Prediction of grain protein content in winter wheat through leaf color measurements using a chlorophyll meter

A field trial was conducted over a 3-year period at the Hokkaido Kitami Agricultural Experiment Station to examine whether the grain protein content (GPC) of a winter wheat cultivar (Triticum aestivum L. cv. Chihokukomugi) suitable for Japanese noodle-making could be predicted before harvest. The prediction of the GPC was accurate based on the color of the second leaf (just below the flag leaf) at the end of the emergence of the inflorescence, when nitrogen application was graded. In order to evaluate the reliability of this test, a survey of 95 wheat fields in the eastern part of Hokkaido was also carried out during a 3-year period. The prediction of the GPC for this cultivar based on the color of the second leaf was less accurate across many sites. The results of this survey, however, suggested that the leaf color could be used as an index for ranking the GPC as low or high in relation to processing requirements. When the leaf color value of the second leaf measured with a chlorophyll meter at the end of the emergence of the inflorescence was less than 40, it was predicted that the GPC would be lower than the processing requirement. This index could be applied to the cultivars grown in the eastern part of Hokkaido, except for those grown on peat soils.     

长期定位试验尿素和堆肥处理下冬小麦自然同位素15N研究

We investigated 15N abundance （δ15N） of winter wheat （Triticum aestivum cv. Jinmai 1） plants and soil at different growth stages in a field with a 13-year fertilization history of urea and compost, to determine whether or not the δ15N of plant parts can be used as an indicator of organic amendment with compost. Plant parts （roots, leaves, stems and grains） and soil were sampled at re-greening, jointing, grain filling and mature growth stages of winter wheat. There were significant differences between the urea and compost treatments in 815N of whole plants, plant parts and soil over the whole growing season. Determination of the δ15N of plant parts was more convenient than that of whole plant to distinguish between the application of organic amendment and synthetic N fertilizer.     

不同抗旱性小麦叶片膜脂过氧化的氮素调控机制

在田间条件下研究了施氮对不同抗旱性冬小麦叶片全生育期黄嘌呤氧化酶(XOD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性以及过氧化氢(H2O2)和丙二醛(MDA)含量的影响。结果表明,施氮提高了叶片CAT和SOD活性,降低了XOD活性和MDA含量,以N180处理效果最明显,而且产量最高,表明N180处理对小麦膜脂抗过氧化能力和产量形成最为适宜;不施氮(N0)处理条件下,旱地品种较水浇地品种具有较高的保护酶系活性和较低的XOD活性、MDA含量。而适量氮素能够提高叶片保护酶系活性和降低XOD活性、MDA含量,所以氮素能够通过提高叶片膜质抗过氧化能力来增强小麦对干旱的适应。由于降低了超氧阴离子的生成量,使XOD活性降低和CAT活性提高,H2O2和MDA含量维持在较低水平,最终提高小麦产量。     

Conservation tillage and optimal water supply enhance microbial enzyme (glucosidase,urease and phosphatase) activities in fields under wheat cultivation during various nitrogen management practices

Field experiments were conducted on sandy clay loam soil at New Delhi, during the winter season of 2007 and 2008 to investigate the effect of tillage, irrigation regimes, i.e. sub-optimal, optimal and supra-optimal water supply, and integrated nutrient management practices (INM) on soil enzymatic activities after cultivation of wheat (Triticum aestivum). Soil glucosidase (54.5%), urease (88.8%), acid phosphatase (97.4%) and alkaline phosphatase (85.3%) activities increased significantly under conservation tillage compared with conventional tillage fields. An optimal water supply (i.e. three irrigations) led to a significant increase in soil enzymatic activity over sub-optimal (i.e. two) and supra-optimal (five) irrigation. Urease activity was slightly lower in the sub-optimal irrigations, but higher in supra-optimal irrigations by 15.5% than in optimal irrigation in conventional tillage. This study suggests that inorganic and organic nutrient combinations with conservation tillage and optimal water supply significantly improved soil enzymatic activities.     

Effect of Zinc on Cadmium Toxicity-Induced Oxidative Stress in Winter Wheat Seedlings

Two hydroponic experiments were conducted to investigate the antioxidant response of winter wheat (Triticum aestivum L.) to cadmium (Cd)-zinc (Zn) interactions, Seedlings of winter wheat (cv. Yuandong 977), were grown in modified Hoagland nutrient solution with the addition of increasing concentrations of Cd (0, 10, 25, 50 μM). In experiment 2, the seedlings of the same cultivar were treated with constant concentration of Cd (25 μM) and varying levels of Zn (0, 1, 10, 50 μM). Hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) as well as the activities of three antioxidant enzymes, catalase (CAT), guaiacol peroxidase (GPX), ascorbate peroxidase (APX) were monitored to estimate the amount of oxidative stress and the antioxidant ability of seedlings treated with Cd and Zn for 10 days. The results showed that levels of H₂O₂ and MDA in experiment 1 were significantly increased with increasing Cd concentrations. The data indicated that Cd could induce oxidative stress and lipid peroxidation in the plants. While H₂O₂ and MDA levels were significantly reduced by addition of Zn in experiment 2, the activities antioxidant enzymes were enhanced. A concentration of 10 μM Zn appeared to be the optimal level in this experiment for seedlings' growth, chlorophyll synthesis and antioxidant status, indicating that Zn alleviated the oxidative stress induced by Cd.     

Early season nitrogen accumulation in winter wheat

Cereal rye (Secale cereale L.) is widely used as a winter cover crop to conserve soil residual nitrogen (N) in the mid‐Atlantic region of the United States. Cereal rye, however, has agronomic drawbacks that may make other winter small grain crops more desirable alternatives. Winter wheat (Triticum aestivum L.) is a small grain that could substitute for cereal rye as a cover crop because it would give growers the flexibility of using it as a cover crop or growing it to maturity. There is currently little information on early season N accumulation of winter wheat cultivars, which is critical for the success of a small grain cover crop. To determine the degree of variation in early season N accumulation and early season biomass yield in soft red winter wheat in the mid‐Atlantic region, twenty‐five commercially available cultivars were evaluated at Beltsville, MD in the 1996/1997 and 1997/1998 growing seasons. Acereal rye cultivar ("Wheeler") was included as a cover crop control. Samples of plant tissue were taken at Feekes growth stage 5 and at physiological maturity each year. There were significant differences among cultivars for early season N accumulation and biomass yield. A large group of wheat cultivars had similar early season N accumulation and biomass yield as the cereal rye cover crop control. This suggests that some cultivars of winter wheat may be as effective as cereal rye as a winter cover crop. Early season N accumulation was highly correlated (r=0.90***) with early season biomass yield rather than with plant N content. These results indicate that soft red winter wheat has potential as a dual grain and cover crop and could be considered an alternative to cereal rye as a winter cover crop for conserving residual soil nitrogen in the mid‐Atlantic region of the United States.     

Chlorophyll Meter Readings in Winter Wheat: Cultivar Differences and Prediction of Grain Protein Content

Leaves of winter wheat (Triticum aestivum L.) were measured with a Hydro N-Tester (HNT), a portable chlorophyll meter, to obtain a relative estimate of leaf chlorophyll content, which gives an indication of plant N-status. The aim was to find if there were differences in HNT values between the winter wheat cultivars investigated, and to assess whether these values could be used for prediction of grain protein content (GPC). In Experiment 1, chlorophyll meter readings were taken at growth stages (GS) Zadoks 31 and 55 in five winter wheat (Triticum aestivum L.) cultivars in 17 annual field trials located in southeast Norway in 1996, 1997, and 1998. There were significant differences in HNT values between cultivars at both GS 31 and 55, but no differences were found between the three most commonly used cultivars in Norway at present, cvs. Bjørke, Mjølner and Rudolf. Because of the variation between years the HNT values at GS 55 were found to be unsuitable for direct prediction of the GPC. In Experiment 2, HNT was used in 21 annual N-fertilizer trials with winter wheat, performed in 1996 and 1997 and located in southeast Norway. A delay in the measurements from GS 55 to GS 65 generally improved the GPC prediction in 1996. Nitrogen applied at GS 55 increased GPC by approximately 1 unit of percent in cv. Folke, regardless of HNT value, while in cv. Portal nitrogen applied at this stage gave no increase in GPC at HNT values beyond 700.     

Response of wheat and maize to different nitrogen sources: II. Nitrate reductase and glutamine synthetase enzyme activities,and plastid pigment content

Glutamine synthetase and nitrate reductase enzyme activities occurred both in roots and leaves of maize (Zea mays L., hybrid Pioneer 3737) and wheat (Triticum aestivum L., cultivar Jantar) plants grown on different nitrogen (N) sources. Enzyme activities and plastid pigment content in maize plants were higher in the treatments with a mixture of nitrate (NO₃) and ammonium (NH₄) than with either N source alone. In wheat plants, plastid pigment content, nitrate reductase activity, and root glutamine snynthetase activity were higher in the treatments where NO₃ alone was applied to the nutrient medium.     

Effect of salicylic acid and salt on wheat seed germination

Abstract

The effects of pretreatment with salicylic acid on wheat seed germination (Triticum aestivum L. cv. Roshan), lipid peroxidation, and superoxide dismutase, catalase, polyphenol oxidase, and peroxidase activity were studied under conditions of salt stress. Seeds treated with different concentrations of salicylic acid were used for measuring germination traits. Salt stress was induced by sodium chloride solution. Seeds were soaked in salicylic acid solution for 24 h, dried with sterile paper, transferred to sterile Petri dishes, and treated with 10 ml NaCl solution at different concentrations. After 1 week, the number of germinated seeds, root length, seedling length, and dry weight were recorded. Antioxidant enzyme activity and lipid peroxidation were also assayed. Salinity decreased seed germination. Thus, a high concentration of NaCl (200 mM) decreased germination by 17.6% compared with control treatment. Salicylic acid significantly increased germination in stressed and control seeds. Salicylic acid increased the level of cell division of seedlings and roots, which increased plant growth. Salt stress significantly increased the activity of the antioxidative enzymes catalase, superoxide dismutase, peroxidase, and polyphenol oxidase in wheat seedlings, and salicylic acid reduced the activity of antioxidant enzymes as stress signal molecules. Our results indicated that scavenging of reactive oxygen species was effective, especially by salicylic acid, and that membrane damage was limited. The aim of the present work was to study the character of changes in enzymatic systems induced by NaCl and salicylic acid in wheat seedlings under conditions of salt stress. In brief, salicylic acid treatment reduced the damaging action of salinity on embryo growth and accelerated a restoration of growth processes; thereupon it may be effective for the improvement of seed germination in arid and semi-arid regions.     

Climate-induced overwintering challenges for wheat and rye in northern agriculture

Abstract

Winters are typically harsh in the northernmost agricultural areas of Europe, and winter rye (Secale cereale L.) and wheat (Triticum aestivum L.) are the only winter grain crops that can be grown. However, climate change is projected to result in milder winters, which may enable cultivation of winter crops to a greater extent in the future than is possible today. In this study we aimed at identifying main temperature, precipitation events and characteristics that have resulted in past poor overwintering of rye and wheat in their current production areas in Finland. Using long-term (1970–2006), multi-location datasets, we compared our findings with the projected major changes attributable to climate change. Mixed models were used to estimate mutually comparable overwintering damage to all experiments and logistic regression was used to determine whether climatic parameters are related to high levels of overwintering damage. Severity of overwintering damage, and associated yield penalties, fluctuate considerably on a year-to-year basis and no consistent reduction in variability was recorded during the study period. Particularly for wheat, severity of winter damage in any one year was associated negatively with area sown in the following year. There was no evidence of consistent genetic improvements in winter hardiness, but rye was more winter hardy than wheat. Current risks associated with rye production related to low temperatures could be alleviated in the future, although overwintering damage currently enhanced by high autumn precipitation could increase due to climate change. For wheat, fluctuating conditions hampered overwintering, which may be an even harder challenge in future when weather variation is projected to increase and extreme weather events are projected to become more common.     

Genetic Gains in Agronomic and Selected End‐Use Quality Traits over a Century of Plant Breeding of Canada Western Red Spring Wheat

Canadian Western Red Spring (CWRS) market class is the predominant type of wheat (Triticum aestivum L.) grown in Canada since the turn of the 20th century. Wheat cultivars ranging from cv. Red Fife to cv. Superb were field tested in a series of 24 replicated trials spanning 19 years in central Saskatchewan, Canada. The objective of this study was to measure the rate of cultivar improvement in light of relatively narrow end‐use quality definitions for the CWRS market class. Regression of cultivar trait means on year of cultivar registration was used to assess the rate of change in yield, productivity traits, and end‐use quality parameters. Yield levels were estimated to be increasing at a rate of approximately 15 kg/ha per year in 1970 and 23 kg/ha per year in 1995. Days to spike emergence and plant height decreased over time. Kernel weight, grain protein concentration, SDS sedimentation volume, farinograph absorption, and dough development time increased over time, whereas farinograph mixing tolerance index and yellow pigment concentration decreased. The results show that improvement in key agronomic and end‐use traits has been achieved in CWRS wheat.     

The health status and yield of winter rapeseed (Brassica napus L.) grown in monoculture and in crop rotation under different agricultural production systems

In a field experiment, winter rapeseed was grown in 5-year monoculture and in crop rotation (winter rapeseed, winter wheat, field peas, spring wheat and winter rapeseed). Two open-pollinated cultivars (Californium and Castille) and one hybrid cultivar (Nelson) were compared in systems with three levels of agricultural inputs, low input, medium input and high input, characterized by different rates of nitrogen and sulfur fertilization and pesticide use. The severity of sclerotinia rot (Sclerotinia sclerotiorum) and verticillium wilt (Verticillium spp.) on plants, dark spot (Alternaria spp.) and grey mold (Botrytis cinerea) on leaves and pods, as well as dry rot (Phoma lingam) on stems was evaluated during the growing season. The yield of winter rapeseed was calculated. Rapeseed grown after a 4-year break was characterized by less severe symptoms of dark spot on leaves and dry rot on stems, but more severe symptoms of grey mold on leaves and pods. The severity of dark spots on rapeseed pods (in crop rotation) was reduced with an increase in agricultural inputs. Cultivars Californium and Nelson were generally rarely infected by Verticillium spp., their leaves were less infected by Alternaria spp. and stems by Phoma spp. Nelson was the highest-yielding cultivar.     

Phenological trends in winter wheat and spring cotton in response to climate changes in northwest China

Understanding of the effects of climatic change on phenological phases of a crop species may help optimize management schemes to increase productivity. This study determined the trend of climatic changes during the period of 1981–2004 in northwest China and assessed the impacts of climatic changes on phenological phases and productivity of winter wheat (Triticum aestivum L.) and spring cotton (Gossypium hirsutum L.) at two locations. There was a clear trend of climate warming during the study period, leading to the earliness of pseudo stem elongation, booting, anthesis, and ripening stages of winter wheat by 13.2, 9.8, 11.0, and 10.8 d during the 24-year period, respectively. The growth period from seedling emergence to stem elongation shortened 16.1 d, but the growth period from anthesis to milk prolonged 8.2 d during the 24-year period. In cotton, the dates of seedling emergence, budding, anthesis, and boll-opening stages became earlier by, respectively, 10.9, 9.0, 13.9, and 16.4 d during the period of 1983–2004. However, the growth periods from five-leaf stage to budding, budding to anthesis, and anthesis to boll-opening stages were prolonged by 2.4, 12.0, and 9.0 d, respectively, for every 1 °C of rise in minimum temperature during their respective growth period. Increasing minimum temperatures during the vegetative period positively affected winter wheat growth but increases in maximum temperatures during the reproductive period negatively affected kernel weight and grain yield. Consequently, the grain yield of winter wheat had decreased, but the yield of cotton had increased during the study period. The trend of climate warming appeared to be favourable for cotton production but unfavourable for winter wheat in northwest China.     

Increased plant nitrogen loss with increasing nitrogen applied in winter wheat observed with 15nitrogen

Nitrogen (N) fertilizer is generally the most costly input for winter wheat (Triticum aestivum L.) production. Therefore, it was important to maximize fertilizer use efficiency and minimize N losses to the environment. One of the mechanisms responsible for decreased N use efficiency (NUE) was plant N loss. The objectives of this experiment were to determine fertilizer N recovery in winter wheat when produced for forage and grain, and to quantify potential plant N losses from flowering to maturity in winter wheat. Two long‐term (>25 years) winter wheat (Triticum aestivum L.) N rate fertility experiments (Experiment 222 and Experiment 502) were selected to evaluate ¹⁵N fertilizer recovery. Percent ¹⁵N recovery was determined from all microplots in plant tissue at flowering, in the grain, and straw at harvest and in the soil. Fertilizer N(¹⁵NH₄ ¹⁵NO₃) was applied atratesof 0, 45, 90, and 135kg N ha^‐1 in Experiment 222, and 0, 22, 45, 67, 90, and 112 kg N ha^‐1 in Experiment 502. The ratio ofNO₃ ^‐to NH₄ ⁺ in wheat forage at flowering was positively correlated with estimated plant N loss. Estimated plant N loss (total N uptake in wheat at flowering minus N uptake in the grain and straw at maturity) ranged from a net gain of 12 kg N ha^‐1 to a loss of 42 kg N ha^‐1, and losses increased with increasing N applied.     

Variation in Polyphenol Oxidase Activity and Quality Characteristics Among Hard White Wheat and Hard Red Winter Wheat Samples

Polyphenol oxidase (PPO) has been related to an undesirable brown discoloration of wheat-based end products. Consumer acceptance and product quality are generally decreased by the darkening phenomena. Two sets of wheat samples (Triticum aestivum L.) were investigated for variation in grain and flour PPO levels. Samples included 40 advanced experimental hard white winter wheat lines grown at two Kansas locations and 10 hard red winter wheat genotypes grown at three Nebraska locations. The variability in grain and flour PPO activities was influenced by growing location and population for the hard white wheat samples. There also was a significant influence of population by growing location interactions on PPO activity in both grain and flour. Genotype and growing location both contributed to variability in flour PPO activity among the hard red wheat samples. The variation in flour PPO activities among growing locations appeared larger than variation produced by genotypes tested for the hard red wheat samples. Quality parameters, such as wheat physical properties, flour protein and ash contents, grain color, and milling yield significantly correlated with grain and flour PPO activities. Among red wheat samples, flour PPO activity was related to 100 kernel weight, first reduction flour yield, and flour ash content. Grain PPO activity was related to variation in grain color observed among hard white samples. The relationship of quality characteristics with grain and flour PPO activities varied among white and red wheat samples.     

Yield and protein quality of five soft red winter wheat cultivars as affected by nitrogen fertilization rate

Abstract

This study reports the relationship between N levels (22, 56 and 112 kg/ha) and its effect on yield and protein quality for five cultivars of soft winter wheat (Triticum aestivum L. em. Thell). The objective was to determine the relationship of amino acid content and total protein at various levels of N. The 56 and 112 kg N/ha rates resulted in higher wheat yields than the 22 kg N rate over the 3 yr. mean. A cultivar x N level interaction for yield occurred when certain cultivars did not respond to higher N rates in 1972. Total seed protein increased with each increase in If. Increasing N levels generally resulted in a higher amlno acid content of the seed. Cultivar effects were found for 6 of the 17 amino acids (threonine, serine, glutamic acid, proline, glycine and lysine) indicating that cultivars differed in total amino acid content. Cultivars Arthur and Holley gave the greatest response (percentage amino acid) to N application. Coker 68–8 was intermediate in response while Coker 68–15 and Blueboy showed small inconsistent responses to H application.     

Influence of Root Chilling on Winter and Spring Wheat Growth and Carbon Dioxide Assimilation

Growth and carbon dioxide (CO₂) assimilation responses of winter wheat (Triticum aestivum     

Nitrogen metabolism in flag leaf and grain of wheat in response to irrigation regimes

Although scarcity of irrigation water is one of the key limiting factors for wheat production in many regions of the world, by using partial irrigation at strategic times during the growing season, it might be possible to enhance productivity. We measured the changes in various parameters related to nitrogen (N) metabolism in flag leaf and grain of wheat (Triticum aestivum L.) plants (cv. Jinan 17 and Lumai 21), which were subjected to five irrigation regimes until physiological maturity. Severely deficient or excessive irrigation during grain filling decreased the photosynthetic rate (A), the concentrations of N, free amino acid, and soluble protein, as well as the activities of nitrate reductase (NR) and glutamine synthetase (GS) and increased malondialdehyde (MDA) accumulation and endopeptidase (EP) activity, though grain protein concentration might mainly depend on genotype. The activities of NR and GS were significantly positively correlated with A, but those of EP were significantly negatively correlated with A. The results indicate that while severe water stress aggravates the adverse effect on nitrogen metabolism, excessive soil moisture is also not useful during the grain‐filling stage, resulting in lower grain yield and quality. Our results suggest that applying an optimal irrigation regime in wheat fields still plays an important role in the improvement of grain yield and quality.     

Tillering,nutrient accumulation,and yield of winter wheat as influenced by nitrogen form 1

When grown with mixtures of nitrate‐nitrogen (NO₃‐N) and ammonium‐nitrogen (NH₄‐N) (mixed N) spring wheat (Triticum aestivum L.) plants develop higher order tillers and produce more grain than when grown with only NO₃. Because similar work is lacking for winter wheat, the objective of this study was to examine the effect of N form on tillering, nutrient acquisition, partitioning, and yield of winter wheat. Plants of three cultivars were grown to maturity hydroponically with nutrient solutions containing N as either all NO₃, all NH₄, or an equal mixture of both forms. At maturity, plants were harvested; separated into shoots, roots, and grain; and each part analyzed for dry matter and chemical composition. While the three cultivars varied in all parameters, mixed N plants always produced more tillers (by a range of 16 to 35%), accumulated more N (28 to 61%), phosphorus (P) (22 to 80%), and potassium (K) (11 to 89%) and produced more grain (33 to 60%) than those grown with either form alone. Although mixed N‐induced yield increases were mainly the result of an increase in grain bearing tillers, there was cultivar specific variation in individual yield components (i.e., tiller number, kernels per tiller, and kernel weight) which responded to N form. The presence of NH₄ (either alone or in the mixed N treatment), increased the concentration of reduced N in the shoots, roots, and grain of all cultivars. The effect of NH₄ in either treatment on the concentrations of P and K was variable and depended on the cultivar and plant part. In most cases, partitioning of dry matter, P, and K to the root decreased when NH₄ was present, while partitioning of N was relatively unaffected. Changes in partitioning between the shoot and grain were affected by N treatment, but varied according to cultivar. Based on these data, the changes in partitioning induced by NH₄ and the additional macronutrient accumulation with mixed N are at least partially responsible for mixed‐N‐induced increases in tillering and yield of winter wheat.