bluuebunny/crossref_metadata_2025 huggingface dataset:
Breeding for High Tiller Number and Yield in Barley1
Authors: Benbelkacem Abdelkader , Mekni Mohamed S. , Rasmusson Donald C.
Published: July 2010

Research was initiated in 1965 to identify and incorporate genes for high tiller number into midwestern six‐rowed barley, Hordeum vulgare L. The objective of this paper is to report on the performance, especially yield, of barleys with high tiller and head number from this program. Cyclic crossing, primarily backcrossing, and selection were used to develop high tillering lines that had agronomic promise. When the source of high tiller number was a two rowed barley, XH‐263, lines were evaluated after four cycles (Exp. 1) and seven cycles (Exp. 2) of breeding and when the source of high tiller number was six rowed Sel. 6194‐63, lines were evaluated after four Cycles of breeding (Exp. 2). Good progress in incorporating the genes for high tillering into a good genetic background was achieved using cyclic crossing and selection. High tillering lines developed in Exp. 1, had better agronomic performance than XH‐263, but they were lower yielding than the checks. However, in Exp. 2, the high tillering parents, Minn 73‐129 and Minn 75‐61, were nearly equal to the checks, Minn 34 and Minn 38, in yield and mean yields of individual high tiller number lines exceeded the checks, although not significantly. In Exp. 2, four groups of lines which differed in tiller number had similar yields. In both experiments, high tillering lines were high in head number and tiller mortality, low in kernel number per head and kernel weight, and susceptible to lodging. Because of high tiller mortality, breeding for increased tiller number was only 36% effective in terms of adding additional heads. We plan to continue this breeding effort since improvement in yield was achieved in the high tillering lines during the several cycles of breeding.
Response of Three Oat Cultivars to N Fertilizer1
Authors: Brinkman M. A. , Rho Y. D.
Published: July 2010

Knowledge of cultivar response to N is helpful to the small grain grower, who can increase yields and profits, and to the small grain breeder, who can manipulate heritable traits to develop cultivars with improved response to N. The objective of this research was to identify morphological and physiological traits influencing grain yield response to N for three oat (Avena sativa L.) cultivars that differed in height. The cultivars were grown at five rates of N fertilizer (0, 28, 56, 84, and 112 kg N/ha) in each of three environments. ‘Stout’ was relatively short and early‐maturing, while ‘Marathon’ and ‘Lodi’ were taller and later‐maturing. The experimental design was a split plot, with N rates as whole plots and cultivars as subpplots. Stout had the largest grain yield response to N (pattern of change across rates of N) because it had better responses for spikelets per panicle and weight per kernel. Consequently, Stout accumulated more dry matter after heading. Panicle number was not positively associated with differential grain yield response to N. Stout also had thicker, heavier leaves than Lodi and Marathon, but none of the three leaf traits measured appeared to contribute significantly to the differential grain yield response among the cultivars. Determining yield component responses to N could be useful in oat breeding programs that are attempting to release cultivars which respond well to highly productive environments. Lines with favorable responses for one or more yield components should be included in a crossing program for high yield response.
Hydroponic Culture of Grass Plants for Physiological Ecxperiments1
Authors: Howard Harold F. , Watschke Thomas L.
Published: July 2010

A hydroponic system has been devised for the culture of large numbers of grass plants to be used in subsequent physiological experiments. This system is inexpensive to construct, requires minimal maintenance, and can be left unattended for several days. Plants produced by this method are of uniform size and are easily harvested and cleaned.
Stomatal Frequency and Size in Vicia faba L.1
Authors: Tanzarella O. A. , De Pace C. , Filippetti A.
Published: July 2010

Variation in stomatal frequency and size and the relationship of those characters with other plant features were studied in Vicia faba L. to provide information about possibilities of modifying water use by breeding. A field trial comprised I0 cultivars belonging to major, equina, and minor types grown at 20 and 40 plants/m2. The main effects studied were cultivars, leaf position on main stem, and plant density. A substantial independence among stomata, trichome, and other plant characteristics was observed. Cultivars differed mainly in stomatal and trichome frequency. Frequency and number of stomata and trichomes per leaflet were affected by plant density. Leaflets on the seventh node had a greater number of stomata and trichomes than leaflets on the first node. The stomatal frequency, number, and dimensions were higher on the lower (abaxial) leaf surface than the upper (adaxial) leaf surface, whereas the frequency and number of trichomes were higher on the upper surface. Cultivar and leaf position had significant effects on almost all characters meao sured. First‐ and second‐order interactions also were significant, but the latter for only a few characters. In general, stomatal size was less affected by the factors tested than stomatal and trichome frequency. The implications of the results for breeding new cultivars based on physiological selection criteria are that stomatal frequency can be altered by breeding to improve water use.
Effect of Daylength Insensitivity on Agronomic Traits and Gain Protein in Hard Spring Wheat1
Authors: Busch R. H. , Elsayed F. A. , Heiner R. E.
Published: July 2010

Daylength insensitivity is an advantageous trait for spring wheat (Triticura aestivum L.) since it allows both a better seed increase from the nurseries in southern latitudes and wider potential use in breeding programs around the world. The ‘Chris’ source of daylength insensitivity was evaluated in the upper Midwest to determine if this trait had adverse effects on agronomic performance. Sixty random daylength insensitive (I) and 60 random daylength sensitive (S) lines from crosses of ‘Era’ with two daylength insensitive lines were evaluated from 1975 through 1977 to select 10 elite lines for yield from each class, S and I. These elite lines were tested in three environments in 1979. Ten near‐isogenic line pairs for I and S were tested in six environments in a paired plot design. These 10 pairs of nearisogenic lines had also been tested from 1975 through 1977 in the random line test. The I lines headed earlier than the S lines in all tests. Grain yield differences between the elite I and S lines and near‐isogenic I and S pairs depended upon the sites tested and their dates of seeding. In general, the S lines tended to be higher yielding at the more northerly location. At the more southerly location, and under delayed seeding conditions, the I lines were similar to or higher yielding than their respective S lines. In general, the Chris source of daylength insensitivity did not appear to seriously affect agronomic performance. However, high yielding I lines may be more difficult to obtain than high yielding S lines for the northern areas. This may be due to either insensitivity or the effect of earlier heading on performance, since the insensitive lines were almost all earlier heading.
Comparison of Some Crop Water Stress Measurement Methods1
Authors: O'Toole J. C. , Turner N. C. , Namuco O. P. , Dingkuhn M. , Gomez K. A.
Published: July 2010

The measurement of crop water stress under field conditions is fraught with technical and logistical problems. Although leaf water potential has become a standard measurement it has spatial and temporal sampling limitations. In the current study, a rice (Oryza sativa L.) crop was used to compare eight measurements indicating crop water status, namely leaf water potential ψleaf), stomatal resistance (ra, transpiration rate (T), net photosynthesis rate (PN), canopy temperature (Tc), canopy minus air temperature (Tc — Ta), crop water stress index (CWSI), and visual leaf rolling score (LRS). The eight measurements were compared across seven water stress levels created by a line source sprinkler irrigation system. The methods were compared for accuracy, sensitivity, sampling time, and the destructive‐disruptive nature of the sampling procedure. Accuracy was estimated by comparison with ψleaf and by the interaction between water stress level and time of day. All methods except PN were significantly correlated with ψleaf at the 1% level. However, Tc, Tc — Ta and CWSI showed less interaction between water stress level and time of day when total variance was partitioned into its relative components; water stress level, time, and the interaction between water stress level and time of day. All methods, with the exception of PN, were equally sensitive to the water stress gradient when “goodness of fit” response functions across the water stress gradient were compared. The visual LRS was the most rapid while the canopy temperature‐based measurements, Tc, Tc — Ta. and CWSI, were nearly three times faster than the gas exchange techniques and about two and a half times faster than ψleaf. Leaf water potential sampling was both destructive and disruptive to the crop plant community. The gas exchange methods were nondestructive but repetitive sampling was disruptive. Only the remotely sensed Tc Tc — Ta, CWSI and LRS were neither destructive nor disruptive to the crop. The interpretive value of various measurements is discussed. The CWSI was found to be highly correlated with mean daily PN and represents a significant advancement in crop level detection and measurement of water stress.
A Rapid Method of Evaluating Growth Rate in Pearl Millet and Its Weedy and Wild Relatives1
Authors: Bramel‐Cox P. J. , Andrews D. J. , Bidinger F. R. , Frey K. J.
Published: July 2010

Vegetative growth rate is a physiological trait that has been hypothesized to be useful in the improvement of grain yield in cereal crops. Usefulness of this physiological trait in a breeding program depends upon a rapid method that allows the evaluation of large numbers of lines. In this study, the objective was to determine if the rates of growth calculated from periodic samplings could be estimated by using only one or two dates of harvest relating to specific stages in the plant's development. Periodic samples of vegetative growth were made on 12 pearl millet (Pennisetum americanum) genotypes, plus three weedy (ssp. stenostachyum) and one wild (ssp. monodii) accession in two seasons once every 2 weeks starting at 21 days after emergence and continuing to maturity. With use of the rates calculated on these periodic samples as the actual growth rate, it was found that samples taken at either one or two dates of harvest could be used to adequately estimate this rate. The two dates of harvest were taken at either 10 days after flowering or at maturity. The rate was calculated as (vegetative dry weight at flowering + 10 days or at maturity)/(number of days to flowering + 10).
Heritability of Total and Fixed N Content of the Seed in Two Soybean Populations1
Authors: Ronis D. H. , Sammons D. J. , Kenworthy W. J. , Meisinger J. J.
Published: July 2010

Improved seed yield in the soybean [Glycine max (L.) Merr.] may result from selection to increase the N2‐fixing ability of the crop. To investigate that possibility, broad‐sense heritabilities of total and fixed N in the seed were estimated for two F2 soybean populations. One population was derived from a cross of high (‘Ware’) and low (D66‐5566) N2‐fixing parents and was grown years. The second population, grown in 1 year only, was derived from a cross of intermediate N2‐fixing parents (‘Williams’ and ‘Calland’). Both populations and their parents were grown in 15N‐labeled soil in the field along with ‘Clark’ rj1rj1 nonnodulating plants as controls. The amount of fixed N in the mature seed at harvest was determined by the 15N‐dilution method for individual plants. Broad‐sense heritability estimates of fixed N content of the seed ranged from 0.53 to 0.60. Estimates for percentage of fixed seed N varied from 0.12 to 0.43. Estimates for total seed N [as a weight (from 0.49 to 0.61) and as a percentage (from 0.20 to 0.87)], for seed yield (from 0.52 to 0.59), and for plant weights (from 0.57 to 0.62) are also reported. strong positive association was noted between seed dry weight and fixed N content of the seed (r = 0.99). These results suggest that improving N2 fixation in the soybean is feasible through selection based on the mass of fixed N in the seed. Selection for high seed yield will probably likewise result in the identification of plants with a high rate of N2 fixation.
Effect of Cultivar, Environment, and Their Interaction and Stability Analyses on Milling and Baking Quality of Soft Red Winter Wheat1
Authors: Baenziger P. Stephen , Clements R. L. , McIntosh M. S. , Yamazaki W. T. , Starling T. M. , Sammons D. J. , Johnson J. W.
Published: July 2010

The effect of cultivar, environment, and their interactions on soft red winter wheat (Triticum aestivum L.) quality has never been determinated in the southeastern United States. In this study, 22 soft wheat cultivars and 2 hard wheat cultivars were grown in 12 southeastern environments in a randomized complete block design having two replications. Flour yield, whole grain protein percent, particle size index, and alkaline water retention capacity were measured. Highly significant differences were detected among environments and cultivars for each of the quality variables. The cultivar ✕ environment interaction was highly significant for all variables. Cultivars with good soft wheat quality and good stability were identified. The cultivar means from an environment were generally highly significantly correlated with the regional cultivar means indicating that for preliminary quality evaluations, data from one environment is sufficient for ranking cultivars.
Use of Infection‐Type Data to Identify Genes for Low Reaction to Puccinia recondita in Several Winter Wheat Cultivars1
Authors: Modawi R. S. , Browder L. E. , Heyne E. G.
Published: July 2010

Knowledge of similarities and differences between cultivars in genotype for reaction to different pathogens is useful in the management of gene resources in disease control programs. To obtain such information about some important winter wheat (Triticum aestivum L.) cultivars, we analyzed infection types produced by 30 cultivars and 20 lines having known Lr genes, each inoculated with 22 Puccinia recondita Rob. ex Desm. cultures. Analyses were made by comparing infection‐type spectra produced by the various host lines with the set of cultures. On the basis of these comparisons, we hypothesize that ‘Parker’, ‘Centurk’, ‘Centurk 78’, ‘Rocky’, and ‘TAM W‐105’ have Lr10. These cultivars also produced low infection types with LR10(TC) virulent cultures; thus they must also have Lr genes other than Lr10. The already known presence of Lr24 in ‘Parker 76’, ‘Sage’, and ‘Payne’ was indicated by these data. We hypothesize that Parker 76 has other Lr gene(s) in addition to Lr24 because of the occurrence of ✕‐infection types with ‘Agent’ virulent cultures. The Lr9 genotype of ‘Arthur 71’ and ‘Riley 67’ was also indicated. We hypothesize that ‘Newton’ and ‘Plainsman V’ have Lrl, and that Plainsman V has Lr3a. Newton must have other Lr gene(s) that are not Lr3a, based on low infection types produced with LR1(TC) and LR3A(TC) virulent cultures. Our indicated the presence of the now ineffective Lr3a in several other cultivars: ‘Bennett’, ‘Homestead’, ‘Gage’, ‘Lancota’, and ‘Warrior’. Hypotheses about host genotypes based on infection‐type data analysis have usually, but not always, been shown to be correct when the hypothesis is tested by making appropriate host crosses and inoculating their progeny with appropriate cultures. Intermediate ✕‐infection t~es were common in the hard red winter wheats and are believed to be important in disease control.
Dinitrogen Fixation in Soybean in Response to Leaf Water Stress and Seed Growth Rate1
Authors: Cure Jennifer D. , Raper C. David , Patterson Robert P. , Robarge Wayne P.
Published: July 2010

Late season declines in N2 fixation by soybean [Glycine max (L.) Merr.] frequently are observed under field conditions but do not always occur under glasshouse and growth chamber culture where water stress is avoided and photoperiod is manipulated to alter rate of seed growth. To evaluate the effects of water stress and photoperiod during reproductive growth on declines in N2‐fixation, nodulated ‘Ransom’ soybeans dependent entirely on N2‐fixation and growing under controlled environment conditions were divided into two groups at the beginning seed (RS) stage. At R5, photoperiod was utilized to experimentally alter the rate of seed growth as a sink for photosynthate and N by imposing a short‐day photoperiod (SD) on half of the plants and a long‐day photoperiod (LD) on the other half. Within each photoperiod treatment, half of the plants were subjected to a single episode of leaf water stress between −1.2 and −1.8 MPa at the full seed (R6) stage, and half served as nonstressed controls. Plants were sampled at 1o to 5‐day intervals between R5 and full maturity (R8) stages and analyzed for N and total nonstructural carbohydrates (TNC). The rate of N accumulation from N2‐fixation declined during reproductive growth for the stressed plants but not for the nonstressed plants. Thus, a water stress can actuate a late season decline in N2‐fixation. When rate of seed growth was slowed under LD, N composition in leaves remained higher following water stress than when a faster rate of seed growth was promoted under SD. Dinitrogen‐fixation activity and dry matter production recovered after rewatering for stressed plants under LD but not under SD. Concentration of TNC in leavlets was greater under LD for both stressed and nonstressed plants. Thus, concentration of TNC in leaflets does not appear to be as important in recovery from water stress as concentration of N.
Comparison of Leaf Gas Exchange and Water‐Use Efficiency in Two Eastern Gamagrass Accessions1
Authors: Coyne Patrick I. , Bradford James A.
Published: July 2010

Eastern gamagrass [Tripsacum dactyloides (L.) L.] is a highly productive, C4, perennial forage grass that is native to the eastern half of the USA. This species is most adapted to subirrigated sites or areas with at least 875 mm annual precipitation. Physiological data useful for improvement of this species are lacking. This paper documents photosynthetic potential and water‐use efficiency (WUE) of two greenhouse‐grown accessions: WW‐1318, a narrow‐leaf and WW‐1462, a wide‐leaf genotype. Carbon dioxide exchange rate (CER) and transpiration (E) were monitored in a temperature‐controlled, steady‐state leaf chamber from which stomatal (g′s) and residual (g′r) conductances for CO2 were calculated. Carbon dioxide exchange rate approached the highest reported values for C4 species under optimum conditions and ranged from 50 (WW‐1318) to 61 (WW‐1462) μmol m‐2s‐1. Although E was relatively high (5 to 6> mmol m‐2s‐1), transpiration efficiency (CER/E) reached 10 mmol mol‐1 which is among the highest reported values. For full sunlight conditions, optimum temperature for CER (Topt=35°C), an external CO2 (Ca) of 13 mmol m‐3, and a vapor pressure difference (VPD) of 2 kPa, these grasses were fixing C at about 0.65 (g′r/g′t g′t=g′s+g′r) of their potential maximum if limited only by CO2 diffusion through the stomata. Eastern gamagrass was highly efficient for a range of environmental conditions because g′r exceeded g′s whenever light was greater than about 0.15 of full sunlight and temperature was between 20 and 40°C. Although CER/E and g′r/g′t increased to maximum levels at one‐third full sunlight at Topt in both accessions, WW‐1318 maintained this efficiency to full light compared to an approximate 15% loss in efficiency in WW‐1462. The response of CER vs. g′s, as light was increased at constant T, VPD, and Ca, was linear for WW‐1318 but curvilinear for WW‐1462. This, together with the decline in WUE for WW‐1462 at higher light levels, suggested better control of stomatal conductance relative to that required to sustain but not limit CER in WW‐1318. Stomata in both grasses tended to function in a manner that stabilized internal CO2, (Ci) at about 2.6 to 4.6 mmol m‐3 for Ca=13 mmol m‐3, once light was above 0.25 full sunlight. The Ci/Ca stabilized at 0.3 to 0.4 at full sunlight once Ca exceeded 12 mmol m‐3 (35°C). Stomatal function appeared more nearly optimized in WW‐1318 in that dCER/dE was much less sensitive to increasing light or temperature than in WW‐1462. These data indicate that Eastern gamagrass has comparatively high photosynthetic and WUE potential when soil water is not limiting. The differences in the measured physiological parameters between these gamagrass strains suggest potential exists for germplasm enhancement with respect to maintaining optimum performance in variable environments.
Dinitrogen Fixation, and N and Dry Matter Distribution During 4 Year Stands of Birdsfoot Trefoil and Red Clover1
Authors: Heichel G. H. , Vance C. P. , Barnes D. K. , Henjum K. I.
Published: July 2010

Birdsfoot trefoil (Lotus corniculatus L.) and red clover (Trifolium pratense L.) are important perennial forage legumes for use as hay or pasture in crop rotations. Despite their traditional usage as a source of N for cropping systems, little information is available on the amounts of N2 that birdsfoot trefoil and red clover fix during long‐term stands. We conducted field experiments with the 15N isotope dilution method over a stand life of 4 years to determine the inter‐ and intra‐annual fixation of N2 and the distribution of dry matter among organs for birdsfoot trefoil and red clover managed for hay production. Each legume species showed significant variation of N2 fixation within a year and among years of the stand. Red clover annually produced 22% greater average herbage dry matter compared with birdsfoot trefoil during the first 3 years of the stand. Nevertheless, the two species had similar quantities of dry matter in roots plus crowns and fixed similar average annual quantities of N2 ranging from about 60 to 120 kg N/ha. Dinitrogen fixation of birdsfoot trefoil exceeded that of red clover by 42% in Year 4 because it obtained a significantly greater proportion of its total N from fixation with similar herbage and root dry matter production. Over the 4‐year stand life, both species averaged 92 kg N/ha annually from N2 fixation. Throughout the experiments, birdsfoot trefoil and red clover distributed 10% or less of their dry matter to roots plus crown, components which usually had a N concentration 0.5 to 0.6 that of herbage. Therefore, the greatest return of fixed N2 to a subsequent crop would result from adoption of management practices that achieve a plowdown of a substantial growth of herbage rather than only roots plus crowns soon after hay harvest.
Complementarity of Genes for High Groat‐Protein Percentage from Avena sativa L. and A. sterilis L.1
Authors: Cox T. S. , Frey K. J.
Published: July 2010

Seventy F2‐derived lines from each of 10 matings between oat (Avena spp.) strains having high groat‐protein percentage (PP)were examined for transgressive segregation and genetic variation to determine the degree of complementarity between high‐PP genes from the cultivated (A. sativa L.) and the wild oat (A. sterilis L.). Six (“intergroup”) matings involve done parent containing high‐PP genes from A. sativa and one parent of chiefly A. sativa parentage, but containing high‐PP genes from A. sterilis. Four (“intragroup”) matings were between two parents with high‐PP genes from within the same species. Transgressive segregation at the 5% probability level occurred at rates of 10.4 and 4.3% in inter‐ and intragroup matings, respectively. Corresponding rates at the 1% probability level were 6.9 and 2.2%, respectively. Most transgressive segregates resulted from three intergroup matings. Mean PP in two of the matings, ‘Otee’ ✕ PI469111 and ‘Dal’ ✕ PI469111, had values equal to that of PI469111, the high‐PP parent. Both also exhibited the largest estimates of genetic variance. Predicted response to selection for PP (10% selection intensity) ranged from 0.44 to 0.96 percentage points, and correlated response of grain yield ranged from −94 (−3.7%) to −443 kg/ha (−17.5%). High‐PP lines with above‐average grain yield did occur, however. This study demonstrated that genes for high PP are more likely to complement each other in interspecific matings of A. sativa and A. sterilis than are similar genes from in traspecific mating is neither species alone. However, some intergroup matings produced larger numbers of transgressive segregates than did others.
Effect of N Fertility on Plant Water Relations and Stomatal Responses to Water Stress in Irrigated Cotton1
Authors: Radin John W. , Mauney Jack R. , Guinn Gene
Published: July 2010

Cotton (Gossypium hirsutum L.) was grown in Phoenix, AZ, in 1981 and 1982. In both years it was irrigated with either 10 or 15 cm of water per application; N was supplied at three rates within each water treatment. Stomatal conductances of the most recently expanded leaves were followed during irrigation cycles to determine effects of N fertility on stomatal responses to water stress. Differences in N status between treatments were small in 1981 but were much greater in 1982. In July 1982 (early in the fruiting period), stomata of low‐N plants closed as leaf turgor neared zero, but stomata of high‐N plants remained open well past this point. As the season progressed, the differential response to water stress was lost as stomata of high‐N plants became more responsive to declining water potentials. Nitrogen had little effect upon predawn osmotic potential (determined by pressure‐volume procedures as the water potential for zero turgor), but low N eliminated the diurnal osmotic cycling seen in high‐N plants. Diurnal oscillations of osmotic potential in high‐N plants had an amplitude of 0.4 MPa early in the fruiting period, then declined to zero only to reappear as fruits matured and vegetative growth resumed. Nitrogen concentrations of the most recently expanded leaves also increased during regrowth. Seasonal changes in stomatal responses to water stress seemed unrelated to either osmotic potentials or overall leaf N status. The loss of the differential response to stress did coincide roughly with a decline in petiole nitrate‐N concentrations to very low levels in all treatments. Seedcotton yields were significantly affected by water in 1981 and by water and N in 1982. In the 2nd year, full irrigation increased yields only on high N; on low N, full irrigation did not affect yield but greatly decreased water‐use efficiency. The effects of N fertility on stomata explain in part the complex effects of N on water use.
Long‐Term Preservation of Hop Pollen in Liquid Nitrogen1
Authors: Haunold Alfred , Stanwood P.C.
Published: July 2010

This research was initiated to evaluate long‐term hop (`Humulus lupulus`` L.) pollen storage for breeding purposes and germplasm preservation. Air‐dried pollen was stored in a refrigerator (3°C), a freezer (−18°C), and in liquid nitrogen (−196°C) and compared with fresh pollen by hand pollination of receptive female flowers and subsequent seed germination tests. Pollen stored in liquid N averaged four seeds per cone in test crosses over a 2‐year period as compared to slightly over five seeds per cone from fresh pollen. Pollen stored at −18°C lost about half of its viability after 1 year, while pollen stored at 3°C became nonfunctional within 1 year. Reducing moisture content of fresh pollen to about 10% prior to cold temperature storage was essential.
Temperature Effects on Seedling Development of Perennial Warm‐Season Forage Grasses1
Authors: Hsu F. H. , Nelson C. J. , Matches A. G.
Published: July 2010

Field establishment of warm‐season perennial forage grasses tends to be difficult due to slow growth and low competitiveness of seedlings. Understanding environmental influences, especially temperature, on seedling development will be helpful in developing and interpreting management practices. We conducted growth chamber studies to evaluate seedling development of Caucasian bluestem (CB) [Bothriochloa caucasica (Trin.) C.E. Hubb.], a native strain of big bluestem (BB) [Andropogon gerardi Vitman), strain IG‐2C‐F1 of indiangrass (IG) [Sorghastrum nutans (L.) Nash], and ‘Cave‐in‐rock’ switchgrass (SG) (Panicum virgatum L.). Crabgrass (CG) [Digitaria sanguinalis (L.) Scop.], an annual weed, was used as a comparison species. Photosynthetic photon flux density was 550 μmol m−2s−1 for 14 h day−1. Relative humidity was near 70%. Seedling growth of all species at 20°C was reduced dramatically when compared with that at 25 and 30°C. Crabgrass developed faster than perennial species, exhibiting the shortest phyllochron (time interval between successive collared leaves) and fastest tillering rate index, leading to the highest leaf number and leaf area. Further, CG initiated permanent roots earlier and faster than did perennial species. Among perennials, SG had the highest leaf elongation rate (LER) and fastest development of permanent roots. Caucasian bluestem had a low LER, but had the fastest phyllochron and the highest tillering rate index, thus developing the largest number of leaves and the fastest leaf area development index among perennials. Switchgrass and CB developed more leaf area and accumulated more dry matter than other perennials over the 28‐day period. Indiangrass emerged rapidly, developed primary and permanent roots earlier than did other perennials, but developed leaf area slowly. Based on a relative index of BB, IG had higher relative total dry matter at early stages than did other perennials. Indiangrass and BB partitioned a greater percentage of dry matter to roots than did SG and CG at early stages. Growth of permanent roots and leaves were both associated closely with total dry matter accumulation. Generally, averaged across temperatures, seedling weight at 28 days was ranked from highest to lowest as CG, SG, CB, IG, and BB, but growth patterns associated with seedling development were markedly different among species. Management practices based on growth responses need to be considered.
Production of Multiple Vacuoles as an Early Event in the Ontogeny of Protein Bodies in Developing Soybean Seeds1
Authors: Adams Clifford A. , Norby Shong Wan , Rinne Robert W.
Published: July 2010

We have made an ultrastructural study of developing soybean seeds, cultivar Wells [Glycine max. (L.) Merr.], using light and electron microscopy in an attempt to resolve the question of protein body ontogeny. Formation of numerous small vacuoles from the central vacuole was observed as early as 17 days after flowering (DAF). The process continued until each cell contained many small vacuoles. There was a close association between development of rough endoplasmic reticulum (RER) and Golgi bodies and the appearance of protein bodies. Proliferation of RER was observed by 34 DAF, and the vacuoles filled with reserve protein to form distinct protein bodies. Many small vesicles were derived from RER and Golgi bodies but these did not appear to develop into protein bodies. These vesicles may be concerned with transport of storage protein to multiple vacuolar sites for deposition of reserve protein into protein bodies. Protein bodies increased both in size and number as the seed developed. At later stages of seed development, around 60 DAF, RER disappeared and many large protein bodies and numerous lipid bodies were visible in cotyledon cells. The results of our study demonstrates the following: (i) early subdivision of the central vacuoles (17 DAF) appears to be the source of protein bodies; (ii) there is no apparent physical connection between the RER and protein bodies; (iii) accumulation of starch and lipid reserves in soybean seed clearly precedes that of storage protein; (iv) appearance of membrane‐bound polyribosomes (not free ribosomes) is consistent with the onset of storage protein; and (v) at physiological maturity, most cell organelles had disappeared.
Divergent Mass Selection for Grain Protein in Sorghum1
Authors: Ross W. M. , Maranville J. W. , Hookstra G. H. , Kofoid K. D.
Published: July 2010

The low, and often variable, protein percentage of sorghum [Sorghum bicolor (L.) Moench] grain is a constraint to utilization of the crop as feed or food. A study was undertaken to determine the effectiveness of fertile plant mass selection for high and low protein percentage in a sorghum random‐mating population under standard field production practices of eastern Nebraska. Four cycles of positive selection increased grain protein content 0.50 percentage points from the base (10.93%), and negative selection decreased it 1.06 percentage points. Calculated heritabilities for high and low protein selection were 0.16 each, but realized heritabilities were 0.10 and 0.19, respectively. Protein yield remained nearly constant regardless of the selection direction. Although grain yields of the base and the selection cycles were not statistically different when all were tested together, a trend existed toward lower yields in the high protein cycles and higher yields in the low protein cycles. An overall phenotypic correlation of −0.86 existed between grain yield and protein percentage. The study demonstrated that mass selection was somewhat effective in changing grain protein percentage, but large positive gains for protein content would be difficult to obtain in common sorghum germplasm without accompanying negative effects on yield. Utilization of protein‐specific genes and index selection may be necessary to attain desired plant breeding goals.
Comparative Effects of Repeated Cycles of Water Stress on Growth and Apparent Dinitrogen Fixation of Ladino and Strawberry Clovers1
Authors: Johnson Kenneth L. , Raguse Charles A.
Published: July 2010

Water stress is a major environmental factor limiting growth and symbiotic N2 fixation of legumes. This study was conducted to determine the effects of repeated short‐term cycles of water stress on growth and N2 fixation of Ladino clover (Trifolium repens L.) and strawberry clover (T. fragiferum L.). In separate experiments, stolons of each species were trained into a calcined, montmorillonite clay medium, grown to a LAI of 4.0 ± 0.5 under controlled conditions of ambient air and root temperature, and provided with N‐deficient nutrient solution. Visible wilting was induced in treatment plants by withholding solution, and stressed plants were re‐irrigated following 10 daylight h of wilting. Additional replicates subsequently were allowed to develop second and third water stress cycles. Canopy‐air temperature differentials did not differ between control and nonwatered plants at 48 h prior to visible wilting; at 24 h, they differed for strawberry clover but not for Ladino. Leaf water potentials differed significantly between successive stages of water stress within a stress cycle, but not between given stress stages for successive cycles. Ladino clover visually wilted at −1.65 MPa, with maximum values of −2.4 MPa at the end of the stress cycle. Strawberry clover followed a similar pattern but exhibited a paraheliotropic response prior to wilting. Nodule dry weights were not influenced by three cycles of water stress, but nodule water content was significantly decreased within a stress cycle. Within conditions of the experiments, rehydration of stressed nodules and restoration of acetylene reduction activity to control plant values was achieved following all three stress cycles. However, significant decreases in total plant N and in leaf, stolon and total plant dry matter were observed for both species by the third stress cycle. Dry matter and fixed N2 yields of stoloniferous forage legumes depend on continued initiation and development of vegetative meristems. The results of these experiments indicate that minor, short‐term water.stresses, if repeated, can result in significant decreases in productivity. This emphasizes the importance of continued availability of adequate soil moisture for these crops.
Transfer of Salt Tolerance from Elytrigia pontica (Podp.) Holub to Wheat by the Addition of an Incomplete Elytrigia Genome1
Authors: Dvořák Jan , Ross Kathleen , Mendlinger Samuel
Published: July 2010

Elytrigia pontica, (Podp.) Holub, 2n = 10x=70, was previously shown to be highly salt‐tolerant. In an attempt to incorporate this salt tolerance into wheat (Triticum aestivum L., 2n=6x=42), E. pontica was hybridized with three wheat accessions that showed relatively good salt tolerance. A large number of hybrid derivatives were produced. Most had aneu‐ or eudecaploid chromosome numbers. A few had aneuploid or euoctoploid or aneuhexaploid or euhexaploid chromosome numbers. The salt tolerance of E. pontica was expressed in derivatives at both the octoploid and decaploid levels. In an attempt to select salt‐tolerant derivatives with a low number of Elytrigia chromosomes, an hypooctoploid family was selected that had salt tolerance superior to the wheat parent. These salt‐tolerant plants had five complete chromosomes and a telosome from E. pontica in addition to the complete wheat chromosome complement.
Penetration of Radiation into Cotton Crop Canopies1
Authors: Marani A. , Ephrath J.
Published: July 2010

The penetration of radiation into cotton (Gossypium hirsutum L., ‘Acala SJ‐2’) canopies was investigated in two field experiments in Negba (1980, irrigated by sprinklers), and in Nahal‐Oz (1981, three irrigation treatments by a drip system). Photosynthetically active radiation (PAR) below the canopy was measured by a sensor moving on a 2 at track across the rows and integrated for periods of 30 min. The PAR was also measured above the canopy, and the percent of penetration was calculated. Plant height and leaf area index (LAI) were measured together with the radiation measurements. A high correlation was found between plant height and LAI, and both were highly correlated with radiation penetration. Plant height was found to be more useful than LAI as a predictor of radiation penetration, because its measurement in the field is more convenient. During periods of moisture stress, radiation penetration was usually lower than predicted by plant height. An examination of our data by using a model revealed that plant width was an important factor determining radiation penetration. The model accurately predicted radiation penetration into the canopy, provided that reliable estimates of essential plant parameters (e.g., plant height and width, LAI, and leaf angle distribution) had been input. Increased growth in height was usually associated with high rates of irrigation, whereas plant width was not. Plant width increased abruptly as soon as the first bolls began to develop, and this was followed by a rapid decrease in radiation penetration.
A Second Dominant Gene for Resistance to Peanut Mottle Virus in Soybeans1
Authors: Buss G. R. , Roane C. W. , Tolin S. A. , Vinardi T. A.
Published: July 2010

The soybean [Glycine max (L.) Merr.] cultivars ‘Arksoy ’. ‘Dorman ’, ‘York ’, ‘Shore ’, and ‘CNS ’ each contain a single dominant gene for resistance to peanut mottle virus (PMV). Crosses were made among these cultivars and F3 progenies of individual F2 plants were inoculated with PMV. The degree and type of segregation that occurred was used to determine the allelic relationship among the genes in these cultivars. This information is valuable to soybean breeders wishing to incorproate PMV resistance into breeding lines. Segregation was not observed in crosses among Arksoy, Dorman, York and Shore. It was concluded that they contain the previously reported Rpv1 gene for PMV resistance. Crosses of CNS with Dorman, Shore, and York segregated for PMV reaction. The data provided a good fit to the ratio expected from two dominant genes segregating independently. Assignment of a symbol for the CNS gene is being postponed until its allelic relationship with rpv2 in ‘Peking’ is determined. No evidence for linkage was found between the two dominant genes for PMV resistance or between them and the pubescence color gene, T‐t.
Genetic Variation for Nitrogen Assimilation and Translocation in Wheat. I. Dry Matter and Nitrogen Accumulation1
Authors: Cox Michael C. , Qualset Calvin O. , Rains D. William
Published: July 2010

This study was conducted to provide basic information on the accumulation of dry matter and N in spring wheat (Triticum aestivum L.) and to develop data necessary for an understanding of the physiological and genetic relationships between N movement and grain yield and protein concentration. ‘Anza’ and ‘Cajeme 71’ and 96 random F4 and F5 lines derived from the hybrid of these two cultivars were studied in field experiments at high and low N fertility regimes. Anza, the high yielding, low grain protein parent, continued to accumulate vegetative dry matter after anthesis, suggesting utilization of postanthesis photosynthates in grain filling. Anza also assimilated more N during the reproductive stage than Cajeme 71, the lower yielding, high protein parent.A considerable loss of vegetative dry matter between anthesis and maturity was observed in Cajeme 71 suggesting a greater reliance on photosynthates formed prior to anthesis for grain filling in this cultivar than in Anza. Significant but low negative correlations between yield and grain protein concentration for 96 F5 lines indicated that simultaneous increases in grain yield and protein concentration could be achieved by selection. Grain yield was positively and grain protein concentration was negatively correlated with time of maturity. However, lines combining both high grain yield and high grain protein concentration (e.g., 8.4 Mg ha‐1, 14.8% protein) were identified over the range of maturity of the majority of lines. Genotypic variation among the F5 lines was significant for all measured traits except one. In that exception total N yield at anthesis in the low N experiment did not show significant genotypic variation in the F5 lines. The genotype ✕ environment interaction variance components were, on the whole, of much less importance than the genotypic components in this small sample of environments.
Hardening Behavior, Winter Survival, and Forage Productivity of Festuca Species and Cultivars in Subarctic Alaska1
Authors: Klebesadel L. J.
Published: July 2010

Marginal to inadequate winterhardiness is a continuing problem in grasses used for forage production and turf purposes in subarctic, southcentral Alaska. Cultlvars or strains from various latitudinal sources within five Festuca species or subspecies were compared in field plots in Knik silt loam soil (coarse‐silty over sandy or sandy‐skeletal, mixed, nonacid Typic Cryorthent) over 18 experiment‐years for relative winterhardiness and forage production. Also three red fescues (F. rubra L.) of diverse latitudinal adaptation and differing widely in winterhardiness here (cvs. Arctared, Duraturf, Illahee) were compared for changes dry matter concentration in crown tissues during winterhardening, food reserves stored by onset of winter, and winter survival of plants left in the field. All broad‐leaved fescues evaluated; including meadow fescue (F. elatior L.) strains ‘Bottnia II’, ‘Tammisto’, ‘An‐2356’, and commercial, and tall fescue (F. arundi. nacea Schreb.) cv. Alta; winterkilled completely during the first or second winter of each test. Fine‐leaved fescues generally deficient in winterhardiness included ‘Highlight’ and commercial chewings fescue (F. rubra var. commutata Gaud.), ‘Durar’ hard fescue [F. ovina var. duriuscula (L.) Koch], and red fescue cultivars from the conterminous 48 states (‘Ranier’, ‘Pennlawn’, Illahee) and from Canada (‘Boreal’, ‘Olds’). Duraturf, selected in Canada from germplasm of Scandinavian origin, was the most winterhardly of introduced cultivars, but it was not as hardy or productive of forage as the extremely winterhardy, subarctic adapted Arctared, developed in Alaska. Hardiness ranking of red fescue cultivars was Arctared > Duraturf > Boreal ≥ Olds > Ranier = Pennlawn > lllahe. Arctared, selected for turf characteristics, produced as much forage as ‘Polar’ bromegrass (predominantly Bromus inermis Leyss ✕ B. pumpellianus Scribn.), an Alaskan cultivar selected for forage productivity. Superior winterhardines of Arctared was associated with northernmost adaptation, highest percent dry matter in crowns, highest levels of stored reserves, and slowest expression of reserves as etiolated growth. Poorest winter survival occurred with southernmost‐adapted Illahee which was lowest in percent dry matter in crowns and stored lowest level of food reserves. Duraturf, of intermediate‐latitudinal adaptation, was intermediate in crown moisture, reserve storage, and winter survival.
Respiration Efficiency and Heterosis in Sugarbeet1
Authors: Doney Devon L. , Theurer J. Clair , Wyse Roger E.
Published: July 2010

with which carbohydrate energy is transferred to ATP would explain heterosis. Mitochondrial respiration (ADP:O ratio) and storage respiration rate (CO2 evolution) are generally considered to be measuring the same oxidative phosphorylation process, even though other reactions may also be involved. A respiration efficient genotype would, therefore, have a high ADP:O ratio and a low CO2 evolution rate per unit of growth. Mitochondrial respiration efficiency (ADP:O ratio) was measured in a set eight sugarbeet (Beta vulgaris L.) hybrids and their respective parents at four different stages of growth. Storage respiration (CO2, evolution) of sugarbeets stored 30 days at 5 ° was measured on an eight parent, diallel cross and a two‐by‐six males ✕ females cross. All hybrids exhibited significant heterosis for root and total sucrose yield. The ADP:O ratios of the hybrids were higher (more efficient) than those of the inbred parents at each stage of growth. The ability of both inbreds and hybrids to transfer carbohydrate energy to ATP (ADP:O ratio) changed significantly with growth demand. The highest ADP:O ratios were obtained when the plants were growing most rapidly (2.07 and 2.26 for inbreds and hybrids, respectively), and the lowest during storage at 5 °C (1.54 and 1.68 for inbreds and hybrids, respectively). Hybrids had significantly lower storage respiration rates (0.456 μmol CO2 kg−1 s−1) than the inbred parents (0.614 μmol CO2 kg−1 s−1). The two males (L33 and L53) in the males ✕ females cross had similar root and sucrose yields, and similar storage respiration rates. In hybrid combination, the L53 hybrids produced significantly larger root and sucrose yields, and a faster cell division rate and a lower storage respiration rate than the L33 hybrids. These data indicate that a major factor contributing to root and sucrose yield heterosis in sugarbeet is the ability of the hybrids to transfer more of the carbohydrate energy into ATP for growth, maintenance, and membrane structure, compared with the inbred parent.