The tolerance of difenzoquat and diclofop-methyl by winter wheat varieties at different growth stages

Winter wheat varieties were treated with the wild-oat herbicides difenzoquat and diclofop-methyl at several growth stages in a series of four field experiments. High rates of difenzoquat damaged the winter wheat varieties Bouquet, Sportsman, Hobbit and Maris Huntsman but not Hustler. Treatment of the sensitive varieties during tillering stimulated excessive tiller production, resulting in more ears with fewer and smaller grains than on the unsprayed controls; later applications reduced the number of grains and severely depressed yield. In contrast, the early applications of diclofop-methyl, during tillering, were more damaging than the later ones. Bouquet was more tolerant of diclofop-methyl than were the other varieties tested.     

Targeting Ascophyllum nodosum (L.) Le Jol. extract application at five growth stages of winter wheat

Seaweed extracts are a category of biostimulant products that have the potential to promote plant growth and thus, have given a promise to develop more resilient systems of crop production that make efficient use of water and nutrients. This field study evaluated the effect of application timing of an Ascophyllum nodosum extract on nutrient uptake and grain yield of winter wheat when the extract was applied singly in five growth stages from 2017 to 2019. Analysis by orthogonal polynomial contrasts indicated that extract application significantly increased yield or biomass in all three site-years. Application at the tillering stage increased average yield by 17%, grain nutrient accumulation (N, P, K) by 21–24%, and N-use efficiency by 11% over the three site-year period, but extract effects were not consistent between site-years both in terms of optimal growth stages of application and magnitude of crop responses. While grain yield increased by 39% with extract application at tillering in 2017, yield gains ranging from 16 to 22% were obtained at the stem elongation and booting stages in 2018. These differences were likely the result of site-year variations in weather patterns and soil properties. Among macro-nutrients, only grain N accumulation was linearly correlated to grain yield across site-years indicating that increased soil N uptake and/or remobilization to the reproductive organs was a key process of the A. nodosum mode of action. An economic analysis indicated that the average return over extract cost was higher than that of the zero-extract control by €79-100 ha^-1 when the extract was applied at the tillering or stem elongation stage and assuming higher dilution rates recommended by the industry. Even greater economic benefits can result if N rates are substantially reduced without an adverse effect on yield gains.

     

强筋与弱筋小麦籽粒蛋白质组分与加工品质对灌浆期弱光的响应

选用强筋小麦品种济麦20和弱筋小麦品种山农1391,在大田试验条件下,分别于籽粒灌浆前期(花后6—9 d)、中期(花后16—19 d)和后期(花后26—29 d)对小麦进行弱光照处理,研究了籽粒产量、蛋白质组分及加工品质的变化。灌浆期弱光显著降低小麦籽粒产量,灌浆中期对济麦20和灌浆后期对山农1391的产量降幅最大。弱光处理后,籽粒氮素积累量及氮素收获指数减少。但弱光使籽粒蛋白质含量显著升高,其中灌浆中期弱光升幅最大,原因可能是由于其粒重降低造成的。弱光对可溶性谷蛋白无显著影响,但增加不溶性谷蛋白含量,使谷蛋白聚合指数显著升高,面团形成时间和稳定时间亦升高,籽粒灌浆中、后期弱光对上述指标的影响较前期大。灌浆期短暂的弱光照对改善强筋小麦粉质仪参数有利,但使弱筋小麦变劣;并均伴随籽粒产量的显著降低这一不利影响。     

Salinity and drought interaction in wheat (Triticum aestivum L.) is affected by the genotype and plant growth stage

Salinity and drought are important agro-environmental problems occurring separately as well as together with the combined occurrence increasing with time due to climate change. Screening of bread wheat genotypes against salinity or drought alone is common; however, little information is available on the response of wheat genotypes to a combination of these stresses. This study investigates the response of a salt-resistant (SARC-1) and a salt-sensitive (7-Cerros) wheat genotype to drought at different growth stages under non-saline (ECe 2.1 dS m^?1) and saline soil (ECe 15 dS m^?1) conditions. Drought was applied by withholding water for 21 days at a particular growth stage viz. tillering, booting, and grain filling stages. At booting stage measurements regarding water relations, leaf ionic composition and photosynthetic attributes were made. At maturity grain yield and different yield, components were recorded. Salinity and drought significantly decreased grain yield and different yield components with a higher decrease in the case of combined stress of salinity × drought. The complete drought treatment (drought at tillering + booting + grain filling stages) was most harmful for wheat followed by drought at booting stage and grain filling–tillering stages, respectively. The salt-resistant wheat genotype SARC-1 performed better than the salt-sensitive genotype 7-Cerros in different stress treatments. A decrease in the water and turgor potentials, photosynthetic and transpiration rates, stomatal conductance, leaf K⁺, and increased leaf Na⁺ were the apparent causes of growth and yield reduction of bread wheat due to salinity, drought, and salinity × drought.     

The effects of herbicides, applied atone and in sequence, on the control of wild-oats (Avena fatua) and broad-leaved weeds, and on yield of winter wheat

Experiments were done to examine the effects of controlling wild-oats and autumn-germinating broad-leaved weeds in winter wheat, early in winter or late in spring. The herbicides used were barban (winter), chlortoluron or isoproturon (winter), and benzoylprop-ethyl, at the recommended doses and at half doses. Sequential treatments of two herbicides at half doses were also examined. All treatments were given a routine broad-leaved herbicide treatment in spring. Yields of wheat were influenced more by the time of weed removal than by the degree of control achieved. Grain yields at three sites with dense autumn broad-leaved weed populations were greatest following the use of chlortoluron or isoproturon. At three other sites with moderate to dense wild-oat populations (60 to 240 plants/m¹), the use of barban at the crop three-leaf stage gave larger yields than benzoylprop-ethyl in late spring at the early stem elongation stage of the crop. Seed formation from surviving A. fatua was similar with both wild-oat herbicides. The treatment which reduced seed production of A. fatua and maintained crop yield most consistently was barban followed by benzoylprop-ethyl, each at half the normal recommended dose.     

追施氮肥时期对冬小麦旗叶叶绿素荧光特性的影响

在大田条件下,研究了不同追氮时期对小麦旗叶叶绿素荧光特性、光合速率及籽粒产量的影响.结果表明,拔节期追肥较起身期或挑旗期追肥,改善了小麦旗叶PSⅡ的活性(F_v/F_o)、光化学最大效率(F_v/F_m)、光化学猝灭系数(qP)、实际量子产量(ΦPSⅡ)及光合速率,降低了籽粒灌浆中前期非辐射能量耗散,有利于叶片所吸收的光能较充分地用于光合作用,提高了籽粒灌浆后期非辐射能量的耗散,减缓了叶片光抑制程度和衰老进程.拔节期追肥可显著增加穗粒数和千粒重,提高产量.     

Variation in growth form in relation to spectral light quality (red/far-red ratio) in Plantago lanceolata L. in sun and shade populations

Plants from a sun and shade population were grown in two environments differing in the ratio of red to far-red light (R/FR ratio). A low R/FR ratio, simulating vegetation shade, promoted the formation of long, upright-growing leaves and allocation towards shoot growth, whereas a high R/FR ratio had the opposite effects. The increase in plant height under the low R/FR ratio was accompanied by a reduction in the number of leaves. Population differences in growth form resembled the differences between plants grown in different light environments: plants from the shade population had rosettes with long erect leaves, whereas plants from the sun population formed prostrate rosettes with short leaves. Plants from the shade population were more responsive to the R/FR ratio than plants from the sun population: the increases in leaf length, plant height, and leaf area ratio under a low R/FR ratio were larger in the shade population. However, differences in plasticity were small compared to the population difference in growth form itself. We argue that plants do not respond optimally to shading and that developmental constraints might have limited the evolution of an optimal response. Received: 8 December 1996 / Accepted: 31 March 1997     

灌溉和种植方式对冬小麦生育后期旗叶光合特性及产量的影响

于2009—2011年通过田间试验,以高产中筋冬小麦品种济麦22为材料,设等行距平作、宽窄行平作、沟播3种种植方式,每种种植方式下设不灌水(W₀)、灌拔节水(W₁)、灌拔节水+开花水(W₂)、灌拔节水+开花水+灌浆水(W₃)4种灌溉处理(每次灌水量为60 mm),研究不同灌溉和种植方式对冬小麦生育后期旗叶光合特性和产量的影响.结果表明: 随冬小麦灌水量的增加,3种种植方式下小麦花后旗叶叶面积和光合速率均增加,光系统Ⅱ最大光化学效率和实际光化学效率也增加;与W₀处理相比,各灌水处理提高了小麦籽粒产量,但水分利用效率(WUE)降低.同一灌溉条件下,与其他两种种植方式相比,沟播方式小麦花后旗叶光合速率、光系统Ⅱ最大光能转化效率和实际光化学效率均较高,且W₂处理籽粒产量显著高于其他处理.统筹考虑冬小麦的籽粒产量和WUE,沟播结合灌拔节水+开花水是华北平原冬麦区较适宜的节水种植方式.     

Activities of key enzymes for starch synthesis in relation to growth of superior and inferior grains on winter wheat (Triticum aestivum L.) spike

Weight of individual grains is a major yield component in wheat. The non-uniform distribution of single grain weight on a wheat spike is assumed to be closely associated with starch synthesis in grains. The present study was undertaken to determine if the enzymes involved in starch synthesis cause the differences in single grain weight between superior and inferior grains on a wheat spike. Using two high-yield winter wheat (Triticum aestivum L.) varieties differing in grain weight and three nitrogen rates for one variety, the contents of amylose and amylopectin, and activities of enzymes involved in starch synthesis in both superior and inferior grains were investigated during the entire period of grain filling. Superior grains showed generally higher starch accumulation rates and activities of enzymes including SS (sucrose synthase), UDPGPPase (UDP-glucose pyrophosphorylase), ADPGPPase (ADP-glucose pyrophosphorylase), SSS (soluble starch synthase) and GBSS (starch granule bound starch synthase) and subsequently produced much higher single grain weight than inferior grains. Nitrogen increased enzyme activities and starch accumulation rates, and thus improved individual grain weight, especially for inferior grains. The SS, ADPGPPase and SSS were significantly correlated to amylopectin accumulation, while SS, ADPGPPase, SSS and GBSS were significantly correlated to amylose accumulation. This infers that SS, ADPGPPase and starch synthase play key roles in regulating starch accumulation and grain weight in superior and inferior grains on a wheat spike.     

Contribution of the wheat (Triticum aestivum L.) flag leaf to grain yield in response to plant growth regulators

In West-Europe, intensive cereal management uses plant growth regulators (PGRs) especially for wheat. A green-house experiment compared the effects of two PGRs on flag leaf characteristics and yield of winter wheat. Chlormequat chloride + choline chloride (CCC) and chlormequat chloride + choline chloride + imazaquin (CCC+I) were applied to winter wheat at growth stage 5 (Feekes Large scale). CCC and CCC+I significantly increased flag leaf surface area at anthesis. Both treatments also enhanced chlorophyll content of the main stem flag leaf. The grain filling period was extended with PGR application by 2 days. CCC and CCC+I significantly increased net CO₂ assimilation rates during the flag leaf life. No effects of PGR spraying were observed on the pattern of ¹⁴C labelled assimilate distribution. Increased grain yield was due to the increase in average grain weight. The results indicate that PGR treatments increased flag leaf contribution to grain filling. The addition of imazaquin (I) to chlormequat (CCC) improved the effects of CCC.     

西北干旱区不同海拔高度地区气温变化对春小麦生长的影响

基于1981—2006年西北干旱区高海拔地（民乐站）和低海拔地（张掖站）农业气象观测站的观测资料,对民乐站和张掖站的气温变化及其对春小麦生长发育和产量的影响进行了研究.结果表明：研究期间,民乐站、张掖站的气温均呈增加趋势,且高海拔地区的增温幅度大于低海拔地区;民乐站春小麦对气温变暖的响〖JP2〗应表现为生育期缩短、产量增加,张掖站春小麦对气温变暖的响应表现为生育期缩短、产量下降;春小麦生育期内日均气温每升高1 ℃,民乐站和张掖站春小麦生育期分别缩短8.3 d和3.8 d.民乐站春小麦生育期内最高气温低于30.4 ℃时,春小麦生育期和产量均小幅增加,当超过30.4 ℃时,春小麦生育期缩短、产量下降.     

Role of thiourea in improving productivity of wheat (Triticum aestivum L.)

The role of thiourea (TU), a sulfhydryl compound, was assessed in wheat via soil and foliar treatments. Results showed that at 30 days after flowering, soil-applied TU treatments did not influence dry matter accumulation or its distribution in leaves, stems, and ears, but foliar-applied treatments brought about significant effects varying with the timing of spray. At harvest, however, soil-applied treatment of 10 kg/ha TU increased the number of ears, grains/ear, weight/grain, biological yield (total above ground biomass), grain yield, and harvest index. Grain yield increased by 17.3% over control. Soil-applied 20 kg/ha TU increased the grain yield by 1.6% over control. Foliar applied treatment of 0.5 kg/ha TU at tillering increased the number of ears, grains/ear, weight/grain, biological yield, grain yield, and harvest index. Grain yield increased by 15.2% over control. Foliar spray of 0.5 kg/ha TU at flowering tended to improve only weight/grain, but biological yield and grain yield increased significantly. Grain yield increased by 6.6% over control. TU spray at both tillering and flowering increased the number of ears, grains/ear, weight/grain, biological yield, grain yield, and harvest index. Grain yield increased by 23.9% over control, and when compared with spray at tillering there was a significant increase of 7.5%. Thus, two foliar sprays of thiourea, at tillering and at flowering, at 1 kg/ha can be recommended for improving wheat productivity.Abbreviations TU thiourea - DMA dry matter accumulation - DMD dry matter distribution     

Combining ability in the F1 and F2 generations of diallel cross in hexaploid wheat (Triticum aestivum L. em. Thell)

The F(1) and F(2) progenies of a ten-parent diallel cross (excluding reciprocals) of hexaploid wheat (Triticum aestivum L. em. Thell) were analyzed for combining ability for quantitative and quality traits. The results indicated significant differences among the parents for general combining ability (gca) and crosses for specific combining ability (sca) for all the characters studied. The gca and sca components of variance were significant for all the traits. However, the gca component of variance was predominant indicating the predominance of additive gene effects for the traits studied. Among the parents Durgapura 65, HD 2285, Lok-1, Raj 1972 and HD 2329 were the best general combiners for grain yield and average to high combiners for tillers per plant, grain yield per spike, grains per spike and 1000-grain weight. The best specific crosses for grain yield were Sonalika x WH 157, HD 2428 x Durgapura 65, Durgapura 65 x Sonalika, HD 2428 x Lok-1 and CPAN 3004 x Raj 1972. The parent Raj 1972, Lok-1 and HD 2285 were the best general combiners for grain yield and protein content, however, Raj 3077 was the best general combiner for protein content. The most suitable specific crosses for protein content were HD 2329 x HD 2285, HD 2428 x Raj 1972 and CPAN 3004 x WH 157. Most of the specific crosses for grain yield as well as protein content involved high x average, average x average and average x poor general combiners. To ensure further increase in grain yield along with high protein, combinations of desirable yield components is advocated. Inclusion of F(1) hybrids showing high sca and having parents with good gca, into multiple crosses and/or bi-parental mating, or diallel selective mating could prove a worthwhile approach for further improvement of grain yield in bread wheat.     

Yield responses of Nepalese spring wheat (Triticum aestivum L.) cultivars to inoculation with Azospirillum spp. of Nepalese origin

Azosprilla were collected in wheat fields from subtropical and temperate soils of central Nepal at various elevations. Different wheat cultivars responded positively and significantly in grain yield, grain N-yield, and total N-yield in plant shoots to the inoculation with Nepalese isolate Azospirillum 10SW. Nepalese wheat cv. Seto responded significantly better with Azospirillum 10SW than with the Brasilian isolate A. lipoferum Sp 108 st, a strain which was found highly efficient in earlier experiments with German wheat cultivars, especially cv. Turbo. Yield of Turbo was increased by inoculations of both Azospirillum strains too, but it showed no significant differences depending from the inoculum used. The higher efficacy of combining Azospirillum 10SW and Seto, both collected from the same locality, indicates the possibility of improved associations using traditional cultivars and local bacteria. ei]{gnR O D}{fnDixon}     

The parameters of grain filling and yield components in common wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) and durum wheat (<Emphasis Type="Italic">Triticum turgidum</Emphasis> L. var. <Emphasis Type="Italic">durum</Emphasis>)

Final grain dry weight, a component of yield in wheat, is dependent on the duration and the rate of grain filling. The purpose of the study was to compare the grain filling patterns between common wheat, (Triticum aestivum L.), and durum wheat, (Triticum turgidum L. var. durum), and investigate relationships among grain filling parameters, yield components and the yield itself. The most important variables in differentiating among grain filling curves were final grain dry weight (W) for common wheat genotypes and grain filling rate (R) for durum wheat genotypes; however, in all cases the sets of variables important in differentiating among grain filling curves were extended to either two or all three parameters. Furthermore, in one out of three environmental conditions and for both groups of genotypes, the most important parameter in the set was grain filling duration (T). It indicates significant impact of environmental conditions on dry matter accumulation and the mutual effect of grain filling duration and its rate on the final grain dry weight. The medium early anthesis date could be associated with further grain weight and yield improvements in wheat. Grain filling of earlier genotypes occurs in more temperate environments, which provides enough time for gradual grain fill and avoids the extremes of temperature and the stress of dry conditions.     

Costs and benefits of hydroxamic acids-related resistance in winter wheat against the bird cherry-oat aphid, Rhopalosiphum padi L.

Estimations of infestation by the bird cherry-oat aphid (Rhopalosiphum padi) as well as measurements of grain yield in 26 Hungarian winter wheat cultivars under field conditions were correlated with the concentration of hydroxamic acids (Hx) in seedlings of those cultivars. The significant inverse relationship between infestation ratings and Hx levels in wheat showed that Hx, despite their decreased accumulation at later plant phenological stages, may be able to confer resistance against aphid infestation in the field. Since no significant relationship was found between grain yield and Hx levels in plants it is suggested that Hx accumulation does not impose a cost to the plant in terms of yield. These findings support earlier claims stressing the potential of Hx as breeding targets for aphid resistance in wheat.     

Genetic dissection of grain yield in bread wheat. I. QTL analysis

Grain yield forms one of the key economic drivers behind a successful wheat (Triticum aestivum L.) cropping enterprise and is consequently a major target for wheat breeding programmes. However, due to its complex nature, little is known regarding the genetic control of grain yield. A doubled-haploid population, comprising 182 individuals, produced from a cross between two cultivars ‘Trident’ and ‘Molineux’, was used to construct a linkage map based largely on microsatellite molecular makers. ‘Trident’ represents a lineage of wheat varieties from southern Australia that has achieved consistently high relative grain yield across a range of environments. In comparison, ‘Molineux’ would be rated as a variety with low to moderate grain yield. The doubled-haploid population was grown from 2002 to 2005 in replicated field experiments at a range of environments across the southern Australian wheat belt. In total, grain yield data were recorded for the population at 18 site-year combinations. Grain yield components were also measured at three of these environments. Many loci previously found to be involved in the control of plant height, rust resistance and ear-emergence were found to influence grain yield and grain yield components in this population. An additional nine QTL, apparently unrelated to these traits, were also associated with grain yield. A QTL associated with grain yield on chromosome 1B, with no significant relationship with plant height, ear-emergence or rust resistance, was detected (LOD ≥2) at eight of the 18 environments. The mean yield, across 18 environments, of individuals carrying the ‘Molineux’ allele at the 1B locus was 4.8% higher than the mean grain yield of those lines carrying the ‘Trident’ allele at this locus. Another QTL identified on chromosome 4D was also associated with overall gain yield at six of the 18 environments. Of the nine grain yield QTL not shown to be associated with plant height, phenology or rust resistance, two were located near QTL associated with grain yield components. A third QTL, associated with grain yield components at each of the environments used for testing, was located on chromosome 7D. However, this QTL was not associated with grain yield at any of the environments. The implications of these findings on marker-assisted selection for grain yield are discussed.     

Response of Spring Wheat (Triticum aestivum L.) Quality Traits and Yield to Sowing Date

The unpredictability and large fluctuation of the climatic conditions in rainfed regions do affect spring wheat yield and grain quality. These variations offer the opportunity for the production of better quality wheat. The effect of variable years, locations and sowing managements on wheat grain yield and quality was studied through field experiments using three genotypes, three locations for two years under rainfed conditions. The two studied years as contrasting years at three locations and sowing dates depicted variability in temperature and water stress during grain filling which resulted considerable change in grain yield and quality. Delayed sowing, years (2009–10) and location (Talagang) with high temperature and water stress resulted increased proline, and grain quality traits i.e. grain protein (GP) and grain ash (GA) than optimum conditions (during 2008–09, at Islamabad and early sowing). However, opposite trend was observed for dry gluten (DG), sodium dodecyl sulphate (SDS), SPAD content and grain yield irrespective of genotypes. The influence of variable climatic conditions was dominant in determining the quality traits and inverse relationship was observed among some quality traits and grain yield. It may be concluded that by selecting suitable locations and different sowing managements for subjecting the crop to desirable environmental conditions (temperature and water) quality traits of wheat crop could be modified.     

喷灌灌水量对冬小麦生长、耗水与水分利用效率的影响

于2006-2008年在中国科学院通州农田水循环与节水灌溉试验基地进行田间试验,研究灌水量对冬小麦生长、耗水、产量和水分利用效率的影响.试验设置了不同的灌水量处理,灌水量以布置在冬小麦冠层顶部20 cm标准蒸发皿蒸发量(E)的倍数表示.试验结果表明:2006-2007生长季节中0.75 E处理和2007-2008生长季节中0.625 E处理所对应的冬小麦产量最高.当灌水量小于0.25 E时,冬小麦生长受到水分胁迫,其产量下降25%以上.两个生长季节中冬小麦耗水量为219～486 mm,耗水量随灌水量的增加而增大.冬小麦产量和水分利用效率与耗水量之间呈二次函数关系.北京地区冬小麦返青后的生长季节内,其适宜喷灌水量为0.50～0.75 E.     

二倍体、四倍体和六倍体小麦产量及水分利用效率

试验选用了6个不同染色体倍性的小麦进化材料（3个二倍体、2个四倍体和1个六倍体）,分别在不同水肥条件下研究其根系、地上生物量、产量、蒸腾耗水量和水分利用效率等指标,旨在阐明小麦进化材料产量及水分利用效率的差异及水肥条件对这些特性的影响。试验表明：不同倍性小麦进化材料的生物量、产量和水分利用存在显著的差异,而且水肥条件对其有显著影响。在染色体倍性由2n→4n→6n的进化过程中,小麦根系及地上生物量均先增加后降低,而产量却显著增加,这与收获指数的增加有关。小麦产量的大小顺序为：T.aestivum〉T.dicoccum〉T.dicoccoides〉Ae.squarrosa〉Ae.speltoides〉T.boeoticum。水分亏缺显著降低小麦的生物量、产量和收获指数;在不同水分条件下,增加施肥量有利于这些指标的增加。但是水分亏缺下,增加施肥却降低各小麦材料的根系生物量。随小麦的进化,蒸腾耗水量显著降低,这与其生育期缩短有关;而生物量水分利用效率和产量水分利用效率却显著升高,且后者的差异要大于前者。各小麦产量水分利用效率的大小排序与产量的完全一致。水分亏缺处理显著减少各小麦进化材料的蒸腾耗水量47％～52％,而显著增加生物量水分利用效率3％～40％;但水分亏缺对产量水分利用效率的促进作用却随染色体倍性的增加而降低,甚至降低六倍体小麦T.aestivum的产量水分利用效率19％。不同水分条件下,高肥处理均有利于蒸腾耗水量、生物量水分利用效率和产量水分利用效率的增加。