bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Low Temperatures and Genotypes on Pollen Development in Wheat1
Authors: Qian C. M. , Xu Aili , Liang George H.
Published: July 2010

To determine the genetic variability for pollen maturation time among wheat (Triticum aestivura L.) cultivars and to provide information on development of early‐maturing wheats, the effects of low temperatures and genotypes on duration of pollen maturation were evaluated by using two day/night temperature regimes (15°/10°C and 11°/6°C) and 10 wheat cultivars (Newton, Trison, Triumph 64, Skala, Jari F66, Anhui 11, Yangmai 1, Ning 7712, Zhjing 908, and Liuhehongtouzi) representing modern and classical cultivars that differ in physiological maturity, response to vernalization, photoperiod, and other agronomic traits. The two day/night thermoperiods were those low temperatures that could occur in spring during pollen formation for wheats of different maturities. Duration of pollen maturity was determined as the period from the quartet stage to anthesis from those plants grown in growth chambers. At 15°/10°C, duration of pollen maturation for the 10 cultivars was partitioned into five groups; at 11 °/6°C four groups were noted. In general, Newton and Skala had the longest, and Liuhehongtouzi and Trison the shortest, pollen maturation time. For the 11°/6°C regime, duration of pollen maturation was prolonged for all cultivars, with Trison being the least and Yangmai 1 the most affected. Likewise, the percentage of spikelets setting seeds was reduced for all cultivars under the 11 °/6°C temperature regime. In order to develop early‐maturing cultivars adapted to areas where low temperatures could occur during pollen‐formation period, insensitivity to temperature changes and a high percentage of seed set should be present in source material. Trison, Triumph 64, Liuhehungtouzi, and Zhejing 908 possess those desirable attributes.
Inheritance and Backcross Breeding of the Hypersensitive Reaction to Bean Yellow Mosaic Virus in Red Clover1
Authors: Taylor N. L. , Ghabrial S. A. , Diachun S. , Cornelius P. L.
Published: July 2010

Bean yellow mosaic virus (BYMV) is an important pathogen of red clover (Trifolium pratense L.). A hypersensitive reaction to the most prevalent strain of BYMV in Kentucky (designated 204‐1) conveys resistance. The objectives of the present study were to backcross the genes for the hypersensitive reaction into 10 clones of ‘Kenstar’ to widen the BYMV resistance of this cultivar and to further investigate the inheritance of resistance. Populations of Fl’s and five backcrosses to each of the 10 parental clones of Kenstar were produced using the clones as recurrent parents and a hypersensitive reacting clone as the nonrecurrent parent. Four Kenstar parental clones were found to possess the hypersensitive reaction, and two had a different type of resistance. Inheritance of the hypersensitive reaction to BYMV strain 204‐1 was similar to that reported earlier. Incorporation of the hypersensitive reaction to strain 204‐1 into the Kenstar clones did not increase virus resistance under spaced‐plant field conditions as compared to Kenstar polycross progenies. Lack of infection in broadcast plots prevented a complete assessment of the potential effect of the hypersensitive reaction. A new strain of BYMV was discovered and designated the red clover or ‘RC’ strain. This strain is similar to previously described isolates of BYMV from soybean, and it was hypothesized that the RC strain may have occurred as a result of the increase in soybean acreage in Kentucky. Phenotypic recurrent selection under spaced‐plant conditions where opportunity exists for infection by many different strains of BYMV and other viruses is suggested as aneffective breeding procedure.
Diploid Perennial Intergeneric Hybrids in the Tribe Triticeae. I. Agropyron cristatum ✕ Pseudoroegneria libanotica and Critesion violaceum ✕ Psathyrostachys juncea1
Authors: Wang Richard R‐C.
Published: July 2010

Twelve Agropyron cristatum (L.) Gaertner (2n=14; PP) ✕ Pseudoroegneria libanotica (Hack.) D. R. Dewey (2n=14; SS) brids and nine Critesion violaceum (Boiss. & Hohen.) A. Löve (2n=14; HVHV) ✕ Psathyrostachys juncea (Fisch.) Nevski (2n=14; NN) hybrids were produced to synthesize new genome combinations for production of amphiploids. These hybrids were obtained by controlled pollination and embryo culture on orchid agar medium. Spikes of these two diploid intergeneric hybrids were intermediate to those of their respective parents. The A. cristatum ✕ P. libanotica hybrids (2n=14; PS) averaged 7.71I, 2.77II, 0.22III, 0.01IV, and 0.01V per cell at metaphase I, 3.06 laggards per cell at anaphase I, and 3.35 micronuclei per quartet. Chromosome pairings were mainly allosyndetic between the Pgenome (large) and the S‐genome (small) chromosomes. Hybrid plants of C. violaceum ✕ P. juncea (2n=14; HVN) averaged 12.18I, 0.79II, and 0.01III per cell at metaphase I, 3.12 laggards per cell at anaphase I, and 1.30 micronuclei per quartet. Neither hybrid combination produced stainable pollen grains. Meiotic pairing in these hybridsuggests that the relationship between the P and S genomes is closer than that between the HV; and N genomes.
Effect of Early Season Square Removal on Three Leaf Types of Cotton1
Authors: Kennedy C. W. , Smith W. C. , Jones J. E.
Published: July 2010

In certain environments, reduced leaf‐open canopy cottons (Gossypium hirsutum L.) allow more light penetration and air circulation within their canopies than do normal leaf types. However, too much reduction in canopy can reduce overall productivity and economic yield. Removal of floral buds (squares) early in the season has been shown to result in larger plant size. Square removal was carried out in the field (fine‐silty, mixed, thermic, Aquic Fragiudalf soil type) on normal, okra, and super okra leaf type near‐isogenic lines of a ‘Stoneville 213’ background cotton for 3 and 6 weeks to determine i) if improved yield could be obtained in one or both open canopy types by enlarging the canopy and ii) if delaying fruit set produced differential responses in these leaf types. Results would form a basis for development of a boll weevil (Anthonomus grandis Boh.) trap crop system using exogenous chemicals to effect square abscission. Removal of squares increased plant height, leaf area index (LAI) and number of sympodial branches. The super okra leaf type produced the greatest responses to square removal. Fruit set was more rapid and occurred during a shorter interval for all leaf types undergoing square removal for 3 weeks, but the greatest response was obtained from super okra. Comprehensive analysis in 1983 indicated the rapid fruit set was due primarily to more sympodia fruiting simultaneously. The 3‐week treatment was more consistent in this response than the 6‐week treatment because of the generally shorter horizontal and vertical flowering intervals. Economic yield of normal and okra leaf types was generally not improved by square removal, whereas the super okra leaf type in the 3‐week square removal treatment produced an average 23.5% greater lint yield than its control. Differences in lint percentage were significant between treatments in 1981 with significant leaf type by treatment interactions in 1983. The data indicate that the super okra leaf type had the most consistent responses to 3 weeks of manual square removal. These results imply that this leaf type would produce the best response to exogenous chemical abscission of squares and the greatest chance of recovery from early season insect pressure.
Production of Freeze Inhibitor Polysaccharides of Rye and Barley in Tissue Culture1
Authors: Olien C. R. , Smith M. N. , Kindel Paul K.
Published: July 2010

Tissue cultures of Secale cereale L., (‘Rosen’ rye) and Hordeum vulgare (‘Hudson’ barley) were developed in order to produce larger quantities of freeze‐inhibitor polysaccharidesle ss expensively than can presently be done from cereal crown tissue. Culture techniques were perfected so that viable aseptic callus was obtained from rye and barley seed embryo with greater than 95% success. The callus was grown on a solid medium for approximately 4 weeks at 23°Ca nd then transferred to liquid shake culture, first at 23°C and then at 0°C. The freeze‐inhibitor ratings of polysaccharides produced by rye and barley in tissue culture were similar to those of polysaccharides extracted from hardened crown tissues of the same cultivars. Arabinose and xylose constituted greater than 75% of the unpurified freezeinhibitor polysaccharidesp roducedin culture.
Normal vs. Okra Leaf Yield Interactions in Cotton. I. Performance of Near‐Isogenic Lines from Bulk Populations1
Authors: Meredith William R. , Welles Randy
Published: July 2010

Okrale af (L2°,L2°) cottons, Gossypium hirsutum L ., have several advantages over normal leaf cottons, but are rarely used commercially because they usually carry approximately a 5% ield disadvantage. Okrale leaf cottons usually have been developed by the back cross method, which presumably places Okra leaf in a physiological background better suited to the normal leaf phenotype. This study was designed to determine if the 5% yield differential could be reduced or eliminated by the use of a different breeding method. ‘Stoneville 7A’ Okra leaf (nectariless) was crossed with ‘Carolina Queen’ (smoothleaf) and ‘Deltapine 5540‘ to produce CQ and DPL populations. From each cross, 50 heterozygous (L2°,l2) F7 plants were selected and near‐isolines of Okra and normal were developed. In 1981, the normal leaf strains average 1068 kg ha−1 lint and the Okra leaf strains average 1015 15kg ha−1 lint, a significant difference. Strain ✕ leaf type interactions were significant for both populations. In 1982, we grew the two highest yielding strains, the five Okra leaf strains that outyielded their normal leaf near‐isolines, and the five normal leaf strains that outyielded their Okra leaf near‐isolines in 1981. Our selection objectives were achieved with the DPL but not with the CQ population in 1982. Okra leaf selections in DPL background yielded 7% more lint than their normal leaf near‐isolines, whereas ‘Stoneville 213’ normal leaf yielded 10% more lint than its backcross‐derived(BC3) Okra leaf isoline. The 1982 DPL and CQ yield patterns were verified with four selection planted at two dates in 1983. Soil type in 1981 and 1982 was a Dubbs silt loam(finesilty, thermic Typic Hapludalfs), and in 1983 was a Dundee silty clay(fine‐silty, mixed, thermic Aeric Ochraqualfs). The results from the three experiments imply that certain populations have the genetic potential of producing Okra leaf cottons with higher yielding ability than that of normal leaf ones.
Reproductive Stage Water Stress and Sterility. I. Effect of Stress during Meiosis1
Authors: Namuco Ofelia S. , O'Toole John C.
Published: July 2010

Increased spikelets sterility is the primary component of yield reduction in rice (Oryzas ativa L.) and other small grains subjected to water stress during reproductive growth stages. The causes of water stress induced spikelet sterility are not clear although the meiotic stage of pollen mother cells is often reported to exhibit yield‐decreasing sensitivity. We exposed rice plants, in which pollen mother cells were actively undergoing meiosis, to the following series of water stress levels as measured by flag leaf water potential: −1.6, −1.9, −2.2, −2.5, −2.8, and −3.5 MPa for 18 to 24 h. Panicles were fixed in Farmer's solution and later examined microscopically for abnormal chromosomal behavior. The occurrence of chromosomal abnormalities such as univalents, lagging of chromosomes, noncongression in metaphase and micronuclei was evaluated in 3822 pollen mother cells in response to increasing water stress levels. Spikelet fertility of comparable panicles grown to maturity decreased linearly from 80% at −1.1 MPa (control) to 50% at −3.5 MPa flag leaf water potential. Chromosomal abnormalities appeared at relatively moderate stress levels (−1.1 to −1.9 MPa) and in general peaked at the −2.2 MPa stress treatment.

In general, water stress increased chromosomal abnormalities, except at severe stress levels (−3.5 MPa) where the meiotic process was partially arrested. Each meiotic stage had particular irregularities associated with water stress. Prophase I and II, univalents; Metaphase I, noncongression of bivalents and lagging chromosomes; Anaphase I and II, lagging chromosomes; Telophase II, micronuclei formation. Blasted or immature, small, colorless spikelets also were observed and their occurrence increased with stress level. Blasted spikelets, not included in the calculation of percent sterility, accounted for 10 to 20% of the total spikelets per panicle at moderate stress levels. The cause of this malady is unknown.
Yield of an Alfalfa Germplasm Selected for Acid Soil Tolerance when Grown in Soils with Modified Subsoils1
Authors: Bouton J. H. , Sumner M. E. , Hammel J. E. , Shahandeh H.
Published: July 2010

Liming and fertilization are required to enhance alfalfa (Medicago sativa L.) yield in acid soils, but rarely do these practices overcome the problem of subsoil acidity. Genetic selection of alfalfa for acid soil tolerance (especially Al tolerance) is felt to be a good method of increasing alfalfa's rooting into acid subsoils resulting in better water and nutrient extraction and, finally, better yield and persistence. In this study, the yield of an alfalfa germplasm selected for acid soil tolerance was compared with that of a germplasm concurrently selected in a limed, fertile soil and the cultivar Apollo. These were tested in the field using the following subsoil treatments: i) an unlimed, unmixed control subsoil, ii) sub‐soil mixed to 1 m, iii) subsoil mixed and limed to 1 m, and iv) gypsum incorporated into the surface to leach into the subsoil. The topsoils were all conventionally limed and fertilized. Overall, deep liming and gypsum additions to the topsoil increased alfalfa yield over the control. The acid soil selected germplasm gave better yield than the limed soil selected germplasm when data were averaged for all subsoil treatments. The acid selected germplasm was significantly higher yielding than the limed selected germplasm in the mixed and limed subsoil treatment and in the mixed subsoil treatment. The mixed subsoil treatment was also found to be the most acid, Al toxic treatment. However, the acid tolerant germplasm was no different in yield from Apollo in the mixed subsoil treatment, and in the control treatment, the acid germplasm gave poorer yield than the limed soil selected germplasm. These data demonstrate acid subsoil problems are severe in reducing yield, but can be overcome with deep liming or gypsum amelioration or, possibly, with more tolerant cultivars.
Tannin Concentration and Quality Changes in Sorghum as Affected by Maturity and Sorghum Type1
Authors: Montgomery C. R. , Nelson B. D. , Joost Richard , Mason L. F.
Published: July 2010

Speculation has arisen over the feeding value of silages produced from bird‐resistant (high tannin) sorghums [Sorghum bicolor (L.) Moench]. The objectives of this study were to determine the effects of maturity on tannin content in the grain and whole plants of bird‐resistant and bird‐susceptible grain and forage sorghums, and to determine the relationship between tannin content and other quality attributes such as crude protein (CP), acid‐detergent fiber (ADF), neutral‐detergent fiber (NDF), and in vitro dry matter digestibility (IVDMD). Four hybrids of each sorghum type were grown in the field, and entire plants were harvested at boot and hard‐dough stages of maturity. Grain was harvested at milk, hard‐dough, and mature stages. Significant differences (P<0.05) were measured in grain tannin level among the three sorghum types. Tannin levels were highest in grain of bird‐resistant hybrids, with forage‐type sorghums being intermediate, and bird‐susceptible entries lowest. Significant reductions (P<0.05) in tannin level occurred in grain of bird‐resistant hybrids as the grain matured, but increased significantly with maturity in the whole plant. Changes in whole‐plant tannin levels over the season were inconsistent in both bird‐susceptible and foragetype sorghums. Crude protein was significantly higher (P<0.05) in grain at the milk stage than at hard‐dough for all hybrids. Significant reductions in CP were observed in all hybrids as the plant matured from boot to hard‐dough. Fibrous constituents, ADF and NDF, decreased and IVDMD increased significantly (P<0.05) as plants matured. Whole‐plant tannin level was negatively correlated with CP and IVDMD, and positively related to fibrous constituents. Results of this study indicate that feeding value of the silage of bird‐resistant sorghum hybrids would be reduced by high concentration of tannin at the hard‐dough stage of maturity.
Relationship between Seed‐Filling Period and Yield among Soybean Breeding Lines1
Authors: Smith James R. , Nelson Randall L.
Published: July 2010

It has been suggested that seed‐filling period (SFP) and seed yield are positively related in soybeans [Glycine max (L.) Merr.]. The purpose of this study was to evaluate the relationship between seed yield and SFP among F5 lines. Estimates of SFP were also made in the F4 and F5 generations, and a reproductive period estimate was also made in the F2. All genotypes came from the cross ‘Williams’ ✕ ‘Kanrich’ and were selected for differences in SFP. Replicated yield and SFP data were taken in 1982 and 1983; soil types for those years were a Drummer silty clay loam (Typic Haplaquall) and a Catlin silt loam (Typic Argiudoll), respectively. Data taken in the F2 and F4 were on single plants and those taken in the F5 were on unreplicated rows. The relationship between reproductive period in the F2 and combined 1982 and 1983 yield data was nonexistent (r = 0.00), while that between SFP in the F4 and F5 and the combined 1982 and 1983 yield data was significantly positive. Within 1982 and 1983, in three maturity groups, a positive relationship between yield and four estimates of SFP was found in most cases, the exception being Maturity Group II lines in 1983. In addition, the three highest yielding lines, over years and maturity groups, all came from F4 plants selected as having a long SFP in the F4 generation. These data suggest a positive relationship between SFP and yield and that progress for yield may be made by selecting for SFP.
Anatomical Characteristics of Three Inbred Lines and Two Maize Synthetics Recurrently selected for High and Low Stalk Crushing Strength1
Authors: Berzonsky W. A. , Hawk J. A. , Pizzolato T. D.
Published: July 2010

Despite progress in improving maize (Zea mays L.) stalk strength, stalk lodging is still a problem. Identification of traits associated with stalk strength will aid breeders in selecting for lodging resistance and improving maize stalk quality. Anatomical features of stalks of two Missouri synthetic populations (MoSQA and MoSQB) were examined to identify those traits most closely associated with stalk strength. Cycles (C6 low = sixth cycle of selection for low crushing strength, C6 high = sixth cycle of selection for high crushing strength, and C10 high = 10th cycle of selection for high crushing strength) and the original population (C0) of each synthetic were grown 37 064 and 74 129 plants ha‐1 at Newark and Georgetown, DE. Stalks of MoSQA had significantly more vascular bundles (C6 low = 338.7, C0 = 375.9, C6 high = 362.7, and C10 high = 368.2) than stalks of MoSQB (C6 low = 281.2, C0 = 304.9, C6 high = 304.4, and C10 high = 317.9). Rind vascular bundles of MoSQA stalks were composed of bundle‐sheaths with significantly larger proportional areas (C6 low = 82.54%, C0 = 80.51%, C6 high = 84.05%, and C10 high = 84.34%) than the rind vascular bundle‐sheaths of MoSQB stalks (C6 low = 79.79%, C0 = 81.37%, C6 high = 80.81%, and C10 high = 80.79%). Stalks of MoSQB had a significantly larger proportion of hypodermal cell‐wall area (C6 low = 76.11%, C0 81.57%, C6 high = 82.33%, and C10 high = 87.42%) compared to stalks of MoSQA (C6 low = 64.32%, C0 = 75.29%, C6 high 72.04%, and C10 high = 75.10%). Anatomical differences between synthetics suggest that MoSQA and MoSQB maintain stalk strength through different struictural compositions. Hypodermal cell‐wall area and rind‐parenchyma interlumen thickness significantly increased with selection for high crushing strength for both synthetics. The increase in rind‐parenchyma interlnmen thickness with selection for high crushing strength is an important consequence of selection given the large area of the maize stalk rind composed of parenchyma cells. Examination of stalk cross‐sections of greenhouse‐grown‐strong, intermediate‐strong, and weak‐stalk inbred lines (DE811, Wf9, and L317, respectively) revealed anatomical rind component differences. Ear‐leaf midrib anatomy reflects rind differences and midribshow promise as a nondestructive selection screen for developing inbred lines and hybrids with stronger stalks to reduce lodging.
Grain Sorghum Root Responses to Water and Temperature during Reproductive Development1
Authors: Rice J. R. , Eastin J. D.
Published: July 2010

Yield reductions in grain sorghum [Sorghum bicolor (L.) Moench] are often traceable to suboptimal water or temperature conditions during reproductive development prior to anthesis. Root growth is rapid during this period of panicle development and could represent a competing sink that may influence seed number potential and grain yield. Root respiration in two grain sorghum hybrids (one stresstolerant and one normal) was monitored in hydroponic culture from panicle initiation through the hard‐dough stage of grain development. Changes in total root respiration of the hybrids were approximately proportional to the respective changes in daily root dry matter accumulation. Rates of root respiration of both hybrids remained relatively constant from panicle initiation to boot stages, increased an average of 32% at the bloom stage, then declined to a minimum at the soft‐dough stage. Root respiration of the normal hybrid was highest at the soft‐dough stage and lowest at the hard‐dough stage, while respiration in the stress‐tolerant hybrid, whichas the greater stalk strength under late‐season drought, was highest at the harddough stage. Higher metabolic activity of the stress‐tolerant hybrid may be associated with its greater stalk strength under late‐season drought. Response to temperature of root respiration for the hybrids was evaluated under control and water stress (‐0.5 and ‐0.75 MPa) conditions during the boot stage. Under control conditions, root respiration of both hybrids increased about 40% with temperature increases from 25 to 30°C, however, no significant increases were detected with further temperature increases to 35 and 40°C.
Net Photosynthesis, Carbon Dioxide Compensation Point, Dark Resperiration, and Ribulose‐1,5‐bisphosphate Carboxylase Activity in Wheat1
Authors: Massachi A. , Giardi M. T. , Tricoli D. , Di Marco G.
Published: July 2010

Net photosynthesis, CO2 compensation point, and ribulose‐1,5‐bisphosphate carboxylase (RuBPCase) activity were measured in the flag leaves of one hard wheat (Triticum durum Desf.) and one soft wheat (Triticum aestivum L.) from anthesis to an advanced state of senescence. Net photosynthesis was not significantly different in the two cultivars. A linear relation was found between net photosynthesis and RuBPCase attributable to the relatively low enzymatic activity. The slope of the line was found to be similar in the two cultivars, indicating similar carboxylation efficiencies. The CO2 compensation points at 210 mL O2 L−1 air did not differ in the two cultivars while a slight difference was observed between the points measured at 22 mL O2 L−1 air only in mature leaves. The extrapolation of the CO2 compensation points to zero O2 concentration gave positive values indicating that mitochondrial respiration was not completely inhibited by light. Approximate values of this respiration were calculated for the two cultivars, based on a recent model of leaf photosynthesis. Dark respiration, measured as O2 uptake by leaf slices, showed little change through maturation and senescence of the leaves. In mature leaves, this respiration was significantly higher in the soft wheat cultivar, while in senescent leaves, this difference disappeared.
Photosynthesis, Chlorophyll, and Transpiration Responses in Aluminum Stressed Wheat and Sorghum1
Authors: Ohki K.
Published: July 2010

Aluminum is a major deterrent to crop production in acid soils. The specific effects of Al toxicity on photosynthesis, chlorophyll, and transpiration in Al stressed plants have received little attention. The objective of this study was to determine the influence of Al stress on photosynthesis, chlorophyll, and transpiration in wheat (Triticum aestivum L.) and sorghum [Sorghum bicolor (L.) Moench] under greenhouse conditions. Plants were grown in modified Steinberg solution containing 10 Al rates (0, 1.9, 3.7, 9.3, 18.5, 37.1, 74.1, 148, 222, and 297 μmol L−1) in the greenhouse for 28 days after transplanting. The initial pHs were 4.0 and 3.3 for wheat and sorghum, respectively. Photosynthesis and transpiration measurements were made on intact recently matured leaves. Chlorophyll concentrations were determined on the same tissue. In wheat, Al toxicity decreased photosynthesis, chlorophyll concentration, and transpiration. The critical Al toxicity levels in wheat blade associated with decreases in photosynthesis, chlorophyll concentration, and transpiration were 0.15, 0.13, and 0.14 mmol kg−1, respectively. In sorghum, photosynthesis and chlorophyll concentration were also decreased by Al stress, but transpiration was increased. The critical Al toxicity levels for these parameters in sorghum could not be determined due to low levels of Al concentration in the blade. Transpiration in nonstressed sorghum was approximately one‐third the rate of wheat. Thus, the growth reduction of wheat and sorghum under Al stress may be due in part to decreased photosynthesis.
Soybean Response to Postemergent Wheel Traffic1
Authors: Wilkens P. W. , Whigham D. K.
Published: July 2010

Considerable researchas demonstrated the yield advantage of soybean [Glycine max (L.) Merrill] grown in narrow‐row spacings, but little information is available concerning postemergent wheel‐traffic effects where row spacing is too narrow to prevent mechanical traffic for conventional intrarow cultivation or spray application. The objective of this study was to determine yield and plant characteristics of soybean subjected to postemergent wheel traffic. Three indeterminate soybean cuitivars, Corsoy, Northrup King 1492, and Asgrow 3127, were planted in a 35‐cm row spacing in 1980 and 1981 on Aquic Hapludoils and Typic Haplaquolls, respectively. Treatments were applied by driving a tractor through the plots at one of six growth stages from VE (emergence) to R4 (full pod). A skip‐row treatment, where wheel track rows were not planted, was also included. Individual rows were harvested within each plot and grouped together as wheel‐track rows (rows driven over), border rows (rows adjacent to the wheel‐track rows), and nonborder rows (rows not bordering wheel track rows). The whole‐plot seed yields of Asgrow 3127 and Northrup King 1492 were not reduced by wheel traffic up to full flowering; whereas, yield of Corsoy was reduced (9‐19%) wheel traffic at vegetative stage V5 and reproductive stages of full flower and full pod. Yield losses ranged from 26% for wheel traffic at emergence to 92% at the full‐pod stage. Yield in borderows increased from an average of 5% for wheel traffic at emergence to 20% at the full‐flower stage in a compensatory response to yield losses in wheel track rows. Seed weight was increased in border rows associated with treatment at the full‐pod stage, and in general, border row plants set pods lower on the stem and had more branches, nodes, and pods per plant. Although cultivars responded differently, the yield advantage to narrow‐row spacing was not seriously reduced by postemergent wheel traffic.
Expression of Tolerance of Na+, K+, Mg2+, Cl− and SO2−4 Ions and Sea Water in the Amphiploid of Triticum aestivum ✕ Elytrigia elongata1
Authors: Dvořák Jan , Ross Kathleen
Published: July 2010

While wheat (Triticum aestivum L.) is moderately tolerant of saline stress, related Elytrigia elongata (Host) Nevski (= Agropyron elongatum Host) is highly tolerant. To determine if salt tolerance of E. elongata can be transferred to wheat, the tolerance of an amphiploid T. aestivum ‘Chinese Spring’ ✕ E. elongata and Chinese Spring of NaCl, KCl, K2SO4, MgSO4, and marine salt was assessed. Seedlings of both genotypes were acclimated by progressively increasing the concentrations of salt in hydroponic tanks until 14.6 g/L NaCl; 18.5 g/L KC1; 18.3 g/L MgSO4; 6.5, 13.2, and 26.1 g/L K2SO4; and 18.0 and 36.0 g/L marine salt were reached. Plants were then maintained in the tanks for their entire life span and their survival, production of dry matter, and seed yield were determined. The amphiploid was more tolerant than Chinese Spring to every salt tested. It outyielded Chinese Spring in dry matter per plant, in seed yield, or in both at 14.6 g/L NaCl, 18.5 g/L KC1, 18.3 g/L MgCO4, 6.5 g/L K2SO4, and 18.0 g/L marine salt.
Genetic Variability for Desirable Agronomic Traits in Populations Containing Glycine soja Germplasm1
Authors: Carpenter Jodi A. , Fehr Walter R.
Published: July 2010

The wild soybean (Glycine soja Sieb. et Zucc.) may be a source of useful characters for improvement of the cultivated soybean [Glycine max (L.) Merr.] species. Successful introgression of genes from G. soja into G. max will require the development of populations with an adequate frequency of segregates that do not possess the undesirable agronomic characters of the wild species. The objective of this study was to determine the genetic variability for desirable agronomic traits of G. max in backcross populations containing different percentages of G. soja germplasm. No selection was conducted during backcrossing to allow the evaluation of segregation patterns that would not be influenced by genetic linkages or physiological associations between desirable and undesirable characteristics in G. soja. The populations were formed by crossing each of two G. soja accessions to a different G. max cultivar, ‘Amsoy 71’ or ‘Century’, and backcrossing to the G. max parent to obtain BC0 to BC5 populations. The F2 plants and their F3 progeny from each population were evaluated for agronomic score, vining, lodging, plant height, days to stage R7, seed weight, shattering, leaf abscission, and seed coat color. The percentage of segregates with an agronomic rating equal to the G. max parent averaged across the Amsoy 71 and Century populations was zero in BC0, and BC1, 2% in BC2, 22% in BC3, 51% in BC4, and 65% in BC5. The results indicated that, in the introgression of G. soja germplasm, at least two backcrosses are required to recover any segregates that are agronomically acceptable when at least 50 plants are backcrossed each generation. Three backcrosses may be preferred to obtain a relatively high frequency of segregates that may be useful in a cultivar development program.
Organogenesis of the Staminate and Pistillate Inflorescences of Pop and Dent Corns: Relationship to Leaf Stages1
Authors: Stevens Susan J. , Stevens E. J. , Lee K. W. , Flowerday A. D. , Gardner C. O.
Published: July 2010

Until recently, popcorn and dent corn (Zea mays L.) were considered analogous in their seasonal developmental patterns. Differences in the rates of seasonal floral development may be important in the relative susceptibility of the respective types of corn to stress. Although several researchers have considered that a relationship exists between the number of leaves emerged on a corn plant and inflorescence development, no intensive attempts to investigate floral development relative to leaf stage have been reported. This is an essential criterion if numeric staging systems are to be developed for use with regression techniques to model corn floral development relative to stress and consequent grain production. The objectives of this pilot study were to relate floral development to external leaf stage, and to compare the rate of floral development between a popcorn and its assumed analogue, a dent corn. Plants of two greenhouse‐grown corn cultivars, ‘Iopop 12’ and ‘B73 ✕ Mo17’, were sampled at intervals from emergence of the third leaf to that of the 13th leaf. The shoot apex and uppermost pistillate inflorescence were excised and examined fresh in a scanning electron microscope (SEM) or fixed and prepared for SEM examination using traditional techniques. Staminate and pistillate spikelet development in B73 ✕ Mo17 and in Iopop 12 followed a similar sequence; but, relative to leaf stages, Iopop 12 tended to lag one to two emerged‐leaf stages behind B73 ✕ Mo17. With respect to emerged‐leaf stages, B73 ✕ Mo17 and Iopop 12, respectively, developed as follows: tassel initiation at fourth vs. fifth, ear initiation at sixth vs. eighth, and pistillate silk formation at 11th vs. 13th. Staminate and pistillate spikelet organogenesis followed a similar sequence both within and between cultivars, with initiation of two bisexual florets and subsequent abortion of appropriate floral organs to form unisexual florets. One floret developed in each pistillate spikelet, whereas two developed in each taminate spikelet. Elongation of the apical dome to 0.4 mm was considered to be the most definitive indicator of tassel and ear initiation. The appearance of the ligule above the auricles of the previous leaf was considered the most definitive indicator of leaf‐blade emergence.
Resistance of Wild Barley Accessions from Israel to Leaf Rust Collected in the USA and Israel1
Authors: Manisterski J. , Treeful Linda , Tomerlin J. R. , Anikster Y. , Moseman J. G. , Wahl I. , Wilcoxson R. D.
Published: July 2010

Wild barley (Hordeum spontaneum C. Koch) is being used to develop improved barley (H. vulgare L.) cultivars. It is a source of genes for resistance against leaf rust (Puccinia hordei Otth) but the evaluation of this source has been done at only a few locations, and to a narrow range of the virulence available. In this study, accessions of wild barley that had been exposed over a 10‐yr period to numerous isolates of leaf rust indigenous in Israel, were reevaluated for resistance in glasshouse and field trials in Israel and the USA to 11 isolates of leaf rust that varied greatly in virulence and origin. Reactions of seedlings confirmed that resistance to leaf rust is common in wild barley. Twelve accessions were resistant or contained plants that were resistant to all the pathogen isolates tested at each location. At St. Paul, MN, accession reactions in the glasshouse and the field were generally similar. At Bet Dagan, Israel, resistance was recognized in the field by low infection types to the rust as well as by slow rusting. Some lines were fully resistant in the USA, but they rusted slowly in Israel. All accessions from dry parts of Israel were susceptible to all isolates of the pathogen probably because they have never been infected with the pathogen. The accessions studied and the methods of study may be useful for indepth work on host‐parasite evolution, especially the incompatible relationships.
Leaching of Metabolites during Imbibition of Sweet Corn Seed of Different Endosperm Genotypes1
Authors: Wann E. V.
Published: July 2010

Sweet corn (Zea mays L.) hybrids with high‐sugar genotypes shrunken‐2 (sh2) and the triple recessive combination of genes amylose extender (ae), dull (du), and waxy (wx) have had limited acceptance for commercial production due to an inherent problem of low seed quality. The seed are lighter in weight and more shrunken than normal, or the sugary (su) genotype, and they frequently give erratic stands and low seedling vigor. This study was conducted to determine leaching of metabolites during imbibition of the high‐sugar seed and whether excessive leaching was associated with genotypes and their inherent low seed quality. Commercial seed of hybrids ‘Iochief’ (su), ‘Florida Staysweet’ (sh2), and ‘Pennfresh ADX’ (ae du wx) were chosen to represent three sweet corn genotypes in this study. Leaching of metabolites during imbibition was determined by measuring electrical conductivity of the leachates and the amount of soluble protein in the leachate at various time intervals after imbibition. Conductivity of leachates was higher for seed of the high‐sugar genotypes than for su. At 24‐ and 48‐h imbibition, leachate conductivity for ae du wx seed was higher than the other two genotypes. Leaching of soluble protein during imbibition was also higher for seed of the high‐sugar genotypes than from seed of su. There were no significant differences in the amounts of soluble protein initially present in seed of the various genotypes when expressed as milligrams per gram of seed. When expressed as milligrams per seed, however, the high‐sugar genotypes had much less soluble protein than su due to their low seed weight. Protein leaching during imbibition appeared to be related to broken pericarps and high membrane permeability in the seed of sh2 and ae du wx endosperm genotypes. These studies suggest that seed pericarps and membranes in the high‐sugar genotypes may be more susceptible to damage during harvest and drying than su and that special care may be required for producing high quality seed of the high‐sugar genotypes.
Stem Cutoff Enhances Selection for Improved Iron Efficiency of Soybean1
Authors: Piper T. E. , Fehr W. R. , Voss B. K.
Published: July 2010

Five cycles of recurrent selection for iron (Fe) efficiency resulted in a soybean [Glycine mar (L.) Merr.] population with a high percentage of segregates that showed little or no yellowing when grown on calcareous soil in the field. Further improvement for Fe efficiency in the population is not possible unless a method is available to enhance the expression of genetic variability. This study was conducted to evaluate stem cutoff as a method for enhancing the expression of genetic variability for Fe efficiency in a population with a high proportion of Fe‐efficient segregates. The parents of Cycles 0 through 5 and 100 S0‐derived lines from the Cycle 5 population of AP9 were grown on calcareous soil. At stage V3, when the second trifoliolate leaf was fully developed, the entries were scored for chlorosis (1 = no yellowing to 5 = severe yellowing); then the main stem was cut off above the unifoliolate node. The new leaves produced were evaluated for chlorosis 2 weeks after treatment. Stem cutoff significantly increased the chlorosis of the parents and S0‐derived lines by an average score of 1.4. The rate of genetic improvement from Cycle 0 to Cycle 5 was the same before and after treatment, with an average decrease in chlorosis score of −0.16 per cycle before treatment and −0.15 per cycle after treatment. Genetic variability among the 100 random lines was significantly increased by stem cutoff. The genotypic variance component estimate was 0.02 ± 0.01 before treatment and 0.10 ± 0.02 after treatment. The results indicated that stem cutoff is an effective method of increasing chlorosis in a population with a high level of Fe efficiency, permitting selection for further improvement of the character.
Response of Five Winter Wheat Cultivars to Growth Regulators and Increased Nitrogen1
Authors: Nafziger Emerson D. , Wax Loyd M. , Brown C. M.
Published: July 2010

Plant growth regulators (PGRs) are widely used in Europe for lodging control in winter wheat (Triticum aestivum L.) grown at high N rates. A 2‐yr experiment was conducted in Illinois to evaluate the effects of three PGRs on grain yield, plant height, and lodging in five cultivars of soft red winter wheat grown at normal and high N rates. Increasing the N rate from 84 to 168 kg ha−1 decreased average yield by 12%. Mefluidide {N‐[2,4‐Dimethyl‐5‐[[(trifluoromethyl) sulfonyl]amino]phenyl]acetamide} at 0.03 kg ha−1 applied at Feekes‐Large growth stage 5 decreased yield by 43%. But CCC 1(2‐chloroethyl) trimethylammonium chloride] at 3.37 kg ha−1 applied at growth stage 5 did not affect yields, and ethephon [(2‐Chloroethyl) phosphonic acid] applied at growth stage 9 had no effect on yield when applied at 0.28 kg ha−1, but decreased yield 6% when applied at 0.56 kg ha−1. A significant cultivar ✕ treatment interaction resulted from differential cultivar sensitivity to mefluidide injury and to yield reduction caused by ethephon. While most PGR treatments were quite effective in decreasing plant height and lodging, these favorable results must be weighed against occasional yield decreases, especially when used on certain cultivars and under less favorable conditions.
Effect of Pod Number on Dry Matter and Nitrogen Accumulation and Distribution in Soybean1
Authors: Schonbeck Mark W. , Hsu Francis C. , Carlsen Tina M.
Published: July 2010

Greenhouse and field studies were undertaken to document the effects of a decreased pod number on dry matter and N accumulation and distribution during grain filling in soybean [Glycine max (L.) Merr.]. Removal of about 40% of the pods significantly shifted dry matter partitioning in favor of vegetative tissues. Total dry matter and N accumulation were not affected, indicating that partial depodding did not cause feedback inhibition of photosynthesis. The crop compensated for the lower pod number with an increased 100‐ seed weight, so that final grain yield was depressed only 7 to 14% below controls.

Vegetative tissue N of control field‐grown plants decreased rapidly during grain filling, and the majority of this loss was attributed to redistribution of N to the growing seed. Partial depodding greatly decreased vegetative N loss, and stem N concentrations actually increased toward the end of grain filling. Apparently, current N2 fixation roughly equalled N demand by the seed in these plants so that little net redistribution occurred. The decreased pod load may also have made more photosynthate available to support greater late‐season N assimilation than occurred in the controls.
Relationships among Grain Quality Indicators in Oats1
Authors: Marshall H. G. , Kolb F. L.
Published: July 2010

Breeding efforts to improve whole grain quality of oats (Avena sativa L. and A. byzantina K. Koch) have been limited by difficulties in measuring the trait. In vitro chemical and biological tests have been used to predict grain digestibility, but laboratory facilities are required, and the procedures are time and labor intensive. Consequently, breeders primarily have used grain test weight as a crude measure of grain quality. Our objectives were to determine the relationships among indicators of grain quality, environmental effects, and practical utility of the measurement techniques. Sixteen oat cultivars were grown at two locations during each of 2 yrs on either Typic or Ultic Hapludalf soils. Traits measured were grain yield, test weight, groat fraction, acid detergent fiber (ADF), permanganate lignin, in vitro dry matter disappearance (IVDMD), groat protein, and whole grain protein. Cultivar means for IVDMD ranged from 600 to 758 g kg−1. There were consistent negative correlations and linear relationships between IVDMD and both ADF and lignin. The relationship between IVDMD and groat fraction was linear and r2 values ranged from 0.61 to 0.81, so groat fraction should be a useful indicator of the digestible energy of whole grain oats. Test weight and IVDMD were not correlated when test weights were near normal, but they were correlated when test weights were light. Test weight was not a reliable indicator of genetic variability for whole grain quality. Groat and whole grain protein concentrations are not associated with IVDMD. Whole grain protein concentration was consistently correlated with groat protein, but only 37 to 69% of the variation in whole grain protein was associated with variation in groat protein concentration. Among the indicators of digestible energy, the least amount of labor was required to determine groat fraction, and no special laboratory facilities were needed. The trait should be especially useful in breeding programs where in vitro determinations are not possible or practical.
Influence of Maturation Temperature and Stage of Kernel Development on Sprouting Tolerance of Wheat and Triticale1
Authors: Plett S. , Larter E. N.
Published: July 2010

This study was conducted to provide some basic information regarding the influence of (i) stage of kernel maturation and (ii) temperature during kernel maturation on sprouting tolerance of triticale (X Triticosecale Wittmack) and wheat (Triticum aestivum L.). Tolerances were compared using in vitro germination tests (17 and 25°C germination temperatures), and by rain simulation. Developing seed harvested from the 2nd to 7th week postanthesis, exhibited a significantly higher rate of loss of sprouting tolerance when germinated at 17°C relative to a 25°C germination temperature. Genotypic differences in tolerance levels, however, were more marked at the 25°C regime. Results from rain simulation closely paralleled those from the 2S°C in vitro germination tests, albeit tolerance scores of the four genotypes tested were approximately 25% lower. The influence of temperature on sprouting tolerance during seed maturation was clearly defined using the 25°C germination test, with the four genotypes under study retaining a highly consistent tolerance score ranking for each of three temperatures maintained during kernel development. From these results it was concluded that the 25°C in vitro germination test provided a suitable alternative for the rain‐simulator facility that may not always be available. The germination test also produced tolerance ratings that consistently differentiated among genotypes over a range of stages of kernel development as well as different temperatures during kernel maturation.
Effect of Water Stress during Seedfill on Impermeable Seed Expression in Soybean1
Authors: Hill H. J. , West S. H. , Hinson K.
Published: July 2010

The impermeable seed‐coat trait in soybean [Glycine max (L.) Merr.) is of interest to researchers because impermeable seeds retain viability better than permeable seeds. The objective of this study was to determine how water stress during seedfllling may influence impermeable seed expression. A 2‐yr experiment was conducted outdoors with potted plants of two soybean genotypes that carried the impermeable seed‐coat trait. Starting at the R6 growth stage, one‐half of the plants were water stressed by imposing successive wilting cycles that consisted of withholding water until all plants in the treatment were wilted and then immediately rewatering until the soil was saturated. The control plants were watered daily. At maturity, seeds from water‐stressed plants were 15 to 33% smaller by weight, 8 to 22% smaller by volume, had a lower percentage of ruptured seed coats, a higher percentage seed coat, and 6 to 37% more impermeable seed (after 72 h of soaking) than well‐watered control plants over both years. The higher impermeable seed percentage (after 72 h of soaking) in the water‐stressed treatment was significantly correlated (r = −0.92**, significant at the 0.01 probability level) with the incidence of ruptured seed coats when data were combined over genotypes and years. Scanning electron microscopy suggested that ruptured seed coats were caused by the cotyledons expanding against the seed coat. The incidence of ruptured seed coat was positively associated with seed weight (r = 0.73*, significant at the 0.05 probability level), seed volume (r = 0.83*), and seed width (r = 0.92**). These data indicate that high soil moisture availability during seedfill will reduce impermeable seed expression by disrupting seed‐coat integrity.