flowering stage. A large portion (>90%) of crop roots was mainly distributed in the 0-60 cm soil profile and the largest amount of crop rooting took place in the top 20 cm soil increment. Pulses had larger diameter roots across the entire soil profile than oilseeds and wheat. Canola had 28% greater root length and 110% more root tips in the top 10 cm soil and 101% larger root surface area in the 40 cm soil under high-water than under low-water conditions. In 2007, drier weather stimulated greater root growth for oilseeds in the 20-40 cm soil and for wheat in the 0-20 cm soil, but reduced root growth of pulses in the 0-50 cm soil profile. In semiarid environments, water availability did not affect the vertical distribution patterns of crop roots with a few exceptions. Pulses are excellent “digging” crops with a strong “tillage” function to the soil due to their larger diameter roots, whereas canola is more suitable to the environment with high availability of soil water that promotes canola root development.     

Genotypic variation for root traits of maize (Zea mays L.) from the Purhepecha Plateau under contrasting phosphorus availability

Phosphorus (P) deficiency is a major constraint for maize production in many low-input agroecosystems. This study was conducted to evaluate genotypic variation in both root (root architecture and morphology, including root hairs) and plant growth traits associated with the adaptation of maize landraces to a P-deficient Andisol in two locations in the Central Mexican highlands. Two hundred and forty-two accessions from the Purhepecha Plateau, Michoacan were grown in Ponzomaran with low (23 kg P₂O₅ ha⁻¹) and high (97 kg P₂O₅ ha⁻¹) P fertilization under rain-fed field conditions, and subsequently a subset of 50 contrasting accessions were planted in the succeeding crop cycle in Bonilla. Accessions differed greatly in plant growth, root morphology and P efficiency defined as growth with suboptimal P availability. The accessions were divided into 3 categories of P efficiency using principal component and cluster analyses, and 4 categories according to the retained principal component and their relative weight for each genotype in combination with growth or yield potential. The distribution of accessions among three phosphorus efficiency classes was stable across locations. Phosphorus-efficient accessions had greater biomass, root to shoot ratio, nodal rooting, nodal root laterals, and nodal root hair density and length of nodal root main axis, and first-order laterals under P deficiency. Biomass allocation to roots, as quantified by the allometric partitioning coefficient (K) was not altered by P availability in the efficient accessions, but inefficient accessions had a lower K under low P conditions. Accessions with enhanced nodal rooting and laterals had greater growth under low P. Dense root hairs on nodal root main axes and first-order laterals conferred a marked benefit under low P, as evidenced by increased plant biomass. Late maturity improved growth and yield under low P. These results indicate that landraces of the Central Mexican highlands exhibit variation for several root traits that may be useful for genetic improvement of P efficiency in maize.     

A simple Method for Selection of Potato Lines with a Higher Root/Total Ratio at an Early Stage in the Seedling Generation

Abstract

The growth directions and elongation rates of axile roots that compose the framework of an upland rice root system are quite varied. The objective of this study was to elucidate the direction of growth of the axile roots relative to their root diameter and the structural characteristics of their root caps. The relationships of photosynthate translocation to either the growth direction or the elongation rate of the axile roots were also examined using a stable isotope 13G. The growth direction of the axile roots significantly correlated with their diameter. The axile roots with a relatively large diameter tended to elongate vertically in the vegetative stage, though the regression coefficients varied according to phyllochrons. The roots that emerged at the reproductive stage elongated horizontally relative to the large diameter. In the roots that emerged at the same phyllochrons, the prophyll roots elongated more vertically than the proximal roots did. The axile roots that elongated vertically formed wide columellae and large amyloplasts in the cap cells. The highest ¹³C abundance in the axile root tip zone was found at 21 hrs after feeding ¹³CO₂. The length of the apical unbranched zone behind the axile root tip positively correlated with the ¹³C abundance in the root apical zones during the first 21 hrs after feeding, indicating that the roots that elongated fast would be superior in photosynthate intake in the apical zone. The axile roots that elongated vertically took in more photosynthate in their apical zones, however, the relationship was not particularly close.     

Rooting systems of oilseed and pulse crops I: Temporal growth patterns across the plant developmental periods

Oilseed and pulse crops have been increasingly used to diversify cereal-based cropping systems in semiarid environments, but little is known about the root characteristics of these broadleaf crops. This study was to characterize the temporal growth patterns of the roots of selected oilseed and pulse crops, and determine the response of root growth patterns to water availability in semiarid environments. Canola (Brassica napus L.), flax (Linum usitatissimum L.), mustard (Brassica juncea L.), chickpea (Cicer arietinum L.), field pea (Pisum sativum L.), lentil (Lens culinaris), and spring wheat (Triticum aestivum L.) were tested under high- (rainfall + irrigation) and low- (rainfall only) water availability conditions in southwest Saskatchewan, in 2006 and 2007. Crops were hand-planted in lysimeters of 15 cm in diameter and 100 cm in length that were installed in the field prior to seeding. Roots were sampled at the crop stages of seedling, early-flower, late-flower, late-pod, and physiological maturity. On average, root length density, surface area, diameter, and the number of tips at the seedling stage were, respectively, 41, 25, 14, and 110% greater in the drier 2007 than the corresponding values in 2006. Root growth in all crops progressed rapidly from seedling, reached a maximum at late-flower or late-pod stages, and then declined to maturity; this pattern was consistent under both high- and low-water conditions. At the late-flower stage, root growth was most sensitive to water availability, and the magnitude of the response differed between crop species. Increased water availability increased canola root length density by 70%, root surface area by 67%, and root tips by 79% compared with canola grown under low-water conditions. Water availability had a marginal influence on the root growth of flax and mustard, and had no effect on pulse crops. Wheat and two Brassica oilseeds had greater root length density, surface area and root tips throughout the entire growth period than flax and three pulses, while pulse crops had thicker roots with larger diameters than the other species. Sampling roots at the late-flower stage will allow researchers to capture best information on root morphology in oilseed and pulse crops. The different root morphological characteristics of oilseeds, pulses, and wheat may serve as a science basis upon which diversified cropping systems are developed for semiarid environments.     

Differences in Cadmium Accumulation and Root Morphology in Seedlings of Japanese Wheat Varieties with Distinctive Grain Cadmium Concentration

Abstract

A low cadmium (Cd) concentration in wheat grain is desirable because of Cd toxicity to humans. Grain Cd concentrations in Japanese wheat differed among the varieties in previous study. In this study, we hypothesized that the varieties with a low concentration of Cd in grain have (1) low Cd uptake from the soil through the roots during early growth and/or (2) low Cd translocation from the roots to shoots, and also, that (3) Cd uptake from soil is affected by root morphology. These hypotheses were verified by investigating the concentration and quantity of Cd in root, shoot and leaf tissues, and examining the root morphology of young seedlings of wheat varieties with high and low grain Cd concentrations. Seedlings of ‘Kitahonami’ and ‘Nanbukomugi’ which had low grain Cd concentration (low Cd/G varieties) had a lower Cd quantity in whole plant tissues than ‘Nishikazekomugi’ and ‘Kitakamikomugi’ which had high grain Cd concentration (high Cd/G varieties) during early growth. Low Cd/G varieties also showed lower root to shoot (aerial parts) translocation of Cd than high Cd/G varieties. Seedlings of low Cd/G varieties showed less root branching than high Cd/G varieties. Root frequency showed a significant positive correlation with Cd quantity in whole plant tissues. These results suggest that low Cd/G varieties used in this study have low Cd uptake and translocation from the roots to shoots during early growth, and furthermore, that low Cd uptake at the seedling stage may relate to slow and/or limited development of branching roots.     

Development and Distribution of Root System in Two GrainSorghum Cultivars Originated from Sudan under Drought Stress

Abstract

The difference in rooting pattern between two grain sorghum cultivars differing in drought tolerance was investigated under drought stress. The cultivars, Gadambalia (drought-tolerant) and Tabat (droughtsusceptible), were grown in bottomless wooden or acrylic root boxes to examine root parameters. Gadambalia consistently exhibited higher dry matter production and leaf water potential than Tabat under drought stress in both root boxes. In the experiment with wooden root boxes, under a drought condition, Gadambalia extracted more water from deep soil layers (1.1-1.5 m), which was estimated from the reduction in soil water content, than Tabat. This was because Gadambalia had a significantly higher root length density in these soil layers. The high root length density was due to enhanced lateral root development in Gadambalia. In the other experiment with acrylic root boxes, though total root length in the upper soil layer (0-0.5 m) was declined by limited irrigation in both cultivars, the reduction in Gadambalia was moderate compared with that in Tabat owing to the maintenance of fine root growth. Unlike Tabat, Gadambalia had an ability to produce the nodal roots from higher internodes even under drought, which resulted in the high nodal root length of Gadambalia. The growth angle of nodal roots was significantly correlated with root diameter, and the nodal roots from the higher internodes had large diameters and penetrated into the soil more vertically. These results indicate that the responses of roots (i.e. branching and/or growth of lateral root, and nodal root emergence from higher internodes) to soil dryness could be associated with the drought tolerance of Gadambalia.     

东北黑土区高产大豆R5期根系分布特征

利用钻土法及根系扫描分析系统研究不同产量类型大豆R5期根系在植株周围、株间及垄间土壤中的空间分布特征。结果表明：高产类型大豆根冠比较高，而且单位根长、根表面积的地上部干物质较高。根干重不仅在根系较集中的植株周围及株间0 ~ 30 cm的土层，而且在较深的土层（> 30 cm）中都有较多的分布；根长在植株周围的0 ~ 45 cm土层范围内表现出一定的优势。直径 < 1.0 mm的细根形成了根系的主要部分，根长差异的主要原因不是细根比例的大小，而是细根数量的多少。除株间0 ~ 15 cm土层外，高产大豆各土层的根/土体积比较高。     

土壤剖面硝态氮非均匀分布条件下小麦根系生长和氮素吸收特征

为探讨土壤硝态氮非均匀分布条件下小麦根系生长及氮素吸收特征,选用石麦15、衡观35、H10和L14等4个小麦品种为材料,进行土壤分层培养试验,模拟土壤剖面中上下层硝态氮空间分布差异,测定和分析了小麦根系长度、直径、分布等形态学特征及植株氮素含量和累积量。结果表明,当土壤中硝态氮施用量上层较低、下层较高时,小麦植株根系总长和表面积在上下土层中分布比值降低,根系趋向下层土壤生长。上下层土壤中硝态氮施用量均较高时,上下层土壤中的根系总长和表面积比值较大,根系趋向上层土壤生长。土壤剖面不同层次中硝态氮供应非均匀条件下,小麦根系发育呈现明显的可塑性反应。小麦根系总长和表面积以及直径≤0.15mm的细根长(占整个根系的比重很大)与植株地上部氮含量和氮素积累量极显著正相关,与土壤中硝态氮含量极显著负相关。     

Root lodging in sunflower. Variations in anchorage strength across genotypes,soil types,crop population densities and crop developmental stages

Root lodging is an important adversity affecting sunflower (Helianthus annuus L.) production in Argentina under current husbandry practices, and may limit progress towards the achievement of higher yields via increased plant population density. Although there are perceptions that lodging susceptibility varies across developmental stages, crop population densities, genotypes and soil types, these perceptions have not been tested for sunflower using a standardized experimental protocol. This study aimed at: (1) identifying the sources of the variation in root lodging susceptibility in response to variations in crop population density in two genotypes of reputedly different susceptibility; (2) detecting the crop developmental stages most susceptible to root lodging; and (3) examining the relationships between root failure moment, root plate diameter and soil shear strength. We mechanically induced lodging at three developmental stages in plants rooted in pre-wetted plots. The crops were grown at 5.6 plants m⁻² over 3 years on either Typic Argiudoll or Typic Hapludoll soils and at 3, 5.6, 10 and 16 plants m⁻² on a Typic Argiudoll. The force needed to induce root lodging (root failure moment) and root plate diameter varied across genotypes, plant densities and developmental stages. Root failure moment and root plate diameters were greater (p < 0.05 for both variables) in the resistant hybrid across the three development stages and almost all crop population densities. For both hybrids, the most susceptible development stage was R2, and root failure moment and root plate diameter diminished (p < 0.05) as crop population density increased. Although root failure moment did not differ between soil types, root plate diameter was greater (p < 0.0001) in the coarser soil. The relationship between root failure moment and the product of root plate diameter cubed by soil shear strength (a measure of plant anchorage strength) for both hybrids, both soil types, and all crop population densities could be described by a single linear relationship (y = 0.2382x; R² = 0.812; p < 0.025).     

大豆成苗期抗旱性与根系生长的关系

选择抗旱性强、中、弱的大豆品种各5个,在试验室条件下研究成苗期抗旱性与根系生长、胚轴伸长的关系。结果表明:抗旱性强的品种发根早,主根长,侧根数量多,侧根总长度长,胚轴长,成苗率高。在干旱条件下的趋势更为明显。     

垄作栽培对寒地水稻根系生长的影响

 以黑龙江省早熟高产优质粳稻品种空育131为材料,通过垄作栽培与平作栽培方式对比试验,研究垄作栽培对寒地水稻根系生长的影响。结果表明，水稻根系的生长和分布在不同栽培方式间有较大差异，供试品种在不同的栽培方式下其根系体积、干质量、根长及活力均存在明显不同。与对照（平作）相比，水稻（空育131）在垄作栽培条件下根系发达，表现为根长增加、根系干质量增大，根量尤其下层根量增多，根系吸收面积增大，根冠比增大，产量提高。     

硝态氮供应对小麦根系形态发育和氮吸收动力学的影响

为给小麦氮素利用效率的提高及氮高效品种的选育提供依据,以秦麦11号和宁麦9号作为供试材料,采用溶液培养方法,研究了不同浓度硝酸盐对小麦根系形态发育特征和硝酸盐吸收动力学的影响。结果表明,在较低的浓度范围内,NO3-可增加小麦总根长和根尖数,促进根系生长;当NO3-浓度超过2 mmol/L时,总根长和根尖数受到强烈抑制,但由于根系平均直径的增加,根系总体积并未明显减少。两个供试小麦品种之间根系NO3-含量并无明显差异,而两个品种的叶片NO3-含量在介质NO3-浓度超过10 mmol/L时表现出了明显差异。叶片、根系NO3-含量与根冠比之间的关系可用一次函数来进行描述,与根长、根尖数之间的关系可用二次函数来进行描述。与宁麦9号相比,秦麦11号的NO3-吸收具有更高Vmax值和Km值,这可能与两个供试小麦品种根系形态特征的差异有关。     

Novel, binder-free fiber reinforced composites based on a renewable resource from the reed-like plant Typha sp.

The aim of this paper is to demonstrate for the first time the technological potential of novel, totally bio-based, binder-free vegetable fiber-composites based on the reed-like plant Typha sp. Binder-free vegetable fiberboards based on Cattails were prepared and their mechanical (flexural modulus of elasticity, flexural strength and water absorption) and surface textural properties were determined. The influence of press time and panel density on the properties was investigated. In contrast to currently known natural fiber composites based on hemp, flax, kenaf or the like annual plants which all require up to 30 wt% of suitable bonding resins, the typha based composites were prepared completely without the addition of any extraneous glue and showed good mechanical performance that clearly exceeded the performance of other natural fiber composites containing low percentages of phenolic binder (15%). Of special interest were the superior surface properties of the typha based panels. Despite the coarse nature of the raw fiber material and the rough texture of the typha based fiber mats, binder-free typha panels showed excellent surface smoothness which makes this novel composite material highly interesting for light-weight applications with high surface quality standards, for example, as powder-coated elements for the automotive and furniture industries.     

氮素供应和pH值对玉米根系形态的影响

实验设正常供氮(0.5 mmol/L NO3-)和高氮(10 mmol/L NO3-)处理,研究不同pH值水平下(4.5～8.0)氮素供应对玉米根系生长的影响。结果表明,氮供应与溶液pH值对玉米根系的影响不存在互作效应。高氮供应不影响地上部与根的干物质积累;pH值提高有利于促进干物质向地上部分配,向根的分配比例相对下降,根冠比下降。高氮使单株根系总长度平均下降,降幅为34.5%,主要是轴根和侧根长度下降,轴根数和侧根密度受影响较小。在两个氮水平下,总根长、轴根长、侧根长均随pH值的上升表现增加的趋势,高pH值主要增加侧根密度。研究表明,在酸性土壤上,不能通过大量施用硝态氮肥缓解氢离子对根系生长的抑制作用。     

耕作方式对玉米根系构型及抗根倒伏能力的影响

通过云南典型的红壤坡耕地对土壤实施深松+旋耕 15 cm（SRT）、深松+免耕（SNT）、深松+翻耕 20 cm（SP1）、深松+翻耕30 cm（SP2）、旋耕15 cm（RT）、免耕（NT）、翻耕20 cm（P1）和翻耕30 cm（P2）8种耕作方式,研究对玉米的根系根条数、根直径、入土角度、根幅、生物量及根系抗拔力等的影响。结果表明,深松+翻耕20 cm处理能增加玉米根条数、根系入土角度和10 cm土层处根系生长幅度,增大根系生物量,尤其是深层土壤（20～30 cm）根系生物量,同时对玉米产量也具有提高作用。深松+翻耕30 cm处理能增大根系的垂直抗拔力。因此,土壤通过深耕处理能改善玉米根系构型和分布,进而增强玉米根系抗倒伏能力。     

Structure and Function of the Root Cap

The root cap (RC) is a multilayered dome of spindle-shaped parenchyma cells that overlies the growing root tip. It is present in the roots of almost all crop species. This paper briefly reviews some topics on the structure and function of the RC in the major crop species such as maize and rice. Special attention is placed on its contribution to the root system formation, that is, the elongation and growth direction of axile roots. The cells produced in the RC meristem are pushed forward as new cells form beneath them, and eventually the cells on the periphery of the RC fall off. The life cycle of RC cells of maize has been studied extensively and ranges from one to seven days. Approximately 4,000 to 21,000 cells are present in a complete maize RC, and 1,400 to 3,200 sloughed cells can be found in the rhizosphere soil per day per root. These cells, called root border cells (RBCs), mix with RC mucilage and play important roles for the root growth in soil. The RBC-mucilage complex effectively reduces the resistance roots experience during penetration into field soil, about 30–40% of the resistance being reduced by the presence of RC alone. The RC is also a tissue integral to gravitropism, and is known to determine the direction of root growth. The size of amyloplasts and coumellae in RCs has a strong influence on determining the growth angle of axile roots. The function of the individual regions of the RC and how the RC tissues and cells are formed should be studied further to advance our understanding regarding the critical roles of the RC in crop root growth.     

施肥量对甜菜产量和生理指标的影响

试验结果表明,为获得2.8～3.0t/亩块根产量,亩施肥量以N8kg、p_2O_59.6kg、K_2O8kg为宜;甜菜含糖率与施肥量呈负相关(r=-0.5484),但未达显著水平;甜菜的NAI与施肥量呈正相关(r=0.9909)。每亩N10kg、P_2O_5;12kg、K_2O10kg处理和N8kg、P_2O_59.6kg、K_2O8kg处理群体发育良好,LAI保持在3.0以上的时期长达45天以上,并有较强的净光合生产率,有利于产量形成;甜菜单株干物重与施肥量呈正相关(r=0.9600)高肥处理虽然生物产量高,但因T/R比高,叶部徒长,分配率低,而导致经济产量低。     

大豆生殖生长期根系形态性状与产量关系研究

以稳定的大豆新品系进行连续2年的生殖生长期根系形态性状的比较研究.结果表明,生殖生长期根系形态性状存在较明显的基因型差异,尤其在R5期后,产量较高的海-560的根系生物量、根体积和根长均大于观-009;施肥有效地促进根系生长,降水较多的年份土壤中的根系密度较高,施肥增强这种趋势,尤以0～30 cm内的土层显著;根系性状与产量间存在显著的相关关系,其中根长与产量的关系更为密切.在雨养农业中,选育根系强大的品种,并根据气候变化因地制宜的科学施肥,协调水肥关系,提高水分及养分利用率,对于提高作物产量是十分必要的.