Potassium deficiency impedes elevated carbon dioxide‐induced biomass enhancement in well watered or drought‐stressed bread wheat

Potassium (K) deficiency reduces photosynthesis and biomass production of crop plants and also renders them vulnerable to drought stress, whereas elevated carbon dioxide (CO₂) has a positive effect on photosynthesis and yield and ameliorates the adverse effects of drought stress. This study aimed to characterize the physiological responses of wheat (Triticum aestivum L.) stressed with K deficiency under elevated CO₂ and drought conditions. Increased biomass production caused by elevated CO₂ as a consequence of increased photosynthesis and water use efficiency was absent in young K‐deficient wheat plants. Shoot K concentration was negatively affected by elevated CO₂ particularly under K‐deficient conditions, whereas K content per plant was greatest in plants supplied with adequate K and adequate water. Specific leaf weight was increased as a consequence of carbohydrate accumulation in the source leaves of K‐deficient plants particularly under elevated CO₂ and drought stress. Potassium deficiency clearly impeded the impact of elevated CO₂ in both well watered as well as drought‐stressed plants. Adequate K fertilization is a prerequisite for efficient harvesting of atmospheric CO₂ through increased photosynthesis, decreased transpiration, and increased biomass production under changing atmospheric CO₂ and soil moisture conditions.     

Shift of grain protein composition in bread wheat under summer drought events

Climate change bears the risk of more frequent drought stress in the northern hemisphere with more frequent early summer drought events affecting main grain crops. Winter wheat (Triticum aestivum L.) is susceptible for such drought events at the flowering and grain filling stages. After drought, the grain yield decrease of three hybrids was about 20% lower compared to three wheat lines analyzed. Wheat grain proteins are classified into four main components such as albumin and globulin, gliadin, and glutenin. The latter two are closely related to the baking quality of flour and might be affected by drought. However, detailed knowledge about the influence of drought on the synthesis of specific storage protein fractions is scarce. By analyzing the grain protein fractions by means of SDS‐PAGE technique, we detected an increase in grain protein content as well as in HMW and some LMW glutenin sub‐fractions. The glutenin fraction seems to be most variable in gene expression under different environmental scenarios such as drought. However, the protein yield as well as the grain yield may be strongly decreased, which might be not acceptable in practice.     

冬小麦越冬期茎尖超微结构变化与玉米赤霉烯酮的关系

应用酶联免疫技术和电镜技术，研究了冬小麦品种燕大１８１７越冬期内源玉米赤霉烯酮（ＺＥＮ）含量和茎尖超微结构的变化，结果表明，随着秋末冬初气温逐渐降低，日照缩短，茎尖ＺＥＮ含量逐渐增加，１１月下旬含量达到高峰，随后急剧下降，到１月下旬又出现一个小的含量高峰。在小麦茎尖ＺＥＮ含量出现高峰前后（１１月底，１２月初），茎尖细胞中线粒体和质体的体积增大，形状也发生变化，线粒体从低温诱导前的圆球形变为长形、哑     

Effect of Weather and Soil Conditions on Yield Components and Bread-Making Quality of Winter Wheat (Triticum aestivum L.) and Winter Triticale (Triticosecale Wittm.) Varieties in North-East Germany

The reduced nutrient and water availability of the sorption‐weak silty sand soil in Thyrow when compared with the loamy sand soil in Berge enhanced the negative effects of unfavourable weather conditions. Winter wheat reacted to weather conditions and soil quality substantially more sensitively than winter triticale, so that the cultivation of wheat on very light sandy soil is combined with a higher risk. Reduced yields resulting from site differences are, for both cereals, mainly a result of reduced ear densities. Low grain yields as in the dry year 2003 led to high crude protein contents, this being more pronounced for winter wheat than for triticale and on the poor silty sand soil in Thyrow to a greater degree than on the loamy sand soil in Berge. For the starch content the contrary holds true. Grain yields were, to a greater extent, decisive for the protein and starch yields than the content values. For both cereals, the sedimentation value, the wet gluten value, the gluten index and the falling number resulted in principally higher values in the dry year 2003 and on the loamy sand soil when compared with the wet year 2004 and the silty sand soil. Only the wet gluten content was not clearly influenced by soil quality. All parameters describing bread‐making quality are clearly lower for winter triticale than for winter wheat. Especially, the falling number was not satisfactory, so that the tested triticale varieties seem only to be suitable for bread‐making by mixing with wheat flour. The internal grain quality of winter wheat varieties is extensively genetically determined. Weather and soil‐induced variations in the quality parameters were, with only few exceptions, greater for winter wheat than for triticale.     

Irrigation and Nutrient Effects on Growth and Water–Yield Relationship of Wheat (Triticum aestivum L.) in Central India

Increasing production of wheat from a limited water supply can result from efficient irrigation and nutrient management. A 3‐year field experiment was conducted at the Indian Institute of Soil Science, Bhopal, to study the growth, yield, seasonal evapotranspiration (ET) and water use efficiency (WUE), and the water–yield relationship of wheat in a soybean–wheat cropping system on vertisols. Three levels of irrigation, viz. I₀, no post‐sowing irrigation; I₁, two irrigations [crown root initiation (CRI) and flowering stage]; and I₂, three irrigations (CRI, maximum tillering and flowering stage) and three nutrient management treatments, viz. F₀, control (without fertilizer/manure); F₁, 100 % NPK (100–21.5–24.9 kg ha^?1); and F₂, 100 % NPK + farmyard manure (FYM‐10 t ha^?1) were tested in a split‐plot design with three replication. It has been established (through anova ) that the year effect was rather negligible and the interaction effects of irrigation and nutrient management on the growth parameters, ET, yield components, yield and WUE were significant. Plant height, progressive leaf area index, dry matter accumulation and crop growth rate were higher in I₂F₂, and I₂F₁ and I₁F₂ were statistically at par. The seasonal ET increased significantly with the increase in water supply in every nutrient treatment and it was highest in I₂F₂ and lowest in I₀F₀. The highest grain yield was obtained in I₂F₂; and a similar yield was recorded in I₃F₁ and I₂F₂. This shows a strong interaction effect between irrigation and nutrients. Yield components, viz. number of ears m^?2, number of grains ear^?1 and 1000‐grain weight were significant. The higher number of ears m^?2 containing greater number of grains with relatively heavier weights appeared to have contributed to the higher yield in I₁F₂, I₂F₁ and I₂F₂. The highest WUE obtained in I₀F₂ did not correspond to the highest yield and maximum ET, but a WUE of 10.43 kg ha^?1 mm^?1 in the I₂F₂ combination corresponded with the highest yield and the seasonal ET requirement was 391.8, which was 137 % greater than the water use at maximum WUE. The ET–grain yield relationship was linear, with a lowest regression slope (i.e. marginal WUE) and elasticity of water production (E_wp) in F₀ and a considerably higher slope and E_wp in F₁ and F₂. As the E_wp is positive and close to one in 100 % NPK treatment, the scope of improving WUE and yield with only inorganic fertilizer is very little, and relatively greater scope exists in the integrated management of organic manure and inorganic fertilizer. The results suggest that integrated nutrient management (100 % NPK + FYM) in conjunction with three irrigations maximized yield of wheat with concomitant improvement in ET and WUE under limited water availability.     

Detection of Allelic Variation in Chinese Wheat (Triticum aestivum L.) Germplasm with Drought Tolerance Using SSR Markers

Allelic variation in two domestic wheat landraces, Pingyaobaimai and Mazhamai, two cornerstone breeding materials and their derived cultivars with drought tolerance was detected by SSR (simple sequence repeat) markers. The clustering of 25 accessions showed that the similarity between Pingyaobaimai and Yanda1817, the latter was developed from the former, was 0.71, the highest one of all accessions, but the similarities were very low between these two accessions and other accessions including their derived cultivars. A similar situation was revealed between Mazhamai and its derived cultivars. Pingyaobaimai and its three derived cultivars shared three alleles at loci Xgwm526, Xgwm538 and Xgwm126 on chromosome arms 2BL, 4BL and 5AL, respectively. There were six shared alleles in Mazhamai and its derived cultivars, in order of Xgwm157,Xgwm126, Xgwm212, Xgwm626, Xgwm471 and Xgwm44 on chromosome arms 2DL, 5AL, 5DL, 6BL, 7AS and 7DC, respectively. Only one shared allele was detected between the pedigrees of Pingyaobaimai and Mazhamai. The difference of shared alleles in two cornerstone breeding materials and their derived cultivars revealed the diversity in Chinese wheat germplasm with drought tolerance and the complication in genetic basis of drought tolerance in wheat.     

Ertragsstruktur alter und neuer Winterweizensorten unter dem Aspekt der Einlagerung und Remobilisation von Fruktanen im Weizenhalm

Yield components in old and new german winter wheat varieties with respect to the storage and remobilization of fructan in the wheat stem
Yield components and changes in carbohydrate content of four old german winter wheat varieties, bred before 1950, were compared with six new varieties over two years in field trials. In both years the old varieties built up more biomass than the new varieties. In the latter a better harvest-index (0,56) as compared to the old varieties (0,43) was obtained, resulting in higher grain yields for the new varieties. Changes in water-soluble carbohydrate (WSC) content were mainly due to variations in fructan content. Maximum of fructan content was mostly reached at the stage of early milk ripeness. In the new varieties a faster and more complete remobilization of fructan occurred; especially in the year with the short grainfilling period.     

Use of the SDS-sedimentation test and SDS-polyacrylamidegel electrophoresis for screening breeder's samples of wheat for bread-making quality

Summary Gelprotein or SDS-insoluble gel-forming glutenin was isolated from wheat flour by extraction with an aqueous 1.5% SDS solution. Remarkable intervarietal differences were observed both in amount and subunit composition of these proteins.The amount of gelprotein and the SDS-sedimentation volume both proved to be good parameters for the bread-making quality of wheat cultivars. A high correlation was observed between amount of gelprotein and SDS-sedimentation volume. The amount of gelprotein was therefore tentatively assumed to be the essential basis of the SDS-sedimentation test.The subunit composition of the gelprotein was studied by SDS-PAGE after reduction of SS bonds by mercaptoethanol. It was found that the average bread-making quality of wheat cultivars and progeny of the cross Atlas 66 x Atys which possessed subunits 3 and 10, coded for by chromosome 1D, was significantly higher than that of wheat samples possessing subunit 2 and 11, their allelic counterparts.     

2··, a new high molecular weight glutenin subunit coded by Glu-A1: its predicted structure and its impact on bread-making quality

The suitability of wheat varieties for bread‐making depends on their glutenin subunits. The amino acid composition of these gluten building‐blocks have a strong influence on the rheology of the dough and, thus, on the suitability of the variety for bread‐making. This study reports a new x‐type high molecular weight glutenin subunit coded by the locus Glu‐A1 and named 2··. To investigate the impact of this allele on 10 quality parameters, a doubled haploid (DH) population of Triticum aestivum, segregating for Glu‐A1, was created. The statistical analysis demonstrates that, at Glu‐A1, the subunit 2·· is as favourable for quality as the subunit 2*. This is in accordance with results showing that the 2·· open reading frame still has the same number of cysteines as 2*. The small differences in the length of the central domain had no detectable effect on the elasticity, tenacity and baking quality, of the dough.