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1.
Approaches are needed to broaden the genetic base and improve earliness and yield potential of large-seeded beans under sustainable cropping systems. The objective of this research was to develop adapted dwarf bean populations having a commercial seed quality and yield suitable for the production in the South of Europe. The original base populations were produced from crosses between genotypes within each Mesoamerica, Nueva Granada and Peru races, and between Peru and Nueva Granada, and Mesoamerica and Nueva Granada races. Visual mass selection for plant performance was practised in the F2 and F3 generations. In the F4 and F5, single plants were harvested under two cropping systems (sole cropping and intercropping with maize). From F4, selection was based on precocity, combined with seed yield and seed commercial type. The F4:7 selected lines from each original population were compared with their parents and five checks at four environments and two cropping systems. Differences among environments, populations, parents and checks were observed for all traits. Under intercropping with maize, there was a 50% reduction in seed yield. Yield of parents and checks belonging to Andean South American races, intraracial (Nueva Granada × Nueva Granada) and interracial (Nueva Granada × Peru) populations, was higher than that of those of Middle American origin. Intraracial crosses within large-seeded Andean South American (Peru race) and Middle American gene pools (Mesoamerica race) did not produce lines yielding more than the highest yielding parent. Only two large-seeded lines selected from crosses between small- and large-seeded gene pools out-yielded the best parent and check cultivar.  相似文献   

2.
Breeding programmes in common bean (Phaseolus vulgaris L.) have mainly focused on performance under monoculture conditions. Interactions among cultivars and cropping systems do occur and genotypes bred for pure cropping may not be suitable for intercropping. This study was undertaken to obtain estimates of genetic parameters of quality traits for bush bean landraces grown in two cropping systems, and the interrelationships of these traits between pure cropping and intercropping with maize (Zea mays L.). Field experiments were conducted at two locations for two years. Expression of most traits was not strongly influenced by genotype × environment interactions. Heritability estimates were similar in both cropping systems for most pod and seed quality traits. Positive correlations were observed between pure cropping and intercropping for pod characters (weight, length, width and texture) and seed characters (dry and imbided weight, length, hardness, coat proportion, water absorption and crude protein). Use of a selection index is suggested for breeding for seed size, water absorption,coat proportion and crude protein for both cropping systems. However, larger gains would be expected in pure cropping for most traits. Bean accessions PHA-0267, PHA-0285, PHA-0286 and PHA-0299 should be used for developing acceptable culinary and high protein breeding lines for either cropping system. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

3.
The selection of cultivars for the predominant cropping systems of small farms in the tropics depends to a large extent on the information obtained by testing their performance across the different systems. The main objective of this experiment was to measure the genotype × cropping system (G × CS) interaction for yield and selected agronomic traits of climbing beans (Phaseolus vulgaris L.) grown as sole crop and intercropped with two morphologically contrasting maize (Zea mays L.) cultivars. A secondary objective was to identify the most efficient and productive bean–maize intercrop combinations. Seven climbing bean genotypes were grown as sole crop and intercropped with two maize varieties, BH 140 (Mix. 1) and Guto (Mix. 2), in a factorial arranged Randomized Complete Block Design with three replications at Bako Agricultural Research Center in western Ethiopia. Main effects due to genotype and cropping system (except days to flowering) were significant for all bean traits considered. The genotypes × cropping system interaction terms were also significant for the number of seeds per pod, 100-seed weight, harvest index and seed yield. While bean seed yield significantly correlated with the number of seeds per pod (in Mix. 1) and with harvest index (in both mixtures), positive and significant correlations occurred with the number of pods per plant and 100-seed weight under sole cropping system. The correlation between bean seed yields of Mix. 1 and Mix. 2 and between Mix. 2 and sole crop were positive and significant. No such relationship was found between Mix. 1 and sole crop. The results suggest that selection of suitable climbing bean cultivars for intercropping with maize varieties predominantly grown in the area should be made under the associated culture of the two crops. Intercropping contributed to a significant reduction in seed yield of the bean genotypes due mainly to its adverse effects on the numbers of pods per plant and seeds per pod. The index tLER1 identified most bean–maize genotype combinations of Mix. 2 as biologically more efficient system than Mix. 1. On the other hand, tLER2 values of more than 1.00 for all treatments of Mix. 2 demonstrated higher overall productivity of the intercrop system when the bean genotypes were grown in association with a late-maturing and high yielding maize hybrid BH 140.  相似文献   

4.
Summary The intereropping of common bean (Phaseolus vulgaris L.) and maize (Zea mays L.) is a common practice in the Northwest of the Iberian Peninsula. In this experiment, 25 populations of bush bean were evaluated for nutritional and culinary traits of dry seed and immature pod in sole crop and in intercrop in two years and in two locations, in order to determine whether selection of bush bean in sole crop can result in genetic progress for intercrop.There were no differences in the population means between cropping systems. Significant differences were detected among populations for all traits tudied except starch content, crude ash, water absorption and coat proportion. Population x environment interaction was significant for pod thickness. Bean populations did not interact with cropping systems for any trait, although there were differences between cropping systems for crude protein. These results suggest that a sole crop system provides sufficient information to select bean populations efficiently for the bush bean-maize intercropping system, although the advanced generations of the breeding program should be tested for quantitative traits such as protein content in the appropriate cropping system (intercropping) to know the competitive ability with the associated species. This would permit to choose bush bean populations which complement more efficiently and would be less competitive with the maize population.  相似文献   

5.
In the Andean region, the Preduza project and its partners combined breeding for durable disease resistance using locally adapted cultivars and farmer participatory methods. The approach taken resembles participatory variety selection (PVS). Farmers participated in the selection of advanced materials, rather than finished cultivars. This paper describes this approach and reports experiences with farmers–breeders collaboration. As breeders involved farmers as participants, they learned more about the most important criteria of male and female farmers for preferred cultivars in the marginal environments of Andean cropping systems. This approach encouraged the use of locally adapted cultivars (often landraces), made the breeders less dependent on foreign materials, and has resulted in selection and development of new wheat, barley, common bean, quinoa, potato and maize cultivars. Breeding programmes based on crossing locally adapted cultivars followed by selection by the breeders in the early phases of the breeding programmes and by participatory selection with the farmers in the more advanced stages of the breeding programmes appeared successful. It became clear that breeders must be well acquainted with the farmer preferences such as the requirements for specific agronomic, storage, processing and marketing traits. Over a period of five years the centralized formal breeding approach predominantly based on material produced by the international institutes was replaced by decentralized breeding approaches based largely on local germplasm with extensive farmer participation.  相似文献   

6.
Knowledge of patterns of genetic diversity among existing cultivars helps to broaden the genetic base of new cultivars and maximizes the use of available germplasm resources. This study examined the organization of diversity for morphological traits in 66 landraces of cultivated common bean (Phaseolus vulgaris) from Galicia and its relationship with phaseolin seed protein diversity. Data on growth habit, seed and pod traits obtained from field evaluations at two locations during the 1989—91 cropping seasons were subjected to multivariate statistical analysis. Cluster analysis based on 14 quantitative variables and five qualitative variables identified 11 groups. The landraces were also characterized by phaseolin electrophoresis. The results allowed separation of these landraces into Middle and Andean American groups, which could be further divided into at least eight groups within the Andean American cultivars and three within the Mesoamerican cultivars. These groups in turn corresponded to the previously described races Nueva Granada and Peru of South American origin, and races Durango, Jalisco and Mesoamerica from the Middle American domestication centre. These results confirm the existence of two major groups of germplasm in the cultivated common bean landraces from Galicia, Mesoamerican vs. Andean American.  相似文献   

7.
Common bean (Phaseolus vulgaris L.), an important food crop in Europe, America, Africa and Asia, is thought to fix only small amounts of atmospheric nitrogen. It contributes significantly to the sustainability of traditional cropping systems because of the predominance of small-scale farmers who cultivate beans in those areas. The objectives of this work were to evaluate bush bean varieties under common agronomic cropping systems and to evaluate breeding lines under low N-fertility sole cropping and intercropping systems. The purpose of the study was to characterize the genotype and cropping system's variability in symbiotic and plant characters and to identify the most suitable genotypes to establish an effective symbiosis with indigenous strains of Rhizobium. No significant differences among the bush bean varieties evaluated under typical fertilization practices were observed for N2-fixation and plant traits except for seed nitrogen. Significant differences among the bean lines studied under low N-fertilization conditions were detected for plant growth,plant component and N2-fixation traits. A significant interaction of bean genotype x cropping system was found for number of nodules per plant and nodule moisture on the bush bean varieties studied, and for days to emergence, days to flowering, end of flowering, shoot length, root dry weight and shoot nitrogen on the bean lines evaluated. Nodulation parameters were correlated positively with the yield components, shoot and root parts and duration of flowering, and correlated negatively with seed crude protein, pod and seed dimensions and seed dry weight. These observations indicate that it may be possible to increase both the symbiotic N2-fixation and seed yield through plant breeding. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

8.
为探讨小麦/玉米/大豆多熟套作体系下小麦根系分泌物的分泌特性及其对根系生长环境和植株氮素吸收的影响,2006-2008年连续两个生长季采用田间定位试验,研究了小麦-大豆、小麦-甘薯、小麦/玉米/大豆和小麦/玉米/甘薯4种种植模式下小麦根系分泌物的数量与种类、小麦根系生长、土壤水分、土壤氮含量及植株吸氮量的变化特性。结果表明,与小麦-大豆和小麦-甘薯两种净作模式及小麦/玉米/甘薯套作模式相比,小麦/玉米/大豆套作降低了开花期和成熟期小麦生长区的土壤湿度、pH值及NO3--N和NH4+-N的含量,提高了小麦植株地上部总吸氮量、根系活力、根干重及土壤总氮含量,并且,开花期小麦根系分泌有机酸总量和可溶性糖含量增加,表现为套作>净作,大豆茬口>甘薯茬口,边行>中行,其中以小麦边行处理的分泌量最高。拔节期根系分泌的有机酸,净作处理以乙酸含量较高,占总量的47.8%~51.6%,套作处理以柠檬酸含量较高,占总量的31.7%~55.1%;开花期根系分泌的有机酸,净作和套作处理均以乙酸含量较高,占总量的33.3%~78.3%。小麦/玉米/大豆套作对小麦根系分泌有机酸和可溶性糖有促进作用,从而改善了根系生长环境,提高了小麦对氮素的吸收。  相似文献   

9.
Strategies employed by dry bean breeders to improve yield include early generation testing, ideotype breeding, selection for physiological efficiency, and selection based on genotypic performance and combining ability across gene pools of Phaseolus vulgaris. Ideotype breeding has been successfully deployed to improve yield in navy, pinto and great northern seed types. The ideotype method is based on an ideal plant architecture to which breeders target their selection. Breeding for physiological efficiency is important in combining increased biomass, high growth rates and efficient partitioning. Genotypic performance and combining ability are also critical for yield improvement, since crosses between gene pools can exhibit negative combining ability and problems with lethality, whereas interracial crosses within the same gene pool exhibit the greatest potential. Breeders must work within specific constraints for growth habit, maturity, seed quality and disease resistance. A three-tiered pyramidal breeding strategy is proposed to facilitate yield improvement in dry bean. Breeding of elite, agronomically acceptable germplasm within the same market class is restricted to the apex of the pyramid. The intermediate level has fewer constraints and greater access to diverse germplasm. Interracial crosses within the same gene pool are utilized to exploit genetic differences within adapted material. Extracting genetic diversity from unadapted sources, including wild germplasm and other Phaseolus species, is conducted at the base of the pyramid. The objective of this breeding strategy is the movement of improved germplasm towards the apex, using different breeding procedures to optimize improvement at each tier of the breeding pyramid. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

10.
Nature and magnitude of genetic diversity was assessed using Mahalanobis's D2 statistics and canonical analysis in 50 genotypes of soybean grown in monoculture and in association with maize. All the genotypes were grouped in 10 clusters in case of monoculture, while 8 clusters were formed for intercropping. Monoculture was more suitable environment for expressing the genetic diversity than intercrop. Some genotypes had consistently the similar clustering pattern in both the cropping systems, while others were affected by the cropping system in expressing the genetic diversity. This was confirmed by the canonical analysis. Days to flowering and maturity, seed yield/plant, plant height and 100-seed weight were mainly responsible for genetic diversity in monoculture. Besides phenological traits, pod length and width, and seed yield/plant exerted marked influence on the genetic diversity of soybean genotypes grown in association with maize. Geographical distribution was not necessarily reflected by the genetic divergence, though some degree of relationship between geographic diversity and genetic diversity was evident under both the cropping systems. The performance of some genotypes varied from cropping system to another, while that of others remained unaffected. Breeding programmes to develop varieties suitable for sole crop, intercrop and both the cropping systems have been suggested.  相似文献   

11.
Summary Breeding for resistance to biotic and abiotic stresses of global importance in common bean is reviewed with emphasis on development and application of marker-assisted selection (MAS). The implementation and adoption of MAS in breeding for disease resistance is advanced compared to the implementation of MAS for insect and abiotic stress resistance. Highlighted examples of breeding in common bean using molecular markers reveal the role and success of MAS in gene pyramiding, rapidly deploying resistance genes via marker-assisted backcrossing, enabling simpler detection and selection of resistance genes in absence of the pathogen, and contributing to simplified breeding of complex traits by detection and indirect selection of quantitative trait loci (QTL) with major effects. The current status of MAS in breeding for resistance to angular leaf spot, anthracnose, Bean common mosaic and Bean common mosaic necrosis viruses, Beet curly top virus, Bean golden yellow mosaic virus, common bacterial blight, halo bacterial blight, rust, root rots, and white mold is reviewed in detail. Cumulative mapping of disease resistance traits has revealed new resistance gene clusters while adding to others, and reinforces the co-location of QTL conditioning resistance with specific resistance genes and defense-related genes. Breeding for resistance to insect pests is updated for bean pod weevil (Apion), bruchid seed weevils, leafhopper, thrips, bean fly, and whitefly, including the use of arcelin proteins as selectable markers for resistance to bruchid seed weevils. Breeding for resistance to abiotic stresses concentrates on drought, low soil phosphorus, and improved symbiotic nitrogen fixation. The combination of root growth and morphology traits, phosphorus uptake mechanisms, root acid exudation, and other traits in alleviating phosphorus deficiency, and identification of numerous QTL of relatively minor effect associated with each trait, reveals the complexity to be addressed in breeding for abiotic stress resistance in common bean.  相似文献   

12.
S. P. Singh 《Plant Breeding》1995,114(3):269-271
The objective of this study was to compare the seed yield, seed weight, and maturity of random lines derived from two contrasting populations of common bean ( Phaseolus vulgaris L.): Middle American (TR 7790) and Andean × Middle American (TR 7791). TR 7790 involved crosses between common-bean races of Middle American origin only (Mesoamerica and Durango), whereas TR 7791 involved crosses between races of Middle American and Andean origin (Mesoamerica and Nueva Granada). A total of 85 random lines from each of these two double-cross, interracial populations, a bulk sample of both populations, and all parents were evaluated in a replications-in-set design in eight environments in Colombia between 1991 and 1993. The mean yields of parents, population bulk, and lines from TR 7790 were significantly higher (P < 0.05) than those of TR 7791. Six lines in TR 7790 and nine lines in TR 7791 yielded significantly higher (P < 0.05) than the mean of their parents. Four lines from TR 7790 out-yielded the highest-yielding line from TR 7791. Moreover, while three lines from TR 7790 out-yielded its best parent, none of the lines from TR 7791 out-yielded its highest yielding parent. Thus, substantial yield gains should be expected from interracial populations within the Middle American group of common beans, whereas selection for higher seed yield from Andean × Middle American populations would seem problematic.  相似文献   

13.
This paper describes how plant breeders and farmers worked together to produce improved varieties of maize for the low-resource farmers of the Panchmahals district of Gujarat, India. Initially, farmers tested a range of maize varieties in a participatory varietal selection (PVS) programme. However, none of these proved to be very popular with farmers, although farmers who had more fertile fields adopted the variety Shweta from Uttar Pradesh. Hence, in 1994 a participatory plant breeding (PPB)programme was begun to generate new, more appropriate varieties. Yellow- and white-endospermed maize varieties were crossed that had been either adopted to some extent following PVS or had attributes, such as very early maturity,that farmers had said were desirable. In subsequent generations, the population was improved by mass selection for traits identified by farmers. In some generations,farmers did this in populations which were grown by breeders on land rented from a farmer. Soil fertility management was lower than that normally used on the research-station. The breeding programme produced several varieties that have performed well in research-station and on-farm trials. One of them, GDRM-187, has been officially released as GM-6 for cultivation in hill areas of Gujarat state,India. It yielded 18% more than the local control in research-station trials, while being seven days earlier to silk. In farmers' fields, where average yields were lower, the yield advantage was 28% and farmers perceived GDRM-187 to have better grain quality than local landraces. PPB produced a variety that was earlier to mature than any of those produced by conventional maize breeding, and took fewer years to do so. The returns from PPB,compared to conventional breeding, are higher because it is cheaper and benefits to farmers are realised earlier. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

14.
Summary To satisfy farmer and consumer preferences, breeding efforts to increase yield potential in common bean must take into account the interrelated effects of growth habit, seed size, maturity, and gene pool on yield expression in segregating populations. To examine the relationships among these traits, a genetic study was conducted to determine the effect of growth habit on yield and seed size in crosses among five bean lines from diverse gene pools. Two parental bean lines had determinate, type I growth habits and large seed size typical of the Neuva Granada-Andean gene pool. Two other lines were tropical Mesoamerican types with type II growth habits and small seed size; and the fifth line, G13625, a landrace of the Jalisco gene pool from the Mexican highlands, had a type IV climbing growth habit and medium seed size. Individual F2 plants from each cross and parental lines were evaluated for growth habit and yield component traits under high input field conditions. The following season, the evaluations were repeated on random F3 plants. Of the five parental lines, only G13625 showed significant GCA effects for yield in both the F2 and F3 generations. Improved yielding ability of G13625 progeny was associated with an increased expression of climbing bean growth habit traits: guide length, climbing ability, node number on main stem, and plant height. Crosses between Andean x Mesoamerican and Andean x Jalisco genotypes, as well between growth habit type I (Andean x Andean) and between type II (Mesoamerican x Mesoamerican) had very low parent-offspring heritability values for yield. Yield heritability was only significant for crosses between Mesomerican x Jalisco gene pools. An apparent simple genetic control of growth habit modification towards semi-climbing and climbing types is proposed as the major reason for increased yields in these crosses. No genetic linkage between genes controlling growth habit and seed size was detected which might restrict the development of high yielding large-seeded type II lines.  相似文献   

15.
Cultivars of common bean (Phaseolus vulgaris L.) capable of yielding well at low levels of native or added phosphorus (P) are highly desirable in many tropical production systems. The objective of the present study was to identify geographical regions which might be sources of such genotypes. A total of 364 landraces, cultivars and wild genotypes, drawn from a broad geographic range, were divided on the basis of growth habit into four field trials, each comprising two levels of P, stressed and unstressed, on an infertile Andosol in Popayan, Colombia. The regression relationship between grain yield per plant in the presence and in the absence of stress was determined, and each genotype's deviation from this relationship was used as a measure of P-efficiency. There was highly significant variation in efficiency among genotypes in all growth habits, and in climbing beans there were consistent regional differences, superior genotypes being identified with greater frequency among those from Bolivia, West Mexico and South Mexico-West Guatemala. The latter region was promising for prostrate bush genotypes also. Wild beans in general performed relatively poorly; it appears that P-efficiency traits in P. vulgaris have been acquired during or after domestication. These results confirm that genetic differences in P-efficiency exist among common bean genotypes and suggest that these are related to geographic origin. Furthermore, the use of a representative sample of germplasm can help to identify segments of the gene bank that are especially promising as sources of desirable traits. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

16.
Breeding for high symbiotic nitrogen (N) fixation (SNF) in common bean (Phaseolus vulgaris L.) is expected to contribute to reduced application of chemical fertilizers in cropping systems involving common bean. The magnitude of variation and the genetic and phenotypic correlation among seed yield, SNF, estimated as the percentage of nitrogen derived from atmosphere, and related traits were studied in a population of 140 F4-derived F5 recombinant inbred lines, developed from a cross between low- and high-SNF bean genotypes ‘Sanilac’ and ‘Mist’, respectively. The experiment was conducted in a total of five location-years in Ontario, Canada, from 2011 to 2013. These location-years were grouped into stress- and optimum moisture test sites, based on the total precipitation during the growing season. In each test site two nitrogen supply management strategies, SNF-dependent and N fertilizer-dependent, were simulated separately in the field by inoculating the seed with a commercial Rhizobium leguminosarum bv. phaseoli and by application of N fertilizers at 100 kg ha?1, respectively. The genetic variation was significant for seed yield, SNF and related traits. The heritability of the traits ranged from 14 to 71% and 4 to 25% in optimum moisture and in stress environments, respectively. No significant correlation between SNF and seed yield indicated that selection for high SNF does not necessarily lead to greater seed yield and that selection for both traits should be performed simultaneously.  相似文献   

17.
A field study evaluated the residual effect of a cropping system in two minor (dry) seasons on the productivity pattern and nitrogen utilization of a maize crop grown in the subsequent major (wet) seasons. The cropping systems established in the minor seasons, where evaporation exceeds rainfall, were either monocultures of maize (Zea mays L), or maize intercropped with either common bean (Phaseolus vulgaris L) or sunhemp (Crotolaria juncea L). In addition, monocultures of two green manures, namely sunhemp (Crotolaria juncea) or Tithonia (Tithonia diversifolia), were established. The residues of maize and beans and the green manures were incorporated at the end of the minor season; at the onset of rains in the major season, maize crops were established on the same plots. Germination of maize was not affected by the previous cropping system. In contrast, crop growth and yields of maize and nitrogen utilization were affected by the previous cropping system. Optimum growth and highest yields were procured in maize that was grown after a green manure crop. Similarly, although the yields were high, the planting of a green manure crop reduced nitrogen utilization by maize in the major season, thereby indicating its potential contribution to sustainability, due to its lower mining of soil nitrogen. On the basis of the results of this two‐year study, the impact of cropping systems in minor seasons on the productivity of maize, a very important highland cereal in the tropics, grown under rain‐fed conditions in a major season, is presented.  相似文献   

18.
Plant breeding is not a discipline that readily comes to mind when agricultural sustainability is being considered. Sustainability is normally associated with farming practices such as stubble retention, direct-drilling, or amelioration practices such as contour farming or liming, or rotation practices for nutrient management and disease control. The contribution of plant breeding will be in providing germplasm for these changed practices and devising new methods of selection. This paper reviews opportunities where plant breeding can contribute to improvements in sustainable farming practices. The emphasis is on rainfed cropping systems and cereal improvement. The main contribution for breeding is to (i) increase crop water and nutrient use so that less escapes from the root profile; and (ii) preserve the soil resource with conservation farming systems by developing cultivars specifically adapted to changed farming systems and competitive cultivars that reduce herbicide use. To achieve these outcomes identification of desirable traits, suitable selection methods and development of appropriate germplasm are discussed.  相似文献   

19.
Participatory plant breeding (PPB) has been suggested as an effective alternative to formal plant breeding (FPB) as a breeding strategy for achieving productivity gains under low input conditions. With genetic progress through PPB and FPB being determined by the same genetic variables, the likelihood of success of PPB approaches applied in low input target conditions was analyzed using two case studies from FPB that have resulted in significant productivity gains under low input conditions: (1) breeding tropical maize for low input conditions by CIMMYT, and (2) breeding of spring wheat for the highly variable low input rainfed farming systems in Australia. In both cases, genetic improvement was an outcome of long-term investment in a sustained research effort aimed at understanding the detail of the important environmental constraints to productivity and the plant requirements for improved adaptation to the identified constraints, followed up by the design and continued evaluation of efficient breeding strategies. The breeding strategies used differed between the two case studies but were consistent in their attention to the key determinants of response to selection: (1) ensuring adequate sources of genetic variation and high selection pressures for the important traits at all stages of the breeding program, (2) use of experimental procedures to achieve high levels of heritability in the breeding trials, and (3) testing strategies that achieved a high genetic correlation between performance of germplasm in the breeding trials and under on-farm conditions. The implications of the outcomes from these FPB case studies for realizing the positive motivations for adopting PPB strategies are discussed with particular reference for low input target environment conditions. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

20.
为探讨小麦/玉米/大豆和小麦/玉米/甘薯套作体系中根际细菌群落多样性与作物氮素高效吸收的差异特性及二者间的关系,应用变性梯度凝胶电泳(DGGE)技术研究了小麦–大豆(A1)、小麦–甘薯(A2)、玉米(A3)、小麦/玉米/大豆(A4)和小麦/玉米/甘薯(A5)5种种植模式的根际细菌群落多样性。结果表明,与A1、A2、A3及A5相比,A4套作提高了各作物在开花期(或吐丝期)与成熟期的籽粒吸氮量、地上部总吸氮量和Shannon-Weiner index多样性指数(H′)。处理间的吸氮量与H′的变化规律为套作>单作、大豆茬口>甘薯茬口,以A4处理最高。不同种植模式下DGGE图谱条带的数量及亮度有较大区别,且有几条特征性条带发生了明显变化。不同种植模式间的细菌群落结构相似性较低,群落相似度系数(Cs)表现为套作与套作间>套作与单作间;A4与A5间的Cs相对较小,二者间的细菌群落结构差异较大。A4模式有利于提高根际细菌群落多样性,增强植株对氮素的吸收能力。  相似文献   

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