Identification in Aegilops species of resistant sources to Hessian fly (Diptera: Cecidomyiidae) in Morocco

Hessian fly, Mayetiola destructor (Say), is the major insect pest of wheat in Morocco. Host plant resistance has been the most effective and practical method of controlling this pest. When 347 accessions of Aegilops species were screened in the greenhouse for resistance to Hessian fly, several accessions of Ae. geniculata Roth, Ae. triuncialis L., Ae. neglecta Req.ex Bertol., Ae. ventricosa Tausch, Ae. cylindrica Host and Ae. markgrafii (Greuter) Hammer showed resistance reaction. All expressed antibiosis as the mechanism of resistance against first instar Hessian fly larvae. These Aegilops sources of resistance could be exploited for transferring Hessian fly resistance to wheat.     

Sources of resistance in primary synthetic hexaploid wheat (Triticum aestivum L.) to insect pests: Hessian fly, Russian wheat aphid and Sunn pest in the fertile crescent

Hessian fly, Mayetiola destructor (Say), Russian wheat aphid (RWA), Diuraphis noxia (Kurdjumov), and Sunn pest, Eurygaster integriceps (Puton), are among the most important insect pests of wheat in North Africa, West and Central Asia. Host plant resistance is the most economical, environmentally friendly and practical means of controlling insect pests. Through field and greenhouse screening, several sources of resistance to Hessian fly, RWA and Sunn pest have been identified in wheat and its wild relatives. To further broaden the genetic base of resistance to these pests, 914 fixed lines of synthetic hexaploid wheat (SHW) commonly designated as primary synthetic wheat were evaluated for resistance to Hessian fly, RWA and Sunn pest. The initial screenings for RWA and Sunn pest were carried out in the field at Tel Hadya, Aleppo, Syria, and for Hessian fly in the greenhouse at Tel Hadya during the 2009 and 2010 seasons. Promising accessions from the initial screening for Hessian fly, RWA and Sunn pest were evaluated for confirmation in replicated trials in the greenhouse and field. Fifteen SHWs showed high levels of resistance to Hessian fly and four showed moderate resistance. A wheat line derived from the cross (Triticum turgidum/T. dicoccoides) also showed a high level of resistance to Hessian fly. The level of resistance to RWA in SHW was considerably lower; only one SHW and one durum wheat ‘Altar 84’ exhibited a high level of resistance, while four SHW were moderately resistant. There were 21 SHW genotypes and one durum wheat ‘Langdon’ found resistant to Sunn pest feeding at the vegetative stage. Crosses between these potentially novel resistance sources and elite bread wheat were initiated. Genetic and genomic studies using these accessions are ongoing to identify and characterize the resistance genes and reveal potentially new resistance genes, which will be useful in breeding programs to develop wheat germplasm with multiple resistances to these pests.     

Sources of resistance to Hessian fly (Diptera: Cecidomyiidae) in Syria identified among Aegilops species and synthetic derived bread wheat lines

The Hessian fly, Mayetiola destructor (Say), is a major pest of wheat in North Africa, southern Europe, North America, and northern Kazakhstan. It is believed this pest (like wheat) originated in West Asia. The Syrian Hessian fly biotype has been found to be the most virulent worldwide, and has been used at the International Center for Agricultural Research in the Dry Areas (ICARDA) for screening wheat and its wild relatives to identify new sources of resistance. The screening was conducted in an insect rearing room set at 20°C and 70% RH using a Hessian fly population collected from Lattakia region, Syria. The experimental design was a randomized complete block with four replications. ‘Nasma’ (bread wheat) and ‘Cando’ (durum wheat) were used as susceptible and resistant checks, respectively. A total of 623 lines/accessions of wheat and its wild relatives (Aegilops and Triticum) were evaluated. Twenty-nine Aegilops accessions and four synthetic derived bread wheat lines were found resistant. The presence of dead first instars confirmed the resistance reaction and also showed that antibiosis is the major mechanism of resistance in these materials. These sources of resistance are used in ICARDA’s wheat breeding programs for the development of Hessian fly-resistant germplasm/varieties.     

Sources of wheat resistance to Sunn pest, <Emphasis Type="Italic">Eurygaster integriceps</Emphasis> Puton,in Syria

Sunn pest, Eurygaster integriceps Puton, is the most damaging insect pest of wheat in West and Central Asia and East Europe. Host plant resistance has been investigated as one component of a total integrated pest management program for the control of this pest. In Syria, field screening of artificially infested wheat accessions from the International Center for Agricultural Research in the Dry Areas (ICARDA) gene bank, selected using the Focused Identification of Germplasm Strategy (FIGS), identified one durum wheat and eight bread wheat accessions with good levels of resistance at the vegetative stage to overwintered Sunn pest adults. ICARDA is using these sources of resistance in wheat breeding programs to develop cultivars resistant to overwintered Sunn pest adults, which damage wheat at the vegetative stage (shoots and leaves). This study also demonstrated that the FIGS approach was effective in mining genetic resource collections for useful traits.     

Haplotype analysis of molecular markers linked to stem rust resistance genes in Ethiopian improved durum wheat varieties and tetraploid wheat landraces

The recent emergence of wheat stem rust race Ug99 (TTKSK) and related strains threaten Ethiopian as well as world wheat production because they overcome widely used resistance genes that had been effective for many years. The major cause which aggravates the ineffectiveness of Ethiopian wheat varieties against stem rust is the narrow genetic base on which the breeding for resistance has been founded, however, little is known about the resistance genotypes of Ethiopian durum wheat varieties and tetraploid wheat landraces. The objective of the study was to identify stem rust resistance genes that are present in the Ethiopian tetraploid wheat landraces and improved durum wheat varieties using molecular markers and assess which genes are effective for current Ethiopian stem rust races of Puccinia graminis f. sp. tritici including Ug99. The investigated 58 tetraploid wheat accessions consisted of 32 (Triticum durum s.l. incl. Triticum aethiopicum Jakubz., Triticum polonicum) landraces and 22 registered T. durum varieties released in Ethiopia between 1966 and 2009 and four T. durum varieties from ICARDA. A total of 17 molecular markers (SSR, EST and InDel) linked or diagnostic for stem rust resistance genes Sr2, Sr13, Sr22 and Sr35 were used for genotyping. Haplotype analysis indicated that only few of the Ethiopian durum wheat varieties carried Sr13. The resistant variety ‘Sebatel’ showed a haplotype for Sr2 and Sr22 and variety ‘Boohai’ for Sr22, however further evaluation is needed for the diagnostic value of these haplotypes. This study is the first report on the presence of stem rust resistance (Sr) genes in Ethiopian durum wheat varieties and tetraploid wheat landraces based on linked or associated molecular markers. Thus it might help in the identification of varieties carrying resistant alleles that provide valuable genetic material for the development of new improved varieties in further breeding programmes.     

Variation in the content of dietary fiber and components thereof in wheats in the HEALTHGRAIN Diversity Screen

Within the HEALTHGRAIN diversity screening program, the variation in the content of dietary fiber and components thereof in different types of wheat was studied. The wheat types were winter (131 varieties) and spring (20 varieties) wheats (both Triticum aestivum L., also referred to as common wheats), durum wheat (Triticum durum Desf., 10 varieties), spelt wheat (Triticum spelta L., 5 varieties), einkorn wheat (T. monococcum L., 5 varieties), and emmer wheat (Triticum dicoccum Schubler, 5 varieties). Common wheats contained, on average, the highest level of dietary fiber [11.5-18.3% of dry matter (dm)], whereas einkorn and emmer wheats contained the lowest level (7.2-12.8% of dm). Intermediate levels were measured in durum and spelt wheats (10.7-15.5% of dm). Also, on the basis of the arabinoxylan levels in bran, the different wheat types could be divided this way, with ranges of 12.7-22.1% of dm for common wheats, 6.1-14.4% of dm for einkorn and emmer wheats, and 10.9-13.9% of dm for durum and spelt wheats. On average, bran arabinoxylan made up ca. 29% of the total dietary fiber content of wheat. In contrast to what was the case for bran, the arabinoxylan levels in flour were comparable between the different types of wheat. For wheat, in general, they varied between 1.35 and 2.75% of dm. Einkorn, emmer, and durum wheats contained about half the level of mixed-linkage beta-glucan (0.25-0.45% of dm) present in winter, spring, and spelt wheats (0.50-0.95% of dm). All wheat types had Klason lignin, the levels of which varied from 1.40 to 3.25% of dm. The arabinoxylan contents in bran and the dietary fiber contents in wholemeal were inversely and positively related with bran yield, respectively. Aqueous wholemeal extract viscosity, a measure for the level of soluble dietary fiber, was determined to large extent by the level of water-extractable arabinoxylan. In conclusion, the present study revealed substantial variation in the contents of dietary fiber and constituents thereof between different wheat types and varieties.     

Inheritance of manganese efficiency in durum wheat

Manganese (Mn) deficiency is a widespread problem on the alkaline soils, particularly for durum wheat (Triticum turgidum L. var. durum), which is more sensitive than either bread wheat or barley. The existence of considerable genetic variation in current germplasm of durum wheat (a relative yield of 58% in Stojocri 2 compared to 15% in check cv Yallaroi) and the development of a consistent selection criterion (Mn content of 35‐day‐old seedlings) has made breeding for Mn efficiency feasible. The development of Mn‐efficient durum wheat would be facilitated if the mode of inheritance was well understood. F1 hybrid, F2, and F2‐derived families from a cross between Stojocri 2 (moderately efficient) and Hazar (inefficient) were studied under controlled‐environment conditions. F1 hybrid was intermediate to the parents, indicating incomplete dominance and dependence on external Mn concentration. Analysis of 110 F2 and 220 F3 single plants (including 20 F2‐derived F3 families) showed that the observed variance was in agreement with the expected variance of a population segregating for two genes. Chi‐square analysis of the segregation ratios of F3 families also supported the digenic segregation hypothesis. Currently Stojocri 2 is used in a breeding program for the transfer of Mn efficiency to commercial varieties, by backcrossing (two backcrosses retain about 88% of recurrent parent genotype).     

Assessment of genetic diversity in emmer (Triticum dicoccon Schrank) × durum wheat (Triticum durum Desf.) derived lines and their parents using mapped and unmapped molecular markers

In the last few years, the renewed interest for emmer wheat (Triticum dicoccon Schrank) in Italy has stimulated breeding programs for this crop releasing improved genotypes obtained not only by selection from landraces, but even by crosses with durum wheat (Triticum durum Desf.) varieties. The purpose of this work has been to uncover the genetic make-up of some emmer × durum derivatives, specifically by comparing the differences from their parents. Genetic diversity of advanced breeding lines and varieties derived from a durum × emmer cross has been evaluated on the basis of AFLP and SSR markers in comparison with the corresponding emmer and durum wheat parent for addressing the seminal question of how much ‘wild’ variation remains after selection for agronomic type.     

Evaluation of Aegilops tauschii Coss. for resistance to wheat stem rust and inheritance of resistance genes in hexaploid wheat

With the objective to identify new sources of resistance to wheat stem rust, a collection of 169 accessions ofAegilops tauschii, obtained from the IPK genebank at Gatersleben, Germany, were screened for resistance undercontrolled conditions. Fourteen (8%) accessions were resistant to stem rust among which 10 were highly resistant(IT 5 ; and 1) and four exhibited a moderately resistance reaction (IT 5 2). From the synthetic hexaploids whichwere produced by hybridizing resistant Ae. tauschii with susceptible Triticum durum, six synthetics expressed ahigh level of stem rust resistance similar to their corresponding diploid parents, while five displayed either areduced or complete susceptibility compared to their Ae. tauschii parents. This suppression of resistance at thehexaploid level suggests the presence of suppressor genes in the A and/ or B genomes of the T. durum parents.Inheritance of resistance from crosses of five stem rust resistant synthetic hexaploids with two susceptible T.aestivum genotypes revealed that three of the synthetics (syn 101, syn 601 and syn 801) possessed one dominantgene each, syn 111 has two different dominant genes and syn 116 has two complementary interacting genes forstem rust resistance. Intercrosses among the four stem rust resistant synthetic hexaploids indicated that the putativegenes conferring stem rust resistance in each of the synthetics are neither allelic nor closely linked to each other.     

Sources of Resistance to Stem Rust (<Emphasis Type="Italic">Puccinia graminis</Emphasis> f. sp. <Emphasis Type="Italic">tritici</Emphasis>) in Ethiopian Tetraploid Wheat Accessions

Seedlings of 41 emmer (Triticum dicoccon Schrank) and 56 durum (T. durum Desf.) wheat accessions were evaluated for their response to stem rust (Puccinia graminis f. sp. tritici) infection under greenhouse condition at Kulumsa Agricultural Research Center, Ethiopia. The objectives were to identify tetraploid wheat accessions that could serve as sources of resistance to stem rust, and postulate the stem rust (Sr) resistance genes through multipatotype testing. The test included screening of accessions for stem rust resistance and multipatotype testing. To ensure vigorous screening, a mixture of six isolates (Si-1a, Am-2, Ku-3, Dz-4a, Ro-4 and Na-22) that were collected from severely infected emmer, durum, and bread wheat (Triticum aestivum L.) varieties of major wheat growing areas of Ethiopia was used as inocula. Out of the tested accessions, 18 emmer and 6 durum accessions exhibited low infection types (0–2) response and hence selected as a source of resistance to stem rust infection. Multipatotype testing was done to postulate Sr genes in the selected accessions. In the test, 10 different stem rust races (A2, A9, A11, A14, A16, A17, B3, B7, B15, and B21), 33 stem rust differential lines, and a universal susceptible check variety, Morocco were used, The high (3–4) and low infection type reaction patterns of the tested accessions and differential lines were used to postulate the genes that exhibit gene-for-gene relationship. The presence of Sr 7b, 8b, 9a, 9b, 10, 14, 24, 27, 28, 29, 30, 31, 32 and Tt-3+10 genes were postulated in 16 selected emmer and 5 durum wheat accessions. Efforts to transfer these valuable Sr genes from cultivated tetraploid wheats could be rewarding to get stem rust resistant varieties and boost wheat production.     

甘肃省麦类作物对禾谷孢囊线虫的抗性鉴定

禾谷孢囊线虫是麦类生产上的重要线虫。为筛选抗禾谷孢囊线虫的小麦和燕麦种质资源,以甘肃孢囊线虫群体为测试对象,采用室内接种法,通过测定单株白雌虫及孢囊数,对燕麦和小麦品种进行抗性分析。结果表明,在供试燕麦品种中无免疫品种,1个高抗品种(陇燕3号),12个中抗品种。同样,在参试的小麦品种中无免疫品种,其中7个品种表现为中抗,包括定丰12号、西旱3号、武春8号等。可将高抗燕麦品种陇燕3号作为抗病亲本,用来培育和选择具有持久抗禾谷孢囊线虫的优良品种。     

Effect of Soft Kernel Texture on the Milling Properties of Soft Durum Wheat

Worldwide, nearly 20 times more common wheat (Triticum aestivum) is produced than durum wheat (T. turgidum subsp. durum). Durum wheat is predominately milled into coarse semolina owing to the extreme hardness of the kernels. Semolina, lacking the versatility of traditional flour, is used primarily in the production of pasta. The puroindoline genes, responsible for kernel softness in wheat, have been introduced into durum via homoeologous recombination. The objective of this study was to determine what impact the introgression of the puroindoline genes, and subsequent expression of the soft kernel phenotype, had on the milling properties and flour characteristics of durum wheat. Three grain lots of Soft Svevo and one of Soft Alzada, two soft‐kernel back‐cross derived durum varieties, were milled into flour on the modified Quadrumat Senior laboratory mill at 13, 14, and 16% temper levels. Samples of Svevo (a durum wheat and recurrent parent of Soft Svevo), Xerpha (a soft white winter wheat), and Expresso (a hard red spring wheat) were included as comparisons. Soft Svevo and Soft Alzada exhibited dramatically lower single‐kernel characterization system kernel hardness than the other samples. Soft Svevo and Soft Alzada had high break flour yields, similar to the common wheat samples, especially the soft hexaploid wheat, and markedly greater than the durum samples. Overall, Soft Svevo and Soft Alzada exhibited milling properties and flour quality comparable, if not superior, to those of common wheat.     

Influence of Soft Kernel Texture on the Flour,Water Absorption,Rheology, and Baking Quality of Durum Wheat

Durum wheat (Triticum turgidum subsp. durum ) production worldwide is substantially less than that of common wheat (T. aestivum ). Durum kernels are extremely hard; thus, most durum wheat is milled into semolina, which has limited utilization. Soft kernel durum wheat was created by introgression of the puroindoline genes via homoeologous recombination. The objective of this study was to determine the effects of the puroindoline genes and soft kernel texture on flour, water absorption, rheology, and baking quality of durum wheat. Soft Svevo and Soft Alzada, back‐cross derivatives of the durum varieties Svevo and Alzada, were compared with Svevo, a hard durum wheat, Xerpha, a soft white winter wheat, and Expresso, a hard red spring wheat. Soft Svevo and Soft Alzada exhibited soft kernel texture; low water, sodium carbonate, and sucrose solvent retention capacities (SRCs); and reduced dough water absorptions similar to soft wheat. These results indicate a pronounced effect of the puroindolines. Conversely, SDS flour sedimentation volume and lactic acid SRC of the soft durum samples were more similar to the Svevo hard durum and Expresso samples, indicating much less effect of kernel softness on protein strength measurements. Alveograph results were influenced by the inherent differences in water absorption properties of the different flours and their genetic background (e.g., W and P were markedly reduced in the Soft Svevo samples compared with Svevo, whereas the puroindolines appeared to have little effect on L ). However, Soft Svevo and Soft Alzada differed markedly for W and L . Soft durum samples produced bread loaf volumes between the soft and hard common wheat samples but larger sugar‐snap cookie diameters than all comparison samples. The soft durum varieties exhibited new and unique flour and baking attributes as well as retaining the color and protein characteristics of their durum parents.     

小麦条锈病抗性基因定位及分子标记技术研究进展

条锈病流行对小麦生产造成巨大损失,选育和种植持久抗性品种是防治小麦条锈病最经济有效的策略。为达到多基因聚合培育持久抗病品种的目标,必须不断发掘抗病种质、解析其抗病遗传机制并开发分子标记。基于文献,对条锈病抗性基因发掘涉及的抗病性、分子标记、基因定位方法和定位进展及其在育种中的应用进行了综述,明确了小麦条锈病基因定位涉及技术的现状、局限性及优势,从而为后续的条锈病抗性基因发掘、多基因聚合和持久抗性小麦品种的选育与生产布局提供技术指导,以降低西北麦区和小麦主产区条锈病流行的频率,进一步促进国家粮食安全。     

国家区试冬小麦品种在甘肃陇南的田间抗条锈病性评价

为精准评价冬小麦品种田间对条锈病的抗性,科学指导抗病育种和抗病材料的合理应用。在位于甘肃陇南不同生态区的甘肃省农业科学院植物保护研究所甘谷试验站和汪川良种场两地,于2017 — 2020年,对122个国家区域试验品种进行了连续3 a的成株期抗条锈病性评价。结果表明,有WJ18-1等19个品种3 a两地均表现抗病,且抗性表现稳定,占供试品种的15.57%; WJ18-494等49个品种具有慢条锈特性,占供试品种的40.16%。绝大多数品种表现出差异性,菌源、环境是主要原因。     

Phenolic Fingerprint of Sicilian Modern Cultivars and Durum Wheat Landraces: A Tool to Assess Biodiversity

Durum wheat landraces have been recognized to have different contents in health‐promoting phytochemicals. These health benefits have been mainly attributed to the presence of phenolic acids and flavonoids existing in this matrix both as soluble free compounds and insoluble bound forms. Sicily is one of the few areas of Southern Europe where it is still possible to find landraces of durum wheat, no longer cropped because of the commercial spread of new high‐yielding varieties. This study aimed to determine the phenolic profile and content of 10 wheat landraces and three genetically improved cultivars to develop an analytical tool for cultivar screening and traceability. Hydroalcoholic extracts from wheat grains were analyzed by means of HPLC with a diode‐array detector and HPLC electrospray ionization MS, revealing 13 metabolites belonging mainly to the classes of hydroxycinnamic acids and flavones C‐glycosides. The quantitative pattern of the 13 phenolic markers, analyzed by applying stepwise linear discriminant analysis, allowed the discrimination between the two groups under study, namely, modern cultivars and durum wheat landraces. Furthermore, all 13 durum wheat varieties were perfectly discriminated in this statistical model, confirming a specific and genotype‐dependent pattern of phenolics concentration.     

甘肃陇南越夏区小麦抗条锈病育种研究进展

甘肃陇南是中国小麦条锈菌最大、最重要的越夏区,条锈病是发生于该区域小麦生产上最主要的病害,持续不断的培育和种植抗病品种是防治该病最绿色、经济的措施。为了持续控制该区域的条锈病、保障粮食安全,总结了自1995年以来甘肃陇南小麦抗条锈病育种成效,分析了存在的问题,提出了强化优异抗条锈病种质资源材料的评价、挖掘、创新与利用;强化生物育种技术的应用;强化抗病品种(基因)布局等建议。     

Characterization of tetraploid wheat germplasm for resistance to Pseudocercosporella herpotrichoides, cause of eyespot disease

Eyespot disease, caused by Pseudocercosporella herpotrichoides, can be devastating to winter wheat grown in northern Europe and the northwest USA. Accessions from eight different tetraploid wheat species randomly extracted from core collections were scored for resistance to eyespot disease using a -glucuronidase (GUS)-transformed strain of P. herpotrichoides. The GUS values for the combined population followed a quasi-Gaussian distribution. Three species, Triticum dicoccoides, T. durum and T. turanicum, showed significant variation (P < 0.001) in disease response with T. dicoccoides having the lowest disease scores, i.e. highest levels of resistance. All tetraploid accessions were less resistant than resistant diploid T. tauschii accessions. Thirteen percent of tetraploid accessions had disease scores that ranged between the average of the resistant accessions of T. tauschii and the moderately resistant hexaploid germplasm line Cerco. Eight accessions (three accessions of T. dicoccoides, two of T. turgidum and three of T. durum) with low disease scores (resistance) to infection were selected for further genetic analysis.     

How to reduce the incidence of black bean aphids (Aphis fabae Scop.) attacking organic growing field beans (Vicia faba L.) by growing partially resistant bean varieties and by intercropping field beans with cereals

Abstract

There is an increasing demand for organically grown pulses and cereal grains in Denmark, which is expected to cause a change in the typical organic farm structure away from dairy farming and towards arable farming. Spring field beans (Vicia faba) could be a popular break crop in organic agriculture. The black bean aphid (Aphis fabae) is generally considered to be a serious pest of spring-sown field beans in northern Europe, and field studies have shown that yield losses can exceed more than 50% due to attacks from the black bean aphid.

The use of insecticides in organically grown field bean crops is not permitted, but it has been known for a long time that the black bean aphid infests different varieties of beans to a very different extent. Therefore, partial resistance to the black bean aphid is one method of stabilizing yields. Another method of cultural pest control is intercropping and a third method could be a combination of both. Six field experiments involving the three methods were carried out. There was a significant difference between the number of aphids per plant on the three investigated bean varieties, where ‘Colombo’ was the most susceptible, ‘Quattro’ was intermediate, and ‘Caspar’ the most resistant variety. ‘Colombo’ intercropping with spring wheat and spring barley reduced the numbers of aphids per plant significantly, and also the number of plants infested. The harvesting of all crops took place during the last fourteen days of August.

It can be concluded that the growing of partial host plant resistant varieties of field beans or the intercropping of field beans with spring cereals separately will reduce the infestation with black bean aphids. If both methods are used, the reduction of infestation will be even higher and consequently also the yield.     

Quality of Spaghetti Made from Full and Partial Waxy Durum Wheat

The waxy character is achieved in durum wheat (Triticum turgidum L. var. durum) when the granule‐bound starch synthase activity is eliminated. The result is a crop that produces kernels with no amylose in the starch. The presence of two Waxy loci in tetraploid wheat permits the production of two partial waxy wheat genotypes. Advanced full and partial waxy durum wheat genotypes were used to study the effect of waxy null alleles on pasta quality. Semolina from full and partial waxy durum wheats was processed into spaghetti with a semicommercial‐scale extruder, and pasta quality was evaluated. Cooked waxy pasta was softer and exhibited more cooking loss than pasta made from traditional durum cultivars. These features were attributed to lower setback of waxy starch as measured with the Rapid Visco Analyser. High cooking loss may be due to the lack of amylose‐protein interaction, preventing the formation of a strong protein network and permitting exudates to escape. Waxy pasta cooked faster but was less resistant to overcooking than normal pasta. Partial waxy pasta properties were similar to results obtained from wild‐type pasta. This indicates that the presence of a single pair of functional waxy genes in durum wheat was sufficient to generate durum grain with normal properties for pasta production. Waxy durum wheat is not suitable for pasta production because of its softening effect. However, this property may offer an advantage in other applications.