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1.
The effect of major dwarfing genes on yield potential in spring wheats   总被引:1,自引:0,他引:1  
Summary A composite convergent cross of 16 spring wheat parents produced a set of unselected progeny lines among which the major dwarfing genes, Rht1, Rht2 and Rht3, were distributed against a common random genetic background. Random subsets of these lines were grown under irrigation and optimal conditions in 4 experiments with replicated bordered plots in southern New South Wales in order to measure the dwarfing gene effect on yield potential. The dwarfing gene composition of each line was determined by test crossing and seedling responsiveness to gibberellic acid.Lodging was negligible in the two experiments in 1982. While present in the two in 1983, it was not strongly associated with yield. Grain yield levels were appropriately high (mean 5.9 t/ha). In all but 1 experiment the Rht1+Rht2 dwarf genotypes gave highest yields while the Rht3 group yielded on average 3% lower, Rht2 9% lower, Rht1 11% lower, and the non-dwarf or tall group yielded 24% lower. These yield differences were positively associated with harvest index, kernels per m2 and kernels per spike, but negatively associated with mature plant height. Even within major dwarfing gene classes, grain yield was significantly and negatively associated with height.  相似文献   

2.
K. N. Rai  A. S. Rao 《Euphytica》1991,52(1):25-31
Summary A d2 dwarfing gene in pearl millet [Pennisetum glaucum (L.) R. Br.] is currently being extensively used for the development of hybrid parents. Its effect on grain yield and yield components is poorly understood. Twelve pairs of tall and dwarf near-isogenic lines developed in the diverse genetic background of three composites were evaluated for grain yield and yield components for 2 years at two locations in southern India. The d2 gene or the genes linked to it, on an average, reduced plant height by 42%, grain yield by 14%, and head girth by 8% but increased head length and number of tillers per plant by about 5–6%. Large variations were observed among pairs (genetic background) for the difference between tall and dwarf near-isogenic lines for all of the above yield components resulting in no significant difference in five pairs and 17–35% less yield in dwarfs as compared to their tall counterparts in six pairs. Days to 50% flowering and seed weight were least affected by the d2 gene with the average difference between tall and dwarf groups of near-isogenic lines being of the order of 1–2%. These results indicate that the advantageous effects of d2 dwarfing gene can be effectively exploited by manipulating the genetic background. The difference between the average grain yields of tall and dwarf groups of near-isogenic lines showed considerable variation across environments with the dwarfs yielding as much as tall group in one environment and up to 30% less than the tall group in the other, thus, indicating that the d2 gene effect may be substantially modified by the environments.Submitted as JA No. 979 by the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT).  相似文献   

3.
Patterns of assimilation and partitioning of photosynthate and nitrogen in isogenic tall, semidwarf, and doubledwarf (Norin 10/5/Pawnee) 'Pawnee' hard red winter wheats ( Triticum aestivum L.) were studied under controlled environmental conditions and field conditions. The objective of the investigations was to determine reasons for the advantageous harvest index associated with dwarf genes. Plants were sampled at four growth stages and separated into plant parts as they developed. Ribulose bisphosphate carboxylase (RuBPC) and nitrate reductase (NR) activities in leaves differed among growth stages but not among isogenic lines. Fructosan in sheaths, stems, and roots increased from the soft dough stage to maturity, but differed little among the lines. Nitrogen concentrations decreased in leaf blades, stems, and roots as plants developed to the soft dough stage and then stayed nearly constant until maturity. Nitrogen in all plant parts frequently varied directly with the complement of dwarfing genes, being lowest in the tall line and highest in the doubledwarf line. The tall and semidwarf lines had significantly higher grain yield, test weight, total dry matter, spike number, and 1000-kernel weight than the doubledwarf line under either or both experimental conditions. The dwarf lines, however, had significantly higher kernel number per spike than the tall line. Harvest index was higher for the doubledwarf line (0.58) than for the two other lines (0.54).  相似文献   

4.
Under field conditions in Germany over three growing seasons the pleiotropic effects on yield and its components of four sets of near isogenic lines carrying the GA insensitive dwarfing alleles Rht1, Rht2, Rht3, Rht1+2, Rht2+3 or rht (tall) in four different genetical backgrounds were examined together with 24 single chromosome recombinant lines segregating for the GA sensitive dwarfing gene Rht8 and the gene for day-length insensitivity Ppd1 in a ‘Cappelle-Desprez’ background. For the GA insensitive semi-dwarfs it was shown that in all three years a higher number of grains per ear was accompanied by a lower grain weight. Depending on the climatic conditions in a particular year, the increase in grain number was sufficient to compensate for the reduction in grain size and resulted in higher yields. For the Ppd1 allele yield advantages were found for wheats grown under environmental conditions of middle Europe.  相似文献   

5.
Relationships between grain yield attributes and response to agronomic practices of dwarf and tall genotypes in the major U.S. wheat region were investigated. Isogenic tall, semidwarf, and doubledwarf (Norin 10/5/Pawnee) 'Pawnee' winter wheat ( Triticum aestivum L.) lines were planted in a split-split-plot design with nitrogen fertilizer rates of 0, 50, and 100 kg ha−1 as main plots and seeding rates of 30, 60, and 90 kg ha−1 as subplots in four replications at Hutchinson and Manhattan, Kansas, during 1980–1981. There was no evidence that dwarf lines responded better than the tall line to nitrogen fertilizer; however, percentage fertile spikelets, spike length, harvest index, and kernel number per spike of the semidwarf line were favored by high nitrogen rates. Grain yield was more responsive to seeding rate in the doubledwarf line than in the other lines, and test weight and spike number per unit area were more responsive to seeding rate in one or both dwarf lines than in the tall line. Grain yield of each genotype depended highly on the predominant yield attributes — usually spike number per unit area and/or kernel weight — at one or both locations.  相似文献   

6.
不同矮秆基因小麦农艺性状的遗传差异   总被引:4,自引:1,他引:4  
对含有不同主效矮秆基因(Rht1,Rht2和Rht1+Rht2)的三组春小麦进行了两年,两地试验。结果表明,具有半矮秆基因Rht1的小麦表现出较高的生物产量,穗粒数和容重,它们以此获得较高的籽粒产量;具有矮秆基因Rht1和Rht2的小麦,则表现出较高的千粒重,通过半大收获指数获得高产;在两个半矮秆组内,籽粒产量与株高之间,粒数/m^2与千粒重之间均为显著负相关,就矮秆组而言,在籽粒产量与粒数/m^  相似文献   

7.
Wheat reduced height (Rht) genes encode modified DELLA proteins, which are gibberellin insensitive, accumulate under stress, restrain growth and affect plant stress response. The seedling reaction to soil water deficit regarding leaf gas exchange and chlorophyll fluorescence was compared in near‐isogenic lines carrying the alleles Rht‐B1a (tall), Rht‐B1b (semi‐dwarfing) and Rht‐B1c (dwarfing) and was related to leaf water content and anatomy. Under drought, Rht‐B1c line was characterized by less decreased CO2 assimilation, delayed non‐stomatal limitation of photosynthesis and higher instantaneous water use efficiency. The functional state of its photosynthetic apparatus was better preserved as evidenced by the less decreased actual quantum yield (ΦPSII) and potential maximum quantum yield (Fv/Fm) of PSII, and the less increased quantum yield of non‐regulated energy dissipation (ΦNO). Rht‐B1b line also tended to perform better than Rht‐B1a, but differences were less pronounced. Although the leaves of both dwarf lines were smaller, thicker and more pubescent, their water content was not higher in comparison with the tall line. Nevertheless, in Rht‐B1c, leaf thickness was less decreased and mesophyll cells were less shrunk under drought. The more effective performance of the photosynthetic machinery of dwarf lines under water deficit could be explained by a combination of morpho‐anatomical and metabolic characteristics.  相似文献   

8.
Summary Wheat varieties tend to be chromosomally unstable producing on average 2–3% of plants with abnormal chromosome numbers. A number of semi dwarf wheat varieties, carrying the gibberellic acid insensitive dwarfing genes Rht1 or Rht2, have been seen to produce distinct tall off types due to reduction in dosage of the chromosome carrying the dwarfing gene. The UK variety Brigand, carrying Rht2 on chromosome 4D, produced very distinct tall off types when this chromosome was reduced in dosage. The frequency of tall off types was sufficiently high to cause the variety to fail United Kingdom statutory uniformity tests. An attempt to prevent the loss of chromosome 4D was made by constructing translocation chromosomes involving the short arm of chromosome 4D, which carries Rht2, and the long arm of chromosome 4S l from Aegilops sharonensis, which carries a gene(s) conferring preferential transmission. The work in this paper describes the field evaluation of two lines carrying 4DS.4DL-4S l L translocations, and demonstrates their success in preventing spontaneously occurring monosomy of chromosome 4D in semi-dwarf wheats.  相似文献   

9.
利用矮秆基因RhtB1-b、RhtD1-b和Rht8特异分子标记对郑麦583和2015-2016年度参加河南省区域试验、河南省品种比较试验、国家黄淮南片区域试验及国家黄淮麦区品种比较试验的共630份小麦材料的基因型进行检测。结果表明,供试材料中检测到549份材料含有RhtB1-b基因;592份材料含有RhtD1-b基因;513份材料含有Rht8基因;422份材料同时含有3个矮秆基因,169份材料仅含有2个矮秆基因,说明3个主要的矮秆基因在河南小麦育种过程中被聚合使用。此外,分析发现,矮秆基因Rht8与株高和每公顷穗数,以及千粒重具有显著相关性。郑麦583等小麦品种聚合了这3个矮秆基因,具有优良的丰产性,通过选择和利用矮秆基因对于培育具有丰产性优点的小麦品种具有一定价值。  相似文献   

10.
利用以春小麦品种AprilBearded为背景的含有不同矮秆基因Rht1、Rht2、Rht3、Rht1+Rht2和Rht2+Rht3的5个近等基因系,研究了不同矮秆基因对小麦生长发育的作用。结果表明:Rht1半矮秆基因显著缩短了小麦植株生长发育进程,促进了地上部干物质积累,加大了旗叶面积和倒二叶面积,提高了单株成穗率,减少了无效分蘖;Rht2半矮秆基因显著增大了倒二叶面积,提高了单株成穗率和穗长,减少了无效分蘖;Rht3矮秆基因显著加大了旗叶面积,但对地上部干物质的积累、单株成穗和穗长均有显著的负向作用;Rht1+Rht2基因结合没有突出的优势存在:Rht2和Rht3基因结合对有利于提高小麦产量性状的作用均为负向最大;上述3种矮秆基因及其不同的结合形式均有显著的使茎秆矮化的作用。因此认为Rht1半矮秆基因在小麦育种中利用价值较大,Rht3矮秆基因利用价值则较小。  相似文献   

11.
The effect of two major dwarfing (Rht-B1b and Rht-D1b) genes varies with environment. Near-isogenic pairs (i.e., tall and semidwarf) of six spring wheat lines, included in the International Adaptation Trial (IAT), were grown in 81 trials around the world from 2001 to 2004. Trial yields ranged from 1 to 8 t ha−1 with a mean of ca. 4 t ha−1. Overall, the yield advantage of the lines possessing the dwarfing gene was ca. 10% and was particularly evident in trials where the mean height of semidwarf isolines exceeded ca. 80 cm. However, the yield advantage was greater in the slightly taller and older lines (Pavon and Galvez) than in the newer lines Nesser and Kauz and the two durum lines. Sixteen pairs of semidwarf/tall near-isolines were grown in six managed drought environment trials at CIMMYT in northwestern Mexico. In these trials, height and yield differences were small and/or negligible in the most droughted environment (2.5 t ha−1) and the slope of yield versus height for each isoline pair became consistently negative with increase in irrigation. In the IAT, the slope of the yield versus height was much more variable at low heights or yields, presumably due to the fact that there were many more factors driving the response. Even at the point where the slope became consistently negative (ca. between 2 and 4 t ha−1), there were some trials where tall isolines equaled or exceeded the yield of semidwarf isolines, particularly in the most recent developed cultivar, Kauz. For submission to Euphytica as part of special issue “Challenges to International Wheat Breeding”. From the International Symposium on Wheat Yield Potential: Challenges to International Wheat Breeding, Days Inn, Ciudad Obregón, Sonora, Mexico, March 19–24th, 2006.  相似文献   

12.
The components of grain yield are altered by adverse growing conditions as the effects of certain environmental factors on crop growth and yield differ depending upon the developmental stages when these conditions occur. Path-coefficient analysis was used to investigate the main processes influencing grain yield and its formation under Mediterranean conditions. Twenty-five durum wheat genotypes, consisting of four Spanish commercial varieties and 21 inbred lines from the ICARDA durum wheat breeding program, were grown during 1997 and 1998 under both rainfed and irrigated conditions in southern Spain. {P}ath-coefficient analysis revealed that under favourable conditions grain yield depended in equal proportion on the three primary yield components (i.e. spikes m−2, grains spike−1, and mean grain weight), whereas in the rainfed experiments, variations in grain yield were due mainly to spikes m−2 and to a lesser extent to grains spike−1. Compensatory effects were almost absent under irrigated treatments; however, under water shortage, spikes m−2 exerted a negative influence on grain spike−1 due mainly to a negative interrelationship between tiller production and apical development. These compensatory effects could partially explain the restricted success in durum wheat breeding observed in water-limited environments of the Mediterranean region. Under rainfed conditions the number of spikes m−2 depended mainly on the ability for tiller production, whereas in the irrigated experiments the final number of spikes was determined mostly by tiller survival.  相似文献   

13.
Laing  D. R.  Fischer  R. A. 《Euphytica》1977,26(1):129-139
Summary With a view to determining the comparative adaptation of semidwarf wheats to rainfed conditions, adaptation analyses were carried out on grain yield data of the 6th and 7th International Spring Wheat Yield Nurseries of the International Maize and Wheat Improvement Centre. Sites were chosen which had not received irrigation: across a combined total of 44 such sites, yield variation was closely related to growing seasonal rainfall. Using these sites, yields of thirty-three common cultivars. Norin 10-derived semidwarf cultivars plus tall ones, were regressed against site mean yield to give a regression slope (b) and deviations from the regression (sd 2) for each cultivar.Semidwarf cultivars generally showed higher mean yields and larger regression slopes (b > 0.9) than tall cultivars from lower latitudes. Tall cultivars from higher latitudes showed the lowest mean yields and the lowest b values (< 0.7). No consistent trends in sd 2 were evident. Despite the greater regression slopes of semidwarf wheats, the best yields under all but the lowest yielding (driest) conditions were given by certain semidwarf cultivars; these had high mean yields and b values close to 1.0 (for example Tobari 66, Inia 66, Pato ArGentino and Sonalika). In contrast other semiwdarfs (notably Chenab 70) of similar mean yield, plant height and phenology, were not well adapted to the drier conditions as indicated by b values close to 1.3. The usefulness of the regression technique and the implications of these results for selection of semidwarf wheats adapted to drier conditions are discussed.Joint contribution from the Department of Agronomy, University of Sydney, N.S.W. 2006, Australia and the International Maize and Wheat Improvement Centre (CIMMYT), Londres 40. Mexico 6, D.F.  相似文献   

14.
Semidwarf genes have made a major contribution to grain yield gains in wheat during this century. These genes have frequently been reported to increase grain number but decrease grain size. To analyse possible causes of this negative association between number of grains per head and mean grain weight, grains from different positions within the spikes were individually weighed in three isolines (standard-height, SH; semidwarf, SD; and dwarf, DD) of the spring wheat cultivar Maringa grown under field conditions. Dwarfing genes affected both grain number and grain weight. Increasing doses of Rht genes resulted in a decreased average grain weight (ca. 22 %) but in a greater increase in number of grains per m2 (ca. 40%). Since the isogenic lines did not differ in either the number of spikes per m2 or number of spikelets per spike, the frequencies of appearance of grains in the distal positions (florets 3 and 4) of the central spikelets and in the top spikelets of the spike was much higher for the SD and DD lines than for the SH line. Averaging across spikelets, basal grains (grains 1 and 2) of SH, SD and DD lines represented ca. 82, 73, and 69 %, respectively, of the total number of grains. On the other hand, grain 4 was almost absent in the SH line but represented around 10 % of the grains in the DD line. Averaging across lines and spikelets, basal grains weighed ca. 30 mg, which is approximately 20 % heavier than grain 3 (ca. 25 mg) and 85 % heavier than grain 4 (ca. 16 mg). Although there was a clear trend for a greater grain weight in the SH line (with no major differences between the SD and DD line) when basal grains were considered, grains 3 and 4 did not show any clear difference between lines. The fact that genotypes with Rht alleles had grains in the distal positions with a much higher frequency of appearance than in the SH line could be the main reason for their lower average grain weight. Therefore, the negative relationship between grain number and average grain weight might be not reflecting that competition for assimilates among grains of the DD and SD lines is stronger than that in the SH line.  相似文献   

15.
In six field experiments conducted over 2 years, the effect of one or two cuttings on grain yield of triticale (× Triticosecale Wittmack) were investigated. In addition, the relationships between triticale grain yield its components were analysed.
Grain yield of the uncut plots invariably exceeded the plots with one or two cuttings, regardless of the environment or year. The reductions in grain yield caused by one cutting ranged from 27 % to 60 % under rainfed conditions and 18 % to 20 % under irrigation. With two cuttings the reduction was 45 % to 70 % for rainfed, and 35 % to 48 % for irrigated conditions.
The yield components which most influenced grain yield of triticale under cutting treatment were the number of ears m−2 in all six experiments and the number of grains per ear under rainfed conditions. At the rainfed sites in 1989 cuttings diminished the number of ears m−2 mainly by increasing plant mortality. Nevertheless, at the rainfed sites of 1990 and at the irrigated site of both years, the reduction in the number of ears m−2 with cuttings was due principally to a lower survival of tillers per plant.  相似文献   

16.
Summary One main reason for the slow improvement of durum wheat in water-limited environments is the lack of clear understanding of the interrelationships among yield components and their compensatory changes under low and erratic moisture availability. Five cultivars, varying in many physiological attributes, were tested under different drought-stress conditions in field and greenhouse experiments. The cause-effect relationships of duration of vegetative period, duration of grain-filling period, number of spikes per m2, kernels per spike, kernel weight and grain yield per m2 were assessed. Furthermore, yield stability was evaluated. Yield reduction was largest under mid-season stress (58%), followed by terminal stress (30%) and early stress (22%). Cultivar Po was very sensitive to terminal stress.Path-coefficient analysis revealed a complex pattern of relationships among the six variables. An increase in vegetative period reduced the grain-filling period under all conditions. It increased number of kernels per spike under non-stress conditions. The direct effect of spikes per m2 on grain yield was significantly positive. However, more spikes per m2 resulted in fewer kernels per spike and a low kernel weight and, as a result, a negative relationship with grain yield under early stress. Grain-filling period had a strong influence on grain yield via kernel weight. Kernels per spike had the largest direct effect on grain yield. However, it was negatively correlated with kernel weight, especially under terminal stress. Grain yield heavily depended on kernels per spike under early stress and grain-filling period and kernels per spike under terminal stress.Variation in drought susceptibility index among cultivars was significant under early and terminal stress conditions, but not under mid-stress conditions. Yield potential and stability were not correlated for the different drought-stress conditions.Longer grain-filling period, increased number of kernels per spike and limited spike number per m2 can be used as selection criteria for sustainable yield in water-limited environments.  相似文献   

17.
The impact of the Rht dwarfing genes on P utilization efficiency (PUTE = grain dry matter per kg P in above-ground biomass), total P uptake (Pt) and related traits was studied in the varietal backgrounds of two tall wheat cultivars, Maringa and Nainari 60. Four sets of near-isogenic lines carrying different combinations of the alleles Rht-B1b, Rht-D1b and Rht-B1c for gibberellin-insensitive dwarfism in the hexaploid wheat (Triticum aestivum L.) were compared with tall controls in two field trials under conditions of adequate nutrient supply and irrigation in Northwest Mexico. The yield-increasing effect of the dwarfing genes Rht-D1b and Rht-B1b led to improved PUTE in Maringa and total P uptake in both cultivars. Also, the double dwarf line of Maringa had larger grain yields and P uptake compared to the tall control. The Rht-B1c genotypes showed low PUTE, thick roots and high P concentration in vegetative biomass indicating a surplus of assimilates and P, which could not be translocated into the grains. A similar problem could be observed in Nainari 60 with Rht-B1b and Rht-D1b, which produced the largest grain dry matter with the lowest P concentrations in grains although they showed high P accumulation in straw. Most of the net P uptake occurred before anthesis. P absorption after anthesis was more critical for the dwarf genotypes. For double dwarfs and Rht-B1c, respectively, only 3% and 21% of the total accumulated P at maturity was absorbed at post-anthesis. The grain P of the dwarf lines came more from P accumulated at pre-anthesis and translocated from the vegetative biomass into the grain. The pre-anthesis P accumulation was positively correlated with spikes per m2 (r = 0.91), whereas post-anthesis P accumulation correlated better with grains per spike(r = 0.72), and thousand kernel weight (r = 0.51). P uptake efficiency played a secondary role under these non-P-limiting conditions, and differences in root length density were only slightly affected by Rht-genes. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

18.
Rht8、Rht10和Rht12矮秆基因对产量构成因子的影响   总被引:1,自引:0,他引:1  
利用携带不同矮秆基因的近等基因系,通过两年、两地的试验研究证明,Rht8半矮秆基因虽然其总小穗数显著低于其他系,但其籽粒产量、小花结实率较Rht10和Rht12显著高.Rht10的降秆作用最强,千粒重显著高于Rht8,但其分蘖成穗率、结实率及小区籽粒产量显著低于其他,表现对环境条件特敏感.Rht12矮秆基因的降秆程度显著高于Rht8,但由于生物产量太低、成熟太晚,造成籽粒产量显著降低,在小麦育种中单独利用价值较低.  相似文献   

19.
During the last decade, the production of off‐season maize has increased in several regions of Brazil. Growing maize during this season, with sowing from January through April, imposes several climatic risks that can impact crop yield. This is mainly caused by the high variability of precipitation and the probability of frost during the reproduction phases. High production risks are also partially due to the use of cultivars that are not adapted to the local environmental conditions. The goal of this study was to evaluate crop growth and development and associated yield, yield components and water use efficiency (WUE) for maize hybrids with different maturity ratings grown off‐season in a subtropical environment under both rainfed and irrigated conditions. Three experiments were conducted in 2001 and 2002 in Piracicaba, state of São Paulo, Brazil with four hybrids of different maturity duration, AG9010 (very short season), DAS CO32 and Exceler (short season) and DKB 333B (normal season). Leaf area index (LAI), plant height and dry matter were measured approximately every 18 days. Under rainfed conditions, the soil water content in the deeper layers was reduced, suggesting that the extension of the roots into these layers was a response to soil water limitations. On average, WUE varied from 1.45 kg m−3 under rainfed conditions to 1.69 kg m−3 under irrigated conditions during 2001. The average yield varied from 4209 kg ha−1 for the hybrids grown under rainfed conditions to 5594 kg ha−1 under irrigated conditions during 2001. Yield reductions under rainfed conditions were affected by the genotype. For the hybrid DKB 333B with a normal maturity, yield was reduced by 25.6 % while the short maturity hybrid Exceler was the least impacted by soil water limitations with a yield reduction of only 8.4 %. To decrease the risk of yield loss, the application of supplemental irrigation should be considered by local farmers, provided that this practice is not restricted by either economic considerations or the availability of sufficient water resources.  相似文献   

20.
Common bean (Phaseolus vulgaris L.) is the most important food legume crop in Africa and Latin America where rainfall pattern is unpredictable. The objectives were to identify better yielding common bean lines with good canning quality under drought, and to identify traits that could be used as selection criteria for evaluating drought‐tolerant genotypes. In all, 35 advanced lines were developed through single seed descent and evaluated with a standard check under drought and irrigated conditions at two locations over 2 years in Ethiopia. Grain yield (GY), pod number per m2, seed number per m2 and seed weight decreased by 56%, 47%, 49% and 14%, respectively, under drought stress. Eight genotypes had better yield with good canning quality under drought compared to the check. Moderate to high proportion of genetic effects were observed under drought conditions for GY and yield components compared to genotype × environment effects. Significant positive correlations between GY and pod harvest index (PHI) in drought suggest that PHI could be used as an indirect selection criterion for common bean improvement.  相似文献   

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