Maple Presto Research Articles

A New Locus for Early Maturity in Soybean

The genetic model for maturity in soybean [Glycine max (L.) Merr.] is a series of near‐isogenic lines, but they do not span the natural variation for early maturity. The objectives of this study were to determine if a single gene in OT98‐17 controls early maturity and if this is a new locus. A cross was made between ‘Maple Presto’ and OT98‐17, an early‐maturing Maple Presto–derived backcross line. A total of 201 F3 progeny rows from this population and Maple Presto were grown at Ottawa, ON, in 1999. In 2000, F4 progeny rows were grown and 150 late‐maturing and 51 early‐maturing families were observed to fit a 3:1 ratio (n = 201, X2 = 0.01, P = 0.90). The early‐maturing allele was transferred to a ‘Harosoy’ background, and isolines were grown from 2002 to 2006 at Ottawa, ON. The isolines were 9 and 6 d earlier maturing in Maple Presto and Harosoy backgrounds, respectively. To determine the independence of this locus, simple sequence repeat molecular markers were used to identify three candidate regions. The gene E8 specifically mapped to linkage group C1 between Sat_404 and Satt136. No other maturity gene has been mapped to this region. The two other candidate regions were both related to maturity quantitative trait loci on molecular linkage group L and may be inadvertently selected along with early maturity. The gene symbol E8e8 has been assigned by the Soybean Genetics Committee. E8E8 results in later maturity and e8e8 results in early maturity. The earliest Harosoy maturity isoline is now rated as maturity group 000.

Soybean Seed Coat Discoloration in Cool‐Season Climates

AbstractSoybean [Glycine max (L.) Merr.] seed with yellow seed coat and hilum is preferred in North America for the export market. Seed coats may darken or discolor when exposed to chilling temperatures during seed development. We examined the effects of chilling temperatures on seed coat discoloration of yellow hilum, isogenic lines of ‘Maple Presto’ soybean (Maturity Group 000) differing in pubescence color (I, r, T, tawny; I, r, t, gray). The isogenic lines were grown in the field for five seasons and once in the growth cabinet (25/20°C day/night). We quantified seed coat discoloration using an image analyzer. When exposed to cool temperatures during seed development, the seed coat darkened. In the extreme case, the seed coat from the tawny line looked gray‐brown. The tawny line discolored more than the gray line, both in the field and the growth cabinet. Seed coat discoloration increased with the accumulation of daily minimum temperature ≤ 115°C during seed development. In years with cool temperatures during seed development, seed coats may discolor, reducing the quality of the seed's appearance.

Relationship between genome size and maturity group in soybean

Previous studies have reported a correlation between genome size and relative maturity among plant species. The objective of this study was to determine whether such a relationship exists in soybean. Twenty cultivars, representing maturity groups ranging from 000 to IX, were analyzed using flow cytometric procedures. A 15% difference in genome size was observed ranging from 'BSR 201' at 2.88 pg to 'Maple Presto' at 2.51 pg. A highly significant correlation (r = 0.55) was observed between maturity and the genome size of the 20 cultivars.

Registration of Four Pairs of ‘Maple Presto’ Derived Soybean Genetic Stocks

Registration of Four Pairs of ‘Maple Presto’ Derived Soybean Genetic Stocks

Effects of temperature and pathogen isolate on laboratory screening of soybean for resistance to Sclerotina sclerotiorum

The effects of temperature and pathogen isolate on laboratory screening of soybean (Glycine max. L.) for resistance to Sclerotinia sclerotiorum were investigated. The screening procedure used excised stems from 5-wk-old plants. Temperature and isolate significantly affected the length of stem lesions on 15 and 10 cultivars, respectively. At 15 °C, lesions were significantly shorter, but there was no difference in lesion length between 20 and 25 °C. One of the isolates caused significantly shorter lesions. There were significant differences among cultivars, but there were no temperature × cultivar or isolate × cultivar interactions. Choice of isolate and temperature between 15 and 25 °C, therefore, should not affect the relative differences among cultivars when screened for resistance using the excised stem method. Maple Presto, Maple Arrow and Maple Ridge were the most resistant of 19 cultivars evaluated. Key words: Soybean, resistance, temperature, isolate, Sclerotinia sclerotiorum

Comparison of Laboratory and Field Evaluations of Resistance in Soybean toSclerotinia sclerotiorum

Fifteen commercial soybean (Glycine max) cultivars were evaluated for resistance to Sclerotinia sclerotiorum in the laboratory, using an excised stem technique, and in the feld during 1988 and 1989. In the laboratory tests, significant differences in the length of stem lesions among cultivars were observed. Maple Presto, McCall, and Clay were significantly more resistant to stem decay then Pride B152, Apache, Merit, and Portage. Maple Presto, and McCall were the most resistant (...)

Field Evaluation of Early Maturing Soybean Genotypes for Differential Adaptation to Low Night Temperatures

Night temperature has a strong effect on soybean [Glycine max (L.) Merr.] productivity. Successful development of soybean genotypes tolerant to low night temperatures depends on the identification of genetic variation for this trait. Field experiments were conducted at Oregon State University and the University of Minnesota in 1984, 1985, and 1986 to assess genetic variation for adaptation to low night temperature within twenty soybean genotypes of maturity groups (MG) 000,00, and 0 of different origins. All genotypes were grown at Corvallis, OR, and St. Paul, MN, which have mean minimum night temperatures of approximately 10 and 16°C, respectively, during the summer months. Mean maximum temperatures for the same period of the year are similar for the two locations. Both locations are also at about the same latitude (ca. 45° N). Indices for adaptation to cool nights were calculated for seed yield, above ground dry matter (excluding leaves), apparent harvest index, seed weight, and days to maturity. These indices were calculated based on the performance of each genotype for a given trait in Corvallis relative to the mean performance of all genotypes within the same maturity group in Corvallis, as compared to the same value calculated for St. Paul. Genetic variations for adaptation to cool nights were identified for all the traits under investigation. In terms of seed yield, ‘Fiskeby V’ (MG 000), ‘Caloria’ and ‘McCall’ (MG 00), and ‘Dawson’ and ‘Evans’ (MG 0) appeared to be most adapted to low night temperatures, while ‘Maple Presto’ (MG 000), ‘Heike 3’ and ‘Maple Arrow’ (MG 00), and PI 290119 and ‘Ozzie’ (MG 0) seemed to be least adapted to cool nights. It also appeared that different characteristics contributed to the differential adaptation of genotypes to cool nights for seed yield. This information should be useful in breeding programs to develop soybean cultivars less sensitive to variations in night temperature.

COMPARATIVE RESPONSES OF PHOTOSYNTHESIS TO GROWTH TEMPERATURE IN SOYBEAN (Glycine max [L.] Merrill) CULTIVARS

The effect of temperature during growth on the photosynthetic characteristics of soybean (Glycine max [L.] Merrill) was studied using cultivars from Maturity Group 00 (Altona, Fiskeby V, Flambeau, Maple Presto, McCall) and MG VIII (Hampton 266–A, Hardee, Johnston, Kirby). In one experiment plants were grown with 950 μmol m−2s−1 photosynthetic photon flux density (PPFD) at 18, 20, 25 and 30 °C. When grown at 20 °C, MG 00 cultivars averaged significantly higher rates of photosynthesis measured at 25 °C and saturating PPFD than did MG VIII cultivars. Cultivars were also grown with a PPFD of 540 μmol m−1 at 17.5, 20.0, 22.5 and 25.0 °C. Maturity Group 00 cultivars averaged higher photosynthetic rates than MG VIII cultivars at the 20.0 and 22.5 °C growth temperatures. The other growth environments produced no significant differences between maturity groups. Photosynthetic rates differed between cultivars, but not maturity groups, after exposure to a single night with a gradual temperature decline to 8 °C. Photosynthetic rates recovered in 28 h. Two cultivars, Altona and Johnston, were grown outdoors at three times during one growing season at Beltsville, and their maximum photosynthetic rates changed depending on the temperatures during leaf development, in agreement with the data from the controlled environment studies.Key words: Soybean, Glycine max [L.] Merrill, photosynthesis, temperature, acclimation

INFLUENCE OF SINGLE STRAINS AND A COMMERCIAL MIXTURE OF Bradyrhizobium japonicum ON GROWTH, NITROGEN ACCUMULATION AND NODULATION OF TWO EARLY-MATURING SOYBEAN CULTIVARS

Seven single strains and a commercial mixture of Bradyrhizobium japonicum were evaluated in association with two early-maturing Canadian soybean (Glycine max (L.) Merrill) cultivars, Maple Presto and Maple Amber. Inoculated and uninoculated plants were grown in pails outdoors. Soil temperature at 15 cm depth was monitored throughout the experiment. At the V2, V3, R2 and R4 growth stages, whole plants were removed from the pails. Nodules were counted and weighed; roots and tops were separated, weighed and analyzed for total nitrogen. Bradyrhizobium japonicum strains 61A148, 61A196, 61A194 and 61A155 were similar in effectiveness, but superior to strains 61A124a, 61A118b, 61A101c and the commercial mixture in earliness of nodule formation, number and weight of nodules per plant, and in promoting greater root and top growth and plant nitrogen accumulation. There were indications that soil temperature may have affected nodulation. Maple Amber showed the greater potential for symbiotic nitrogen fixation. This cultivar supported earlier nodulation, had a greater number of nodules, accumulated more nitrogen in the tops and roots and had greater growth than Maple Presto.Key words: Soybean, Glycine max (L.) Merrill, soil temperature, soybean growth stages, Bradyrhizobium, nodulation

KG 20 SOYBEAN

KG 20 is an early-maturing, high-yielding soybean (Glycine max (L.) Merr.) cultivar with similar maturity and higher yield than Maple Amber and Baron in the western, central and maritime regions in Canada. It is about 8 d later than Maple Presto and outyields it by 33% in western Canada and by 27% in Ontario. The main advantage of KG 20 is its yield performance as an early-maturing cultivar.Key words: Glycine max (L.) Merr., soybean, cultivar description

Emergence and Vigor of Soybean in Relation to Initial Seed Moisture and Soil Temperature1

AbstractThis study was undertaken to assess the effects of initial seed moisture and of soil temperature on emergence and seed yield of soybean [Glycine max (L.) Merr.] in phytotron and field studies. Increasing the effective growing period would help in the establishment of soybean in more northern latitudes. Replicated lots of 100 seeds of two early maturing soybean entries, ‘Maple Presto’ and ‘King Grain X005’, were equilibrated to 6.6, 13.3, and 23.3% moisture levels. Phytotron studies involved day/night soil temperature regimes of 11.3/5.6, 16.7/10.7, and 20.5/14.l°C. Planting dates in the field were 22 May, 29 May, and 5 June 1979. Phytotron emergence exceeded 88% in all cases. Each 1°C decrease in mean soil temperature between 17.3 and 8.5°C resulted in a 2‐day delay of emergence. Emergence was independent of survival among different soil temperatures. Days to 80% emergence varied from 29 for the coolest temperature to 11 for the warmest in the phytotron and from 27 days for 22 May to 13 days for 5 June in the field. After 50% emergence, increasing differences were associated with differences in initial seed‐moisture contents. Maximum emergence took 1 to 2 days longer for the moistest than for the driest seeds. No differences were detected among lines for total emergence or for days to reach a certain level of emergence. No seed yield differences were associated with the initial seed‐moisture contents and planting dates, in spite of differential stands in the field. Equilibrating seed cannot be recommended. Using early maturing cultivars and seed lots with high germinability and seeding when soil temperatures are above 10°C are the recommendations for climatically marginal soybean areas such as southern Alberta.

TOLERANCE OF EARLY-MATURING SOYBEAN CULTIVARS TO METRIBUZIN

McCall, Maple Presto, Maple Amber and OT80-3 soybean (Glycine max (L.) Merr.) cultivars were evaluated under field conditions for their response to metribuzin. Maple Amber was found to be less tolerant than the other cultivars. In controlled environment chamber studies, injury to this cultivar was more severe on a sandy loam soil than on a clay loam soil. Fall applications of metribuzin, alone or tank-mixed with trifluralin, were tolerant to Maple Amber soybeans and such applications may offer a practical alternative to spring treatments for broad spectrum weed control in the less tolerant soybean cultivars grown in Manitoba.Key words: Metribuzin, trifluralin, preplant incorporation, fall treatments, soybean cultivars

Release of Soil-Bound Prometryne Residues Under Different Soil pH and Nitrogen Fertilizer Regimes

The release of soil-bound14C-prometryne [N,N′-bis(l-methylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine] residues was affected by soil pH, fertilizer treatments (with or without plants), and the crop species wheat [Triticum aestivum(L.) Merr. ‘Marquis’] and soybean [Glycine max(L.) Merr. ‘Maple Presto’]. More of the bound radioactivity was released following large pH changes in the soil than with small deviations. In addition, more14C-prometryne was found in the extracts of the soil incubated with large pH alterations. Fertilizing with ionic nitrogen sources (NO3–and NH4+) in the absence of plants was also responsible for releasing higher levels of radioactivity than with the nonionic fertilizer urea. These fertilizer-induced differences in release were not apparent when wheat plants were added to the system. Release of the bound radioactivity, however, was plant specific, particularly in the rhizoplane, since soybean roots elicited a greater release in the rhizoplane than wheat roots. Transport and metabolism of these residues were also plant specific.

Inheritance of seed protein and seed oil content in early maturing soybean

The inheritance of seed protein, seed oil, and the sum of protein and oil was investigated in two early maturing soybean crosses, 'Maple Presto' × 'Sioux' and 'Maple Presto' × X446-2-1, in 2 years (1981 and 1982) at one location (Winnipeg). Analyses of variance of the parental performance over years indicated that the parents differed significantly for all three traits studied and that genotype by year interactions were effectively zero. Generation means analysis indicated that gene action for seed protein was primarily additive, with partial dominance for low protein. Seed oil was also conditioned primarily by additive gene action. Partial dominance was not consistently detected over years and therefore was of minor importance. Additive × additive epistatic effects for seed oil were also detected but were not consistent over years. The sum of seed protein and oil was conditioned solely by additive gene action. Variance analyses indicated a predominance of additive genetic variance for all three traits. Dominance variance was also detected for both seed protein and the sum of protein and oil. Broad sense heritability for the F2 generation ranged from 76 to 83% for seed protein and from 68 to 86% for the sum of protein and oil, while narrow sense heritability ranged from 34 to 72% for seed protein and from 39 to 65% for the sum of protein and oil. Narrow sense heritability values equalled broad sense values for seed oil and ranged from 58 to 68%. Heritability was also estimated from standard unit parent – progeny regression analyses and values for all three traits were found to approach the variance analyses estimated broad sense heritabilities. Comparisons with the results of late maturing soybean crosses are made and implications of the results obtained in this study on early maturing soybean breeding programs are discussed.Key words: Glycine max, heritability, 00 and 000 maturity groups, breeding strategies.

MAPLE RIDGE SOYBEAN

Maple Ridge is a soybean (Glycine max (L.) Merr.) cultivar of early maturity, later than Maple Presto but earlier than Maple Amber. Seed yields are generally equal to those of Maple Amber and about 20% greater than those of Maple Presto.Key words: Glycine max (L.) Merr., soybean, cultivar description

DETERMINATION OF CLIMATICALLY SUITABLE AREAS FOR SOYBEAN (Glycine max (L.) MERR.) PRODUCTION IN MANITOBA

The effects of daily maximum and minimum temperature and photoperiod on the phenological development of soybean cultivars Maple Presto and McCall were studied under field conditions over the period 1979–1982. Experimental sites were located throughout the agricultural area of Manitoba. Data collected were used to derive a biometeorological time scale for each cultivar. For this purpose, the growth of the crop was divided into four stages: planting to emergence, emergence to flowering, flowering to beginning pod fill, and beginning pod fill to maturity. When the biometeorological time scale developed from the first 3 yr of the study was used to predict the duration of each stage of development during the fourth year, the largest root mean square error of estimation was 4.0 days. A biometeorological time scale developed from all 4 yr of data was applied to historical weather station data in order to determine the probability of maturing soybeans in Manitoba. According to the analyses, only a small area in central Manitoba south of 50° N latitude is capable of maturing the cultivar McCall 90% of the time. Most of the agricultural region can expect to mature the cultivar Maple Presto 90% of the time.Key words: Soybeans, climatically suitable areas

Multistrain vs. Single Strain Rhizobium japonicum Inoculants for Early Maturing (00 and 000) Soybean Cultivars: N2Fixation Quantified by 15N Isotope Dilution1

AbstractEarly maturing soybean cultivars (groups 00 and 000) adapted to western Canada are now available but since the soils contain no indigenous Rhizobium japonicum, it is important to determine if strains selected for efficient N2fixation with American soybean cultivars are also efficient with Canadian cultivars and if single strain are superior to multistrain inoculants. Accordingly, a 2‐year evaluation was made of the effect of up to eight single strains and two commercial multistrain combinations of R. japonicumgranular inoculants on maturity, seed yield, oil and protein content, and N2fixation (as determined for the first time by 15N isotope dilution) for three promising soybean lines. Rhizobium japonicumstrains 61A148 (USDA 142) and 61A118 (USDA 138) were consistently superior in N2fixation with all soybean cultivars, resulting in seed yields and seed protein higher than those of the other strains. Strain 61A101 was consistently an inefficient N2fixer. These differences in efficiency between strains were not related to documented ability to take up H2evolved by nitrogenase because, although strain 61A148 is considered Hup+, strain 61A118 is Hup–. Several strains resulted in percent plant N derived from the atmosphere exceeding 50% with N2fixed as high as 151 kg N ha−1for strain 61A148 on King Grain line X005. However, over all strains, Maple Amber was superior for supporting N2fixation, averaging 91 kg while X005 had 83 kg and Maple Presto 60 kg N fixed ha−1. Line strain combinations resulting in lower levels of N2fixation assimilated more soil N such that total N yields averaged over lines and strains were generally similar. These strains selected for U. S. soybean cultivars are also acceptable for Canadian soybeans. Interstrain competition occurred with one multistrain inoculant, to the detriment of plant yield. A commercial mix containing four strains (61A101, 61A118, 61A124, 61A148) had low N2fixation similar to that of strain 61A101. This suggested that strain 61A101 was highly competitive and may have formed a majority of the nodules thereby excluding the highly efficient strains 61A118 and 61A148. However, a new commercial mix containing three strains which were clones of 61A101, 61A118, and 61A124 did not exhibit any detrimental interstrain competition. Thus, the new multistrain soybean inoculant can be recommended for Canadian soybean cultivars.

PRODUCTION PRACTICES FOR EARLY MATURING SOYBEANS IN SOUTHERN ALBERTA

Four experiments were conducted at two locations in southern Alberta, where no indigenous Rhizobium japonicum existed, to determine the effects of seeding dates, fertilizers, irrigation, and method of inoculant placement on the yield and quality of several early-maturing soybean (Glycine max (L.) Merrill) cultivars. Highest yields were obtained when soybeans were seeded during the first half of May. Irrigation requirements varied between years but yields were similar whether soil moisture was depleted to the 6 × 104-Pa or the 3 × 104-Pa level before irrigating to field capacity. Soybean yields increased substantially from N fertilizer when the inoculant was applied to the seed without a sticker. When granular inoculant was banded with the seed there was no response to N, and the yields of inoculated plants were higher than those of plants that were uninoculated and received up to 160 kg N/ha. When properly inoculated, early-maturing cultivars such as King Grain strain X005 and Maple Presto were capable of maturing and producing seed of acceptable yield and quality in southern Alberta.Key words: Cultivars, fertilizer, irrigation, inoculant, Glycine max (L.) Merrill

PHOSPHORUS NUTRITION OF SOYBEANS AS AFFECTED BY PLACEMENT OF FERTILIZER PHOSPHORUS

Growth chamber and field experiments were conducted on Southern Manitoba soils, low in available soil phosphorus, to investigate the effects of various placement methods and levels of phosphorus fertilizer on soybean (Glycine max (L.) Merrill ’Maple Presto’). It was found that soybean responded well to applied phosphorus on low-P soil in growth chamber studies. In the first growth chamber experiment, P was applied in solution to 100%, 50%, 25%, 12.5% and 1% of the total soil volume. Dry matter yields, total phosphorus uptake and utilization of fertilizer P increased at each level of applied P as the size of the phosphated band was decreased. The results were partly attributed to greater chemical availability of P in the smaller zones of P fertilizer reaction. In a second growth chamber experiment, soybeans responded differently to phosphorus banded in six different locations. Placement of the fertilizer 2.5 cm directly below the seed was more effective in increasing dry matter yield, total phosphorus uptake and fertilizer P utilization than placement 2.5 cm and 5 cm away at the same depth or placement 5 cm below the seed, whether the band was directly below, 2.5 cm away or 5 cm away. Soybean yield responses in the field were greatest with P banded 2.5 cm directly below the seed on low-P soils. Placement of P 2.5 cm below the seed resulted in grain yields that were 64% and 50% higher (at the two sites) than those obtained in control plots. Sidebanding P, 2.5 cm below and 2.5 cm away from the seed at the same level of application, improved grain yields of control plots by 40% and 39%. Seed placement and broadcast applications of P were not as effective in increasing grain yields. Broadcasting P in fall or in spring at rates of up to 52.38 kg P/ha did not result in significantly higher grain yields than those obtained in control plots. Placement of P in contact with the seed appeared to reduce seedling emergence, resulting in depressed yields when 52.38 kg P/ha were applied. Key words: Glycine max L. Merrill, ’Maple Presto’

Nickel Is Not Required for Apourease Synthesis in Soybean Seeds

Soybeans (Glycine max L. Merr. cv ;Maple Presto') harvested from plants cultured in nickel-free medium had <0.005% the activity of nickel-sufficient beans and only 15% the activity of a urease-null variety, Itachi. However, whereas Itachi has no detectable urease protein, nickel-free beans of the variety Maple Presto exhibit normal or near normal levels of urease apoprotein. Thus, nickel isn't necessary for urease apoprotein synthesis. The apoprotein wasn't activated by nickel in vitro but, upon seed imbibition of nickel, urease was partially activated. This in vivo activation was not inhibited by cychoheximide.