Effects of elevated atmospheric CO2 on grain quality of wheat

Wheat (Triticum aestivum L.) is one of the most important agricultural crops worldwide. Due to its high content of starch and unique gluten proteins, wheat grain is used for many food and non-food applications. Although grain quality is an important topic for food and feed as well as industrial processing, the consequences of future increases in atmospheric carbon dioxide (CO₂) concentrations on quality parameters such as nutritional and bread-making rheological properties are still unclear. Wheat productivity increases under CO₂ enrichment. Concomitantly, the chemical composition of vegetative plant parts is often changed and grain quality is altered. In particular, the decrease in grain protein concentration and changes in protein composition may have serious economic and health implications. Additionally, CO₂ enrichment affects amino acid composition and the concentrations of macro- and micro-elements. However, experimental results are often inconsistent. The present review summarises the results from numerous CO₂ enrichment experiments using different exposure techniques in order to quantify the potential impacts of projected atmospheric CO₂ levels on wheat grain yield and on aspects of grain composition relevant to processing and human nutrition.     

Increasing atmospheric CO2 modifies durum wheat grain quality and pasta cooking quality

The present study focused on the quality traits of durum wheat grains (protein and content, gluten content, yellow pigment content), semolina (gluten index and yellow index) and pasta (firmness, yellow index, cooking time) obtained from 12 durum wheat genotypes grown under elevated atmospheric CO₂ concentration in an open field Free Air CO₂ Enrichment (FACE) experiment. The aims were to evaluate the impact of elevated CO₂ on durum wheat pasta making related traits as well as investigate genetic differences existing in a panel of old and modern cultivars. The protein content showed a not significant decrease (7%), the GC decreased significantly (13.3%), while the GI showed an increasing significant tendency (14%). The overall pasta quality (firmness and weight) worsened in ELE. Correlation between all traits and pasta firmness demonstrated that the decrease in pasta firmness under ELE was correlated with GPC and GC while it was not with the GI. All varieties, although to different extent, showed lower pasta firmness values compared to the ambient condition. Among the varieties tested, some were more sensitive than others to the increased atmospheric CO₂ concentration, a finding that can be exploited by breeding for designing novel genotypes with lower sensitivity to increased atmospheric CO₂.     

Wheat grain quality under increasing atmospheric CO2 concentrations in a semi-arid cropping system

We investigated wheat (Triticum aestivum) grain quality under Free Air CO₂ Enrichment (FACE) of 550 ± 10% CO₂ μmol mol⁻¹. In each of two full growing seasons (2008 and 2009), two times of sowing were compared, with late sowing designed to mimic high temperature during grain filling. Grain samples were subjected to a range of physical, nutritional and rheological quality assessments. Elevated CO₂ increased thousand grain weight (8%) and grain diameter (5%). Flour protein concentration was reduced by 11% at e[CO₂], with the highest reduction being observed at the late time of sowing in 2009, (15%). Most of the grain mineral concentrations decreased under e[CO₂] - Ca (11%), Mg (7%), P (11%) and S (7%), Fe (10%), Zn (17%), Na (19%), while total uptake of these nutrients per unit ground area increased. Rheological properties of the flour were altered by e[CO₂] and bread volume reduced by 7%. Phytate concentration in grains tended to decrease (17%) at e[CO₂] while grain fructan concentration remained unchanged. The data suggest that rising atmospheric [CO₂] will reduce the nutritional and rheological quality of wheat grain, but at high temperature, e[CO₂] effects may be moderated. Reduced phytate concentrations at e[CO₂] may improve bioavailability of Fe and Zn in wheat grain.     

大气CO2浓度升高对大豆不同器官碳水化合物积累的影响

研究大气CO2浓度升高对非结构性碳水化合物分配积累的影响,可填补大豆气候变化生物学的部分空白,也又可为选育适应未来气候条件的大豆品种以及高产栽培策略提供理论支撑。本研究以大豆品种紫花4（ZH4）、小黄金（XHJ）、丰收10号（FS10）和嫩丰1号（NF1）为材料,利用开顶式气室模拟研究大气CO2浓度升高到550 μmol·mol-1对大豆鼓粒期（R5）和完熟期（R8）不同器官光合产物积累和分配的影响。结果表明：大气CO2浓度升高对不同器官C浓度的影响存在品种间差异。除了R5期XHJ叶片和R8期NF1根系,大豆不同器官C浓度表现出增加的趋势。大气CO2浓度升高显著增加R5期大豆叶片可溶性糖浓度（33.4%~90.0%）;而蔗糖和淀粉浓度对大气CO2浓度升高的响应受到品种因素的影响,XHJ叶片蔗糖浓度和FS10叶片淀粉浓度分别降低9.7%和13%,其余品种叶片蔗糖和淀粉浓度显著增加。在R8期,大气CO2浓度升高后大豆籽粒可溶性糖、蔗糖和淀粉浓度均表现出增加的趋势,籽粒可溶性糖浓度平均增加22%。同R5期相比,R8期大豆营养器官的碳水化合物浓度显著下降,表明营养器官碳水化合物的再利用能力决定大豆产量的增幅。ZH4、XHJ和FS10的产量平均增加32.7%,而NF1产量增加不显著。大气CO2浓度升高显著提高了大豆植株C的同化能力,但不同品种间差异显著。“源端”叶片蔗糖转化能力强,“流端”茎秆装卸同化产物效率高,以及“库强”较大的大豆品种在未来大豆品种选育和生产中应该是重点关注对象。     

Critical and minimum N contents for development and growth of grain sorghum

This paper quantifies the effects of N-stress on development and growth of sorghum by identifying critical values for stover N% (SNC) and specific leaf nitrogen (SLN) for a range of physiological processes (rates of leaf appearance, leaf expansion, leaf area increase, and biomass accumulation). It also compares the merits of the SNC and SLN approach for implementation in the N-routines of crop growth simulation models. Data from experiments covering a range of nitrogen treatments, grown at three contrasting locations in Australia, were used in the analyses. For the rate of biomass accumulation, the critical and minimum SLN were constant for most of the growing season, except for early stages prior to approximately panicle initiation. For SNC, however, the critical and minimum values continued to decline throughout the growing season, although the decline was limited at later development stages. During the stage of leaf growth, the critical N content was similar for all processes considered. Although critical SLN was less sensitive to development stage than SNC, identification of a critical SLN was hampered if environmental effects on specific leaf area were present. The merit of each approach in simulation models will depend upon their ability to capture genotypic differences in N-dynamics.     

Determination of grain number in sorghum

Grain number is an important component of grain yield in sorghum. Research in wheat and maize has indicated a dependency of grain number on the crop or panicle growth rate around anthesis (CGR_a and PGR_a respectively), but little quantitative information is available for sorghum. The aim of this paper was firstly to quantify the effect of CGR_a and PGR_a on grain number and secondly, to identify other parameters that could be used as substitutes for PGR_a. Analyses included data from a number of experiments, covering a range in nitrogen and drought treatments and including both tall (single dwarf) and short (triple dwarf) hybrids. CGR_a and SGR_a (stem growth rate) were calculated from the derivative of a curvilinear function fitted to experimental data, and PGR_a was obtained by subtraction of SGR_a from CGR_a. Results indicated a linear relationship between grain number and CGR_a, but the slope differed for tall and short hybrids. This was due to a difference in the proportion of dry matter allocated to the reproductive organs around anthesis (P_r), as PGR_a was closely related to grain number, irrespective of crop height. Since panicle dry mass at maturity (excluding grain) was closely correlated with reproductive biomass shortly after anthesis, this indicator represents an integration of panicle growth during the critical period for yield determination in sorghum (i.e. flag leaf until start of grain filling). Panicle biomass at maturity (excluding grain) was thus also linearly related to grain number, and the relationship was independent of crop height and of the timing, severity, or type of stress. Our results indicate that panicle mass at maturity could provide an alternative to PGR_a for the estimation of grain number.     

Nutritional quality of proteins in grain sorghum

Grain sorghum is low in protein content Lysine, threonine and tryptophan are the limiting amino acids in the proteins of grain Sorghum. Protein fractionation studies have shown that prolamine and glutelin are the principal protein fractions. Increase in protein content of grain Sorghum leads to an increase in prolamin fraction and decreases the nutritional quality. Environmental factors such as location, chemical fertilizers, plant population and chemical treatments influence the protein content and amino acid pattern. The presence of tannins in grain Sorghum reduces the digestibility and nutritional quality.

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Zusammenfassung Die Caryopsen von Sorghum-Hirse haben einen geringen Eiweißgehalt. Lysin, Threonin und Tryptophan sind die limitierenden Aminosäuren ihres Eiweißes. Untersuchungen über die Eiweiß-Frankrionierung haben ergeben, daß Prolamin und Glutelin die Haupt-Eiweißfranktionen sind. Erhöhung des Eiweißgehaltes von Sorghum-Korn führt zur Erhöhung der Prolamin-Fraktion und damit zum Abfall der Biologischen Eiweißwertigkeit. Umweltfaktoren, wie Standort, chemische Dünger, Pflanzendichte und chemische Pflanzen-Behandlung beeinflussen den Eiweißgehalt und die Art des Aminosäuremusters. Anwesenheit von Tanninen (Gerbstoffen), im Sorghum-Korn reduzieren seine Verdaulichkeit und die Biologische Eiweißwertigkeit.

     

Milling and cooking of hybrid sorghum grain

Fourteen commercial hybrid cultivars of sorghum grain were examined for physical characteristics before and after being milled by abrasion. Milling to 10% total loss in weight resulted in the pigments in the pericarp being effectively removed but colour spots on the hilar and germ remained on most cultivars and the testa was exposed on some cultivars. Milling showed that the cultivars were of varying degrees of hardness but all gave >80% yield of unbroken kernels with the germ attached. The milled grains were boiled like rice but the cooking time was high for all cultivars (range 57–64 min) although the water uptake and swelling of the cooked grain was satisfactory and the solids lost during cooking was low.     

Interactions between elevated atmospheric CO2 and defoliation on North American rangeland plant species at low and high N availability

Although common disturbances of grazing lands like plant defoliation are expected to affect their sensitivity to increasing atmospheric CO₂ concentration, almost no research has been conducted to evaluate how important such effects might be on the direct responses of rangelands to CO₂. This growth chamber experiment subjected intact plant–soil cylinders from a Wyoming, USA, prairie to a 3‐way factorial of CO₂ (370 vs. 720 μL L^?1), defoliation (non‐clipped vs. clipped) and soil nitrogen (control vs. 10 g m^?2 added N) under simulated natural climatic conditions. Above‐ and below‐ground biomass and N dynamics of the functional groups C₃ grasses, C₄ grasses and forbs were investigated. CO₂ and defoliation had independent influences on biomass and N parameters of these rangeland plants. Growth under CO₂‐enriched conditions enhanced above‐ground biomass 50% in C₃ grasses alone, while shoot N concentration declined 16% in both C₃ and C₄ grasses. Plant‐soil ¹⁵N uptake was unaffected by CO₂ treatment. In contrast, defoliation had no effect on biomass, but increased tissue N concentration 29% across all functional groups. Without additional N, forage quality, which is in direct relation to N concentration, will decline under increasing atmospheric CO₂. Increased dominance of C₃ grasses plus reduced forage quality may necessitate changes in grazing management practices in mixed‐species rangelands.     

Characterization of sorghum grain and evaluation of sorghum flour in a Chinese egg noodle system

Sorghum is a gluten free grain that has potential to be used as an alternative to wheat flour for the Celiac Sprue market. There are thousands of sorghum lines that have not been characterized for grain, flour or end product quality. The objective of the research was to gain an understanding among grain sorghum quality factors and Chinese egg noodles quality. Four sorghum hybrids were characterized and evaluated for kernel characteristics, proximate analysis, flour composition and end product in a Chinese egg noodle system. Kernel size and weight affected the flour particle size and the amount of starch damage. Flour with fine particle size and high starch damage conferred noodles with high firmness and high tensile strength. Water uptake was highest for flour with smaller particle size (38 μm at 50% volume) and higher starch damage (6.14%). Cooking losses for all samples were below 10%. Starch of particle size <5 μm (C-type) contributed to firmer and higher tensile strength noodles. Water absorption was significantly affected by flour particle size, starch particle size and starch damage. Through control of sorghum grain and flour quality characteristics it is possible to manufacture a Chinese egg noodle with good physical attributes.     

Implications of Elevated CO2-Induced Changes in Agroecosystem Productivity

SUMMARY

Since CO₂ is a primary input for crop growth, there is interest in how increasing atmospheric CO₂ will affect crop productivity and alter cropping system management. Effects of elevated CO₂ on grain and residue production will be influenced by crop selection. This field study evaluated soybean [C₃; Glycine max(L.) Merr.] and grain sorghum [C₄; Sorghum bicolor (L.) Moench.] cropping systems managed under conservation tillage practices and two atmospheric CO₂ concentrations (ambient and twice ambient) for three growing seasons. Elevated CO₂ increased soybean and sorghum yield by 53% and 17% increase, respectively; reductions in whole plant water use were also greater for soybean than sorghum. These findings suggest that increasing CO₂ could improve future food security, especially in soybean production systems. Elevated CO₂ increased aboveground residue production by > 35% for both crops; such shifts could complement conservation management by increasing soil surface cover, thereby reducing soil erosion. However, increased residue could negatively impact crop stand establishment and implement effectiveness during tillage operations. Elevated CO₂ increased total belowground dry weight for both crops; increased root proliferation may alter soil structural characteristics (e.g., due to increased number and extent of root channels) which could lead to increases in porosity, infiltration rates, and subsequent soil water storage. Nitrate leaching was reduced during the growing season (due to increased N capture by high CO₂-grown crops), and also during the fallow period (likely a result of altered decomposition patterns due to increased C:N ratios of the high CO₂-grown material). Enhanced crop growth (both above-and be-lowground) under elevated CO₂ suggests greater delivery of C to soil, more soil surface residue, and greater percent ground coverage which could reduce soil C losses, increase soil C storage, and help ameliorate the rise in atmospheric CO₂. Results from this study suggests that the biodegradability of crop residues and soil C storage may not only be affected by the environment they were produced in but may also be species dependent. To more fully elucidate the relationships between crop productivity, nutrient cycling, and decomposition of plant materials produced in elevated CO₂ environments, future studies must address species effects (including use of genetically modified crops) and must also consider other factors such as cover crops, crop rotations, soil series, tillage practices, weed management, and regional climatic differences.     

Simulating grain yield and plant development of ratoon grain sorghum over diverse environments

Crop simulation may provide an inexpensive means to evaluate the feasibility of different cropping practices to optimize productivity and profitability. One practice, ratoon-cropping, may increase productivity and reduce per-unit production costs associated with conservation tillage farming systems in tropical and subtropical regions. sorkam, a dynamic plant growth model for grain sorghum [Sorghum bicolor (L.) Moench], was used to evaluate the potential of rainfed ratoon grain sorghum over diverse climatic regions of Texas. Eleven independent data sets collected in the U.S.A. from sites in Georgia and Texas were used to determine the model's accuracy. The model produced realistic estimates of grain yield for planted, ratoon, and combined (planted + ratoon) crops. Simulated grain yields usually were within 25% of the observed yield for the planted, ratoon, and combined crops with cultivars that produced the highest ratoon grain yield at each location. Ratoon grain yield results of multi-year simulations (10–30 years) from 14 locations over the eastern half of Texas using historic, location-specific, meteorological data indicated that the probability of obtaining ratoon grain yield > 3.0 Mg/ha was confined to the upper coastal plain region of Texas. The area best suited for rainfed ratoon grain sorghum appeared to be confined south and east of a line running from west of Corpus Christi to Beeville to College Station to west of Center, Texas. Use of crop models can play an important role in identifying strengths and weaknesses of potential cropping systems when used in combination with historical climatic data and/or computer weather generators.     

北方地区大豆施肥技术初探

大豆施肥技术是大豆生产的关键技术之一,掌握正确的大豆施肥技术对提高大豆单产和节省生产成本具有十分重要的意义。本文阐述了大豆各种施肥技术和施肥方法,为北方的大豆生产和大豆施肥提供参考依据。     

Efficacy of postemergence herbicides tankmixes in aryloxyphenoxypropionate-resistant grain sorghum

The development of aryloxyphenoxypropionate (APP)-resistant grain sorghum could provide additional opportunities for postemergence herbicide grass control in grain sorghum. Field experiments were conducted in Texas (Bushland, and Yoakum), Kansas (Dodge City, Garden City, Hays, Manhattan, Colby, Ottawa, and Tribune), and South Dakota (Highmore) to evaluate the efficacy of quizalofop tank mixes in APP-resistant grain sorghum. Quizalofop was applied alone or in combination with dicamba, 2,4-D, prosulfuron, 2,4-D + metsulfuron methyl, or halosulfuron methyl + dicamba. Herbicides were applied when sorghum was 12–50 cm in height. Overall weed control was greater when quizalofop was applied with other herbicides than when applied alone. At 2 and 4 weeks after treatment (WAT), large crabgrass [Digitaria sanguinalis (L.) Scop.], giant foxtail (Setaria faberi Herrm.), and green foxtail [Setaria viridis (L.) Beauv.] control were greater than 90% when quizalofop was applied alone or in combination with dicamba, halosulfuron methyl + dicamba, or prosulfuron. Palmer amaranth (Amaranthus palmeri S. Wats.), puncturevine (Tribulus terrestris L.), and tumble pigweed (Amaranthus albus L.) control were greater than 90% in all treatments except when quizalofop was applied alone. Herbicide treatments, except those that included 2,4-D, caused slight to no sorghum injury. Grain sorghum yield was greater for all herbicide treatments compared to the weedy check. This research showed that application of quizalofop in combination with broadleaf weed herbicides provided excellent weed control in sorghum.     

Crop rotation and N fertilization effects on growth,yield, and disease incidence in potato

Crop rotation can be an effective mechanism for reducing disease incidence and contributing nitrogen (N) to succeeding crops. Interactions of plant pathogen suppression and soil nutrient availability may also exist, adding to the cropping system complexity. This study examined the impact of crop rotation, N fertilization, and their interaction on growth, yield, andRhizoctonia solani incidence in potato (Solanum tuberosum L. Norwis). Potato was grown continuously and in two-year rotations with annual alfalfa (Medicago sativa L. Nitro), hairy vetch (Vicia villosa Roth), white lupin (Lupinus albus L. Ultra), and oat (Avena sativa Astro). Fertilizer was banded at potato planting with 0, 45, 90, 135, 180, or 225 kg N ha^?1 as (NH₄)₂SO₄. Approximately 58% of continuous potato possessed stem lesions caused byR. solani, but only 12 to 22% of potato stems from other rotations possessed lesions. Tuber dry weight was affected by crop rotation in 1989, a dry year, but not in 1990. Apparent N fertilizer replacement values for hairy vetch, Nitro alfalfa, white lupin, and oat were 65, 43, 26, and 11 kg N ha^?1, respectively. All crop rotations studied appeared to enhance potato production by reducing stem infection byR. solani. Vetch and alfalfa provide additional benefits through their N contributions.     

克山县大豆施肥技术研究

本试验针对克山县大豆盲目施肥严重的现象,研究不同施肥量配比对大豆产量和效益的影响。结果表明：配方施肥对克山县黑土大豆生长发育和产量有明显的促进作用,与习惯施肥相比较,配方施肥（OPT）增产14．1％;不施氮肥减产14．2％;不施磷肥减产8．8％;不施肥（CK0）减产11．8％。     

Note on effects of soil surface crust on the grain yield of sorghum (Sorghum bicolor) in the Sahel

The prominent effects of a soil surface crust on crop production, impedance to seedling emergence and reduced infiltration rate, were examined using a quantitative land evaluation model under the Sahelian environmental and soil conditions of north-central Burkina Faso. The model integrated data from climate, soil and crop for quantifying potential grain yield of sorghum (Sorghum bicolor), grown on a sandy loam soil for 14 production years (1977–1990). Crust development was induced using `simulated rainfall' with an intensity of 75 mm h⁻¹ from a 2 m height. Results revealed that seeding sorghum in small holes without sufficiently breaking the surface crust depressed grain yield. Observed and potential yield correlated closely over a 7-year period (r = 0.79, p < = 0.05). Substantial yield gap was found between estimated potential yield (crust broken scenario set to 75% of the predicted yield) and observed, indicating however, the possibility of significantly improving yield by using appropriate tillage to break the crust before seeding.