Indeterminate Growth Habit Research Articles

Dessecação química em pré-colheita da mamona

A mamona (Ricinus communis) tem hábito de crescimento indeterminado, com expressiva desuniformidade de maturação dos grãos, o que dificulta sobremaneira a colheita mecanizada. O objetivo deste trabalho foi avaliar a eficiência do herbicida glifosato, isolado, ou, em mistura com 2,4-D, e também do paraquat, na dessecação em pré-colheita da mamona. Foram realizados dois experimentos de campo, no delineamento em blocos ao acaso, com quatro repetições, em Rancharia-SP, de março a setembro de 2005. No experimento 1, avaliou-se a mistura de doses de 2,4-D e de glifosato, e no experimento 2 a dessecação somente com paraquat. Foi determinado o teor de água da parte aérea de plantas de mamona em diferentes dias após a aplicação (DAA). A dessecação da mamona com a mistura de 2,4-D e glifosato tem efeito somente a partir de 20 DAA. O 2,4-D aplicado isoladamente tem expressiva capacidade de desidratação do dossel vegetal, porém, inferior à da mistura de 2,4-D e glifosato. A melhor dessecação é com 1,34 kg ha-1 de 2,4-D mais 1,42 kg ha-1 de glifosato. A dose de 1,2 kg ha-1 de paraquat reduz expressivamente o teor de água das plantas da mamona, porém, com desempenho inferior ao da mistura de 2,4-D e glifosato.

Water relationships of castor bean ( Ricinus communis L.) seeds related to final seed dry weight and physiological maturity

Castor bean ( Ricinus communis L.) seeds develop inside capsules from sequential racemes. The indeterminate growth habit causes seeds to have different developmental stages among different orders of racemes. Determining the moment of physiological maturity (PM) for the whole plant and at the crop level presents a challenge. Also, it is unclear if a relationship exists between the final seed size of different orders of racemes and the seed-filling rate, seed-filling duration, or maximum seed water content (MWC mg, absolute amount of water per seed). The aim of the present work was to study the dynamics of seed dry weight (SDW) and seed water content (absolute WC mg) with the objectives of (i) associating final SDW to its seed-filling rate, seed-filling duration and maximum WC mg; (ii) identifying the timing of PM on the basis of seed water concentration (WC %); and (iii) predicting PM at the crop level using simulation models based on plant WC % and SDW relationships. Two genotypes (FAUBA 1 and AL GUARANI 2002), contrasting in seed size and branching degree, were studied under field conditions in Buenos Aires in 2006–2007. The evolution of SDW and WC mg was followed in racemes of first (R1), second (R2) and third (R3) order, from the beginning of flowering to harvest maturity. Bi-linear functions were fitted to SDW/WC % relationships, and the model was validated. Across both genotypes and all orders of racemes, final SDW (FSDW) was associated with seed-filling duration (expressed in both days and thermal time) to a greater extent than with seed-filling rate. Also, a clear positive association between FSDW and MWC mg was observed for a broad range of seed sizes (250–600 mg seed −1). Physiological maturity was attained when seeds exhibited a WC % of 21.8 ± 2.4% ( n = 232; R 2 = 0.94; P < 0.001). The model was successfully validated with independent data ( R 2 = 0.96). Simulations were performed to explore the effects of variations in the timing of flowering between racemes at the plant and crop level on fruit WC % at maximum yield. At the crop level, 22% WC % corresponded to 90–92% of the maximum attainable seed yields when harvest was delayed until the last growing seeds reached PM. We conclude that a relationship exists between FSDW and MWC mg, and ca. 22% of seed WC % is a good predictor of PM in castor bean at seed and crop level.

Carman Black dry bean

Balasubramanian, P. M., Hou, A., Conner, R. L., Kiehn, F. A. and Mundel, H.-H. 2011. Carman Black dry bean. Can. J. Plant Sci. 91: 519–521. Carman Black is a high-yielding black bean (Phaseolus vulgaris L.) with an upright indeterminate growth habit (Type 2a) and early maturity. Carman Black was developed at the Agriculture and Agri-Food Canada (AAFC) Research Station, Morden, MB, in collaboration with the AAFC Research Centre, Lethbridge, AB. Carman Black has a black seed coat with an intermediate (matte-shiny) seed luster or glossiness. Carman Black is well adapted to the Red River Valley of Manitoba, with maturity earlier than the check cultivars AC Harblack and CDC Jet.

Performance of semi-determinate and indeterminate cowpeas relay-cropped into maize in Northeast Nigeria

Field trials were conducted in 2005 and 2006 in Tilla (northern Guinea savanna) and Sabon-Gari (Sudan savanna) in northeast Nigeria to determine the performance of two improved cowpea varieties when relay-intercropped with early and late maize, 6 and 8 weeks after planting the maize. Grain yield, number of branches and number of pods per plant were higher for the variety IT89KD-288 than for IT97K-499-35, whether planted sole or relay-intercropped with maize. Grain yield was lower for IT97K-499-35 than for IT89KD-288 when relay-intercropped with maize irrespective of the maturity period of the companion maize crop. This may be due to the indeterminate growth habit and shade tolerance of IT89KD-288 which allowed a higher pod load than IT97K-499-35. However, relay-intercropping with early maize gave higher yield than relay-intercropping into late maize. Also relay-intercropping at 6 weeks after planting maize (WAP) gave a higher yield than relay-intercropping at 8 WAP. This therefore, suggests that introducing cowpea into short statured early maize may mean less competition for light and soil resources compared to taller late maize. Also introducing the cowpea earlier may allow the crop to make full use of soil moisture during the cropping season.

Registration of the Chickpea Germplasm PHREC‐Ca‐Comp. #1 with Enhanced Resistance to Ascochyta Blight

The chickpea or garbanzo bean (Cicer arietinum L.) germplasm PHREC‐Ca‐Comp. #1 (Reg. No. GP‐282, PI 659664) was developed by the former Alternative Crops Breeding Program at the University of Nebraska Agricultural Research Division and was released in 2010. It was bred specifically for adaptation to growing conditions in Nebraska and for enhanced resistance to Ascochyta blight, a major disease of chickpea caused by Ascochyta rabiei (Pass.) Labr. PHREC‐Ca‐Comp. #1 is a composite of PI 315797, PI 343014, PI 379217, PI 471915, PI 598080, and W6 17256. The composite was developed in the fall of 2002 and was evaluated in six irrigated and four dryland environments at Scottsbluff, Sidney, and Alliance, NE, from 2004 to 2009. Across irrigated environments, PHREC‐Ca‐Comp. #1 had the lowest severity rating for Ascochyta blight and a higher yield under both irrigated and dryland conditions than ‘Sierra’, ‘Dwelley’, ‘Dylan’, and ‘Troy’. PHREC‐Ca‐Comp. #1 is a small, round, cream‐colored kabuli‐type chickpea. It exhibits an upright, indeterminate growth habit. Plants average 66 cm in height and have excellent resistance to lodging. PHREC‐Ca‐Comp. #1 has a fern leaf structure and white flowers and blooms 44 d after planting. It is a midseason bean, maturing 116 d after planting. Although its seed size does not meet commercial standards, PHREC‐Ca‐Comp. #1 has value in breeding programs as a source of resistance to Ascochyta blight and because of its high yield potential.

Registration of ‘UA 4910’ Soybean

‘UA 4910’ soybean [Glycine max (L.) Merr.] (Reg. No. CV‐501, PI 659315) was developed by the Arkansas Agricultural Experiment Station, Fayetteville, AR and was released as a high‐yielding, maturity‐group (MG) IV, conventional cultivar in 2010. UA 4910 is a selection from the cross between ‘Asgrow A4715’ and ‘DP 3478’ and has been evaluated in 115 environments in Arkansas and other southern states from 2001 to 2009. When grown in Arkansas, UA 4910 had a significantly greater seed yield than ‘UA 4805’. In the USDA Southern Uniform and Preliminary Tests from 2004 to 2008, the yield of UA 4910 was comparable to the widely grown, high‐yielding Roundup Ready cultivars ‘Asgrow AG4903’, ‘DK 4868’, and ‘DK 4866’. UA 4910 has a relative maturity of 4.9, indeterminate growth habit, white flowers, light tawny pubescence, and tan pod walls. UA 4910 is resistant to southern stem canker [caused by Diaporthe phaseolorum (Cooke &amp; Ellis) Sacc. var. meridionales F.A. Fernandez] and moderately resistant to sudden death syndrome [caused by Fusarium solani (Mart.) Sacc. f. sp. glycines].

Grape Tomato Breeding Lines: NC 1 Grape, NC 2 Grape, and NC 3 Grape

Over the last several years, grape tomato production has grown to become an important segment of fresh-market tomatoes and strongly competes for market share with cherry tomatoes. Demand for grape tomatoes has increased as a result of consumer satisfaction with their vine-ripened flavor, especially their high sugar content, and desirable fruit size and crisp texture. Breeding of improved grape tomato types in the North Carolina fresh-market tomato breeding program has resulted in the release of three breeding lines, NC 1 Grape, NC 2 Grape, and NC 3 Grape, that are useful in producing improved cultivars of grape tomatoes. NC 1 Grape and NC 2 Grape have indeterminate growth habit, whereas NC 3 Grape has determinate growth habit. NC 1 Grape and NC 3 Grape have jointless fruit pedicels, whereas NC 2 Grape has jointed pedicels. NC 1 Grape and NC 3 Grape develop a uniform bright red exterior and interior color in ripe fruits, whereas NC 2 Grape develops a deep yellowish orange color on mature fruit.

Effects of growth temperature and chilling duration on leaf phenology of Fauria crista-galli subsp. japonica, an alpine snowbed geophyte

I examined the effects of growth temperature and winter duration on the leaf phenology of Fauria crista-galli plants, which have an indeterminate growth habit. After a 220-day chilling treatment, the leaf expansion and green periods of plants maintained at 25/20°C were much longer than those of plants maintained at 15/10°C and of plants at the natural habitat obtained in a previous study. The results indicate that early growth cessation and early leaf senescence in the natural habitat are not only due to endogenous rhythm but determined to some extent by cool summer temperatures. When grown at 15/10°C, the green period of individual leaves and plants was much shorter after a long chilling treatment (220days) than after a short chilling treatment (110days). The plants sprouted during or immediately after the termination of chilling treatment, suggesting that the decrease in the green period results partly from an advance of endogenous developmental stages during the chilling treatment and that the timing of snowmelt potentially affects the time of leaf senescence in the natural habitat.

Registration of ‘Bellagio’ Cranberry Bean

‘Bellagio’ cranberry bean (Phaseolus vulgaris L.) (Reg. No. CV‐297, PI 659109), developed by the Michigan Agricultural Experiment Station was released in 2010 as a new edible, dry‐bean cultivar combining virus and anthracnose resistance with excellent canning quality. Bellagio was developed using pedigree selection to the F4 generation followed by pure‐line selection for disease, agronomic, and quality traits. Bellagio is a vine cranberry that combines improved plant architecture and full‐season maturity with disease resistance and superior canning quality. In 4 yr of field trials, Bellagio yielded 2282 kg ha−1, the plant height averaged 49 cm, the lodging resistance score was 2.5, and the seed size was 53.5 g 100 seed−1 Bellagio differs from the commercial ‘Michigan Improved Cranberry’ (MIC) vine cranberry cultivar in possessing resistance to Bean common mosaic virus and anthracnose. Bellagio and MIC both possess the type‐III indeterminate growth habit, but Bellagio has a more upright structure and better resistance to lodging. Bellagio flowers in 43 d and matures in 96 d, 3 d earlier than MIC and has excellent canning quality that is equivalent to that of MIC.

Artificial selection for determinate growth habit in soybean

Determinacy is an agronomically important trait associated with the domestication in soybean (Glycine max). Most soybean cultivars are classifiable into indeterminate and determinate growth habit, whereas Glycine soja, the wild progenitor of soybean, is indeterminate. Indeterminate (Dt1/Dt1) and determinate (dt1/dt1) genotypes, when mated, produce progeny that segregate in a monogenic pattern. Here, we show evidence that Dt1 is a homolog (designated as GmTfl1) of Arabidopsis terminal flower 1 (TFL1), a regulatory gene encoding a signaling protein of shoot meristems. The transition from indeterminate to determinate phenotypes in soybean is associated with independent human selections of four distinct single-nucleotide substitutions in the GmTfl1 gene, each of which led to a single amino acid change. Genetic diversity of a minicore collection of Chinese soybean landraces assessed by simple sequence repeat (SSR) markers and allelic variation at the GmTfl1 locus suggest that human selection for determinacy took place at early stages of landrace radiation. The GmTfl1 allele introduced into a determinate-type (tfl1/tfl1) Arabidopsis mutants fully restored the wild-type (TFL1/TFL1) phenotype, but the Gmtfl1 allele in tfl1/tfl1 mutants did not result in apparent phenotypic change. These observations indicate that GmTfl1 complements the functions of TFL1 in Arabidopsis. However, the GmTfl1 homeolog, despite its more recent divergence from GmTfl1 than from Arabidopsis TFL1, appears to be sub- or neo-functionalized, as revealed by the differential expression of the two genes at multiple plant developmental stages and by allelic analysis at both loci.

White Mold Management in Common Bean by Increasing Within-Row Distance Between Plants.

White mold of common bean (Phaseolus vulgaris), caused by Sclerotinia sclerotiorum, is a major yield-limiting disease during the fall-winter season in Brazil. This study was conducted to evaluate the efficacy of decreasing within-row densities for an indeterminate growth habit (type IIIa) cultivar, keeping constant the between-row spacing of 0.5 m, to manage the disease. A modification of within-row plant distributions was also attempted in order to reduce white mold intensity. The study was conducted with sprinkler irrigation in two growing seasons (2000 and 2001) in Viçosa, State of Minas Gerais, Brazil, in an area naturally infested with sclerotia. In 2000, treatments were arranged as 3 × 2 × 2 factorial combination of within-row densities (15, 7.5, or 5 plants/m), within-row plant distributions (single and equidistant plants or equidistant groups of three plants), and fluazinam treatments (with or without). In 2001, 16, 12, 8, or 4 plants/m were combined with fluazinam treatments. Fluazinam was applied at both flowering onset and 10 or 13 days later. Average incidence was 92.6% in 2000 and 77.8% in 2001; severity index was 69.8% in 2000 and 40.2% in 2001; and yield was 1,656 kg/ha in 2000 and 2,542 kg/ha in 2001. White mold decreased and yield increased as within-row densities were reduced, regardless of fluazinam treatments. A distribution of equidistant groups of three plants was ineffective in reducing disease. The use of 4 equidistant plants/m in infested irrigated areas was an effective strategy in white mold management.

Extensive diversity and inter-genepool introgression in a world-wide collection of indeterminate snap bean accessions

Common bean can be grown as a grain crop (dry beans) or as a fresh vegetable (snap beans/green beans), both items being important in nutritional terms for providing essential minerals and vitamins to the diet. Snap beans are thought to be derived predominantly from dry beans of the Andean genepool and to be of a recent European origin; however, the existence of Mesoamerican genepool characteristics especially in traditional indeterminate growth habit snap beans indicates a wider origin. The objective of this study was to evaluate genetic diversity within a set of 120 indeterminate (pole type) snap beans and 7 control genotypes representing each genepool using amplified fragment length polymorphism (AFLP) and simple sequence repeat or microsatellite (SSR) markers. The genotypes were predominantly from Asia, Europe and the United States but included some varieties from Latin America and Africa. AFLP polymorphism ranged from 53.2 to 67.7% while SSR polymorphism averaged 95.3% for the 32 fluorescent and 11 non-fluorescent markers evaluated and total expected heterozygosity was higher for SSR markers (0.521) than for AFLP markers (0.209). Both marker systems grouped the genotypes into two genepools with Andean and Mesoamerican controls, respectively, with the Mesoamerican group being predominant in terms of the number of genotypes assigned to this genepool. Phaseolin alleles were not tightly associated with genepool assignment indicating that introgression of this locus had occurred between the genepools, especially with phaseolin "S" in the Andean group (23.5%) and phaseolins "T" and "C" in the Mesoamerican group (12.2 and 8.2%, respectively). The implications of these results on the origin of pole type snap beans and on breeding strategies for this horticultural crop are discussed.

Regulation of seed yield and agronomic characters by photoperiod sensitivity and growth habit genes in soybean

Soybean genotypes are adapted to narrow bands of latitude due to photoperiod sensitivity. There are several photoperiod-sensitive loci (E1, E2, E3, E4, E5, E6, E7, E8). Determinate and indeterminate growth habits are controlled by a single locus. The objective of our research was to examine the effects of photoperiod sensitivity and growth habit alleles on seed yield and other agronomic characters using isogenic lines. Twenty 'Harosoy' isolines with 11 photoperiod-sensitive genotypes many with both indeterminate and determinate growth habits were grown in the field at Ottawa, ON, from 2003 to 2007. Maturity ranged from 97 to 127 days, and seed yield increased linearly with maturity until about 112 days when it plateaued. Determinate lines were always shorter than indeterminate lines of equivalent maturity. Seed yield was associated with plant height, maturity, seed sugar concentration, seed weight and lodging. Effects of alleles at individual loci, and additive and epistatic effects across multiple loci were examined. At a single locus, photoperiod-insensitive alleles produced isolines that matured 8-11 days earlier, yielded less, and had shorter plants with reduced lodging. In multiple loci analyses, additive effects explained most of the variation in agronomic characters since additive models with E1, E3, E4, E7 and Dt1 loci included compared well to additive plus epistatic models and genotype-based models. Variation in photoperiod sensitivity and growth habit alleles results in a range of maturity, with pleiotropic effects on seed yield and agronomic characteristics, and play an important role in providing adaptation across latitudes.

Stem growth habit affects leaf morphology and gas exchange traits in soybean

The stem growth habit, determinate or indeterminate, of soybean, Glycine max, varieties affects various plant morphological and developmental traits. The objective of this study is to identify the effect of stem growth habit in soybean on the stomatal conductance of single leaves in relation to their leaf morphology in order to better understand the ecological and agronomic significance of this plant trait. The stomatal conductance of leaves on the main stem was measured periodically under favourable field conditions to evaluate g(max), defined as the maximum stomatal conductance at full leaf expansion, for four varieties of soybean and their respective determinate or indeterminate near isogenic lines (NILs). Leaf morphological traits including stomatal density, guard cell length and vein density were also measured. The value of g(max) ranged from 0.383 to 0.754 mol H(2)O m(-2) s(-1) across all the genotypes for both years. For the four pairs of varieties, the indeterminate lines exhibited significantly greater g(max), stomatal density, numbers of epidermal cells per unit area and total vein length per unit area than their respective determinate NILs in both years. The guard cell length, leaf mass per area and single leaf size all tended to be greater in the determinate types. The variation of g(max) across genotypes and years was well explained by the product of stomatal density and guard cell length (r = 0.86, P < 0.01). The indeterminate stem growth habit resulted in a greater maximum stomatal conductance for soybean than the determinate habit, and this was attributed to the differences in leaf structure. This raises the further hypothesis that the difference in stem growth habit results in different water use characteristics of soybean plants in the field. Stomatal conductance under favourable conditions can be modified by leaf morphological traits.

Genetic Characterization of a New Growth Habit Mutant in Tomato (Solanum lycopersicum)

A mutant tomato cultivar (HT10-3-2) with indeterminate growth habit was obtained from a cultivar (T10-3-2) with determinate growth habit. The character of indeterminate growth habit in HT10-3-2 could be inherited stably. Unlike other normal growth habit cultivars, which are controlled by the SELF PRUNING gene, it was shown here that HT10-3-2 has no mutation in the sp gene. Two hundred random amplified polymorphic DNA (RAPD) primers were used to screen for polymorphism between the two genotypes from genomic DNA, and a polymorphic fragment (S1681458) was obtained and subsequently sequenced. However, Basic Local Alignment Search Tool searches indicated that the sequence of this RAPD fragment shares no significant homology with known sequences in GenBank. The RAPD marker (S1681458) was converted to a sequence characterized amplified region (SCAR) marker, SCA1681453. The SCAR marker was tested using an F2 population derived from the cross of T10-3-2 and HT10-3-2 and the results showed that this marker was closely linked with the unknown factor influencing the growth habit in HT10-3-2.

Morphological development and nutritive value of herbage in five temperate grass species during primary growth: analysis of time dynamics

AbstractIn a 2‐year field experiment, morphological development and measures of the nutritive value of herbage for livestock during primary growth in Meadow foxtail, Tall oatgrass, Cocksfoot, Perennial ryegrass and Yorkshire fog were investigated. All measured variables were affected significantly by both species and sampling date, and their interaction (P &lt; 0·001), in the period of primary growth. Changes with time in mean stage weight for Meadow foxtail and Cocksfoot were different from the other species due to their indeterminate growth habits. Mean stage weight of Tall oatgrass and Yorkshire fog increased more rapidly than that of Perennial ryegrass with time. Changes in mean stage weight with time were described by linear, parabolic and sigmoid relationships. Crude protein (CP) concentration of herbage was higher for Cocksfoot and Meadow foxtail than for Perennial ryegrass. A parabolic relationship of CP concentration with time was typical for all the species. Concentrations of neutral‐detergent fibre (NDF) and acid‐detergent fibre (ADF) in herbage of the species differed most during the mid‐period of primary growth. Their increases with time showed curvilinear (sigmoid and parabolic) relationships. Perennial ryegrass had lower concentrations of both NDF and ADF in herbage than the other species. Differences between the in vitro dry matter (DM) digestibility among the grasses increased in mid‐ and late periods of primary growth. Perennial ryegrass had higher values for in vitro DM digestibility but the difference from other species was small in the early period of primary growth and from cocksfoot in the late period of primary growth. In vitro DM digestibility showed, in most cases, a sigmoid and, in others, a linear decrease with time. Principal component analysis showed that perennial ryegrass and meadow foxtail were the most distinctive of the species in characteristics relating to morphological development and the nutritive value of herbage to livestock.

White Mold–Resistant Interspecific Common Bean Germplasm Lines VCW 54 and VCW 55

Interspecific breeding lines (IBL) VCW 54 (Reg. No. GP‐276, PI 655531) and VCW 55 (Reg. No. GP‐277, PI 655532) of common bean (Phaseolus vulgaris L.) resistant to white mold [WM; caused by Sclerotinia sclerotiorum (Lib.) de Bary] were jointly developed at the University of Idaho‐Kimberly Research and Extension Center and Colorado State University, Fort Collins, CO. The Agricultural Experiment Stations of Idaho and Colorado released VCW 54 and VCW 55 on 10 Dec. 2008. Both IBL were derived from congruity backcrossing between small‐seeded tropical black bean cultivar ICA Pijao and P. coccineus L. accession G 35172. ICA Pijao has an indeterminate upright growth habit Type II and resistance to bean common mosaic virus and some races of rust pathogen, and tolerance to bean golden mosaic virus (BGMV). G 35172 has large purple‐mottled seeds, an indeterminate climbing growth habit Type IV, and resistance to BGMV. G 35172 also is variable for WM reaction. VCW 54 has scarlet flowers, purplish black seed, and the highest WM resistance. VCW 55 has white with pink‐striped flower, black seed, and an intermediate level of WM resistance. Both IBL also have growth habit Type II, small seeds, and are late maturing, requiring ≥100 d from planting to maturity in southern Idaho. White mold resistance from VCW 54 and VCW 55 should be pyramided with WM resistance from across Phaseolus species and introgressed into common bean cultivars using appropriate crosses, population sizes, and disease screening and selection methods.

Root foraging and yield components underlying limited effects of Partial Root-zone Drying on oilseed rape, a crop with an indeterminate growth habit

We report on two experiments with oilseed rape (Brassica napus L.) to test if partial root-zone drying techniques improve yield in a crop in which vegetative and reproductive growth overlap (indeterminate growth habit), and to investigate what plant morphological responses contribute to the yield that is realized. Deficit irrigation resulted in smaller plants with smaller yields but larger seeds compared to treatments with shallow groundwater (first experiment) and with fully watered conditions (second experiment). Different partial root-zone drying treatments (water supply patterns) under deficit irrigation, however, had little effect on plant growth and yield components (number of branches, branch lengths, number of pods, etc.). Our results suggest that partial root-zone drying doesn’t work well with oilseed rape. Detailed measurements of soil water contents and root distribution indicate that roots were extremely plastic, effectively foraging for water, and these root responses may have overwhelmed physiological effects of partial root drying on the shoot. Furthermore, in crops with indeterminate growth with a short vegetative growth phase, partial root-zone drying may be ineffective in enhancing the major yield components. Further reasons for the lack of success are discussed.

Analysis of Genetic Structure in Widely Distributed Common Bean Landraces with Different Plant Growth Habits Using SSR and AFLP Markers

ABSTRACTThe genetic variation in common bean (Phaseolus vulgaris L.) landraces with different growth habits, which are grown over a wide and environmentally heterogeneous area in southern Italy, was studied to help define strategies for conservation of genetic resources. Accessions of three landraces, a'Marrozzo and Poverella with indeterminate growth habits, and Verdolino with a determinate growth habit, were scored for 30 simple sequence repeat (SSR) and 393 amplified fragment length polymorphism (AFLP) loci using eight primer combinations. Very low heterozygosity was observed, and all 73 plants analyzed showed different genotypes when comparing their alleles at the SSR or AFLP loci. The analyzed genotypes were clustered first according to plant growth habit and then in distinct groups according to landrace classification. Genetic differentiation among landraces was higher for AFLP (FST = 0.64) than for SSR loci (FST = 0.31), and variation within landraces was higher in a'Marrozzo, which is widely distributed over four river catchment basins. The proportion of alleles common to all three landraces was much larger for AFLP (62.34%) than for SSR (27.13%), while the alleles found in only one landrace were more frequent for SSR (47%) than for AFLP (8.14%). The large number of SSR and AFLP alleles shared between a'Marrozzo and Poverella (both with indeterminate growth habits) indicates their common evolutionary history.

Registration of Soybean Germplasm SS93‐6012 and SS93‐6181 Resistant to Phomopsis Seed Decay

Soybean [Glycine max (L.) Merr.] germplasm SS93‐6012 (Reg. No. GP‐362, PI 652442) and SS93‐6181 (Reg. No. GP‐363, PI 652443) were developed and released by the University of Missouri–Columbia in January 2006 as resistant to Phomopsis seed decay (PSD), caused by Phomopsis spp. Both lines were developed from a cross between MO/PSD‐0259 (PI562694) (PSD‐resistant MGIV germplasm) and ‘Asgrow 3834’ (PSD‐susceptible MGIII cultivar) made in 1990 at the Bradford Research and Extension Center of the University of Missouri, Columbia, MO. The lines were composited in the F5 generation and evaluated for yield and Phomopsis seed decay infection. These lines are highly resistant to Phomopsis spp. SS93‐6012 has a relative maturity of 4.2, purple flowers, gray pubescence, an indeterminate growth habit, tan pods at maturity, yellow color seeds, buff hila, and seed weight of ∼14 g per 100 seeds. SS93‐6181 has a relative maturity of 4.0, purple flowers, tawny pubescence, an indeterminate growth habit, tan pods at maturity, yellow color seeds, imperfect black hila, and seed weight of ∼16 g per 100 seeds. So far, PSD‐resistant commercial soybean cultivars are not available, and these two lines may be used for development of PSD‐resistant high‐yielding soybean cultivars.