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Labile organic carbon (C) in soil can act as a sensitive indicator of its quality, and understanding its response to crop residue incorporation rates is critical to increase soil C storage by residue return in conjunction with chemical fertilisation. A 30-year field experiment was carried out to study the effects of various rates of maize residue return on soil organic C fractions in the presence of chemical fertilisers in a wheat-maize cropping system in north-central China. Studies included a no-fertiliser and no-residues control (CK) and maize residue return at rates of 0 (S0), 2250 (SI), 4500 (S2), and 9000 kg [ha.sup.-1] (S3) using chemical fertilisers. Soil total organic C (TOC) and labile organic C fractions were determined. The S0 treatment increased soil microbial biomass C (MBC), KMn[O.sub.4]-oxidisable C (KMn[O.sub.4]-C), and TOC, but did not change water-soluble organic C (WSOC), light fraction organic C (LFOC), and particulate organic C (POC), relative to CK. All organic C fractions did not differ between S0 and S1; however, S2-S3 increased MBC, WSOC, LFOC, POC, KMn[O.sub.4]-C, and TOC by 31.8-41.0%, 17.7-28.6%, 33.9-81.3%, 35.3-82.4%, 19.3-42.8%, and 9.7-20.4% compared with S0 respectively. The KMn[O.sub.4]-C had the highest correlation with TOC, with LFOC and POC showing higher sensitivity to different residue-return rates. Redundancy analysis showed that LFOC, POC, and KMn[O.sub.4]-C were mainly affected by residue-C and root-C, while MBC was closely correlated with rhizodeposition-C levels. Overall, low rates of residue return did not affect soil labile organic C and TOC, with they only started to increase significantly when annual residue return exceeded 4500 kg [ha.sup.-1] under chemical fertilisation; and the rate of increase for labile organic C was found to be higher than for non-labile C as residue inputs were increased.Additional keywords: crop residues, residue incorporation, soil carbon sequestration, soil labile organic carbon, soil quality.Received 3 May 2018, accepted 11 October 2018, published online 13 November 2018, IntroductionSoil organic carbon (SOC) is a potential sink for atmospheric carbon (C), and its maintenance plays an important role in ensuring soil quality and crop productivity (Kundu et al. 2007; [...]

Abstract: Tropospheric ozone is considered to be the most phytotoxic air pollutant because of its oxidizing power. The main objective of this study was to analyze the effect of intra- [...]

The effect of different nitrogen (N) management strategies (i.e. N rate; 0, 25, 50, 100 kg [ha.sup.-1], split N application, foliar N application, legume precropping) were assessed for how they may reverse the reduction of grain protein concentration (GPC) under elevated C[O.sub.2] (eC[O.sub.2]; 550 [micro]mol [mol.sup.-1]) of wheat (cv. Yitpi) using the Australian Grains Free Air C[O.sub.2] Enrichment facility. GPC did not increase significantly under eC[O.sub.2] for most of the N management strategies assessed when compared with ambient C[O.sub.2] (a C[O.sub.2]; 390 [micro]mol [mol.sup.-1]). Grain yield of cv. Yitpi under aC[O.sub.2] increased by 43% (P< 0.001) with application of 100 kg N [ha.sup.-1] when compared with 0 kg N [ha.sup.-1] at sowing; this response was approximately double (82%) when 100 kg N [ha.sup.-1] was applied under eC[O.sub.2] conditions. Under aC[O.sub.2] conditions, by adding 100 kg N [ha.sup.-1] at sowing, the GPC increased by 37% compared with the GPC at N0; whereas under eC[O.sub.2] conditions, by adding the same quantity of N fertiliser, the GPC increased by only 28%. The highest level of N applied (100 kg [ha.sup.-1]), chosen for economic and practical reasons in a low-rainfall, yield-limiting environment, was lower than that reported in other global studies (250-350 kg [ha.sup.- 1]). In a low-rainfall, yield-limiting environment, it is not practical to increase GPC by applying N alone; new cultivars may be required if grain growers are to maintain grain protein (and functionality) in the future as C[O.sub.2] levels continue to increase. Additional keywords: Australian Grains Free Air C[O.sub.2] Enrichment (AGFACE), nitrogen management., Introduction Atmospheric carbon dioxide (C[O.sub.2]) levels have risen from 280|[micro]mol [mol.sup.-1] in the 1750s to an unprecedented level of over 400 [micro]mol [mol.sup.-1] in 2016 (Prentice et al. 2001; Hatfield [...]

Two groups of six spring bread wheat varieties with either high or low grain yield under the dry conditions of Central and Northern Kazakhstan were selected for analysis. Experiments were set up with the selected wheat varieties in controlled environments as follows: (1) slowly progressing drought imposed on plants in soil, (2) rapid dehydration of whole plants grown in hydroponics, (3) dehydration of detached leaves, and (4) ABA treatment of whole plants grown in hydroponics. Representatives of two different families of transcription factors (TFs), TaDREB5 and TaNFYC-A7, were found to be linked to yield-under-drought using polymorphic Amplifluor-like SNP marker assays. qRT-PCR revealed differing patterns of expression of these genes in the leaves of plants subjected to the above treatments. Under drought, TaDREB5 was significantly up-regulated in leaves of all high-yielding varieties tested and down-regulated in all low-yielding varieties, and the level of expression was independent of treatment type. In contrast, TaNFYCA7 expression levels showed different responses in the high- and low-yield groups of wheat varieties. TaNFYC-A7 expression under dehydration (treatments 2 and 3) was higher than under drought (treatment 1) in all high-yielding varieties tested, while in all low-yielding varieties the opposite pattern was observed: the expression levels of this gene under drought were higher than under dehydration. Rapid dehydration of detached leaves and intact wheat plants grown in hydroponics produced similar changes in gene expression. ABA treatment of whole plants caused rapid stomatal closure and a rise in the transcript level of both genes during the first 30 min, which decreased 6 h after treatment. At this time-point, expression of TaNFYC-A7 was again significantly upregulated compared to untreated controls, while TaDREB5 returned to its initial level of expression. These findings reveal significant differences in the transcriptional regulation of two drought-responsive and ABA-dependent TFs under slowly developing drought and rapid dehydration of wheat plants. The results obtained suggest that correlation between grain yield in dry conditions and TaNFYC-A7 expression levels in the examined wheat varieties is dependent on the length of drought development and/or strength of drought; while in the case of TaDREB5, no such dependence is observed. [ABSTRACT FROM AUTHOR]

Maturity traits such as days to heading and days to physiological maturity have a large impact on agronomic characteristics of wheat (Triticum aestivum L.) cultivars grown in specific environments. Extended green leaf and green glume duration after heading in hard red spring wheat have been shown to result in longer grain-fill duration, increased kernel weight, and higher grain yield in dry environments. The genetic relationship between maturity traits, seed quality, and functional bread-making characteristics was investigated for three sets of recombinant inbred lines derived from crosses between hard red spring wheat parents. Early heading date was correlated with increased seed quality as indicated by test weight and kernel weight in all three genetic populations. Days to heading was not consistently correlated with functional quality related to bread-baking. Longer green glume and green leaf duration after heading were typically positively related to seed quality traits including test weight and kernel weight in the three populations. However, increased green leaf and green glume duration after heading were often negatively correlated with functional quality parameters related to bread baking. Our results suggest that selection for long green leaf or green glume duration after heading to stabilize grain yield in a warmer climate may also result in a decrease in breadmaking potential. [ABSTRACT FROM AUTHOR]

Laser land leveling has been increasingly adopted in the irrigated rice (Oryza sativa L.)-wheat (Triticum aestivum L.) cropping system in the state of Haryana (India), located in the north-western Indo-Gangetic Plains. Still, many farmers have applied it to only a fraction of their land. In this study, we used data collected from 621 farm households in Haryana and applied a double-hurdle model for assessing the factors that determine the adoption and intensity of laser-leveling technology. The results show that large land holders are more likely to laser level their farm land; however, we found a negative association between land holdings and the proportion of laser-leveled land. Information about technology through farmer-to-farmer communication and through private traders, participation in agricultural training and membership in local agricultural institutions increased both the likelihood and the intensity of adoption. Our findings call for a closer collaboration among the various stakeholders, specifically to promote farmer-to-farmer communication through increased participation in local institutions and increase the rate of adoption of laser leveling technology. [ABSTRACT FROM AUTHOR]

Purpose: The in situ stabilization of multielement-contaminated agricultural soils has limited effectiveness when using common single amendments. This study examined the use of drinking water treatment residues (WTR), based on (hydr)oxides of Fe, Al, or Mn, as a cost-effective solution to optimize the immobilization of metals (Cd, Pb, Zn) and As.Materials and methods: Trace elements (TE) bioavailability was assessed under semi-controlled conditions in a pot study cultivating winter wheat (Triticum aestivum L. cv. Tiger) until maturity. An Fe-based WTR and a Mn-based WTR, applied at rates of 0.5 and 1% (m/m), were related to effects of lime marl (LM) application. Additionally, a bioassay with earthworms (Dendrobaena veneta) was conducted. Both bioassays were compared with measurements of NH4NO3-soluble, diffusive gradients in thin film (DGT)-available and soil solution TE concentrations, representing well-established surrogates for mimicking the bioavailable element fractions in soil.Results and discussion: The application of the Fe-based WTR reduced As accumulation in vegetative wheat tissues (by up to 75%) and earthworms (by up to 41%), which corresponded with the findings from soil chemical analyses and improved plant growth and earthworm body weight. However, As concentrations in cereal grains were not affected, Cd or Pb accumulation by wheat was not mitigated, and Zn uptake was enhanced. By contrast, the Mn-based WTR effected the greatest reduction in Pb uptake, and lowered Cd transfer to wheat grain (by up to 25%). Neither the NH4NO3-soluble nor DGT-available concentrations matched with Cd and Zn accumulation in plants or earthworms, indicating interferences due to competition for binding sites according to the biotic ligand model.Conclusions: The results obtained in this study suggest that a bioassay with key species prior to field application should be mandatory when designing in situ stabilization options. The application of WTR to an agricultural soil strongly affected TE bioavailability to plants and earthworms. Low application rates tended to improve biomass production of biota. Higher application rates involved risks (e.g., P fixation, TE inputs), and none of the amendments tested could immobilize all targeted elements. [ABSTRACT FROM AUTHOR]

Farmers’ responses to the winter wheat cropping policy in groundwater funnel areas are the key factor in promoting fallow plans. Therefore, this study discusses the farmers’ responses and the influencing factors for the winter wheat fallow policy in the Hebei groundwater funnel area of China by using an ordered multivariate logistic model; it aims to provide a theoretical basis for scientifically and rationally developing a rotation policy in the groundwater funnel area. The results revealed that the number of households, proportion of farmers, per capita area of cultivated land, and machinery used had a negative impact on support for the fallow policy. The dependency ratio and land fragmentation had a significant positive impact on support for the fallow policy. Occupation had the greatest marginal effect on the understanding of the fallow policy and satisfaction with fallow policy compensation, and the dependency ratio has the greatest marginal effect on support for the fallow policy. Finally, this study proposes policy recommendations including the transfer of the surplus labor force, stronger government supervision of fallow policy compensation, stronger cultural education and greater promotion of the fallow policy. [ABSTRACT FROM AUTHOR]

The effects of elevated O3 (EO3) on greenhouse gas (GHG) emissions and global warming potential (GWP) from wheat systems with differential O3 sensitivity are not well understood. The nitrous oxide (N2O), methane (CH4), and carbon dioxide (CO2) emissions from cropping (CP) and bare soil or root-free (BS) plots, GWP, GWP per unit yield, and biomass and its allocation to belowground between O3-sensitive (cultivar YN19) and tolerant (cultivar Y15) wheat (Triticum aestivum L.) systems were investigated at EO3 and ambient O3 (AO3) with an openair O3 fumigation system. Results indicated that a 50% elevation above AO3 significantly reduced belowground biomass of the two cultivars. The EO3 significantly increased the cumulative emissions of CO2 and N2O but did not change that of CH4 in YN19 CP. For BS, it significantly increased the emission of CO2 but decreased that of CH4 and N2O. The EO3 significantly increased the GWP and GWP per unit yield in YN19 CP but reduced the GWP in BS. The O3 sensitivity of wheat cultivar affected the responses of gaseous C and N emission, GWP and GWP per unit yield to EO3. The O3-sensitive wheat cultivar would release more freshly assimilated C, increasing cumulative GHG emissions, GWP and GWP per unit yield in response to O3 stress, when compared to the O3 O3-tolerant wheat cultivar. Our results suggest that EO3 may impair soil C and N sequestration in an O3 O3-sensitive wheat-soil system in view of lower root biomass but higher CO2 and N2O emissions under EO3. [ABSTRACT FROM AUTHOR]

The winter wheat (Triticum aestivum L.)-fallow (WF) dryland production system employed in the Central Great Plains has evolved in the past 40 yr to include a diversity of other crops, with a reduction in fallow frequency. Wheat remains the base crop for essentially all cropping systems. Decisions to change a farming system benefit from information about average wheat yields, yield stability, and probabilities of obtaining a specified minimum wheat yield. The objective of this experiment was to quantify wheat yields, yield stability, and the probability of obtaining a specified minimum yield in eight dryland rotational systems varying in cropping intensity. The study was conducted over a 24-yr period at Akron, CO. Yield stability was characterized with six stability measures. The probability of obtaining a yield less than 1500 kg ha-1 was also calculated for each rotation. Wheat yields were greatest in rotations where wheat followed a fallow period and least where wheat followed millet production. Rotations ranked from most stable to least stable wheat production (averaged over the six stability measures) were WF(NT), WF(CT), WMF, WCMP, WCM, WCMF, WM, and WCF. The probability of producing <1500 kg ha-1 was very low for rotations with wheat following fallow (about 0.03) and much higher for wheat following pea (0.35) or millet (0.48-0.58). The study results identified the WMF rotation as an intensified rotation with relatively high average wheat yields and yield stability. [ABSTRACT FROM AUTHOR]

Leaching of nitrogen (N) in intensive irrigated agriculture can be a significant loss pathway. Though many studies have focussed on losses of mineral N, and in particular nitrate, dissolved organic N (DON) has received less coverage. In the present study, over a 5-year period (2008-2013), 740 kg N [ha.sup.-1] fertiliser was applied to an irrigated cotton-wheat-maize rotation on a cracking clay (grey Vertosol). Deep drainage from the undisturbed soil profile at the site was measured at 2.1 m below the soil surface using a variable tension lysimeter. In total, 108 mm of drainage occurred during the 5 years and the majority of the drainage and the irrigations occurred during the cotton seasons. The majority of the N loss occurred during the first 3-4 irrigations and neither the N loss nor its composition were affected by the product or timing of the fertiliser application. The N in the drainage was composed of 12.8 kg N[O.sub.x]-N [ha.sup.-1], 8.7 DON-N and 0.1 N[H.sub.4.sup.+]-N kg [ha.sup.-1], which shows that DON is an important component (40%) of the deep drainage N from irrigated Vertosol cotton production systems. Overall the total N flux lost via deep drainage represents 3% of the applied N fertiliser. Additional keywords: ammonium, DON, nitrate, tension lysimeter, Vertosol., Introduction Nitrogen (N) fertiliser is required to produce high yielding dryland and irrigated crops; without this fertiliser it is estimated that only 60% of the world's current population could be [...]

Human selection, changes in environmental conditions and management practices drove the phenotypic trajectory of crops during domestication. The characterization of the crop domestication syndrome lies mostly on reproductive characters. However, biophysical and ecophysiological constraints during vegetative growth are also at play and can strongly impact crop phenotypes. It has been argued that a broadened examination of crop phenotypes through a functional trait-based lens should improve our understanding of the domestication syndrome., We used a collection of 39 genotypes representative of key steps during tetraploid wheat domestication and grew them in a common garden experiment. We quantified the vegetative phenotype of each genotype through the measurements of 13 functional traits related to root, leaf and whole-plant dimensions., In modern cultivars, compared to ancestral forms, leaf longevity was shorter, while net photosynthetic rate, leaf production rate and nitrogen content were higher. Modern cultivars had a shallower root system and exhibited a larger proportion of fine roots, preferring to invest biomass above-rather than below-ground. We found ancestral forms to be integrated phenotypes characterized by coordination between above- and below-ground functioning. Conversely, in modern forms, human selection appeared to have broken this coordination and to have generated a new type of network of trait covariations., Synthesis and applications. The examination of leaf, root and whole-plant traits of wheat accessions indicated a strong shift in plant functional strategies over the course of domestication. Elite genotypes tended to better optimize resource-use acquisition strategies than ancestral ones. The characterization of the crop phenotype based on vegetative traits thus suggests a much more complete domestication syndrome. Our findings highlight the benefits of using a functional trait-based characterization of crop phenotypes to document the extent of domestication syndrome and to further advance the agroecological management of cereals. [ABSTRACT FROM AUTHOR]

Scarcity of water is a severe constraint, which hinders the wheat productivity worldwide. However, foliage application of osmoprotectants may be useful in reducing the drought-induced yield losses in wheat ( Triticum aestivum L.). In this study, potential of foliage applied osmoprotectants (proline, gamma-aminobutyric acid) in improving the performance of bread wheat against terminal drought was evaluated. Both proline and gamma-aminobutyric acid ( GABA) were foliage applied at 50, 100 and 150 mg/L at anthesis stage ( BBCH-identification code- 61), in two bread wheat cultivars viz. Mairaj-2008 and BARS-2009. After 1 week of foliage application of these osmoprotectants, drought was imposed by maintaining the pots at 35% water holding capacity. Imposition of drought caused significant reduction in the grain yield of both tested bread wheat cultivars; nonetheless, foliage applied osmoprotectants at either concentration improved the chlorophyll contents, accumulation of proline, glycinebetaine and total soluble phenolics and reduced the malondialdehyde contents, which resulted in better stay green, maintenance of grain weight and grain number under drought stress, thus resulting in better grain yield, water-use efficiency and transpiration efficiency in both wheat cultivars. However, foliage applied proline at 150 mg/L, and GABA at 100 mg/L was most effective than other concentrations of these osmoprotectants. Performance of cultivar Mairaj-2008 was quite better than cultivar BARS-2009. In crux, foliar application of proline and GABA at pre-optimized rate can be opted as a shotgun approach to improve the performance of wheat under terminal drought. [ABSTRACT FROM AUTHOR]

Wheat is highly prone to terminal heat stress (HS) under late-sown conditions. Delayed-sowing is one of the preferred methods to screen the genotypes for thermotolerance under open field conditions. We investigated the effect of terminal HS on the thermotolerance of four popular genotypes of wheat i.e. WR544, HD2967, HD2932, and HD2285 under field condition. We observed significant variations in the biochemical parameters like protein content, antioxidant activity, proline and total reducing sugar content in leaf, stem, and spike under normal (26 ± 2°C) and terminal HS (36 ± 2°C) conditions. Maximum protein, sugars and proline was observed in HD2967, as compared to other cultivars under terminal HS. Wheat cv. HD2967 showed more adaptability to the terminal HS. Differential protein-profiling in leaves, stem and spike of HD2967 under normal (26 ± 2°C) and terminal HS (36 ± 2°C) showed expression of some unique protein spots. MALDI-TOF/MS analysis showed the DEPs as RuBisCO (Rub), RuBisCO activase (Rca), oxygen evolving enhancer protein (OEEP), hypothetical proteins, etc. Expression analysis of genes associated with photosynthesis (Rub and Rca) and starch biosynthesis pathway (AGPase, SSS and SBE) showed significant variations in the expression under terminal HS. HD2967 showed better performance, as compared to other cultivars under terminal HS. SSS activity observed in HD2967 showedmore stability under terminal HS, as compared with other cultivars. Triggering of different biochemical parameters in response to terminal HS was observed to modulate the plasticity of carbon assimilatory pathway. The identified DEPs will enrich the proteomic resources of wheat and will provide a potential biochemical marker for screening wheat germplasm for thermotolerance. The model hypothesized will help the researchers to work in a more focused way to develop terminal heat tolerant wheat without compromising with the quality and quantity of grains. [ABSTRACT FROM AUTHOR]

Climate change is impacting the human life and allied activities throughout the world. In few regions, the impact is positive while in most of the others, it is negative. Pakistan is among those regions which are experiencing the change in climate in all parts of its territory. The current study is intended to investigate the impact of climate change on rice crop in rice-wheat zone of Pakistan. Data were collected from three districts of Punjab province and two districts of Sindh province. The selection of districts was based on the relative rice production rank of the districts in the country. Multivariate Linear Regression approach was applied to analyze the data. Three different models were used to investigate the impact of climate change on rice crop. The results showed that both rise in temperature and precipitation have positive impacts on rice crop. The present study could not quantify the level of increment in temperature and rainfall and its benefits for rice crop. There is further scope to identify the level beyond which it started impacting the crop negatively. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of the Chinese Society of Agricultural Engineering is the property of Chinese Society of Agricultural Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nonylphenol polyethoxylates (NPEOs) are a group of surfactants that are widely used in industrial and household products and often detected in the environment. The metabolite of NPEOs, named nonylphenol (NP), has proven to be an endocrine disruptor, and its environmental behavior and eco-toxicity have been widely investigated in previous studies. However, to the best of our knowledge, insight into the toxicity differences of NP and NPEOs on important crops remains limited. Therefore, this study investigated the comparative toxicity of NP, nonylphenol-4-ethoxylate (NP4EO), and nonylphenol-10-ethoxylate (NP10EO) on wheat seedlings using hydroponic experiments. The results indicated that NP is most toxic to wheat followed by NP4EO, and NP10EO is the least toxic to wheat. The adverse effects of NP on wheat were observed for all the tested parameters including germination, shoot length, root length, chlorophyll, lipid peroxidation, and enzymatic activities. To gain insight into the molecular response, we analyzed the transcript abundance of SOD-Cu/Zn and CAT with NP, NP4EO, and NP10EO exposure using quantitative real-time PCR. The data revealed that both genes exhibited up- or down-regulated expression patterns that were consistent with the activities of the two enzymes. This result further conformed that NP is most toxic to wheat plants. [ABSTRACT FROM AUTHOR]

Climate change and variability has the potential to impact crop growth by altering components of a region's water balance. Evapotranspiration driven by higher temperatures can directly increase the demand of irrigation water, while indirectly decreasing the length of the annual crop growth period. The accompanying change in precipitation also affects the need to supply irrigation water. This study focuses on the spatial and temporal variation of historical and future irrigation water requirements of winter wheat ( Triticum aestivum L.) in the Haihe River Basin, China. Irrigation water requirement is estimated using a simple water balance model. Climate change is incorporated by using predicted changes in daily precipitation and temperature. Changes in evapotranspiration and crop phenophase are then calculated for historical and future climate. Over the past 50 years, a decrease in total net irrigation water requirement (NIR) was observed mainly due to a reduction in the crop growth period length. The NIR is shown to decrease 2.8∼6.9 mm with a 1-day reduction in growth period length. In the future, sowing period will come later and the heading period earlier in the year. The NIR in November, March and April is predicted to increase, especially in April. Increased NIR can result in increased water deficit, causing negative impacts on crop yield due to water stress. In the future, more attention should be paid to water resource management during the annual crop growth period of winter wheat in the Haihe River Basin. [ABSTRACT FROM AUTHOR]

The Water and Nitrogen Management Model (WNMM) was applied to simulate nitrous oxide (N20) emissions from a wheat-cropped Vertosol under long-term management of no-till, crop residue retention, and nitrogen (N) fertiliser application in southern Queensland, Australia, from July 2006 to June 2009. For the simulation study, eight treatments of combinations of conventional tillage (CT) or no-till (NT), stubble burning (SB) or stubble retention (SR), and N fertiliser application at nil (ON) or 90 (90N) kg N/ha x year were used. The results indicated that WNMM satisfactorily simulated the soil water content of the topsoil, mineral N content of the entire soil profile (0-1.5 m), and [N.sub.2]O emissions from the soil under the eight treatments, compared with the corresponding field measurements. For simulating daily N20 emissions from soil, WNMM performed best for the treatment CT-SB-90N ([R.sup.2] = 0.48, P Additional keywords: mitigation, N20 emissions, wheat cropping, Vertosol, WNMM simulation., Introduction Nitrous oxide ([N.sub.2]O) is one of the potent greenhouse gases contributing to global warming (IPCC 2006). According to FAO/IFA (2001) and Mosier et al. (1998), ~57% of total global [...]

Copyright of Jordan Journal of Agricultural Sciences is the property of University of Jordan and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Taprooting crop species are capable of creating soil biopores (>2 mm in diameter) in the subsoil due to their large root size and deep-rooting habit. The aim of this study was to quantify root growth dynamics of wheat in the subsoil during its complete growth season as affected by crop sequence. Temporal observation on root length (km m) of wheat inside and outside of biopores at four growth stages (tillering, booting, anthesis, and milk) was conducted by using the profile wall method under the two crop sequence treatments involving two precrops, viz., chicory and tall fescue. Frequency of biopore presence measured on vertical profile walls depended on the choice of precrops in which chicory precrop resulted in higher frequency (2.3 %) compared with tall fescue (1.5 %). Root length of wheat measured inside biopores was significantly higher when grown after chicory (0.024 km m) in comparison to tall fescue (0.006 km m). On average, root length outside biopores after growing chicory was 45.9 % higher than tall fescue until the stage of anthesis. We conclude that at the site under study biopores as pathways for rapid root growth into deeper soil layers allow roots to re-enter and explore the subsoil. Thus, cereals cultivated in rotation with taprooted crops can draw benefit from enhanced uptake of water and nutrients from deeper soil layers during early growth stages. Model simulations with various abiotic and biotic factors will be helpful to reveal the direct evidence of biopore-root-shoot relationship in the future. [ABSTRACT FROM AUTHOR]