bluuebunny/crossref_metadata_2025 huggingface dataset:
Field Evaluations of Morphactins and Other Growth Regulators for Senescence Delay of Flax, Soybean, Wheat, and Oats1
Authors: Dybing C. Dean , Lay Charles
Published: July 2010

Field trials were conducted from 1975 through 1979 to detect chemicals which would delay senescence of flax (Linum usitatissimum L.), soybean [Glycine max (L.) Merrill], wheat [Triticum aestivum (L.) em Thell], and oats (Avena sativa L.). Of 18 regulators tested 2 or more years on flax, 11 delayed leaf yellowing after single applications in at least I year. The morphactin chlorflurenol (methyl 2‐chloro‐9‐hydroxyfluorene‐9‐carboxylate), applied postbloom at rates of 25 to 50 g/ha retarded losses of chlorophyll and leaf area and promoted shoot growth and flowering. Early‐flowering cultivars were more responsive than late cultivars. Dichlorflurenol (methyl 9,7‐dichloro‐9‐hydroxyfluorene‐9‐carboxylate) and n‐butyl flurenol (n‐butyl 9‐hydroxyfluorene‐9‐carboxylate), were slightly less and markedly less effective than chlorflurenol, respectively. Other regulators which were effective when applied postbloom were 3‐CPA (2‐(3‐chlorophenoxy)propionamide), TIBA (2,3,5‐triiodobenzoic acid), ethephon (2‐chloroethyl)phosphonic acid), SD‐8339 (N‐ (phenylmethyl)‐9‐(tetrahydro‐2H‐pyran‐2‐yl)‐9‐ H‐purin‐6‐amine), BA + GA4,7(6‐(benzylamino) purlne plus gibberellins 4 and 7), and PP528 (ethyl 5‐(4‐chloro‐phenyl)‐2H‐tetrazole‐2‐acetate). Treatments made earlier than postbloom often resulted in growth abnormalities. Combination of cytokinin or gibberellin with other regulators usually did not enhance effectiveness.

Chlorflurenol delayed yellowing of ‘Swift’ soybean when applied in R5 stage at rates of 25 and 50 g/ha. Applications at higher rates or earlier dates caused growth abnormalities. Other effective chemicals included dichlorflurenol, BA, and BA + GA4,7. For oats and wheat, chlorflurenol was ineffective when applied from boot stage to postanthesis at rates up to 1000 and 2000 g/ha, respectively.
Exotic Cottons as Genetic Sources for Drought Resistance1
Authors: Quisenberry J. E. , Jordan W. R. , Roark B. A. , Fryrear D. W.
Published: July 2010

As irrigation water becomes more limited and energy costs increase on the Southern Great Plains, more cotton (Gossypium hirsutum L.) acreage will be diverted to dryland production. Because water is the most limiting resource for cotton production in this region, production will be positively related to changes which increase the water supply or make more efficient use of water. The purpose of this study was to evaluate plant (shoot) dry matter accumulation in photoperiodic (exotic) cotton strains under irrigated (water optimal) and dryland (water stressed) field conditions, to estimate their water‐use efficiency under dryland, and to determine the relationship between field growth parameters, laboratory evaluations of heat tolerance, and greenhouse estimates of root growth. Fifteen photoperiodic strains and one commerciacl ultivar were planted in irrigated and dryland field tests at Big Spring, Texas and in acrylic tubes in the greenhouse at Temple, Texas. In the Big Spring test, dry weight harvests from both the irrigated and the dryland plots were made at 44, 58, 72, and 86 days after planting (DAP). Soil‐water use was measured with a neutron probe in the dryland plots, and leaf discs were taken from both the irrigated and the dryland tests to measure heat tolerance. In them Temple test, shoot dry weight, leaf area, taproot length, and the number of major root laterals were measured 35 DAP. Analyses of variance and regression analyses were used to evaluate the data.

Significant variability was demonstrated among entries for shoot dry weights under both irrigated and dryland conditions, for water‐use efficiency in the dryland test, for heat tolerance at Big Spring, and for root growth at Temple. The number of lateral roots measured in the greenhouse was positively associated with shoot dry weights in the dryland plots, but not in the irrigated plots. Root morphology and root growth potentials appear to be important traits in the adaptation of cotton to conditions where limited soil‐water availability is a major constraint on plant growth.
Vernalization and Photoperiod Requirements for Maximum Flowering of Cicer Milkvetch1
Authors: Townsend C. E.
Published: July 2010

Cicer milkvetch (Astragalus cicer L.) does not flower in artificial environments that are used to induce flowering of the more commonly grown forage legumes. Therefore, the objectives of this study were to determine the vernalization and photoperiodic requirements of cicer milkvetch and to develop a practical chilling treatment for subsequent flowering in a greenhouse environment. When field grown plants of the cultivar ‘Lutana’ were brought to the greenhouse every 2 weeks from mid‐September through December, percent of plants flowering increased linearly from 29 to 100. Removal of top growth in mid‐September reduced subsequent flowering from 75 to 33%. Flowering after vernalization at 5 C night/20 C day (5/20 C) the laboratory was better than after vernalization in the field except for the late November and early December sampling dates. Percentge of plants flowering (95 to 100%) and profuseness of flowering (12 to racemes/plant) were similar [or the 5/20 C laboratory treatment and the late field sampling dates. The 5/20 C treatments were 6 weeks in duration with a total of 364 hours at 5 C.

Considerable variability exists among vernalized plants of the cultivar Lutana for photoperiodic response to flowering. Although only 30% of the plants flowered at the 13‐hour photoperiod, a few plants flowered profusely. The highest percentage of plants flowering (98%) and the most profuse flowering (13.3 racemes/plant) occurred at photoperiods of 15 and 16 hours.
Digestibility of Kleingrass Forage Grown Under Moisture Stress1
Authors: Pitman W. D. , Victor D. M. , Holt E. C.
Published: July 2010

Low forage digestibility of warm‐season perennial grasses frequently limits performance of grazing animals. Digestible energy intake is of particular concern during hot, dry periods of mid‐summer. Although relationships between plant characteristics affecting digestibility and temperature, irradiance, and soil fertility have been reported, the relationship between forage digestibility and moisture stress has yet to be clearly determined. The purpose of this study was to determine the influence of moisture limitations on digestibility of kleingrass (Panicum coloratura L.) forage.

Kleingrass plants cloned from a single parent were grown in pots under greenhouse conditions at five watering levels. Soil moisture ranged among watering levels from field capacity down to near the permanent wilting point. Four pots or replications for each of five watering levels were arranged in a randomized block design. Plants were harvested on four successive harvest dates after a 15‐day period of regrowth. In vitro digestible organic matter (IVDOM) of leaves and stems, gravimetric soil moisture, plant water status (leaf xylem pressure potential), forage yield, and plant leafiness were determined at each harvest date. Although percent soil moisture and leaf xylem pressure potential declined as a result of successively lower watering levels, yields per pot and IVDOM of both leaves and stems were not significantly reduced until reduced watering lowered soil moisture to 9.1% and leaf pressure potential to −7 bars. Only leaf growth occurred when soil moisture and leaf xylem pressure potential were reduced to 7% and −14 bars, respectively. Leaf and stem IVDOM ranged from 63.8% and 60.8% with non‐stressed material down to 33.6% and 42.8% at the most stressed level producing leaf or stem growth, respectively. The results indicate that low forage digestibility of warm‐season grasses in midsummer may be associated with moisture limitations.
Effect of Fall or Spring Infection and Sources of Tolerance of Barley Yellow Dwarf of Winter Wheat1
Authors: Cisar G. , Brown C. M , Jedlinski H.
Published: July 2010

Seventeen hundred‐twenty selections of winter wheat (Triticurn aestivum L. em Thell.) were screened for tolerance to the barley yellow dwarf virus (BYDV), and the effects of fall and spring BYDV infections on several traits were investigated in different years. Fall infection was more damaging than spring infection for all traits measured except kernel weight and harvest index where spring infection caused more severe reductions. Grain yield was reduced an average of 63% for fall, and 41% for spring infections. No outstanding sources of tolerance were discovered, though some entries were more tolerant than others. Several alloplold derivatives from crosses of winter wheat with tall wheatgrass [Agropyron elongatum (Host) Beauv.] were highly tolerant. A significant interaction of selections with date of inoculation indicated differential response of some entries to fall and spring infections. Some selections were tolerant regardless of the time of infection. The relationship between visual disease severity ratings and plant damage as measured by yield of infected plots as percentage of control plots was sufficiently strong (r = 0.65) to ensure genetic advance toward reduced yield loss by selection based on visual assessment of disease severity.
Selection Procedures for Developing Fertility Restorer Lines in Wheat1
Authors: Ghiasi H. , Lucken K. A. , Hammond J. J.
Published: July 2010

The effectiveness of selection for anther extrusion in fertility restorer lines of wheat (Triticum aestivum L. em Thell.) to improve cross‐pollination potential and the relationship between the self‐fertility of the restorer lines and the fertility of their testcrosses were examined in six R/B (restorer/conventional line) crosses and one R/R (restorer/restorer) cross. A common restorer parent, R109, was used in all crosses. One hundred and fifty‐two F6 R‐lines, selected from 722 F5 lines, were evaluated in yield trials at three locations in North Dakota in 1979. All F6 lines were testcrossed to male steriles with Triticum timopheevi Zhuk. cytoplasm, and fertility of testcross progeny was used as the criterion for fertility restoration potential. The effect of restorer genes on several agronomic and quality traits also was investigated.

Regressions of the F6 on F5 generations indicated that selection for anther extrusion in the F5 was effective although somewhat less effective than selection for heading date and plant height. Forty percent of the variation in the F6 for anther extrusion was determined by variation in the F5 compared to 64 % for heading date and 72 % for plant height. R‐line anther extrusion was only slightly indicative of fertility restoration potential; the R2 for testcross F1 seed set vs. F6 R‐llne anther extrusion was 10%.

Among the 152 R‐lines, there was a low negative association between anther extrusion and 200‐kernel weight and a low positive association between R‐line test weight and testcross seed set, When lines were grouped by testcross fertility, no differences among testcross fertile, testcross partially fertile, and testcross male‐sterile lines were found for any trait except R‐line anther extrusion and testcross anther extrusion. The R109‐derived restorer genes and their associated linkage blocks had no deleterious effects on agronomic traits.
Genotype ✕ Environment Interaction Bias to Parent‐Offspring Regression Heritability Estimates1
Authors: Casler M. D.
Published: July 2010

Parent‐offspring regression is a commonly‐used technique for estimating narrow sense herltability of quantitative characters in crop species. However, regression of progeny means on parent values evaluated in the same or similar environments may lead to biased heritabillty estimates. This bias arises from genotype ✕ environment interaction and error covarlances between parents and progenies. This paper deals with the theoretical effects of these covariances on parent‐offspring regression heritability estimates and emphasizes some considerations necessary in estimating heritability. Covariance analysis is recommended as a method of obtaining more meaningful narrow sense heritabillty estimates than simple parent‐offspring regression for a set of parents and their offspring evaluated in a set of environments.
Abscisic Acid and Abscission of Young Cotton Bolls in Relation to Water Availability and Boll Load1
Authors: Guinn Gene
Published: July 2010

A field experiment was conducted to determine whether two factors, water deficit and fruit load, that are known to affect fruit abscission might also affect the concentrations of ABA in young cotton (Gossypium hirsuturm L. ‘Deltapine 70’) bolls. The effects of water deficit were estimated by comparing ABA concentrations and abscission rates of boils in control and stressed plots, and by following changes during irrigation cycles. The effects of fruit load were determined by removing about 4/7 of the flowers in partially defruited plots, and by comparing changes as boll load increased during the season.

Both ABA concentration and abscission rate of bolls increased with water deficit and decreased with relief of stress by irrigation. Boll abscission rates increased as boll load increased, and were lower in the partially defrulted than in the fruited plots. Bolls in the partially dcfruited plots contained less ABA on some, but not all, harvest dates. Watei: deficit apparently had a greater effect than boll load on the ABA content of young bolls.

The results indicate that water deficit increases the ABA content of cotton bolls, and they provide additional circumstantial evidence that ABA is one regulator of young boll abscission in cotton. However, differences in ABA content did not account for increased boll abscission rate with increasing boll load during the season nor for differences in abscission between fruited and partially defruited plants.
Effects of Air Temperature on Disease Severity and Peroxidase Activity of Soybean Leaves Infected by Peronospora manshurica1
Authors: Dunleavy J. M.
Published: July 2010

The objectives of this study were to determine if soybean leaves infected by Peronospora manshurica, the downy mildew fungus, have a higher peroxidase activity than healthy leaves and to determine if peroxidase activity is releated to symptomatology. After leaves were inoculated with conidia, leaf chlorosis appeared in 8.5 and 4.2 days at 10 and 35 C, respectively. A high negative correlation (r=−0.98) occurred between air temperature and the appearance of chlorosis after inoculation. Disease symptoms were most severe at 25 C, but decreased at both higher and lower temperatures. Peroxidase activity of uninoculated leaves was affected only slightly by the air temperatures. Infection resulted in large, significant (p<0.01) increases in peroxidase activity at all temperatures. A highly significant correlation (r=0.97) occurred between leaf disease ratings at 10 days after inoculation and maximum peroxidase activity of infected leaves at 9 to 13 days after inoculation at the temperatures tested.
Turgor Changes with Accelerated Aging of Soybeans1
Authors: Parrish David J. , Leopold A. Carl , Hanna Milford A.
Published: July 2010

If membranes are a primary site of aging in dry seeds, the ability of seeds to develop turgor should be increasingly affected by increasing aging stress, and turgor reduction should be evident immediately upon hydration. We used the Instron Universal Testing Machine to examine the rheological properties of freshly imbibed ‘Wayne’ soybean (Glycine max (L.) Merr.) cotyledons as a measure of turgor characteristics. Turgor reductions by osmotica showed a lowering of the apparent modulus of elasticity (E') in parallel with tissue pressure potential. Turgor reductions were detected following seed aging; such reductions were detectable immediately upon imbibition and were evident after 2 days of accelerated aging stress (41 C and 100% relative humidity), whereas significant reductions in germination and growth appeared only after 3 or 4 days of aging. The experiments illustrate the utilization of rheological properties as measures of turgor and show a lowering of turgor levels in imbibed accelerated‐aged soybeans, presumptive evidence for a primary effect on membranes in seed aging.
Sampling for Eggs, Larvae, and Adults of the Bluegrass Billbug1,2
Authors: Kindler S. D. , Kinbacher E. J.
Published: July 2010

A test was conducted to determine the precision of a pyrethrlns drench applied to the surface of Kentucky bluegrass, Poa pratenis (L.), to estimate the densities of soil and thatch inhabiting adult and root‐feeding larvae of the bluegrass billbug, Spenophorus parvulus Gyllenhal. Eighty‐seven percent of the adults were recovered from in situ sod with a 0.45 cm thick thatch while 82% of the adults were recovered from in situ sod with a 1.15 cm thick thatch. Root‐feeding larvae did not respond to the pyrethrins drench.

In tests comparing a food blender extraction method with a hand dissection, method of extracting eggs and young larvae from infested plants, the number of eggs and larvae recovered from the blender extraction method did not differ significantly from the number of eggs and larvae recovered by hand dissecting the plant material.
Effect of Cereal Leaf Beetle on the Yields of Resistant and Susceptible Winter Wheat1
Authors: Webster J. A. , Smith D. H. , Hoxie R. P.
Published: July 2010

Field tests were conducted with l0 winter wheat (Triticum aestirum L. em. Thell.) genotypes to determine the effectiveness of cereal leaf beetle (CLB), Oulema melanopus (L.), resistant wheat reducing larval densities and yield losses. Yield loss data were obtained by comparing yields of insecticide‐treated plots with CLB infested plots. The test included a cereal leaf beetle resistant cultivar, ‘Downy’, and three other resistant genotypes. All four resistant entries had pubescent leaf surfaces. Larval densities and larval feeding damage were lower on pubescent‐leaved entries than on wheat lines without high levels of leaf surface pubescence. In 1978 there was no grain yield reduction in three resistant entries, while the yield loss of susceptible lines ranged from 17.6 to 25.6%. Larval density on these cultivars ranged from 4.3 to 10.4 larvae per stem. Kernel weight was the most sensitive yield component in this test, with significant reductions in four of the six susceptible cultivars. Winter wheat breeders in localities where the CLB has been a problem should at least maintain resistant germplasm even though parasitoids have been established in many areas for biological control of the CLB.
Apomictic Interspecific Hybrids Between Pearl Millet and Pennisetum orientale L. C. Rich1
Authors: Hanna Wayne W. , Dujardin Michael
Published: July 2010

Pearl millet, Pennisetum americanum (L.) Leeke, is an important world food and forage crop. Pennisetum orientale L. C. Rich has genes for apomixis, perennial growth habit, pest resistance, and drough tolerance which could be used to improve pearl millet. The objectives of this research Were to determine the cytotaxonomic relationship of these two species and to explore the feasibility of interspecific germplasm transfer. Five interspecific hybrids, 2n = 25, with 7 large P. americanum millet (A) and 18 small P. orientale (0) chromosomes were produced by pollinating cytoplasmic male sterile pearl millet with P. orientale pollen. The O chromosomes paired mainly as bivalents and the A chromosomes remained as univalents. A low frequency of AO chromosome associations were observed. Although the possibility of germplasm exchange existed, the two species appeared to be not closely related. Among three hybrids examined, one was a facultative apomict, one was an obligate apomict and another was highly apomictic with 3% of ovules with sexual embryo sacs. Sixteen backcross progenies were established from interspecific hybrids pollinated with pearl millet pollen. Seven plants were 2n = 23 with 14 A + 9 0 chromosomes, five were 2n = 27 with 7 A + 20 O chromosomes and four were 2n = 32 with 14 A and 18 O chromosomes. The balanced chromosome number for both species in these latter plants should provide a mechanism for restoring fertility in the interspecific hybrid thus enabling germplasm transfer. The interspecific hybrids were male sterile but set about 1% seed when pollinated with pearl millet pollen.
Response to Selection for Low Temperature Sprouting Ability in Tomato Populations1
Authors: De Vos D. A. , Hill R. R. , Hepler R. W.
Published: July 2010

Selection for low temperature sprouting ability was conducted in field and laboratory environments in parental and F2 families derived from a six‐parent dial lei of tomatoes (Lycopersicon esculentum Mill.). Two cold tolerant (CT) and four non‐cold tolerant (NCT) parents were examined. Variation among parental and F3 progeny selections was partitioned into average effects and into linear and quadratic responses to selection. The results of the selection experiment were compared with expectations based on a previous experiment which involved the parents and F1 hybrids.

Variation among parents for average effects was highly significant, but no response to selection was observed in families derived from the parents. Average response to selection in the field was significant for families derived from CT ✕ NCT crosses, and there was significant variation among families in this group for the magnitude of response to selection. A response to selection in the field was not observed in families derived from CT ✕ CT or from NCT ✕ NCT crosses. Average response and variability among families for response to selection in the laboratory was significant for each of the family groups, but the greatest response was observed in families derived from CT ✕ NCT crosses.

Observed responses to selection did not always agree with expectations based on diallel analysis of the parents and F1 hybrids. Some families for which the F1 analysis indicated a great degree of genetic diversity showed almost no response to selection.
Advanced Generation Analysis of Days to Heading in Three Winter Wheat Crosses1
Authors: Avey D. P. , Ohm H. W. , Patterson F. L. , Nyquist W. E.
Published: July 2010

Three hierarchal populations in the F6 generation were used to estimate the importance of additive, additive‐by‐additive, and dominance genetic variances for heading date in three winter wheat (Triticum aestivum L. em. Thell) populations. The populations were progenies from three single crosses between the cultivars ‘Aobakomugi’, ‘Doublecrop’, and the Purdue Univ. line, P6879. Under Indiana conditions, Aobakomugi heads about 5 and 14 days earlier than Doublecrop and P6879, respectively.

Two random F3 plants were grown from each of 291 random F2 plants from the three crosses. Two random F4 plants were grown from each of the F3 plants. Twenty random F5 plants from each of the 1164 F4 plants were grown in a row 1 m long. F6 seed from plants within each row was bulked to give rise to the 1164 F6 lines.

F6 lines, the three parents, and two cultivars, ‘Monon’ and ‘Beau,’' were grown in a randomized complete block design in experiments at Lafayette and Sullivan. Ind. in 1980 and analyzed as a nested effects model.

Additive variance was significant for heading date in the cross Aobakomugi/Doublecrop; additive and dominance variances were significant in the cross Aobakomugi/P6879; and additive × additive effects were significant in the cross Doublecrop/P6879. A duplicate dominant genetic system is proposed to account for part of the genetic variance in populations from crosses with P6879. The appropriateness of early and advanced generation selection for heading date is briefly discussed.
Soybean Mosaic Virus Investigations with Susceptible and Resistant Soybeans1
Authors: Hartwig E. E. , Keeling B. L.
Published: July 2010

The soybean mosaic virus (SMV) susceptible soybean [Glycine max (L.) Merr.] breeding line D60‐9647 was inoculated with SMV‐1 at five different stages of development in each of 4 years to observe the effects of SMV in an area where vector dissemination of SMV is not apparent. Mean reduction in seed yield over the 4‐year period was 12%. Time of inoculation made little difference. There was a large increase in percent mottled seed following SMV inoculation with the highest percentage resulting from inoculation at the V7 stage of development. Percent of seedlings showing virus symptoms (15%) was highest from the inoculation at the V7 stage. Percentage of seed germination was reduced from 95 to 88%.

Another study was conducted in which closely related SMV resistant and susceptible lines were compared using seed harvested from susceptible lines which had been inoculated with SMV. Seed yield of the susceptible lines, not again inoculated, did not differ from that of the resistant lines. Seed yield of SMV‐susceptible lines inoculated with SMV‐1 averaged 8% lower in seed yield than resistant lines in 1974 and 12% lower in 1975. The results indicate that under conditions similar to those in which our studies were conducted, seed from SMV infected plants can be utilized for planting with no undesirable effects.
Variation in Leaflet Orientation among Soybean Cultivars1
Authors: Wofford T. J. , Allen F. L.
Published: July 2010

The degree of leaflet orientation was measured for five soybean (Glycine max L., Merr.) cultivars on an hourly basis from 0620 (0700 EST) until 1820 (1900 EST) hours Local Solar Time during the 10 node stage of development (V10) and from 0520 (0700 EDT) until 1820 (2000 EDT) hours during the beginning pod stage (R3). Measurements were taken on 4 separate days during each growth stage. Our primary objective was to determine if differences exist among soybean cultivars in degree of leaflet orientation.

There was significant variation among cultivars in the degree of orientation of the center and the side leaflets of trifoliolates at different times of the day.during both growth stages. The orientation of the center leaflets of a trifoliolate differed from that of the side leaflets. The vertical inclination of the center leaflets tended to change over time while the horizontal inclination remained relatively constant. On the other hand, the horizontal inclination of the side leaflets tended to change over time while their vertical orientation remained relatively constant. However, due to their location relative to each other, the different directions of movement of the center vs. side leaflets seem necessary in order for all three leaflets to attain similar exposures to incoming radiation.

Maximum variation in leaf movement was noted from 0820 until 1620 hours during both V10 and R3 stages of development. Higher angles of inclination were obtained and maintained during R3 than V10.

The K concentration in pulvini was significantly higher (p < 0.01) during the tense state (higher angles of leaflet orientation) than during the relaxed state. It appears that the K concentration in the pulvinus might have some role in regulating the bending and straightening movements of the pulvini, perhaps by inducing changes in turgor pressure.
A Flexible In Vitro Shoot Culture Propagation System for Sugarbeet that Includes Rapid Floral Induction of Ramets1, 2
Authors: Saunders Joseph W.
Published: July 2010

In vitro shoot cultures of sugarbeet (Beta vulgaris L.) were established from lateral buds of flowering plants, providing a flexible vegetative propagation system for a polycross breeding scheme. Monthly transfers of cultures on Murashige‐Skoog medium with 1.1 µM benzyladenine had a shoot multiplication rate of 3 to 5 per month, with higher rates at more frequent transfers. Shoots were rooted on Murashige‐Skoog medium with 16 µM α‐naphthalene‐acetic acid or in Jiffy‐7 peat pots. Shoots of most genotypes multiplied in vitro by axillary shoot growth as well as by adventitious shoot regeneration from petiole surfaces. Shoot regeneration from petioles increased with greater benzyladenine concentration in the range 0–11 µM, but was less in the presence of 0.38 or 3.8 µM ± cistrans abscisic acid. One genotype failed to regenerate shoots from petioles. Shoot cultures also returned to vigorous growth after 56 weeks storage at 4 C in the dark. Shoot culture ramets from most genotypes tested flowered in as little as 26 days in continuous incandescent light in a growth chamber at 14/10 hours fluorescent light/dark at 20/14 C, without the cold treatment usually employed with sugarbeets.
Probable Genotypes of Hard Red Spring Wheats for Resistance to Puccinia recondita f. sp. tritici1
Authors: Rizvi Syed S. A. , Statler Glen D.
Published: July 2010

Simultaneous inoculations of 20 hard red spring wheat (HRSW) cultivars (Triticum aestivum L. em. Thell.) and 20 near‐isogenic HRSW lines with known genes for low reaction were made with each of 20 selected cultures of Puccinia recondita f. sp. tritici. The infection types were classified as low infection types (LIT) and high infection type (HIT). Comparisons of infection type (IT) data was facilitated by a Fortran computer program. Absence of cultures in the LIT:HIT category in paired near‐isogenic line to cultivar comparisons and similarities of IT data was used to hypothesize genotype(s) in the host cultivars. We used this comparative infection type data to speculate on the presence of seedling genes for resistance to P. recondita f. sp. tritici in many of the commercially grown HRSW cultivars in North Dakota. Several cultivars had genes in addition to those hypothesized and some have genes in common. This technique has utility for the mass identification of gene pools and favors rapid selection of the genes that condition resistance to the populations of P. recondita f. sp. tritici.
Maize Yield Response to Increased Assimilate Supply1
Authors: Schoper J. B. , Johnson R. R. , Lambert R.J.
Published: July 2010

The capacity of the maize (Zea mays L.) ear to accept greater assimilate supplies is an important parameter in some strategies to increase grain yield. This problem was studied by increasing assimilate supply at several growth stages and determining the effects on grain yield, yield components and partitioning ratios. During a 2‐year period, a single‐eared hybrid was grown at a control density of 64,500 plants/ha and was thinned to 43,000 and 21,500 plants/ha at growth stages ranging from soon after emergence to 3 weeks after silk emergence. In a second experiment, light reflectors were placed between rows of three different hybrids for 2‐week intervals ranging from about 3 weeks before to about 6 weeks after silk emergence. Both thinning and reflector treatments were designed to increase assimilate supply to the ear.

In thinning experiments, control densities yielded about 10,700 kg/ha during 1978 and 1979. Thinning at 2.5 weeks before silking increased yield per plant up to 41% while thinning at 3 weeks after silking caused an 11% increase. Increased kernel number and weight/kernel accounted for the yield increase, and the relative contribution of each shifted from one year to the next even though yields were similar both years. Ear number, kernel row number and duration of grain fill were unaffected by increased assimilate supply. Yield increases obtained by thinning to the intermediate density occurred with little change in partitioning ratio of dry weight and N. Thinning to the lowest density caused a decline in the partitioning ratios. Reflector experiments in spite of some heat stress demonstrated that increased assimilate supply for short, discrete periods could cause similar results. We conclude that under our U.S. Corn Belt conditions, increasing assimilate supply can result in a grain yield increase per plant and can do this without altering the length of grain‐filling or the partitioning ratios.
Allelic and Linkage Relations among Genes for Stem Rust Resistance from Triticum turgidum, ‘Mindum,’ ‘Acme’ Selection, ‘Palestine,’ and ‘Khapli’1
Authors: Williams N. D. , Miller J. D.
Published: July 2010

The objective was to determine allelic and linkage relations among genes for resistance to stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. & E. Henn) in 13 lines of tetraploid wheat (Triticum turgidum L.) derived from crosses of susceptible ‘Marruecos 9623’ with resistant ‘Mindum’ (three lines), ‘Acme’ selection (three lines), ‘Khapli’ emmer (four lines), and ‘Palestine’ (three lines). Each of the 13 lines had a single gene for resistance to stem rust. A partial diallel cross was made among the lines, and F2 seedlings were tested for reaction to cultures 111‐SS2 and 56‐1 of stem rust. Absence of segregation indicated that the parents had allelic or closely linked genes for resistance; segregation for resistance and susceptibility indicated nonallelism.

A uniformly resistant F2 from a cross between lines Srda‐2 (gene for resistance from Acme selection) and Srdm‐1 (gene for resistance from Mindum) indicated that these lines had allelic (or closely linked) genes for resistance. Also, lines Srda‐3, Srdm‐2, and Plt‐C (genes for resistance from Acme selection, Mindum, and Palestine, respectively) had allelic (or closely linked) genes for resistance. All other crosses segregated resistant and susceptible seedlings which indicated that the parental lines had different single genes for resistance.

Twenty‐eight crosses appeared to segregate into three classes, one like the parent having the highest level of resistance, one like the parent having the lowest level of resistance, and one susceptible. Of the 28 crosses, segregation in 19 was a good fit to a 12:3:1 ratio. Genes conditioning high levels of resistance usually masked those conditioning low levels.

Segregants more resistant than either parent occurred in 11 crosses and indicated that genes for resistance from the two parents had cumulative effects. Genes for resistance in parental lines in each of five crosses conditioned similar levels of resistance, and most of these F2s segregated in ratios of approximately 15 resistant:1 susceptible. Statistically significant deviations from tested ratios occurred in the F2 from 16 crosses, but the direction of the deviations did not imply linkage. The F2 data of seven crosses were not tested by chi‐square because sample sizes were small or segregation ratios were irregular.
Linkage Relationships between Le and Gl Alleles in Cotton1
Authors: Lee Joshua A.
Published: July 2010

The major leaf‐gland alleles of cotton, Gossypium hirsutum L., Gl2 and Gl3, were shown to be linked with the complementary lethality alleles, Le1 and Le2. Linkage between Gl2 and Le1 was estimated at 27.5 ± 2.8 centimorgans, and linkage between Gl3 and Le2 was estimated at 22.9 + 2.2 centimorgans. Because the complementary lethality allele from G. davidsonii Kell., Ledav is also linked with the gl3 locus of Gossypium, the question arose as to whether or not Le,dav and Le2 are alleles at a common locus. Direct methods of testing are not possible inasmuch as combining the two alleles in a zygote results in the death of the embryo, or the plant, stemming therefrom. However, indirect results as well as reconstruction of probable pathways in the evolution of alleles at the le loci in various Gossypium taxa led to the tentative conclusion that Le2 and Ledav although antagonistic in combination, are alleles at a common locus.
Direct and Maternal Genetic Variances and Covariances of Seedling Characters in Tobacco1
Authors: Van Sanford D. A. , Matzinger D. F.
Published: July 2010

A diallel crossing scheme was used to estimate genetic parameters for seedling weight, root length, and day of germination in a random mating tobacco (Nicotiana tabacum L.) synthetic population. Estimates were obtained from plants grown under two nutrient levels in aseptic culture in controlled environmental growth chambers. Significant estimates of direct additive and dominance variances and, maternal additive variance for seedling weight were obtained in both stress and optimal nutrient levels. The heritability for seedling weight in the optimal environment, 0.178, was larger than that in the stress environment, 0.124. Predictions of selection response were greater for performance on either the stress or optimal nutrient level if selection would be conducted in the optimal environment. Correlations among characters varied between the two nutrient levels. The large correlations between seedling fresh weight and root length for direct additive and maternal additive effects were of opposite sign, leading to prediction of little change in root length when selecting for increased seedling weight.
Stability of S Alleles in a Doublecross Hybrid of Red Clover1
Authors: Taylor Norman L.
Published: July 2010

The S‐allele system used for controlling crossing in doublecross hybrid red clover (Trifolium pratense L.) is expected in theory to produce four heterozygous allelic types arbitrarily designated S1S5, S1S7, S3S5, and S3S7. This study was undertaken to ascertain if this theoretical segregation is achieved in a doublecross produced under field cages where crosses are made with honey bees (Aphis mellifera L.). S‐alleles of doublecross hybrid plants were identified by presence or absence of seed produced from crosses to four homozygous I1 parents, and from chain crosses. Among 77 plants examined, 16 had S1S5, 11 had S1S7, 14 had S3S5, 11 had S3S7, 12 had one unknown allele, and 10 had two unknown alleles. Three exceptional plants were found that appeared to be S5S7 but set seed when intra‐crossed suggesting an unusual genetic control. No S1S3 or S1S7 plants other than the three plants described above, were found. About 68% of the population conformed to theoretical expectations. The remainder apparently resulted from generation of new S‐specificities, contamination, or both. Either possibility would have serious consequences for control of crossing by the S‐allele system.
Field Evaluation for Cool‐Tolerance in Grain Sorghum1
Authors: Clegg M. D. , Eastin J. D. , Nelson L. A.
Published: July 2010

Sorghum [Sorghum bicolor (L.) Moench] may be injured at low nonfreezing temperatures. Therefore, there is interest in identifying genetic material which can tolerate cooler temperatures. The objectives of this research were to develop a procedure that quantitated the developmental rate of sorghum under cool nighttime temperatures and to determine if genetic variation existed for this trait. A developmental index (DI), based on relative heat units to 50% anthesis for each genotype grown in two environments, was used. One environment had a high nighttime temperature while the other had a low nighttime temperature. Developmental index values obtained were positive, negative, or zero. Genotypes with positive DI values maintained their developmental rate relatively better under cooler nighttime temperatures and were considered cool‐tolerant. Results showed that lines and hybrids from Canada or the northern USA generally had positive DI values. Lines selected in the environment with the high nighttime temperatures (seasonal average 14 C) generally had negative DI values, whereas, lines selected in the environment with the low nighttime temperatures (seasonal average 8 C) generally had positive DI values. Parent lines identified as cool‐tolerant tended to pass the trait to their progeny. Maturity among these genotypes seemed to be independent of the DI value for that genotype. Days to 50% anthesis for these genotypes ranged from 50 to 72 days. This DI appeared to quantitate the ability of a sorghum genotype to maintain a relative developmental rate under cooler nighttime temperatures and there seemed to be substantial genetic variation for the trait this index measures. This DI should be useful in quantifying this trait for further experimentation and for selection in breeder's nurseries.
Evaluation of Recurrent Selection in BSSS, BSCB1, and BS13 Maize Populations1
Authors: Smith O. S.
Published: July 2010

A population diallel (including sells) of the C0, C4, and C7 cycles of BSSS(R), BSCB1(R), and BS13(HT) and crosses involving the C5 and C8 cycles of BSSS(R) and BSCB1(R) were used to evaluate effects of recurrent selection for grain yield in maize (Zea mays L.). The response in BSSS(R) and BSCB1(R) was calculated separately for cycles 0–4 and cycles 4–8. Both direct and indirect responses to reciprocal recurrent selection were greater in cycles 4–8 than in the initial cycles, indicating that the use of machine‐harvesting and the use of S1 plants in making the testcrosses were effective for increasing machine‐harvested grain yields. The response of the population cross to RRS was estimated to be 4.3% per cycle when averaged over all cycles. Estimates of indirect effects (gains in the populations per se), adjusted for the effects of drift, were larger than estimates of direct effects in the BSSS(R) ✕ BSCB1(R) population cross. Mean yield of the BSSS(R)C7 ✕ BSCB1(R)C7 population cross was 87% of the single‐cross check B73 ✕ Mo17. Changes in other agronomic characters were generally in the desired direction with the exception of grain moisture. It was concluded that recurrent selection was effective for increasing grain yield and improving other agronomic characters in population crosses, but effects of drift due to small population size were evident in the populations per se.
Chromosome Stability and Fertility of a Nitrous Oxide‐Derived Tetraploid Population of Red Clover1
Authors: Giri N. , Taylor N. L. , Collins G. B.
Published: July 2010

The first and sixth generations of a randomly mated, autotetraploid red clover (Trifolium pratense L.) population (2n=28) derived by treatment with nitrous oxide were examined to determine changes in male and female fertility. Characters measured were chromosome pairing, pollen stainability, and seed set. Approximately equal numbers of aneuplolds (2n−1, 2n+1, 2n+2) were observed in each generation tested. These aneuploids produced less stainable pollen and seed than did euploids in greenhouse crosses, but under field cage conditions, only 2n=27 genotypes produced fewer seeds per head than the euploid genotypes (2n=28). However, clones with 27, 28, and 30 chromosomes produced lighter weight seeds than clones with 29 chromosomes. It was concluded that six generations of random mating were ineffective in changing meiotic configurations, pollen stainability, and seed yield. Although not directly compared in this study, aneuploids appeared to be produced in about the same frequency in nitrous‐oxide and colchicine‐derived tetraploid populations. Aneuploids apparently are not a major factor in the low seed yields of tetraploid red clover. It is suggested that direct selection for high seed yield may be more effective than selection for absence of aneuploids.
Effect of Environments and Genetic Backgrounds on Evaluation of Cotton Isolines1
Authors: Meredith William R.
Published: July 2010

This study was conducted to measure the influence of genetic backgrounds in cotton (Gossypium hirsutum L.) and of environments on the effects that two traits, Okra leaf L02 and frego bract (fg), exert on lint yield and its components. The genetic backgrounds used were DES 24‐8ne, a normal leaf and bract strain; ORH 55, an Okra leaf and frego bract strain; and two F3 plant selections derived from the cross of DES 24‐8ne X ORH 55. For each of the four genetic backgrounds, four near‐isogenic lines were produced among all homozygous combinations of normal vs. Okra leaf and normal vs. frego bract. The 16 genotypes were evaluated for lint yield in 1979 and 1980 under two insect‐control regimes (for a total of four environments). One regime was produced by applying early‐season insecticides; the other was produced by applying no early‐season insecticides and by growing plants of mustard [Brassica juncea (L.) Czern. & Coss.] near the plots to enhancearly‐season insect infestations. Lint yield varied greatly among years, averaging 742 and 479 kg/ha for 1979 and 1980, respectively. Cotton grown with and without early‐season insect control yielded 667 and 554 kg/ha, respectively. The effect of Okra leaf on lint yield and its components was influenced greatly by environments but relatively little by genetic backgrounds. Average yield of Okra and normal leaf types was 597 and 625 kg/ha, respectively. Bract types were more sensitive than leaf types to environments and genetic backgrounds. Normal‐bract isolines, however, yielded more lint in all environments than did their frego‐bract counterparts. The average yield for normal and frego‐bract types grown under the insect control regime was 751 and 582 kg/ha; and under the no control regime was 674 and 435 kg/ha, respectively. Varying environments were more important in the evaluation of these traits than varying genetic backgrounds.
Stand Establishment Characteristics of Barley Genotypes of Different Plant Heights1
Authors: Bacaltchuk B. , Ullrich S. E.
Published: July 2010

There is a trend to develop short‐statured barley (Hordeum vulgare L.) cultivars, primarily to reduce lodging. Considering the short coleoptile length and consequent stand establishment problems associated with the development semi‐dwarf wheat (Triticum aestivum L.) this study was conducted to investigate the situation in barley. Seedling and stand establishment characteristics of 18 spring barley genotypes of various plant heights were studied in the laboratory, greenhouse, and field. The temperature for maximum coleoptile elongation was 20 C, although individual cultivar variation occurred in response to temperature. Significant differences among genotypes were observed for coleoptile length. In the greenhouse, emergence [emergence rate index (ERI) and percent final stand] was highest at the 3 cm planting depth and decreased with deeper planting. The cultivar with the shortest coleoptile length had the highest ERI (emerged the quickest) at 8 and 13 cm planting depths. In the field ERI's varied with spring and summer plantings. Final stands were affected less. Variation in response for the cultivars varied over the range of the three environments studied. Some of the shortest‐stemmed cultivars had the longest coleoptiles and established the best stands. Among the traits studied, few significant correlated responses were observed especially involving coleoptile length. There was a negative correlation between coleoptile length and final stand for one of the plantings (r = −0.64). Yield was negatively correlated with plant height for one of the plantings (r = −0.64) in the absence of lodging. The strong relationships among plant height, coleoptile length, and stand establishment typically found for wheat did not occur in the barley genotypes used in this study.
Soluble Carbohydrates in Development Sorghum Caryopses1
Authors: Newton R. J. , Meckenstock D. H. , Miller F. R.
Published: July 2010

Soluble components of sorghum [Sorghum bicolor (L.) Moench] caryopses of field‐grown plants taken from anthesis to 45 days postanthesis were assayed with gas‐liquld chromatography and correlated with caryopsis fresh weight, dry weight, and maturity. Levels of the three primary sugars present, sucrose, fructose and glucose, were maximum (µg/caryopsis) at 12 to 15 days; inositol and raffinose were maximum at 18 to 21 and 27 to 33 days, respectively. Sucrose concentrations decreased to a constant level at day 24 and remained constant through day 45. During the first 15 days, glucose and fructose levels were similar;, thereafter, fructose levels were lower than glucose and only low fructose levels were detected in the caryopsis by day 39. Three major time intervals can be described by the data in the development and metabolism of the caryopsis: I, 8 to 18 days; II, 21 to 30 days; and III, 33 to 45 days. Rate of fill, water content, and sugar concentrations reached a maximum during Interval I. The rapid decrease of sucrose with the subsequent attainment of constant levels, the attainment of maximum caryopsis fresh weight, and the beginning of black layer formation were observed during Interval II. Maximum dry weight (physiological maturity), minimum rate of water loss and increased molar concentrations of sucrose were observed during Interval III. Day 33 was determined as the precise time of physiological maturity. Total sugars comprised about 5% of the caryopsis dry weight at day 15 and 0.8% on day 42.