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1.
Genetic Diversity and Relationships of Wheat Landraces from Oman Investigated with SSR Markers 总被引:4,自引:3,他引:4
P. Zhang S. Dreisigacker A. Buerkert S. Alkhanjari A. E. Melchinger M. L. Warburton 《Genetic Resources and Crop Evolution》2006,53(7):1351-1360
Little is known about genetic diversity and geographic origin of wheat landraces from Oman, an ancient area of wheat cultivation.
The objectives of this study were to investigate the genetic relationships and levels of diversity of six wheat landraces
collected in Oman with a set of 30 evenly distributed SSR markers. The total gene diversity, (HT), conserved in the three durum wheat (Triticum durum desf.) landraces (HT = 0.46) was higher than in the three bread wheat (Triticum aestivum L.) landraces (HT = 0.37), which were similar to Turkish and Mexican bread wheat landraces calculated in previous studies. Genetic variation
partitioning (GST) showed that variation was mainly distributed within rather than among the durum (GST = 0.30) and bread wheat (GST = 0.19) landraces. Based on modified Rogers’ distance (MRD), the durum and bread wheat landraces were distinct from each
other except for a few individuals according to principal coordinate analysis (PCoA). One bread wheat landrace (Greda) was
separated into two distinct sub-populations. A joint cluster analysis with other landraces of worldwide origin revealed that
Omani bread wheat landraces were different from other landraces. However, two landraces from Pakistan were grouped somewhat
closer to Omani landraces indicating a possible, previously unknown relationship. Implications of these results for future
wheat landrace collection, evaluation and conservation are discussed. 相似文献
2.
S. Al Khanjari K. Hammer A. Buerkert M. S. Röder 《Genetic Resources and Crop Evolution》2007,54(7):1407-1417
For millennia, wheat (Triticum spp.) has been grown in traditional aflaj-irrigation systems of remote mountain oases in Oman. However, little is known about
the diversity of the ancient landraces used. Given recent reports about the occurrence of novel germplasm in such material,
the objective of this study was to evaluate the genetic diversity of hexaploid wheat (Triticum aestivum L.) landraces in relation to their geographic origin using microsatellites. The collection covered most of the cultivation
areas in northern Oman where wheat landraces are growing. Total genomic DNA was extracted from six pooled plants representing
each accession. A total of 161 wheat accessions were assayed using 35 microsatellite loci in which a total of 305 polymorphic
bands were recorded for the 35 microsatellites. The polymorphic information content (PIC) across the 35 microsatellite loci
ranged from 0.02 to 0.89 with an average of 0.50. A heterozygosity percentage value of 9.09 was determined and the highest
level recorded for accessions from the Batinah district. Rare alleles averaged 1.85 with the highest value being from the
Dakhilia district. The results indicated a significant correlation between gene diversity and number of alleles across districts.
The correlation coefficient between these two variables over the 35 loci was 0.657, whereby correlation coefficients of 0.718,
0.706, 0.657 and 0.651, respectively, were found for the Batinah, Dhahira, Dakhilia and Sharqia materials. Genetic distances
indicated that all landraces were closely related. The cluster analysis discriminated most of the landraces accessions. However,
it failed to achieve region-specific groupings of landraces. The present study demonstrated the presence of high diversity
in Omani landraces and also indicated the effectiveness of microsatellites to describe it. 相似文献
3.
S. Al Khanjari K. Hammer A. Buerkert M. S. Röder 《Genetic Resources and Crop Evolution》2007,54(6):1291-1300
Results of archaeological studies indicate a millennia-old cultivation history for wheat (Triticum spp.) in Oman. However, in spite of numerous collection surveys and efforts for phenotypic characterization of Omani wheat
landraces, no attempts have been made using molecular tools to characterize this germplasm. To fill this gap, 29 microsatellite
markers revealing 30 loci were used to study the genetic diversity of 38 tetraploid wheat landrace accessions comprising the
species T. dicoccon, T. durum and T. aethiopicum. A total of 219 alleles were detected whereby the number of alleles per locus ranged from 2 to 16 with an average number
of 7.1 alleles per locus. The highest number of alleles occurred in the B genome with on average 7.9 alleles per locus as
compared to the A genome with 6.5 alleles per locus. Heterogeneity was detected for all microsatellites except for GWM 312, GWM 601 and GWM 192B with an average heterogeneity over all primers and lines of 14.4%. Approximately 10% of the accessions contained rare alleles
with an average allele frequency <4%. Gene diversity across microsatellite loci ranged from 0.26 to 0.85. The pairwise comparison
of genetic similarity ranged from 0.03 to 0.91 with an average of 0.2. Cluster analysis revealed a clear separation of the
two species groups T. dicoccon versus T. durum and T. aethiopicum. Within the species clusters regional patterns of subclustering were observed. Overall, this study confirmed the existence
of a surprisingly high amount of genetic diversity in Omani wheat landraces as already concluded from previous morphological
analyses and showed that SSR markers can be used for landraces’ analysis and a more detailed diversity evaluation. 相似文献
4.
Doriane P. Rodrigues Spartaco Astolfi Filho Charles R. Clement 《Genetic Resources and Crop Evolution》2005,51(8):871-882
RAPD markers were used to evaluate the genetic variability and structure of seven morphologically defined landraces of pejibaye (Bactris gasipaes Kunth, Palmae) to determine their validity and phylogenetic relationships. Two hundred and twenty plants of four Amazonian and three Central American landraces of var.gasipaes (the domesticate) and 30 plants of var.chichagui (H. Karsten) Henderson (the crop ancestor) maintained at the National Research Institute for Amazonia, Manaus, Amazonas, Brazil, were utilized. Eight RAPD primers yielded 113 markers, with good reproducibility, of which 97 were polymorphic. The four Amazonian landraces had an average heterozygosity of 0.30, with 86% polymorphism, greater than the Central American landraces (0.25; 74.3%) and var.chichagui (0.27; 80%). Among landrace genetic diversity (GST) was 15%, while within (Hs) was 85%, essentially equivalent to the AMOVA within (82.2%) and among (17.8%) variances. The Jaccard similarities, PCA, gene flow coefficients and Exact tests suggested that only one landrace exists in Central America, called Utilis after the first taxon described there, and that the Solimões landrace is part of the Putumayo landrace, rather than a separate entity. The Pará and Pampa Hermosa landraces were validated in accordance with their morphometric interpretations. The dendrogram of Neis genetic distances among valid landraces and var.chichagui supported the hypothesis of a single origin for pejibaye in southwestern Amazonia, with two migration routes: one to the northeast, becoming the Pará landrace, and another to the northwest along the Andes, spreading into western Amazonia (Pampa Hermosa and Putumayo landraces) and across the Andes, reaching Central America (Utilis landrace). 相似文献
5.
Morphological spike diversity of Omani wheat 总被引:2,自引:2,他引:0
S. Al Khanjari A. A. Filatenko K. Hammer A. Buerkert 《Genetic Resources and Crop Evolution》2008,55(8):1185-1195
Little is known about the diversity of field crops in Oman. The objective of this study therefore was to characterize wheat
accessions from this country using individual spikes collected from different wheat cultivation areas. The phenotypic assessment
of 15 qualitative and 17 quantitative characters showed variations among Omani wheat landraces. The standardized phenotypic
diversity index (H′) was with 0.66 higher for quantitative characters than for qualitative characters (0.52) in tetraploid
wheats and with 0.63 and 0.62, respectively, in hexaploid wheats. Overall, the morphological data revealed a surprisingly
high diversity among landraces and showed that simple morphological characters can be used for an effective characterization
of diversity in Omani wheat. 相似文献
6.
K. Chabane O. Abdalla H. Sayed J. Valkoun 《Genetic Resources and Crop Evolution》2007,54(5):1073-1080
Accurate and reliable means for identification are necessary to assess the discrimination between landraces of tetraploid
wheat [T.␣turgidum L. subsp. durum (Desf.) Husn.] and hexaploid wheat (T. aestivum L. em. Thell.). In Afghanistan, farmers usually cultivate mixed landraces, and thus distinction between bread and durum is
difficult. A set of 18 microsatellites derived from the DuPont EST-database were used to describe genetic diversity in a sample
of 82 Afghan wheat landraces. A total of 101 alleles were detected, with allele number per locus ranging from 2 to 13, and
a mean allele number of 6.31. The percentage of polymorphic loci was 89%. The EST-SSRs markers showed different level of gene
diversity: the highest Polymorphism Information Content value (0.921) was observed with DuPw 221. Our results demonstrated
that with a reasonable number of expressed sequences target microsatellites (EST-SSRs) it is possible to discriminate between
T. durum and T. aestivum species of wheat germplasm. Our results showed that EST-databases could be a useful source for species-specific markers and
have the potential for new genic microsatellites markers that could enhance screening germplasm in gene banks. 相似文献
7.
J. F. Pedler M. J. Webb S. C. Buchhorn R. D. Graham 《Biology and Fertility of Soils》1996,22(3):272-278
Two successive experiments described here show that the Mn-oxidizing ability of isolates of the take-all fungus Gaeumannomyces graminis var. tritici is positively correlated with the isolate virulence. Isolates of G. graminis var. tritici were screened for virulence on wheat in soil culture pot tests and visually scored for Mn-oxidizing capacity on agar plates. A comparison between experiments showed that the Mn-oxidizing ability of an isolate may be attenuated, as is virulence, with subculturing. Using a solution culture system, we calculated the rate of oxidation of Mn2+ by a virulent isolate, Ggt 500, as 4 nmol g-1 (dry weight hyphae) h-1. The significance of these results to the epidemiology of the take-all disease of wheat is discussed. 相似文献
8.
Marc Moragues Jorge Zarco-Hernández Ma Angeles Moralejo Conxita Royo 《Genetic Resources and Crop Evolution》2006,53(5):993-1002
The genetic diversity of high and low molecular weight glutenin subunits of 63 durum wheat landraces from different geographical
regions in the Mediterranean Basin was studied using SDS-PAGE. Great variability in glutenin composition was found, with 42
high and low molecular weight glutenin haplotypes, 20 allele combinations at the HMW-GS loci, and 18 at the LMW-GS. All five possible LMW models were detected in all Mediterranean regions. Rare alleles were found at Glu-B1 locus in high frequencies and a priori related alleles to grain quality were also observed. Global genetic diversity index was relatively high (0.67); it ranged
from 0.33 to 0.66. Cluster analysis on the frequency patterns of origins grouped genotypes following a geographical structure.
Rogers’ distance coefficient on frequency pattern for each region of origin showed two germplasm pools with distinct quality
profiles, where South West Asian landraces were very different from the landraces of other Mediterranean areas. The relationship
between different regions of origin is discussed and two possible ways of introduction of wheat in the Iberian Peninsula (N
Africa and SE Europe) are hypothesized. The use of Mediterranean durum wheat landraces as source of genetic variability for
grain quality improvement is highly recommended. 相似文献
9.
Reaction to powdery mildew and stripe rust in related species and landraces of wheat 总被引:1,自引:0,他引:1
Danxia He Hongjie Li Shichang Xu Xiayu Duan Yilin Zhou Lihui Li 《Genetic Resources and Crop Evolution》2007,54(2):213-219
Field and controlled environmental tests indicated that the 49 accessions of closely related species and 12 landraces of wheat
(Triticum aestivum L. em. Thell.) from the National Gene Bank of China showed different reactions to powdery mildew (Blumeria graminis (DC.) E. O. Speer. f. sp. tritici) and stripe rust (Puccinia striiformis Westend f. sp. tritici) at adult and seedling stages. Unknown Pm genes or alleles were postulated with Triticum baeoticum Boiss. accessions BO 3 and Triticum monococcum L. MO 4 and MO 5 when inoculated with 21 powdery mildew isolates at seedling stage. Fourteen accessions of T. baeoticum, T. monococcum,
Triticum durum, and wheat landraces were inoculated with 30 stripe rust isolates at seedling stage. Unknown Yr genes or alleles were postulated with T. baeoticum Boiss. accession BO 5, as well as wheat landraces Xiaobaimai, Laomangmai, and Shaanxibai. Heterogeniety in reaction to powdery
mildew isolates and stripe rust races were observed in related species and landraces of wheat. 相似文献
10.
K. Hammer A.A. Filatenko S. Alkhanjari A. Al-Maskri A. Buerkert 《Genetic Resources and Crop Evolution》2004,51(2):111-113
Emmer (Triticum dicoccon ) was collected recently in northern Oman. The material was analyzed morphologically and phenologically. It belongs to the Asiatic emmers (subsp. asiaticum) and not to the Ethiopian ones (subsp. abyssinicum), distributed in Ethiopia and Yemen, as originally expected. The determination of the material resulted in var. haussknechtianum and var. aeruginosum. 相似文献
11.
Natalia V. Melnikova Ganka D. Ganeva Zapryanka G. Popova Svetlana P. Landjeva Alexander M. Kudryavtsev 《Genetic Resources and Crop Evolution》2010,57(4):587-595
The polymorphism of gliadins was studied in 98 Bulgarian durum wheat (Triticum durum Desf.) landraces and classified according to the existing catalogues of blocks of gliadin components. In total, 31 alleles,
including 12 new ones, were revealed for five gliadin-coding loci. Nine allele families, which included several alleles coding
similar blocks differed only by minor components, were found. The gliadin loci had a high genetic diversity (H = 0.70), and Gli-A2
d
was the most polymorphic locus. Significant differences in allele distribution were observed through the Bulgarian region
under study. The results made it possible to explain the distribution by historical factors. Presumably, the genetic material
flew into the country via two different ways and different durum wheat subgroups contributed to the formation of Bulgarian
landraces. The landraces were a result of long-term selection and, probably, had a close association with the history of the
human populations of the region. 相似文献
12.
Nasab K. Rawashdeh Nasri I. Haddad Mohamad M. Al-Ajlouni Munir A. Turk 《Genetic Resources and Crop Evolution》2007,54(1):129-138
Durum wheat landrace genotypes are disappearing from the main wheat areas in Jordan, because of spreading of new uniform cultivars
and the serious reduction in wheat cultivation. This study was conducted to evaluate genetic diversity in durum wheat landraces
from Jordan and to identify desirable agronomic traits. Landraces were collected from two target areas: Ajloun and Karak.
The collected material was grown under rainfed conditions using an augmented design with five blocks and four repeated check
cultivars. Data were collected for 14 morphological and agronomic traits. Phenotypic diversity index (H′) was estimated, and
the relationships among accessions were measured using cluster analysis and dendrogram similarity matrix. The results revealed
the presence of a wide range of variability among landraces., which possess high levels of variability for biological yield,
fertile tillers, number of seeds per spike, seed weight per spike and weight of 1000 seeds. These landraces must be considered
as a reservoir of genes that plant breeders need in their wheat improvement programs and should be conserved both ex situ and in situ. 相似文献
13.
Summary Esterase isozymes of tetraploid wheat landraces originating from four localities in the central highlands of Ethiopia were studied using the horizontal starch gel electrophoresis. The landraces studied consisted of 60 Triticum turgidum L., one T. dicoccon Schrank, one T. polonicum L. and an improved local cultivar. One introduced durum cultivar was also included for comparison.A total of 12 esterase zymograms were detected in the landraces. Among these, the types C, A and G were found to be the most prevalent. The esterase isozymes exhibited high variation in the landraces. The esterase zymograms of the introduced durum cultivar and T. dicoccon differed from those of the landraces while the patterns attained in T. polonicum and the improved local cultivar were identical to those of the other landraces.The total number of bands detected was 10, of which 2 were rare, being displayed by only 1 pattern each. The band content of zymograms was in the range of 3–6 and the average was 4. The unique bands were observed in zymograms with both high and low prevalences in the landraces. Two zymograms, including zymogram C which had the highest frequency, occurred in all the localities. The high yielding landraces displayed 4 of the zymograms, one of which belonged to two of the zymograms with widest distribution. 相似文献
14.
P. Routray O. Basha M. Garg N. K. Singh H. S. Dhaliwal 《Genetic Resources and Crop Evolution》2007,54(6):1315-1326
Seed samples of 27 landraces of wheat were collected from farmers’ fields of hilly areas of Himalaya in Uttaranchal state
of India during April 2004. Genetic diversity among 41 genotypes (cultivars and landraces of wheat) was studied using morphological
traits, microsatellite markers and SDS-PAGE of HMW-GS. The dendrogram and PCA (Principal Component Analysis) based on morphological
data clearly separated landraces of wheat from cultivars. In the dendrogram based on microsatellite markers data all the wheat
cultivars released after the introduction of high yielding dwarf wheat varieties from CIMMYT, used in this study, were grouped
separately with the exception of NP4. The pre-green revolution indigenous varieties grouped with landraces suggesting that
the same had been probably developed through selection among landraces in India. The landraces had higher diversity for HMW-glutenin
subunits coded by Glu-B1, with distinct subunit combinations 6 + 8, 7 + 9, 13 + 16, than within the wheat cultivars analyzed. Most of the landraces
except IITR10 and IITR14 are clearly distinct from the indigenous and modern wheat cultivars released in India in the 20th
century. More than half of the landraces were heterogeneous mixture of plants with different glume color, awnness, grain color
and HMW-GS profile and hence need purification through single plant selection. Some of the landraces with resistance to yellow
rust and powdery mildew and distinct HMW-GS subunits can be used in appropriate breeding programs. It will be desirable to
conserve and protect the landraces as geographical indications of Uttaranchal. 相似文献
15.
A. Buerkert M. Oryakhail A. A. Filatenko K. Hammer 《Genetic Resources and Crop Evolution》2006,53(1):91-97
After 23 years of war, current information about the biodiversity of crops in the Hindukush mountains of Afghanistan is scarce.
This study aimed at assessing the genetic composition of farmers wheat (Triticum spp.) populations through a survey of 21 randomly chosen cereal fields on both sides of the Panjsher river in the upper Panjsher
valley of Northern Afghanistan. A stratified sampling of wheat heads according to morphological differences was followed by
estimates of field size and grain yield and a formal interview with the landowner about the cropping sequence and the inputs
used. About 75% of the cereal fields were cropped in rotation systems with faba bean (Vicia faba L.), barley (Hordeum vulgare L.), potato (Solanum tuberosum L.), maize (Zea mays L.) or fallow. Manure application at between 2.3 and 5.3 t ha−1 was the major source of nutrient inputs at grain yield levels between 1.2 and 4.7 t ha−1. The morphological characterization of the collection revealed 19 taxonomically different varieties of bread wheat (Triticum aestivum L.) but also barley and triticale (Triticosecale Wittm.) grown in mixtures. Populations within one field consisted of up to seven botanical wheat varieties. Farmers did not
differentiate between morphological differences within such mixtures but identified their populations instead according to
grain color, cooking properties and resistance to mildew and frost. Triticum aestivum var. subferrugineum was the most widespread wheat variety and no effects of altitude on biodiversity of wheat was noted across the transect.
Particularly interesting was the occurrence of T. aestivum var. subferrugininflatum and var. subgraecinflatum which so far have only been reported from Mongolia. The finding of triticale indicated the active seed exchange with lowland
or long-distance seed sources. 相似文献
16.
Iran is one of the primary centers of diversity for wheat and its relatives. Wild wheats, in particular diploid species, are
extensively distributed in various parts of Iran. Of these, the existence of two “A" genome donor species, i.e., T. baeoticum and T. monococcum, has already been reported in Iranian floras. However, the existence of the other important “A" genome donor, i.e., T. urartu, has not been clearly reported. In a germplasm collection survey in several regions of Iran, T. urartu was identified, collected, and described, and is reported here for the first time. In a detailed and extensive taxonomic
program, the collected germplasms of the above three species were studied. Morphological characters and species-specific traits
of the three species were evaluated and compared. Using the monographs by Gandilyan (1980) and Dorofeev et al. (1979) for
the collected germplasms, 14 varieties were identified of T. boeoticum, 3 varieties of T. urartu, 2 forms of T. monococcum. Of these 5 varieties of T. baeoticum ssp. baeoticum (var. albinigrum, var. garniense, var. zuccarinii, var. baeoticum, var. pseudobaeoticum), 3 varieties of T. baeoticum ssp. thaoudar (var. abovjanii, var. albinigrescens, var. ebrahimzadehae, var. viridinigrireuteri) and 1 variety of T. monococcum (var. mansfeldii) are new to Iran. In addition, 1 variety of T. baeoticum ssp. baeoticum (var. khorramabadicum), 3 varieties of T. baeoticum ssp. thaoudar (var. ebrehimeadena var. taleghanicum, var. ilamicum) and 2 varieties of T. urartu (var. iranicum, var. sardashticum) are new to the wheat botany. 相似文献
17.
N. P. S. Dhillon R. Ranjana Kuldeep Singh I. Eduardo A. J. Monforte M. Pitrat N. K. Dhillon P. P. Singh 《Genetic Resources and Crop Evolution》2007,54(6):1267-1283
Diversity among 36 snapmelon landraces, collected from 2 agro-ecological regions of India (9 agro-climatic sub-regions), was
assayed using RAPD primers, morphological traits of plant habit and fruit, 2 yield-associated traits, pest and disease resistance
and biochemical composition (TSS, ascorbic acid, titrable acidity). Typical differences among accessions were observed in
plant and fruit characteristics and snapmelon germplasm with high titrable acidity and possessing resistance to downy mildew,
Cucumber mosaic virus, Zucchini yellow mosaic virus, Papaya ringspot virus, Aphis gossypii and Meloidogyne incognita was noticed in the collection. RAPD based grouping analysis revealed that Indian snapmelon was rich in genetic variation
and region and sub-region approach should be followed across India for acquisition of additional melon landraces. Accessions
of var. agrestis and var. momordica clustered together and there was a separate cluster of the accessions of var. reticulatus. Comparative analysis of the genetic variability among Indian snapmelons and an array of previously characterized reference
accessions of melon from Spain, Israel, Korea, Japan, Maldives, Iraq, Pakistan and India using SSRs showed that Indian snapmelon
germplasm contained a high degree of unique genetic variability which was needed to be preserved to broaden the genetic base
of melon germplasm available with the scientific community.
N. P. S. Dhillon and Ranjana contributed equally to this work and are considered the first authors. 相似文献
18.
19.
Xingquan Zeng Yajuan Wang Weiyan Li Changyou Wang Xinlun Liu Wanquan Ji 《Genetic Resources and Crop Evolution》2010,57(8):1141-1150
In order to evaluate and compare the germplasm resources of wheat in Tibet, we analyzed the genetic diversity of 136 Triticum aestivum ssp. tibetanum Shao and 119 Tibetan wheat landraces (Triticum aestivum L.) by using Intron-Splice Junction (ISJ) primers. The results showed that polymorphism of PCR products were obtained by
33 primer combinations, which accounted for 11% of the 300 primer combinations produced by 26 ISJ primers. A total of 333
stable bands can be amplified from the T. aestivum ssp. tibetanum Shao and 243 bands were polymorphic, which accounted for 72.9% of the total bands. Tibetan wheat Landraces produced 316 stable
bands, of which 197 bands were polymorphic. The polymorphic bands accounted for 62.34% of the total bands produced from Tibetan
wheat landraces. The genetic diversity of T. aestivum ssp. tibetanum Shao was higher than that of Tibetan wheat landraces in Tibet, suggesting that T. aestivum ssp. tibetanum Shao can be used as important genetic resource for the breeding and genetic improvement of wheat in Tibet. Matrix (1, 0)
was generated according to the presence or absence of the bands produced from a particular wheat accession. Clustering and
principle coordinates analysis showed that T. aestivum ssp. tibetanum Shao and Tibetan wheat landraces were divided into two groups. We conclude that high polymorphisms produced by ISJ primers
can reflect the genetic diversity between T. aestivum ssp. tibetanum Shao and Tibetan wheat landraces. 相似文献
20.
Mario Augusto Pagnotta Linda Mondini Pasquale Codianni Clara Fares 《Genetic Resources and Crop Evolution》2009,56(3):299-310
Emmer wheat (Triticum dicoccon Schrank, 2n = 4x = 28) consists in a hulled wheat; its cultivation has been drastically reduced during the last century as a consequence of
its low yield. Recently, its agronomic and nutritive values, as well as the increase of popularity of organic agriculture,
have led to a renewed interest making its cultivation economically viable in the marginal lands with an increase of the cultivated
areas. In Italy, it mainly survives in few marginal lands of central and southern Italy, where local varieties, adapted to
the natural environment from where they originate, are used; moreover, some selected lines have also been developed. In the
present work, agro-morphological and qualitative traits, together with molecular analyses of 20 emmer accessions consisting
of Italian landraces, breeding lines, and cultivars, were performed. The field experiments were conducted for two consecutive
years (2001/2002–2002/2003) in two locations: Viterbo in central Italy, and Foggia in south Italy. The analyzed emmer wheat
accessions showed a good amount of genetic variability for both evaluated agro-morphological and molecular traits. This study
illustrates an increase in earliness, GY, TW, TKW, and YI going from landraces, breeding lines to cultivars, while the variability
does not change proportionally. 相似文献