Root Weight Density Research Articles

Soil Water Effect on Root Activity, Root Weight Density, and Grain Yield in Winter Wheat

Soil water has a significant effect on root characteristics, influencing overall growth. Understanding the optimal timing, depth, and volume of irrigation is important. Two years of field experiments were conducted to determine the effect of soil water content on root activity, root weight density, and yield in winter wheat (Triticum aestivum L.). Six water treatments (W) were applied: W1 [35–45% field water capacity (FC)], W2 (45–55% FC), W3 (55–65% FC), W4 (65–75% FC), W5 (75–85% FC), and W6 (85–95% FC). Soil samples were collected at depths of 0 to 20 cm (Layer 1, L1), 20 to 40 cm (Layer 2, L2), and 40 to 60 cm (Layer 3, L3) at 58, 110, 147, 177, 199, 206, and 217 d after sowing (DAS). Irrigation to maintain soil water content at 65 to 75% FC resulted in the highest root activity and root weight density, with the highest value at 177 DAS (flowering). Root activity and root weight density were highest in L2. Growth stage and soil water had a significant effect on root activity and root weight density; soil layer also had a significant effect on root weight density. Root activity and root weight density were closely related to grain yield. Associations with grain yield showed a stronger relationship with yield at later rather than early stages. The findings suggest that the optimal irrigation to promote root activity and root weight density in wheat was 65 to 75% of FC at 20 to 40 cm.

Spatial distribution of soil water, soil temperature, and plant roots in a drip-irrigated intercropping field with plastic mulch

Intercropping and drip irrigation with plastic mulch are two agricultural practices used worldwide. Coupling of these two practices may further increase crop yields and land and water use efficiencies when an optimal spatial distribution of soil water contents (SWC), soil temperatures, and plant roots is achieved. However, this coupling causes the distribution of SWCs, soil temperatures, and plant roots to be more complex than when only one of these agricultural practices are used. The objective of this study thus was to investigate the effects of different irrigation treatments on spatial distributions of SWCs, soil temperatures, and root growth in a drip-irrigated intercropping field with plastic mulch. Three field experiments with different irrigation treatments (high T1, moderate T2, and low T3) were conducted to evaluate the spatial distribution of SWCs, soil temperatures, and plant roots with respect to dripper lines and plant locations. There were significant differences (p < 0.05) in SWCs in the 0–40 cm soil layer for different irrigation treatments and between different locations. The maximum SWC was measured under the plant/mulch for the T1 treatment, while the minimum SWC was measured under the bare soil surface for the T3 treatment. This was mainly due to the location of drippers and mulch. However, no differences in SWCs were measured in the 60 100 cm soil layer. Significant differences in soil temperatures were measured in the 0 5 cm soil layer between different irrigation treatments and different locations. The soil temperature in the subsoil (15 25 cm) under mulch was higher than under the bare surface. The overlaps of two plant root systems in an intercropping field gradually increased and then decreased during the growing season. The roots in the 0 30 cm soil layer accounted for about 60% 70% of all roots. Higher irrigation rates produced higher root length and weight densities in the 0 30 cm soil layer and lower densities in the 30 100 cm soil layers. Spatial distributions of SWCs, soil temperatures, and plant roots in the intercropping field under drip irrigation were significantly influenced by irrigation treatments and plastic mulch. Collected experimental data may contribute to designing an optimal irrigation program for a drip-irrigated intercropping field with plastic mulch.

Above- and belowground patterns in a subalpine grassland-shrub mosaic

Many mountain pastures consist of a mosaic of grassland and shrub communities. Ongoing changes in mountain agriculture have affected the balance between the two elements of the mosaic. In order to understand the consequences of these changes for ecosystem functioning, we studied patterns in vegetation, root structure and soil properties along transects of varying grassland-to-shrub proportions. Our hypothesis was that differences in the vegetation aboveground are accompanied by differences belowground, related to soil properties and depth. The research was conducted at a subalpine site in the Trentino region (South-eastern Alps), consisting of Nardus stricta grasslands alternating with shrub patches of Rhododendron ferrugineum. Our investigation showed that the composition of vegetation was mainly governed by R. ferrugineum cover and less by soil properties. Plant species richness peaked at low to intermediate degrees of shrub cover and composition between transects became more similar with increasing shrub cover. Where R. ferrugineum cover was higher, Hemicryptophytes caespitosae were replaced by Nano-phanerophytes with consequences for belowground structures. At increasing shrub cover, root length density decreased, especially in the top soil, while root weight density remained stable and C content increased insignificantly. We discuss that theses structural changes along the gradient of R. ferrugineum cover affect a number of ecosystem services. The presented evidence suggests that maintaining grasslands with a low cover of R. ferrugineum balances a number of services, namely plant species diversity, carbon stabilization in soil and the prevention of soil erosion.

Interactive effect of water and nitrogen regimes on plant growth, root traits and water status of old and modern durum wheat genotypes.

The selection of the ideal root drought adaptive traits should take into account the production and maintenance of root tissues alongside the capacity to capture soil resources. Ten old and modern Spanish durum wheat (Triticum turgidum L. var durum) genotypes were grown in lysimeters under two contrasting water and nitrogen regimes to study the effect of such growth conditions on: (1) the aerial biomass, (2) the growth and structure of the roots and (3) the relationships of the root structure with aerial biomass, photosynthetic and transpirative characteristics and water use efficiency. Both high water and nitrogen regimes significantly increased aerial biomass. Root dry biomass and root length increased and decreased in response to improved water supply and nitrogen regimes, respectively. No significant correlations were detected between aerial biomass and any root trait under well-watered conditions. Under water stress aerial biomass was negatively correlated with root dry biomass, root length and root weight density and positively correlated with the specific root length, particularly for the subset of old genotypes. The high nitrogen regime significantly enriched the carbon isotope composition of the flag leaf (δ (13)CFL) and hindered the effect of the high water regime on decreasing δ (13)CFL enrichment. Thus, positive correlations of aerial biomass with δ (13)CFL were detected regardless of the water regime. The study revealed: (1) the importance of root traits for higher aerial biomass under the low water regime; (2) that the interaction between nitrogen and the water regime may affect the predictive nature of the δ (13)C in drought breeding programs; and (3) the selection of the ideal root system structure should take into account the metabolic costs of the production and maintenance of root tissues alongside the capacity of capturing resources.

Influence of Glomus–Rhizobium Symbiosis on Productivity, Root Morphology and Soil Fertility in Garden Pea in Himalayan Acid Alfisol

ABSTRACTThe influence of dual inoculation of arbuscular mycorrhizal fungi (AMF) and Rhizobium was assessed on garden pea productivity, root morphology and soil fertility during 2011–2012 at Palampur, India, in a medium phosphorus (P) acid Alfisol. Field experimentation comprised 13 treatments involving Rhizobium, AMF and inorganic fertilizers in (RBD) replicated thrice. The dual inoculation of Rhizobium and AMF exhibited nominal effect on pea pod length, pod girth and number of seeds per pod. However, average pod weight (APW) and productivity increased by 14.1 and 20% following dual inoculation, respectively, over generalized recommended nitrogen, phosphorus and potassium (NPK) dose general recommended dose (GRD). Dual inoculation of pea seed with both symbionts sharply increased the root volume (RV), root dry weight (RDW), root weight density (RWD) and root nodules per plant by 34.5, 13.3, 13 and 44%, respectively. Similarly, the highest AMF root colonization was registered under dual-inoculated plots compared to sole application of Rhizobium or AMF. Different treatments including dual-inoculated ones did not alter the soil organic carbon (SOC), available N, K and diethylenetriaminepentaacetic acid (DTPA)-extractable micronutrients iron, zinc, copper and manganese (Fe, Zn, Cu and Mn) status significantly; however, a nominal buildup in the above-mentioned parameters was registered under dual inoculation. Available P status increased to the tune of 6.7 and 8.7% following dual inoculation with Rhizobium and AMF over their respective sole inoculations. Overall, the current study suggests that Glomus–Rhizobium symbiosis has great potential in enhancing productivity through better proliferation of the root system and improved soil fertility status. Furthermore, dual inoculation of AMF and Rhizobium can save up to 25% fertilizer N and P in garden pea in acid Alfisol of the northwestern Himalayas (NWH).

Root growth, soil water variation, and grain yield response of winter wheat to supplemental irrigation

Water shortage threatens agricultural sustainability in the Huang-Huai-Hai Plain of China. Thus, we investigated the effect of supplemental irrigation (SI) on the root growth, soil water variation, and grain yield of winter wheat in this region by measuring the moisture content in different soil layers. Prior to SI, the soil water content (SWC) at given soil depths was monitored to calculate amount of irritation water that can rehydrate the soil to target SWC. The SWC before SI was monitored to depths of 20, 40, and 60 cm in treatments of W20, W40, and W60, respectively. Rainfed treatment with no irrigation as the control (W0). The mean root weight density (RWD), triphenyl tetrazolium chloride reduction activity (TTC reduction activity), soluble protein (SP) concentrations as well as catalase (CAT), and superoxide dismutase (SOD) activities in W40 and W60 treatments were significantly higher than those in W20. The RWD in 60–100 cm soil layers and the root activity, SP concentrations, CAT and SOD activities in 40–60 cm soil layers in W40 treatment were significantly higher than those in W20 and W60. W40 treatment is characterized by higher SWC in the upper soil layers but lower SWC in the 60–100-cm soil layers during grain filling. The soil water consumption (SWU) in the 60–100 cm soil layers from anthesis after SI to maturity was the highest in W40. The grain yield, water use efficiency (WUE), and irrigation water productivity were the highest in W40, with corresponding mean values of 9169 kg ha−1, 20.8 kg ha−1 mm−1, and 35.5 kg ha−1 mm−1. The RWD, root activities, SP concentrations, CAT and SOD activities, and SWU were strongly positively correlated with grain yield and WUE. Therefore, the optimum soil layer for SI of winter wheat after jointing is 0–40 cm.

Influence of AM fungi and inorganic phosphorus on fruit and root characteristics, root colonization and soil phosphorus in okra-pea cropping system in Himalayan acid Alfisol

In Himalayan acid Alfisol, the influence of arbuscular mycorrhizal fungi (AMF) on fruit and root characteristics in okra-pea cropping system was assessed at varying inorganic phosphorus and irrigation regimes (40 & 80% available water capacity). In okra, AMF inoculation significantly improved the fruit length, fruit girth and fruit weight besides enhancing rooting depth (13%), root volume (7%), root dry weight (7%) and root weight density (6%) over non-AMF treatments. In pea, AMF sharply increased the average pod weight (10%), rooting depth (9%), root volume (16%), root dry weight (13%) and root weight density (12%) over non-AMF counterparts. AMF enhanced mycorrhizal root colonization by 2 to 2.3-fold both in okra and pea besides significant improvement in available soil-P pool (21%). ‘AMF + 75% soil-test based P dose (STB-P)’ at both irrigation regimes remained statistically alike with generalized recommended nutrient-cum-irrigation dose (GRD) and ‘AMF + 100% STB-P’ with respect to fruit and root parameters in okra-pea system, thus, indicating an economy of about 25% applied-P through AMF inoculation in acid Alfisol. Hence, AMF had positive influence on fruiting and root characteristics, fertilizer-P economy and availability in Himalayan okra-pea production system.

Soil amendment with biochar increases maize yields in a semi-arid region by improving soil quality and root growth

Biochar has been widely proposed as a relatively novel approach to improve soil quality and increase crop productivity, but its underlying mechanisms are not well understood. A large root system in plants is either a constitutive or an inducible trait dependent on the uptake of resources and the production of shoot dry matter. Here a field experiment was conducted to investigate the effects of biochar amendment on the dynamic growth and development of maize (Zea mays L.), both above- and belowground, and to explore the relationship between soil condition, root traits and shoot biomass over two growing seasons on the Loess Plateau in northern China. Biochar was added to a maize field at rates of 0, 10, 20 and 30 t ha–1 without mulching and at rates of 0 and 20 t ha–1 with film mulching before sowing the first crop. The application of straw biochar with 30 t ha–1 decreased soil bulk density by 12% and increased soil total porosity by 13% in the 0–10-cm soil layer 6 months after biochar addition. Biochar amendment increased soil organic carbon, total soil nitrogen, carbon : nitrogen ratio, and available phosphorus and potassium at the end of each growing season. Although, root growth was inhibited at a rate of 30 t ha–1 in the early stage of the first year, biochar amendment exhibited a positive effect in other stages, resulting in higher root weight density, root length density and root surface-area density. These responses led to higher growth rates, maize biomass, grain yields and uptake of nitrogen, phosphorus and potassium as the rate of biochar addition increased. Film mulching with biochar amendment achieved the greatest root and shoot biomass and grain yield in both crops, despite differences in climate conditions. Biochar aged in the field for 2 years had the same effect on soil properties and crop production, suggesting that the application of straw biochar may be a promising option for increasing productivity in semi-arid farmland.

Heterosis for water status in maize seedlings

Heterosis is one of the greatest practical achievements of plant breeding and has been extensively used in crop improvement in maize. However, the physiological basis of heterosis still remains poorly understood despite its manifestation at early stages of the plant life cycle. Therefore, a better understanding of the physiological mechanisms associated with heterosis may enable further exploitation of this phenomenon. Five maize hybrids and their parental lines were grown in a greenhouse under two water regimes (well watered and water stressed). Plant growth, different root traits, plant water use and water use efficiency and gas-exchange and chlorophyll fluorescence, nitrogen content and stable oxygen, carbon and nitrogen composition and stomatal density of leaves were measured. Plant height, shoot biomass and leaf area were higher in hybrids than in their respective parents in both control and stress conditions. Moreover, hybrids showed a better water use and water use efficiency for biomass than inbred lines. Significant heterosis was also found for photosynthetic rate, stomatal conductance, transpiration rate and the Ci/Ca ratio under water stress conditions, whereas for control conditions the differences were not significant. Likewise, root weight density and root length density were higher in hybrids than parents, especially underwater stress. No heterosis occurred for stable isotope composition under either water regime. The results do not support a constitutively better water status as a cause of heterosis under well watered conditions.

Effects of vegetation cover and road-concentrated flow on hillslope erosion in rainfall and scouring simulation tests in the Three Gorges Reservoir Area, China

Roads play a significant role in altering hydrological processes. Roads cause more erosion to be generated from the hillslope for both road-concentrated flow and rainfall. In this study, six treatments (Natural Restoration, Grass, Grass & Shrub, Sodded Strip, Grass & Farmland, and Farmland) were used to recolonize hillslope plants on a newly built unpaved road. Rainfall simulation (rainfall intensity of 90mmh−1 and 120mmh−1) and scouring simulation (scouring flow rate 15Lmin−1 and 20Lmin−1) tests were conducted to identify the effects of plants on soil erosion. In the rainfall simulation test, Grass & Shrub was more effective at reducing hillslope erosion than the other treatments, and Grass & Shrub also had a lower runoff coefficient, soil detachment rate, and higher efficiency in trapping runoff and sediment. The hydrological responses of all of the tested plots in the scouring test were much faster than in the rainfall simulation, as indicated by the lower lag time to runoff generation. The hillslope erosion in the scouring test was significantly higher than in the rainfall simulation. The water-stable aggregate, saturated hydraulic conductivity, vegetation cover, root length density, and root weight density were important factors that conditioned the runoff generation and sediment yield from the hillslope in both experimental tests. In the scouring test, in infiltration improvement and flow erosivity reduction, Grass was more effective at trapping runoff and sediment because of its dense well-developed system of fine roots. Therefore, except for an immediate surface cover, in the areas where the hillslope has a risk of road-concentrated flow scouring, the enhancement of topsoil roughness was also very important in weakening the impact of road-concentrated flow on the hillslope.

轮耕对关中一年两熟区土壤物理性状和冬小麦根系生长的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 轮耕对关中一年两熟区土壤物理性状和冬小麦根系生长的影响 DOI: 10.5846/stxb201404140716 作者: 作者单位: 西北农林科技大学资源环境学院,西北农林科技大学资源环境学院,西北农林科技大学资源环境学院,西北农林科技大学资源环境学院,西北农林科技大学资源环境学院,西北农林科技大学资源环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 陕西省农业厅项目(k332021312);陕西省科研推广项目(413020211203533) Effects of rotational tillage on soil physical properties and winter wheat root growth on annual double cropping area Author: Affiliation: College of Resources and Environment,Northwest A＆F University,Yangling,College of Resources and Environment,Northwest A＆F University,Yangling,College of Resources and Environment,Northwest A＆F University,Yangling,College of Resources and Environment,Northwest A＆F University,Yangling,College of Resources and Environment,Northwest A＆F University,Yangling,College of Resources and Environment,Northwest A＆F University,Yangling 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:针对关中地区土壤连续单一耕作存在的主要问题,进行了土壤轮耕效应研究.2009年至2012年在关中一年两熟区采用连续4a旋耕(RT)、翻耕-免耕-翻耕-免耕(PNT)和深松-免耕-深松-免耕(SNT)3种耕作处理,对土壤容重、紧实度及小麦根系生长进行了研究.结果表明,与试验前相比,夏玉米收获后(2013年10月)两种轮耕处理显著(P < 0.05)降低了0-10、10-20 cm土壤容重,旋耕处理在0-10 cm处差异不显著,而10-20 cm土壤容重显著增大;与旋耕处理相比,两种轮耕处理0-10、10-20 cm土壤容重在第4季冬小麦整个生育期内变异系数较小,土壤紧实度较低,且改善效果在冬小麦生育中后期10-20 cm土层体现更为显著;旋耕处理0-10、10-20 cm土壤紧实度与含水量均呈显著负相关,相关系数分别为-0.89、-0.85,两种轮耕处理相关性不显著;0-40 cm土层根重密度和根系活力表现为:两种轮耕处理>连年旋耕.可见,长期旋耕后进行轮耕(免耕与翻耕、深松)有利于改善土壤物理状况,促进作物根系生长. Abstract:Rotary tillage is a very common practice in the Guanzhong area. However, many problems occur for winter wheat fields with long-term rotary tillage, including poor soil water vapor transmission and low soil fertility, which are not favorable to winter wheat growth. To solve these problems, a 4-year field experiment was carried out from 2009 to 2012 in Yangling, Shaanxi Province of China, which is an annual double cropping area. The experiment compared three tillage patterns: RT (rotary tillage for 4 years), PNT (a deep plowing followed by a non-tillage year alternation) and SNT (a subsoiling year followed by a non-tillage year alternation). This study evaluated the impacts of the three tillage patterns on soil bulk density, soil compaction across the 0-40 cm soil profile, and winter wheat root growth. Results showed that after the summer maize harvest (October, 2013), the soil bulk density under the SNT and PNT treatments significantly (P < 0.05) decreased at 0-10 and 10-20 cm compared with the previous treatment, but the soil bulk density significantly increased under the RT treatment at 10-20 cm, with no significant difference at 0-10 cm. The dynamic changes of soil bulk density at 0-10 and 10-20 cm at different times were a measure of the ability of the soil to maintain structural stability. During the whole growth period of the fourth season winter wheat, the variation coefficient of soil bulk density under the SNT and PNT treatments at 0-10 and 10-20 cm was lower than that under the RT treatment. The soil compaction under the SNT and PNT treatments at 0-10 and 10-20 cm was also lower than that under the RT treatment. The improved efficiency of the SNT and PNT treatments on soil physics was more evident at 10-20 cm during the late growth period of winter wheat. There was a significant negative correlation between the soil compaction and soil water content under the RT treatment at 0-10 and 10-20 cm, with correlation coefficients of -0.89 and -0.85, respectively, but there was no significant correlation at these depths between the SNT and PNT treatments. This indicated that the soil structure in the RT treatment was more sensitive to the change in environment than in the SNT and PNT treatments. Soil aggregates were decomposed into smaller aggregates and particles during the frequent tillage, and this would be the main factor causing the reduced porosity and poor soil structure performance. The SNT and PNT treatments were more effective in increasing root weight density and root vigor of winter wheat in the 0-40 cm soil layer than the RT treatment. The results suggested that the effects of the SNT and PNT treatments on soil physical properties and root development were better than those of the RT treatment. After long-term rotary tillage, deep plowing and subsoiling alternated with non-tillage can improve soil physical properties and increase crop yield. 参考文献 相似文献 引证文献

Tillage practices effect on root distribution and water use efficiency of winter wheat under rain-fed condition in the North China Plain

Water shortage has limited the agricultural sustainable development of North China Plain (NCP), where winter wheat (Triticum aestivum L.) is the major irrigated crop that consumes 60–80% of available deep groundwater for agriculture production, leading to the significant decline in groundwater resource. The protection of water resources is important for the sustainable development of agriculture in NCP. The objective of this study was to evaluate the effect of plow-tillage (PT), rotary-tillage (RT) and no-tillage (NT) on root growth, water consumption characteristics, grain yield, water use and water use efficiency (WUE) under rain-fed condition conducted in a field with 20-year of rotary tillage history. Findings of this research show that plow-tillage (PT) and rotary-tillage (RT) decreased the soil bulk density in the 0–20cm soil depth and the penetration resistance in the 0–30cm soil depth. During two growth seasons, PT had greater root weight density (RWD), root length density (RLD) and root surface density (RSD) than those under NT across the 0–110cm soil profile at the tillering stage and in the 0–40cm soil profile at the flowering stage, respectively. However, RWD, RLD and RSD of PT were lower than NT at 0–10cm soil depth and greater at 10–20cm soil depth at the ripening stage. Similar trends were observed under RT compared with NT. Soil water content (SWC) under PT and RT were lower compared with NT from tillering to flowering stage across 0–110cm, but higher than under NT in 0–20cm soil profile at ripening stage. Evapotranspiration (ET) values under PT were higher than under NT from sowing to flowering stages, but significantly lower at the ripening stage. Moreover, tillage practices had no notable influences on pre-planting soil water storage and total ET under rain-fed condition during two growing season, but PT significantly enhanced grain yield through higher spike number and grain weight compared with NT, which led to higher WUE under PT. The findings of this study show that PT practice can reduce soil bulk density and penetration resistance at the tillage zone, which can lead to greater RWD, RLD and RSD and greater ET from tillering to flowering stage. This can increase plant population and cause greater WUE and grain yield under rain-fed condition.

Research on Regulating the Effect of Different Mulching Measures on Root Spatial Distribution and the Root-Shoot Ratio of Maize

The effects of four types of mulching models (surface tillage with straw mulching, no-tillage with straw mulching on furrow, no-tillage with stubble mulching, and no-tillage with straw mulching on ridge and furrow) on the root spatial distribution and the relationship between the roots and shoots of maize were investigated using stratified digging methods, with maize as the test crop. The distribution of maize roots was cone shaped and gradually extended from 20 cm to 40 cm below the surface during the elongation stage. Under the different mulch tillage models, the effects on maize root growth were positive. The mulching measures significantly affected the control and support of the early and later stages of maize growth. The maize significantly differed in the root weight density (P=0.026&lt;0.05) and the root surface area (P =0.005&lt;0.01) with different mulching measures. No-tillage with straw mulching on the ridge and furrow was the only mulching model in which the growth of the roots and leaves of maize was limited. However, the other maize growth measures were better than conventional tillage. In addition, no-tillage with straw mulching on the ridge and furrow had an advantage in terms of the growth of the surface roots, while stubble mulching and strip mulching had advantages in terms of the growth of deep roots and radial roots, respectively. Surface tillage with straw mulching was an ideal cultivation method for the cold and arid regions of North China and had significant advantages in terms of the growth of the root weight, root surface area and root-shoot ratio.

Effects of deficit irrigation and groundwater depth on root growth of direct seeding rice in a column experiment

Rice is an essential crop in Iran that is grown mostly in areas where depth to groundwater is low. Root growth and water uptake of rice under shallow groundwater has not been thoroughly studied. This experiment was conducted to determine the lowland rice (cv. Ghasrodashti) root distribution above shallow groundwater in relation to deficit irrigation and groundwater depth in cylindrical greenhouse lysimeters. The irrigation treatments were continuous flood irrigation (CFI) and intermittent flood irrigation (4- and 8-day intervals IF-4 and IF-8). The groundwater depths (GWD) were 0.3, 0.45 and 0.6 m from the soil surface. In general, 40-60% of root dry weight was observed in the top 10 cm of soil in CFI treatments and IF-4 with 0.3 m GWD resulted in 20% increase in root dry weight in 10-20 cm layer compared with 0-10 cm. However, the root dry weight in 0-10 cm at 0.60 m GWD was 58% lower in intermittent irrigation compared to CFI. There was no significant difference in mean root length density in IF-4 with 0.3 m GWD compared with CFI. In general, lowland rice showed good ability to develop its root system in shallow groundwater level conditions in order to extract water due to lower soil water content in the intermittent flood irrigations. Simple equations were presented to predict the groundwater contribution to evapotranspiration based on the root length density and root weight density. Therefore, in areas with shallow groundwater depth (up to 0.45 m from the soil surface) and low potential evapotranspiration, application of IF-4 instead of CFI can be useful management especially where water scarcity is a serious problem.

Effects of different irrigation and nitrogen regimes on root growth and its correlation with above-ground plant parts in high-yielding wheat under field conditions

We evaluated the effects of irrigation and nitrogen regimes on wheat root growth under high-yielding conditions in the Huanghuai wheat production area of China by performing field experiments at three locations in Henan Province. The grain yield, which was significantly affected by irrigation and nitrogen fertilization regimes, ranged from 6801 to 8340kgha–1 in Kaifeng, 2055 to 7190kgha–1 in Zhengzhou and 3711 to 6859kgha–1 in Wenxian. The root weight density (RWDV) in the soil at 0–100cm reached a maximum at the flowering stage, ranging from 115.59 to 143.49gm–3 in Kaifeng, 39.75 to 113.85gm–3 in Zhengzhou and 53.90 to 114.56gm–3 in Wenxian. RWDV in the 0–40cm soil layer accounted for 72.8–87.4% of the density in 0–100-cm-deep soil across the three locations. The irrigation significantly increased the RWDV (by 46.6% and 27.2% at the flowering stage in Zhengzhou and Wenxian, respectively). The effect of nitrogen on RWDV depended on soil water conditions. The application of N180 produced the maximum RWDV under irrigation conditions, but N0 produced the highest value under water stress conditions. Both no-irrigation and N0 treatments significantly increased the R/S, and the combined treatment (W0N0) produced the maximum R/S, which indicated that stress has a relatively strong effect on the growth of the above-ground parts of wheat plants. The grain yield was strongly, positively correlated with RWDV in the 20–40cm and 40–60cm soil layers but negatively correlated with RWDV in the deep soil layers. The yield components were also closely correlated with RWDV in various soil layers; in particular, the 1000-grain weight was strongly positively correlated with RWDV in most soil layers at the late stage of development in wheat. W2N240 and W2N180 treatment produced the highest grain yield and RWDV values, respectively.

Effects of vegetation on runoff generation, sediment yield and soil shear strength on road-side slopes under a simulation rainfall test in the Three Gorges Reservoir Area, China

Vegetation recolonization has often been used to control roadside slope erosion, and in this paper, four restoration models – Natural Restoration, Grass, Grass & Shrub, Sodded Strip – were chosen to recolonize the plants on a newly built unpaved roadside slope in the Three Gorges Reservoir Area. After eight months growth, eight rainfall simulations (intensity of 90mmh−1 for 60min) and in-situ soil shear strength test were then carried out to identify the impacts of vegetation on roadside slope erosion and soil shear strength. The erosion on cutslopes was higher than that on fillslopes. The runoff coefficient and soil detachment rate were significantly lower on the Grass & Shrub model (4.3% and 1.99gm−2min−1, respectively) compared with the other three, which had the highest surface cover (91.4%), aboveground biomass (1.44kgm−2) and root weight density (3.94kgm−3). The runoff coefficient and soil detachment rate on roadside slopes showed a logarithmic decrease with the root weight density, root length density and aboveground biomass. The soil shear strength measured before and after the rainfall was higher on Grass & Shrub (59.29 and 53.73kPa) and decreased on Grass (46.93 and 40.48kPa), Sodded Strip (31.20 and 18.87kPa) and Natural Restoration (25.31 and 9.36kPa). Negative linear correlations were found between the soil shear strength reduction and aboveground biomass, root weight density and root length density. The variation of soil shear strength reduction was closely related to the roadside slope erosion, a positive linear correlation was found between runoff coefficient and soil shear strength reduction, and a power function was shown between soil detachment rate and soil shear strength reduction. This study demonstrated that Grass and Grass & Shrub were more suitable and highly cost-effective in controlling initial period erosion of newly built low-volume unpaved road.

Establishment and Rooting Response of Bermudagrass Propagated with Saline Water and Subsurface Irrigation

ABSTRACTIrrigating with non‐potable, saline water using a subsurface drip system has been suggested as a strategy to conserve water used for turfgrass. However, it is unknown if turfgrasses can be established from sod when saline water is applied from the subsurface. A two‐year study was conducted at New Mexico State University to investigate the establishment of ‘Princess 77’ bermudagrass [Cynodon dactylon (L.) Pers.] from sod, irrigated from either a sprinkler or a subsurface drip system, with potable (electrical conductivity [EC] = 0.6 dS m−1) or saline (EC = 2.2 dS m−1) water and propagated either early (mid‐March) or late (mid‐June). Establishment rate was calculated on the basis of percentage of green cover, which was determined by means of digital image analysis. At the end of each growing season, root samples were collected and analyzed for root weight density, root length density, and root diameter at three soil depths. When coverage data were averaged over water qualities, plots propagated in 2009 and irrigated from a sprinkler system established fastest, followed by sprinkler‐irrigated plots propagated in 2008. Drip‐irrigated plots were the slowest to reach full coverage. Root length density was higher in sprinkler‐irrigated plots than subsurface drip irrigation plots at all depths. In conclusion, early propagation of Princess 77 bermudagrass resulted in complete coverage with a denser root system at the end of the growing season, regardless of the water quality or irrigation system used. If propagated early, subsurface drip‐irrigated bermudagrass did not require supplemental irrigation from a temporary sprinkler system to successfully establish.

Influence of straw mulching on soil water/salt movement and cotton root distribution under drip irrigation

干旱区棉田残膜污染日益严重, 秸秆覆盖能从根本上杜绝农田残膜增量。为探索秸秆覆盖代替塑料薄膜与滴灌结合的可行性, 需了解秸秆覆盖对滴灌棉田土壤水盐分布及棉花根系的影响特点, 同时探索耕作层以下30 cm处埋设一层秸秆进行深层秸秆覆盖与滴灌结合的效果。本文采用测坑试验研究了3种秸秆覆盖方式(表层覆盖、30 cm深层覆盖和无覆盖)与滴灌结合在2种土壤条件下(非盐碱土和盐碱土), 棉花根系分布稳定后的絮期土壤水盐运移及棉花根系分布特征。结果表明: 表层覆盖对于土壤整体保水性较好, 能有效抑制耕层水分散失和盐分聚集; 30 cm深层覆盖整体保水性优于无覆盖, 相对表层覆盖仅在秸秆层以下靠近滴灌带的有限范围内具有优势, 并显著提高耕层以下土壤水分含量, 但在棉花絮期对于盐分抑制作用不明显。秸秆覆盖通过对水盐运动的影响而显著影响棉花根系分布, 尤其对深层根系分布影响更大。非盐碱土条件下, 0~28 cm土层, 无覆盖处理根长密度、根重密度、根长密度比重均最大, 表层覆盖根长密度最小, 但根重比重最大, 30 cm深层覆盖根重密度最小; 在28~70 cm土层, 30 cm深层覆盖根长密度最大, 表层覆盖根长密度最小, 但根长密度比重最大, 无覆盖根长密度比重最小, 其中在28~56 cm土层30 cm深层覆盖根重密度和根重比重均最大。盐碱土条件下, 0~28 cm土层, 表层覆盖与30 cm深层覆盖根长密度和根长比重均高于无覆盖处理, 同时表层覆盖根重密度最高, 30 cm深层覆盖根重密度和根重比重均最低; 在28~70 cm土层情况相反, 30 cm深层覆盖处理根重比重最大, 但根重密度最小。说明表层覆盖可促进非盐碱土及盐碱土耕作层根系发育, 30 cm深层覆盖限制上层根系发育, 但促进30 cm以下土层根系发育, 在盐碱逆境下秸秆覆盖可促进根系向更细更长方面发育。秸秆覆盖与滴灌结合在干旱区具有良好应用前景。

Soil water status and root distribution across the rooting zone in maize with plastic film mulching

Knowledge on rooting systems and soil water status across rooting zones is essential in developing effective cropping systems. This study determined (i) the temporal and spatial growth patterns of roots in maize under different film mulching systems, (ii) the effect of film mulching on soil water status at various depths in a semiarid area. We hypothesized that (1) rooting systems and soil water profiles varied with different mulching systems, and (2) full-film mulching on double ridges-furrows increases root growth and improves soil water profile in semiarid areas. Maize (cv. Shengdan 16) was grown in five mulching systems in northwestern China (35°42′N, 107°20′E), in 2008 and 2009. Maize plants rooted to 160cm deep, but the majority of roots were in the 0–30cm depth with root volume decreasing substantially with depth. Maize in the full-film mulching (FF) systems had significantly greater root weight density (RWD), root length density (RLD), and root diameter compared to half-film mulching (HF) or the flat planting with unmulched check (CK). Maize in the FF system achieved the greatest RWD in the 30–60 and 90–100cm depths at the tasselling stage and in the 120–150cm soil depth at the filling stage. Compared to the CK, the FF treatment significantly improved soil water content in the 0–160cm depth, and consequently, increased maize grain yield by 81% in 2008 and 92% in 2009. Full-film mulching is an effective, sustainable cropping system for maize production in semiarid areas because of the improved rooting systems, enhanced soil water content at different soil depths, and increased crop productivity.

Effects of Vesicular Arbuscular Mycorrhizae and Applied Phosphorus through Targeted Yield Precision Model on Root Morphology, Productivity, and Nutrient Dynamics in Soybean in an Acid Alfisol

A field experiment was conducted in a phosphorus (P)–deficient acidic Alfisol in northwestern Himalayas to study the effect of three vesicular arbuscular mycorrhizae (VAM) cultures [VAML, local VAM culture (Glomus mosseae) developed by CSK Himachal Pradesh Agricultural University, Palampur, India; VAMT, VAM culture (Glomus intraradices) developed by Centre for Mycorrhizal Research, The Energy and Resources Institute (TERI), New Delhi, India; and VAMI, VAM culture (Glomus mosseae) developed by Indian Agricultural Research Institute (IARI), New Delhi, India] on growth, productivity, and nutrient dynamics in rainfed soybean. Plant height, aboveground dry matter, root dry matter, total dry matter, root length, root weight density, Rhizobium root nodule count, root colonization, yield attributes, yield, and nutrient uptake of soybean increased consistently and significantly with increase in inorganic P levels from 25 to 75% of recommended P2O5 dose based on targeted yield precision model coupled with various VAM cultures. VAMT (Glomus intraradices) at each P level showed its superiority over VAMI and VAML. Sole application of any of the three VAM cultures produced similar growth and development parameters as well as grain yield (18.68 to 19.08 q ha−1) as produced through farmers’ practice (nitrogen at 20 kg ha−1), indicating that VAM has a vital role in root morphology and nutrient dynamics in a soil–plant system, though significantly greater productivity was obtained with 100% of the recommended P2O5 dose based on soil-test crop response (STCR) precision model without VAM inoculation. Targeted grain yield of soybean (25 q ha−1) was achievable with 75% of the recommended P2O5 dose applied with any of the three VAM fungi cultures without impairing soil fertility, thereby indicating that VAM fungi can save about 25% P fertilizer in soybean in P-deficient acidic Alfisols of northwestern Himalayas.