The occurrence and inheritance of a brittle rachis phenotype in Italian durum wheat cultivars

Italian and Tunisian durum wheats from different eras of breeding were assessed for the presence of a gene for brittle rachis. Nine of 15 Italian durum landraces had brittle rachides. Strampellis achievement was the release of the well-known variety, Senatore Cappelli, which was derived from a Tunisian landrace, Jenah Rhettifah, which has a brittle rachis. Rachides of two Tunisian landraces were also brittle. Since the 1950s, 16 accessions were released as selections from crosses or mutagenesis involving Senatore Cappelli. Seven of these accessions have brittle rachides. F₂ segregation in intercrosses of Senatore Cappelli with other durum accessions with brittle rachides indicated a common allele for brittle rachis. Segregation of the F₂ from Senatore Cappelli/ANW 10A and the F₂ of Senatore Cappelli/ANW 10B showed that the gene for brittle rachis of Senatore Cappelli was allelic to the brittle allele of the Br-B1 locus on chromosome 3B. Senatore Cappelli was presumably the only source of brittle rachis used in Italian breeding programmes. The genes for brittle rachis have been retained in the gene pool of durum wheat, suggesting that the brittle rachis character is not associated with an appreciable yield loss in modern farming systems in Mediterranean environments.     

土壤不同营养状况与强筋小麦产量和品质的影响

试验研究了土壤不同营养状况对强筋小麦子粒产量和品质的影响。结果表明：在10个处理中,土壤长期施用N,P,K等主要营养元素且配合比为1：1：1(N120．0kg／hm^2,P2O5 120．0kg／hm^2,K2O 120．0kg／hm^2)时产量最高为5433．0kg／hm^2,不施肥(ck)产量最低为1260．0kg／hm^2;蛋白质含量以单施N素(N120．0kg／hm^2)时最高达17．00％,N、P元素配合比为1：1(N60．0kg／hm^2,P20560．0kg／hm^2)时蛋白质含量最低为10．53％;蛋白质产量以N、P配合比为3：1(N180．0kg／hm^2,P20560．0kg／hm^2)时最高为696．0kg／hm^2,以单施P素蛋白质产量最低为156．0kg／hm^2。     

Genetics of grains per spike in durum wheat under normal and late planting conditions

Parental, F₁, F₂, BC₁, BC₂, BC₁₁, BC₁₂, BC₂₁, BC₂₂, BC₁ self and BC₂ selfed generations of three crosses involving six cultivars of durum wheat (Triticum durum Desf.) were studied for grains per spike under normal and late sown environments to analyze the nature of gene effects. A 10-parameter model did not fully account for the differences among the generation means. In two cases more complex interactions or linkage were involved in the inheritance of grains per spike in durum. Both digenic and trigenic epistatic interactions had a role in controlling the inheritance of grains per spike, however, trigenic interactions contributed more than digenic interactions. Non-fixable gene effects were many times higher than fixable ones in all three crosses and in both sowing environments indicating a major role of non-additive gene effects in the inheritance of this trait. Duplicate epistasis between sets of three genes under both environments was recorded for the cross Raj 911 × DWL 5002. Epistatic interactions, particularly the trigenic ones, contributed the maximum significant heterosis. Epistatic interactions involving dominance in the F₂ generations caused significant inbreeding depression. Selective diallel mating and/or biparental mating could be used for amelioration of grains per spike in durum wheat.     

QTL analysis of morphological and developmental traits in the Ler × Cvi population of Arabidopsis thaliana

Drought frequently constrains production of wheat (Triticum aestivum L.), but development of tolerant cultivars is hampered by low heritability for drought tolerance and a lack of effective selection strategies. Our objective was to identify an optimum selection regime for wheat in drought-prone environments. Six-hundred entries derived from 10 crosses were developed by selection under continuous high moisture, alternating high with low moisture, alternating low with high moisture, and continuous low moisture conditions for five generations. The selections were evaluated in two low-yield, a medium-yield, and a high-yield environment in the Yaqui Valley, Sonora, Mexico. The mean performance of entries derived from a particular selection regime was dependant on the stress level of the evaluation environment. Lines developed and selected under continuous high moisture and continuous low-moisture regimes produced the highest mean yields in the low moisture evaluation environment. There was no relationship between continuous selection under either high yielding conditions or low yielding conditions and the mean performance of the resultant lines in their respective high and low yielding evaluation environments. The mean yield of lines selected using the alternating high/low moisture regime as well as the five highest yielding lines were superior in the HY environment, and had similar performance with other regimes under the low yielding evaluation environment. Our results indicate that alternating selection between high and low yielding environments is the most effective way to develop wheat germplasm adapted to environments where intermittent drought occurs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Wheat starch biosynthesis

Starch biosynthesis in plants involves the concerted action of a numberof enzymes, including ADPglucose pyrophosphorylase, starch synthases,branching enzymes and debranching enzymes. We report on the cloningand characterisation of genes encoding these enzymes from wheat and ontheir chromosomal locations. The prospects for manipulating wheat starchstructure and functionality using these genes is discussed.     

The Effects of the Growth Retardant Chlormequat (CCC) on Plant Height and Yield in GA Insensitive Wheats

Seven GA insensitive wheats differing in their final plant height were grown, over three years, in ran-domized field plots and analyzed for their response to CCC. Whereas the shorter lines Were virtually unaffected by the chemical, the ‘tall dwarfs’ responded with reduced straw height and higher yields as a consequence of higher number of grains per ear. Therefore, depending on the genetical background, spraying with growth retardants to achieve optimal plant height may be beneficial to grain yield.     

冬小麦常用亲本以及配组一代花药培养力的研究

对３００个冬小麦常用亲本和它们的部分Ｆ１后代花药培养力的研究表明，愈伤组织诱导率和绿苗分化率都是可遗传性状。它们受不同的遗传基因控制，具有各自的遗传特性。杂种１代的愈伤组织诱导率具有明显的加性效应和杂种优势，而绿苗分化率则介于双亲之间。     

土壤水分胁迫对冬小麦耗水规律及产量的影响

在温定盆栽和池栽防雨旱棚条件下，研究了土壤水胁迫对冬小麦耗水规律及产量的影响，结果表明，随土壤水分胁迫加剧，干物质积累减少，子粒千物质来自贮藏同化物的比例上升，产量下降，产量构成三因子中穗粒数，亩穗数下降均极显著，而千粒重下降较少，随水分胁迫加剧，拔节前耗水量占总耗水量的比率增高，从播种到拔节期，耗水量占总耗水量的比例愈高，拔节后植株衰老死亡愈早，产量降低就愈大，中度水分胁迫下，虽然水分生产率和经     

Polyacrylamide gel electrophoresis of wheat gliadins: the use of a moving boundary for improved resolution

Summary The process of the separation of gliadin proteins of wheat, using polyacrylamide gel electrophoresis, was studied in detail. It was shown that electrophoresis is a dynamic process during which the pH of the gel changes together with the potassium ion concentration. The most positive effect on the separation of the gliadins was generated by a moving front, which is a boundary between regions with a low concentration of K⁺ ions and a low pH, and region with a high concentration of K⁺ ions and a high pH, after optimization of the concentrations of the cations and anions in the electrode solutions. The finding was exploited for the development of an extremely simple electrophoresis system, in which buffers were not needed for obtaining a high resolution. The system was further improved by applying a stacking gel. The advantages of this system are discussed. This new approach may be useful for improving electrophoresis systems for other applications.     

小麦单茎库源比值与产量关系的初步研究

利用10个小麦品种，对单茎库、源及其比值与产量的关系进行了初步研究。结果表明，库性状、源性状与子粒产量的相关性均未达到显著水平，小麦单茎库源比值与产量均呈正相关趋势。穗粒数／旗叶面积、穗粒重／旗叶面积与产量的表型和遗传正相关均达到极显著水平，对各产量构成因素均无明显不利影响，可作为小麦高产育种的重要筛选指标。