bluuebunny/crossref_metadata_2025 huggingface dataset:
Yield and Water Relations of Pearl Millet Genotypes under Irrigated and Nonirrigated Conditions1
Authors: Singh Piara , Kanemasu E. T. , Singh Phool
Published: July 2010

Drought resistance in pearl millet [(Pennisetum americanum (L.) Leeke] makes it BIR important food crop in arid and semiarid regions, but research is limited on drought resistance and physiological responses to water stress. To study the relationship of pearl millet yield to physiological characteristics, 10 pearl millet genotypes were grown under irrigated and nonirrigated conditions on a silt loam soil (fine‐silty, mixed mesic, Pachic Haplustoll). Leaf diffusion resistance of adaxial (LDRad) and abaxial (LDRab) surfaces, leaf water potential (ΨL, leaf osmotic potential (ΨrL, and stem osmotic potential (Ψrs) of genotypes were recorded in both treatments in the afternoon (1200 to 1700 h) when the crop was water‐stressed. Leaf diffusion resistance (LDR) for a leaf was calculated as LDR = (LDRad × LDRab/(LDRad + LDRab). LDRad, LDRab, LDRab, LDR, ΨL, ΨrL, and Ψrs observed for each genotype were averaged over the stress period and correlated with yields and yield ratios (nonirrigated yield/irrigated yield) of genotypes. Majority of genotypes studies did not differ significantly (P<0.05) in average afternoon LDRab, ΨL, ΨrL, and Ψrs, and water use (WU) in both the treatments except that genotypic differences were significant in average afternoon LDRad and LDR in the nonirrigated treatment. Grain yield was significantly correlated with LDRab in both irrigated (r = −0.90) and nonurigated (r = −0.72) treatments, suggesting that high LDRab of genotypes is associated with low grain yield. Grain yield ratio was significantly correlated with LDRab (r = 0.71) and LDR (r = 0.66) in the irrigated treatment and with ΨrL (r = 0.64) and Ψrs (r = 0.78) in the nonirrigated treatment. Average afternoon ΨL did not correlate with grain yield or grain yield ratio. It is concluded that average afternoon LDRab could be used to rank pearl millet genotypes for their grain yield in both stressed and nonstressed environment.
Tall Fescue Sward Response to Mefluidide and Nitrogen1
Authors: Gerrish J. R. , Dougherty C. T.
Published: July 2010

Introduction of legumes into grass‐dominant pastures often requires destruction or suppression of existing vegetation to minimize competition for light, soil water, and plant nutrients. Mefluidide (N‐[2,4‐dimethyl‐5‐ [[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide) has been used as a growth retardant of cool‐season turf grasses but has not been evaluated as an aid to legume establishment in pasture renovation. Three field experiments conducted at the Kentucky Agric. Exp. Stn., Lexington, Ky. in 1979 and 1980 examined responses of tall fescue (Festuca arundinacea Schreb.) to mefluidide [0.56 kg (a.i.)ha−1] applied in March and/or May under different levels of fertilization on a Maury silt loam (mixed, montmorillinitic, mesic Typic Paleudult). Mefluidide, applied 2 to 4 weeks after spring growth was initiated, reduced tiller weight, leaf weight/tiller, leaf area/tiller, and tiller populations. Mefluidide had no effect on the rate of leaf appearance and increased leaf/stem ratio from 1.38 to 2.34. Fertilizer N increased tiller populations, leaf dry weights, and leaf area/tiller. March applications of mefluidide reduced canopy leaf area index (LAI), but 65 days later LAI values of these plots were 50% higher than LAI's of untreated plots. Mefluidide application in May reduced LAI more severely than March applications and it did not lead to an increase in LAI later in the season. Application of N tended to offset the reduction of LA1 by mefluidide. Annual dry matter yields of tall fescue were reduced 12, 21, and 40% by March, May, and March plus May applications of mefluidide. Mefluidide broadcast in March reduced dry matter yields harvested on 7 May by 54%, but yield obtained at the next harvest was 23% higher than on untreated plots. Mefluidide applied in May reduced dry matter yields at the next harvest by 60% but subsequent yields were similar to those of untreated plots. At the third harvest on 1 August, dry matter yields of plots receiving 80 kg N haΨ1 were 22, 27, and 49% higher when mefluidide was applied on 29 March, 15 May, or on both dates, respectively. While mefluidide suppressed grass growth for 6 to 8 weeks after application, subsequent stimulation of grass growth may increase competition from grasses. Fertilizer N stimulated grass growth even when treated with mefluidide, and would increase competitiveness of established species.
Mineralization of N from Several Sources and Establishment of ‘Penncross’ Creeping Bentgrass on Putting Green Media1
Authors: Mazur A. R. , White C. B.
Published: July 2010

The practice of using little if any soil in putting green mixtures combined with the annual application of large quantities of N fertilizer provides a high potential for loss of N through leaching. Studies were conducted on two putting green media with and without soil [70% (vol.) sand + 20% peat + 10% Cecil sandy loam and 70% sand + 30% peat] to 1) investigate the nitrifier and denitrifier populations; 2) measure the mineralization products of ureaformaldehyde (UF), sulfur‐coated urea (SCU), isobutylidene diurea (IBDU), and urea under both laboratory and field conditions; and 3) determine the leaching losses and rate of ‘Penncross’ creeping bentgrass (Agrostis palustris Huds.) establishment with the respective N source materials. Initially the mixture containing soil had Nitrosomonas and Nitrobacter populations 490 × and 41.5 × higher, respectively, than the mixture without soil. In the field studies no treatment differences were found in nitrifying bacteria populations after 1 month. Little if any urea‐N or NH4+‐N was found in the leachate samples. The influence of percolating water was most evident on leaching losses with SCU and IBDU in the soilless media. The establishment of bentgrass was most rapid with the IBDU treatment in the mixture containing soil with 50% coverage 4 weeks after seeding and 83% coverage after 9 weeks. Even in the soilless mixture establishment rate of bentgrass was greater at 4 weeks with IBDU (22%) than with urea (7%) or UF (8%) but not significantly greater than SCU (18%).
Nitrogen from Legume Cover Crops for No‐Tillage Corn1
Authors: Ebelhar S. A. , Frye W. W. , Blevins R. L.
Published: July 2010

Many of the advantages of no‐tillage crop production are due to the presence of a mulch from a cover crop or from crop residue. Legumes can be used to provide the mulch and biologically fixed N to nonlegumes in the system. Field experiments were conducted from 1977 through 1981 to determine the amount of biologically fixed N provided to no‐tillage corn (Zea maysL.) by winter annual legume cover crops of hairy vetch (Vicia villosaRoth), big flower vetch (Vicia grandifloraW. Koch var. Kitailbeliuna), and crimson clover (Trifolium incarnuturnL.). The legumes were compared to a cover of corn residue only and a cover crop of rye (Secale cereuleL.). The soil was a Maury silt loam (Typic Paleudalfs, fine‐silty, mixed, mesic). Fertilizer N treatments of 0, 50, and 100 kg ha−1were combined with each cover treatment. Corn was planted by no‐tillage directly into the cover treatments and the cover crops were killed with herbicides. Hairy vetch produced more dry matter with a higher N percentage which resulted in a higher N concentration in corn plants and substantially more inorganic N (KCI extractable NH+4and NO−3) in the soil than with the other legumes. Big flower vetch and crimson clover provided much less N than hairy vetch. Five‐year average yields of corn grain following hairy vetch cover crop with no N fertilizer were about 2.5 Mg ha−1more than corn yields when following corn residue or rye cover crop. We estimated that hairy vetch supplied biologically fixed N equivalent to approximately 90 to 100 kg ha−1fertilizer N annually to the corn, based on a comparison of grain yields with corn grown in corn residue and rye. In addition to functioning as an effective mulch, certain legume cover crops can provide a substantial portion of the N for no‐tillage corn production, decreasing the amount of N fertilizer needed.
Date of Pod‐Set and Chalcid Fly Infestation in Alfalfa Seed Crops in the Southern Great Plains1
Authors: Ahring R. M. , Moffett J. O. , Morrison R. D.
Published: July 2010

abstract

Alfalfa (Medicago sativa L.) is grown for hay and seed throughout the Southern Plains. Because of cropping practices and the extended reproduction period of the plant, seed pests are a serious problem in the region. Our objectives were to determine the level of alfalfa seed chalcid infestation by the approximate date of pod‐set, to estimate its effect on present crop yields, and to identify alternatives to current cropping practices. Alfalfa seed pods were classified into four color groups according to pod maturity and studied in seasonlocation combinations of one moist subhumid, two dry subhumid, and one semiarid environments. Differences among pod‐color groups in the mean number of chalcid‐damaged seeds were examined using the appropriate LSD with a = 0.05. In each environment, statistically significant differences were found among the four pod‐color groups. Crops harvested from the moist subhumid environment were found to have a severe alfalfa seed chalcid infestation problem throughout the growing season. However, this problem was less severe in the fall. Crops harvested from other environments showed an increasing infestation problem as the cropping season progressed. Harvesting the first, and possibly the second, alfalfa growth of the season for hay and allowing the second or third cut to mature seed (current cropping practice) may present the optimum seed production system for moist subhumid environments. In other environments, using thin stands established in rows and timing the crop to obtain seed in midsummer may reduce the losses currently seen in fall harvests
15N‐Determined Time Course for N2Fixation in Two Cultivars of Field Bean1
Authors: Rennie R. J. , Kemp G. A.
Published: July 2010

Dinitrogen (N2) fixation was measured for two bean cultivars, ‘Aurora’ and ‘Kentwood’, in a 2‐year field experiment, at four growth stages and two levels (10 and 40 kg ha−1) of fertilizer N1as Ca(NO3)2. Both 15N isotope dilution and modulation parameters were used to determine if nitrogenase activity at these growth stages could explain Aurora's superiority in symbiotic N2fixation. Nodules were actively reducing C2H2at the first trifoliate stage and acetylene‐reducing activity (ARA) increased until anthesis or various stages of pod filling, depending on the cultivar and the year. The addition of fertilizer N at 40 kg ha −1did not alter the pattern of ARA over time although nitrogenase activity was affected. Although nodules were reducing low levels of C2H2at physiological maturity, no activity was observed at harvest maturity. Acetylene‐reducing activity peak activities of 120 and 151 nmol C2H4min−1plant−1for Aurora and 69 and 192 nmol C2H4min−1plant−1for Kentwood in 1981 and 1982, respectively, were similar to values observed for other temperate zone beans. Only a single peak of ARA was observed. The two bean cultivars received similar proportions of their plant N requirements from the atmosphere, averaging 72% in 1981 but only 54% in the cooler year, 1982. Plants apparently had the ability to alter their assimilation of different N sources (air, soil, and fertilizer) to compensate for the lower %Ndfa in the cooler year, 1982. Soil and fertilizer N uptake was particularly important to plant yield in early growth stages until N2 fixation was actively established. Aurora fixed 124 and 114 kg N ha−1(at the 10 kg N ha−1rate) and 124 and 100 kg N ha−1(40 kg N ha−1) in 1981 and 1982, respectively. Kentwood fixed 70 and 97 kg N ha−1(10 kg N ha−1) and 93 and 79 kg N ha−1(40 kg N ha−1) in 1981 and 1982. This superiority of Aurora was due to a longer vegetative phase supporting N2fixation. The ARA severely underestimated N2fixation (as determined by 15N‐isotope dilution) and we believe that N2fixation in beans has been underrated solely because of the inadequacies of ARA. ‘Galt’ barley served as an excellent non‐fixing control plant for 15N isotope dilution to measure N2fixation in these bean cultivars because its pattern of assimilating N from the soils was similar to that of the beans at all growth stages.
Root Growth and Morphology, Nutrient Uptake, and Nutrient Status of Early Growth of Soybeans as Affected by Soil P and K1
Authors: Hallmark W. B. , Barber S. A.
Published: July 2010

Little information is available on the effects of levels of soil P and K on soybean [Glycine max(L.) Merr] root growth and morphology. Soybeans were grown for 9, 16, and 21 days in Raub silt loam soil (fine‐silty, mixed, mesic Aquic Argiudoll) to measure the effect of increasing soil P and K on root growth and morphology and its relation to shoot growth, nutrient status of shoots, and net nutrient influx. Increasing soil P increased shoot weight, root surface area per plant, root surface area per g of root, P, K, Ca, and Mg influx and P, K, Ca, and Mg concentration of shoots. Adding P decreased the root surface area per g of shoot and increased root surface area per g of root. Increasing soil K increased shoot weight (with high P soil), P, K, and Ca influx, and P and K concentration of shoots. Potassium decreased Mg influx and Mg concentration of shoots. Significant positive P ✕ K interactions were found for secondary root radius, P, K, and Mg influx and shoot concentration showing that P and K had their greatest effect when the other nutrient concentration in the soil was high. The effect of P and K on nutrient concentration of shoots followed the same pattern as that for nutrient influx. Since adding P or K changes root surface area per g of shoot, influx of other nutrients changes when they are added. Where influx increases, a sufficient soil level of each nutrient is then needed so that soil supply does not limit influx.
Value of Rice Characteristics in Selection for Resistance to Salinity in an Arid Environment1
Authors: Lehman W. F. , Rutger J. N. , Robinson F. E. , Kaddah M.
Published: July 2010

The reaction of rice (Oryza sativaL.) plants to soil salinity was studied to identify characteristics of possible value in selection and to develop rapid, reliable selection procedures for use in the development of salinity‐resistant rice cultivars. Fourteen characteristics were measured on six cultivars growing in the greenhouse on a mixed hyperthermic Typic Torripsamment‐Rositas very fine sand treated with three levels of salinity for 2 years. Year, cultivar, salinity, and the year ✕ cultivar interaction had highly significant effects on most characters. The significant differences for cultivars ✕ years indicate that observations should be made for 2 or more years. Few characteristics showed significant interactions for the year ✕ salinity and cultivar ✕ salinity interactions. Important exceptions were the reproductive characteristics of percent underdeveloped spikelets and chaff weight (an estimate of blanking). From this it appeared selections could be made to reduce the percentage of underdeveloped spikelets and chaff weight. Characteristics with the highest correlation with seed weight were tillers at seedling stage and panicle length. Straw weight and weight of chaff plus straw had significantly positive correlations with the other vegetative characters, plant height and days to maturity, but significantly negative correlations with the reproductive characters of panicle and seed number and weight. Significant correlations and interactions indicate selections should be made for young plants with many tillers and against vigorous adult plants failing to develop reproductively.
Automated Determination of Chlorides in Soil and Plant Tissue by Sodium Nitrate Extraction1
Authors: Gaines T. P. , Parker M. B. , Gascho G. J.
Published: July 2010

An accurate, precise, and fast automated method for determining Cl in large numbers of soil and plant samples was needed in the confirmation that Cl toxicity was the cause of leaf scorch, a new disorder of soybean [Glycine max(L.) Merr.] grown on Atlantic Coast Flatwoods soils of Georgia. The method described involves the use of 0.1 M NaNO3as an extractant for soil and plant tissue samples with Cl being determined colorimetrically on a Technicon Auto‐Analyzer. Several studies including evaluation of extractants, shaking time, soils of varying texture, tissues of plants, and varying amounts of sample‐ and carbon‐weights were conducted to compare the proposed method with available methods of Cl analysis. Recovery of Cl after KCl was added to soils was 97% using 0.1 M NaNO3. Chloride concentrations in water and 0.1 MHNO3soil extracts could not be accurately determined due to turbidity and acidity interferences. Recovery of Cl from soils by the NaNO3extractant was not aflected by shaking times of 5, 10, and 20 min. Ten days after soils were incubated with KCI the NaNO3extractant was as effective in extracting CI(84%) as Mehlich No. 1 double acid extractant was in extracting K (86%). The NaNO3 extractant was equally effective in extracting Cl from sandy clay, sandy clay loam, loamy sand, and sand soils. Most of the error in the method was in the extraction procedure rather than in the measurement by the Auto‐Analyzer. The NaNO3extraction method compared favorably to the longer ashing method for leaf samples, but ashing was more accurate for seed samples. Fifty samples per hour can be determined by the Auto‐Analyzer.
Effect of Management Practices on Grain Yield, Test Weight, and Lodging of Soft Red Winter Wheat1
Authors: Roth G. W. , Marshall H. G. , Hatley O. E. , Hill R. R.
Published: July 2010

Little yield improvement of soft red winter wheat (Triticum aestivumL. em Thell.) has occurred in Pennsylvania and other northeastern states during the past 30 years while wheat yields have nearly doubled in several European countries. In England and Wales, about 40% of this increase is attributed to improved management. Our objective was to determine the potential yield increases under Pennsylvania conditions from near optimum combinations of seeding rate, row spacing, seeding depth, and N fertilization in the spring. Field experiments were conducted at a total of 15 locations during 1981 and 1982 on either Typic or Ultic Hapludalf soils. The cv. Roland was used, and treatments were seeding rates of 100,168, or 235 kg ha−1, 19 or 38 mm seeding depths, 127 or 178 mm row spacing, and 0, 34, 67, or 100 kg ha−1of N fertilizer topdressed in March at growth stage 3 (Feekes scale). Grain yields ranged from 2642 to 5342 kg ha−1and averaged 4134 kg ha−1. Yields increased in 14 of 15 environments when row spacing was decreased to 127 mm. The average yield increase from using narrow row spacing was about 7.5%. The effect of spring N fertilization was variable but grain yields and test weights were decreased at N levels above 34 kg ha−1. Seeding rate responses also were variable, but averaged over all environments, yields were not increased by using more seed than 168 kg ha−1. The greatest response to seeding rate occurred following late planting. At five of six locations where seeding depth effect was significant, yields were greatest from deep seeding. The best combination of treatments was 168 kg ha−1of seed, 38 mm seeding depth, 127 mm row spacing, and 34 kg ha−1of N. The average yield for this combination was 4630 kg ha−1which is more than double the state average yield.
Allelopathic Effects of Annual Weed Residues on Growth and Nutrient Uptake of Corn and Soybeans1
Authors: Bhowmik P. C. , Doll J. D.
Published: July 2010

Annual weeds have shown allelopathic potential in recent years. Few studies clearly compare effects of weed residues on growth inhibition and nutrient uptake in corn (Zea maysL.) and soybeans [Glycine max(L.) Merr.]. Therefore, the residues (aboveground biomass) of common lambsquarters (Chenopodium albumL.), redroot pigweed (Amaranthus retroflexusL.), common ragweed (Ambrosia artemisifoliaL.), velvetleaf (Abutilon theophrastiMedic.), and yellow foxtail [Setaria glauca(L.) Beauv.] were evaluated for their allelopathic effects on growth and uptake of N, P, and K in corn and soybeans in controlled environments. Weed residues in silica sand produced more inhibitory effects than the mixture of soil (Typic Agriudoll) and sand. The growth inhibition was more (8 to 14%) when the residues were incorporated in all soils than when they were surface applied. All residues except common ragweed reduced corn (6 to 20%) and soybean (2 to 20%) dry matter production. The inhibition or stimulation of N, P, and K uptake in both crops was not consistent and depended on the residue source, residue placement, or soil texture. Addition of supplemental N and P to various residues provided no alleviating effect on crop growth. Addition of P markedly enhanced P uptake without affecting total dry weights of both test species when compared to the controls. Yellow foxtail and common ragweed residues increased K uptake (21 to 48%) in corn but not in soybeans. The weed residues demonstrated an allelopathic inhibition of growth independent of N and P nutrition, and suggest that the inhibitory effects are not related to nutrient uptake.
Minimum‐Tillage Forage Turnip and Rape Production on Hill Land as Influenced by Sod Suppression and Fertilizer1
Authors: Jung G. A. , Kocher R. E. , Glica Anna
Published: July 2010

Insufficient herbage during the fall in the temperate areas of the world has long been a serious limitation in animal production. The purpose of this research was to determine the feasibility of producing Brassicaspp. forage crops for fall grazing of sheep on hill land. The experiment was conducted near Waynesburg, Pa., in a 4‐ha hill pasture, predominantly Dormont silt loam (fine‐loamy, mixed, mesic Ultic Hapludalf) on the sideslopes and Culleoka loam (fine‐loamy, mixed, mesic Ultic Hapludalf) on the ridge. A split‐plot block arrangement was used with blocks of ‘Sirius’ turnip, (Brassica rapaL.) ‘Fora’ rape, (B. napusL.), and ‘Perko P.V.H.’ winter rape (B. rapaL.) randomized in each of six blocks. Competition from the existing species was suppressed with paraquat (l,l′‐dimethyl‐4,4′‐bipyridinium ion) or glyphosphate [isopropylamine salt of N‐(phosphonomethyl)glycine] at 1.1 kg a.i. ha−1. Nitrogen and P fertilizer treatments were assigned to subplots in a randomized complete block design. Fertilizer was applied before seeding in 1978 and 1979 to provide 0, 33, 66, 99, or 132 kg N ha−1and 0, 15, 30, 45, or 60 kg P ha−1in a 52factorial arrangement. The crops were minimumtillage (min‐till) planted on 10 Aug. 1978 and 25 July 1979. Dry matter (DM) yields were determined 60 and 90 days after planting. Select samples were taken to determine crude protein, in vitro dry matter disappearance (IVDMD), and mineral element composition. Mean crop yields were similar for the two herbicide treatments in 1978 but were−35 to 75% higher on glyphosate‐treated plots than on paraquat‐treated plots in 1979. Grass yield in the Brassicaplots in 1979 were twice as high in the paraquat‐treated plots as in the glyphosate‐treated plots. At the higher rates of applied N and P, DM yield exceeded 7000 kg ha−1in 1978 and 9000 kg ha−1in 1979. Crop yield responses were quadratic functions for N fertilizer rates and linear functions for P fertilizer rates for both harvests in 1978. In 1979, yield responses were linear functions for N fertilizer rates for both harvests and for P fertilizer rates for the 60‐day harvest; and were quadratic for P rates for the 90‐day harvest. Yield of turnip and rape was affected more by P fertilizer before the 60‐day harvest than afterwards. Crude protein concentration ranged from 60 to 250 g kg−1. Nitrogen and P fertilizers differentially affected the crude protein concentration of forage turnip and rapes. Mean IVDMD was 950 and 900 g kg−1for turnip tops and roots, respectively, 910 g kg−1for Fora rape, and 930 g kg−1for Perko rape. Yield of digestible DM of turnip was up to 67% higher than that of stockpiled orchardgrass. The Brassicaspp. had different DM mineral element compositions, and concentrations of P, K, Ca, Mg, and Zn generally were higher in Brassicaspp. than in orchardgrass checks.
Photosynthesis and Stomatal Conductance with CO2‐Enrichment of Containerand Field‐Grown Soybeans1
Authors: Sionit N. , Rogers H. H. , Bingham G. E. , Strain B. R.
Published: July 2010

The present experiment was an attempt to study the differences between photosynthetic responses of pot‐grown and field‐grown soybean [Glycine max(L.) Merr., ‘Bragg’] plants to atmospheric CO2enrichment at six levels of irradiance and four leaf temperatures. Plants were grown in field soil or in pots containing an artificial substrate at five elevated atmospheric CO2levels and two water regimes in open top field chambers. Under well‐watered conditions plants grown in the pots had lower stomatal conductances and lower rates of net photosynthesis than plants grown in the field. However, the field‐grown plants responded to a less extent to increasing atmospheric CO2concentration than pot‐grown plants. The photosynthesis‐ irrdiance relationships were linear in the field‐grown plants and curvilinear in the pot‐grown plants. At the highest irradiance level tested (1400 µmol m−2s−1), the field‐grown plants had maximum net photosynthetic rates of 43 and 48 mg CO2dm−2h−1at 332 and 623 µL L−1CO2respectively. The pot‐grown plants were irradiance saturated at a level of 700 µmol m−2s−1and net leaf photosynthetic rates were 18 and 28 mg CO2dm−2h−1at 332 and 623 µL L−1CO2, respectively. Water stress caused a reduction in both stomatal conductance and net photosynthetic rate in the leaves of pot‐grown plants. The effect of leaf temperature on net photosynthethis and stomatal conductance depended upon the atmospheric CO2concentration and rooting media. High temperature increased net photosynthetic response to CO2enrichment at high CO2concentrations but not at low CO2concentrations.
Influence of Seed Size and Planting Date on the Performance of Austrian Winter Field Peas1
Authors: Murray G. A. , Swensen J. B. , Auld D. L.
Published: July 2010

Production of Austrian winter field pea [Pisum sativum spp. arvense (L.) Poir] is limited by a lack of information on cultural practices and potential productivity. Field studies were conducted to determine the influence of seed size and planting date upon spring seedling vigor, seed yield, and seed weight of several Austrian winter field pea cultivars. The Moscow studies were situated on a Palouse silt loam soil (fine‐silty, mixed, mesic, pachic Ultic Haploxeroll) and the Grangeville study on a Chicane silt loam (fine, montmorillonitic, mesic Xeric Argialboll). Small‐sized seed (<5.2 mm diam) significantly reduced spring seedling vigor of Austrian winter field pea planted in October under cool, wet conditions. Seed yields of Austrian winter field pea planted in October under cool, wet conditions in 1977 at Grangeville, Idaho, and in October under dry conditions in 1978 at Moscow, Idaho were reduced by 742 and 255 kg ha−1, respectively when Austrian winter field peas were established from small vs large‐sized seed. Improved seedling vigor of Austrian winter field pea from large‐sized seed did not improve yield of Austrian winter field peas planted at locations, planting dates, and environments favorable for pea growth. At Grangeville in 1977, the Austrian winter field peas planted in September produced 1298 kg ha−1 more seed than October‐planted Austrian winter field pea. September and early October planting dates had no influence on seed yield at Moscow, but Austrian winter field peas planted in late October failed to establish economic stands in both years, probably because of low October precipitation in both years and very low winter temperatures in 1978 to 1979. Seed weight of most Austrian winter field pea lines declined an average of 1.6 g 100−1 seed as seeding date was delayed from September until October. Reduced seed weight accounted for part of the seed yield reduction observed at Grangeville. Seed weight of a semi‐dwarf Austrian winter field pea increased significantly as seeding date was delayed from September until October. ‘Melrose’ had the best seedling vigor and ‘Common’ the worst seedling vigor of all cultivars tested. No differences in seed yield were observed between ‘Fenn’, Melrose, and Common at either location.
Effect of Moisture Stress on Seed Growth in Soybeans1
Authors: Meckel L. , Egli D. B. , Phillips R. E. , Radcliffe D. , Leggett J. E.
Published: July 2010

The growth of an individual soybean [Glycine max (L.) Merr.] seed is an important part of the yield production process. An understanding of the effect of environmental factors on the growth of individual seeds is needed to enhance our understanding of the effect of the environment on yield. Soybeans were grown in the field on a Maury silt loam soil (fine, mixed, mesic Typic Paleudalfs) for 3 years (1979 to 1981) and subjected to varying levels of moisture stress to investigate the effect of moisture stress on seed growth. Irrigated controls were compared with moisture stress treatments from planting to beginning seed fill (growth stage RS), during seed filling (growth stage R5 to R7) or from planting to maturity (severe stress). Fruits were tagged at beginning seed fill and sampled at weekly intervals to estimate the seed growth rate and the effective filling period (EFP). Although the stress treatments reduced yield and vegetative growth, the rate of seed growth (mg seed−1 day−1) was not affected. The seed‐filling period (estimated as days from growth stage R5 to R7 or EFP) was shortened by the severe stress treatment in 1979 and 1981 (statistically significant only in 1979), and there was a trend for the period of R5 to R7 to be shortened by late stress in 1980 and 1981. The data suggest that the rate of individual seed growth is less sensitive to moisture stress than other plant processes. The seed filling period was more sensitive to moisture stress than seed growth rate and the effect of moisture stress on the duration of seed fill may be one way that stress reduces soybean yield.
Foliar Applications of Nutrients on Maize. I. Yield and N Content of Grain and Stover1
Authors: Below F. E. , Lambert R. J. , Hageman R. H.
Published: July 2010

Crop yield response to foliar fertilization has been variable, but few studies have utilized detailed plant analyses of field grown maize (Zea maysL.) hybrids known to differ in C and N metabolism and content to establish a role for foliar fertilization especially in plant and grain development. Field studies were conducted in 1981 and 1982 to determine whether foliar application of N would delay the remobilization of leaf N and leaf senescence thereby maintaining photosynthesis and increasing productivity. In 1981, N‐P‐K‐S (12 kg N ha−1per treatment) was applied to plants of five hybrids at 7 days before and 12 days after anthesis. In 1982, urea (two equal applications for a total of 67 kg N ha−1) was applied to three hybrids (B73 × Mo17, Pioneer brand 3382, and Farm Services brand 854) at 12 and 6 days before anthesis and 9 and 15, and 25 and 32 days after anthesis to give treatments 1, 2, and 3, respectively. Soil type was Drummer silt loam (fine‐silty, mixed, mesic Typic Haplaquoll) in 1981 and a Flanigan silt loam (fine, montmorillonitic, mesic Aquic Arqiudoll) in 1982. In 1981, grain yield and N content, and the accumulation of dry weight and reduced N by the whole plant were unaffected by the spray treatments. In 1982, increases in whole plant N at physiological maturity in response to urea sprays were 0.1, 0.1, and 0.4 g N plant−1for the first spray, 0.5, 0.4, and 1.0 g N plant−1for the second spray and 0.4, 0.5, and 0.5 g N plant−1for the third spray for P3382, B73 × Mo17, and FS854, respectively. Grain yields of all hybrids were not affected by any treatment and significant increases in whole plant dry weight and grain yield of erect plants were noted only for FS854 (second treatment). Grain N of all hybrids was increased significantly by the third treatment and for FS54 by the second treatment. Adverse effects of urea treatments were that stalk lodging was increased, and that the harvest indices for dry weight and N were not altered. Foliar application of N did not delay the remobilization of N from the leaves, and had little consistent effect on net photosynthesis or productivity. The use of foliar N sprays for increasing grain yield of maize grown at soil N levels commonly used for commercial production is not recommended.
Comparison of N Balance and 15N Isotope Dilution to Quantify N2Fixation in Field‐Grown Legumes1
Authors: Rennie R. J.
Published: July 2010

Two techniques are commonly used to estimate N2fixation integrated over the growing season in field‐grown legumes: total N balance (NB) (the classical difference method), and methods based on the principle of 15N isotope dilution. Many researchers do not have access to 15N or to isotope ratio mass spectrometers and thus rely on the NB method. A comparison of these two techniques of estimating N2fixation in several experiments over 3 years showed that the NB method generally resulted in a lower estimate of N2fixation and was consistently less precise (higher experimental error). Good agreement existed between the two methods in 70% of the experiments for estimating the amount of N2fixed but in only 60% of the experiments for percentage N2fixed. Even when high correlation coefficients were found, the unacceptable characteristics of the regression equations (i.e., deviation from a slope of unity and a y‐intercept of zero) made predictions difficult. Nitrogen balance was most reliable in experiments when soil N was low, so that non‐fixing plants showed signs of N deficiency by anthesis. Still, it was not possible to determine when NB would agree with 15N isotope dilution for estimates of N2fixation. Negative values for fixing systems or positive values for non‐fixing systems for N2fixation were found when using NB. In only one circumstance will NB accurately quantify N2fixation: when the fertilizer use efficiency (or, in unfertilized experiments, soil N uptake) of the fixing system is identical to that of the non‐fixing system. Since this occurs sporadically, NB cannot be used with confidence to estimate N2fixation in field‐grown legumes.
Estimation of Spring Wheat Leaf Growth Rates and Anthesis from Air Temperature1
Authors: Bauer Armand , Frank A. B. , Black A. L.
Published: July 2010

Seasonal variability in climate within and between the major spring wheat (Triticum aestivumL.) growing regions of the world causes large differences in plant development patterns. A major need of models attempting to describe crop growth as a dynamic process is an evaluation of phenological development. Researchers modeling growth and yield would benefit from a meteorologically‐based phenological index that accurately and reliably predicts the development stage. The objective of this study was to develop capability to estimate leaf growth rate and crop growth stage from planting to anthesis under variable management and climatic conditions. Aboveground morphological entities of 16 hard red spring (HRS) and 3 durum (T. durumDesf.) wheats were rated in Haun scale designations in seven field trials grown on Williams loam (fine‐loamy, mixed Typic Argiboroll). These designations were regressed with growing degree‐days (GDD), photothermal units (PTU), and days (DAYS) after emergence. Time to emergence did not differ among cultivars within a trial. Among the seven trials, emergence occurred 7 to 15 days after planting; accumulated GDD ranged from 94 to 138, and averaged 106. Eighteen of the cultivars produced eight leaves, ‘James’ produced seven. Main‐stem phyllochron interval was 73 GDD for the HRS cvs. Butte and Waldron combined for analysis, and about 81 GDD for either “other” eight‐leaved HRS cultivars or for the durums combined for analysis, and for James. The R2value for any combined analysis was no less than 0.970**, significant at the 0.01 level. Soil water level and fertilizer N rate had no effect on main stem development rate, but did affect the maximum number of tillers produced per plant. The GDD accumulated per plant growth unit from emergence to anthesis (leaves plus four stages after expansion of the flag leaf) was the same as from emergence through full expansion of the flag leaf. Precision of estimating growth rates and stages with GDD was the same as with PTU, and both were superior to DAYS.
Seasonal Response of Uninoculated Alfalfa to N Fertilizer: Soil N, Nodule Turnover, and Symbiotic Effectiveness of Rhizobium meliloti1
Authors: Jenkins M. B. , Bottomley P. J.
Published: July 2010

Information exists on the effects of fertilizer N upon alfalfa (Medicago sativa L.) grown either in the greenhouse or during the establishment year in the case of field‐grown plants. Very little information has been obtained by using fertilizer N as a means to assess the performance of symbiotic N, fixation during postestablishment growing seasons. ‘Anchor’ alfalfa was established from uninoculated seed on three soils (two Xerollic Durargids and one Xerollic Camborthid) of limited depth (0.6 m) in central Oregon. After the year of establishment, alfalfa was harvested annually in three cuttings. Fertilizer N (NH4NO3,) was applied at rates of up to 230 kg N ha−1 In mid‐April and immediately after the first and second harvests. Most of the responses to added Noccurred in the third harvest. Significant increases were observed in dry weight in three of seven cuttings, in total reduced N in four of seven cuttings, and in the percentage of reduced N in the herbage in two of seven cuttings. At least one of these responses was enhanced with added N in five of the seven third harvest cuttings. Increases were not seen in the first harvest cuttings and only in two of seven second harvest cuttings. Mineral N levels in the soil profiles under the non‐fertilized plants at two of the sites declined during the growing season. This decline (35 and 40 kg N ha−1) approximated the difference between the total reduced N in the herbage of N‐fertilized and non‐fertilized plants in five of six cases (40 to 70 kg N ha−1). Symbiotic effectiveness tests of isolates of Rhizobium meliloti taken from nodules of 10‐week‐old plants during the establishment year showed that 20% of the isolates were ineffective, 16% were of intermediate effectiveness, and 64% were highly effective. In the 3rd year, although no ineffective nodule isolates were recovered, nodule numbers declined from 66 to 11 per plant between the first and third harvest and no isolates recovered from nodules at the third harvest were highly effective. The influence of nodule turnover, nodule occupants of suboptimum effectiveness, and the contribution of soil N on alfalfa production during postestablishment seasons requires more attention.
Bloom and Pod Set in Determinate and Indeterminate Soybeans Grown in China1
Authors: Gai Junyi , Palmer R. G. , Fehr W. R.
Published: July 2010

Precise description of soybean [Glycine max (L.) Merr.] blooming and pod set characteristics are necessary for proper utilization of these characteristics in crop improvement. Seven determinate and five indeterminate soybean land cultivars from the lower Yangtze and Hwai Valleys (31° to 35°N 115° to 122°E) were examined in Nanjing, China (32°N 118°48'E) to describe the blooming habit and estimate the percentages of bloom and pod set. The plants had main raceme and subraceme (including subbranch) subdivisions on the floral nodes at the top, and primary branch and secondary branch subdivisions on the branch nodes at the bottom. In both determinate and indeterminate cultivars, the most important sectors in producing flowers and pods were the main raceme and the primary branch subdivisions. With a similar maturity, the determinate type had fewer main racemes, more subracemes, more primary and secondary branches, and more flowers per main raceme at a corresponding node than did the indeterminate type. The peak blooming period of a plant was from the 4th to the 14th day after first flowering. For the two stem‐termination types, on each subdivision, the flowering order was basically from the lower flowers to the upper ones, with the subraceme beginning to flower about the time that the main raceme at the same node finished blooming. For both stem‐termination types, the percentage of pod set was negatively correlated with maturity date and number of flowers. The percentage of pod set was relatively high on the terminal raceme for the determinate type. Percentage pod set of subracemes tended to decrease from the lower nodes to the upper ones for both types, but, at corresponding nodes, the percentage pod set of the determinate type was higher than that of the indeterminate type.
Luxury Water Use by Bermudagrass Turf
Authors: Kneebone W. R. , Pepper I. L.
Published: July 2010

In an earlier study of the effectiveness of turf‐soil filters for tertiary treatment of sewage effluent, we irrigated with effluent at very high application rates, and noticed that water use increased with application rate. This study investigates luxury water use by bermudagrass, and the effect of high application rate on evapotranspiration (ET). The primary objective of this study was to measure the effects of three high irrigation levels (114, 243, and 364 mm 7 days−1) on ET from seeded certified bermudagrass (Cynodon dactylon L. Pers.) turf growing on three sand‐soil substrates (19:1, 18:2, and 16:4) mixed with Pima clay loam (fine‐silty, mixed, thermic Typic Torrifluvent). The data used were derived from a study of the effectiveness of bermudagrass turf growing in sand‐soil mixes irrigated with secondary treated sewage effluent. Percolation lysimeters were irrigated twice each week with effluent. Leachate was collected and measured each week. The difference between applied effluent and recovered leachate measured ET. The lysimeters were arranged in three complete blocks. In each block, the nine treatment combinations of sandsoil mixes and irrigation levels were assigned at random. As irrigation levels increased, ET levels increased. Mean values at the three rates averaged over sand‐soil mixes were 31,49, and 53 mm 7 days−1. Evapotranspiration levels were highest on substrates highest in soil, and values averaged over all rates were 36, 44, and 53 mm 7 days−1. Differences due to irrigation levels and to sand‐soil mixes were significant at the 0.001 level. Overall rates of irrigation were 254, 540, and 808% of Class A pan evaporation during the 1 year study period. Corresponding ET values were 68, 109, and 119% of Class A pan. Fluctuations in ET paralleled pan evaporation but the ratios of ET to pan were higher during periods of low pan evaporation in winter and spring. Calculations based on solar radiation showed that advective heat from nearby streets and bare ground was a component of the latent heat represented in ET levels measured.
Measurement of Viable Plant Roots with the Image Analyzing Computer1
Authors: Ottman M. J. , Timm H.
Published: July 2010

Investigation of the spatial arrangement of plant roots in soils is limited by the time required to remove the roots from the soil and measure the viable roots. A root measurement technique is reported which includes differentially staining viable root tissue and extraneous organic matter with trypan blue, photographing the roots, and presenting the photographic negatives to an Image Analyzing Computer, which can predict root length or area in seconds. The staining procedure did differentially stain the viable roots and organic matter since addition of dried organic matter did not increase the Image Analyzer estimation of length or surface area. The photographic process, however, contributed to lower and more variable Image Analyzer estimates of root surface area when comparing specimens presented as photograhic negatives or in bulk without photography. The Image Analyzer provides reliable estimates of surface areas for root and wire samples presented in bulk with a coefficient of variation of 3.3 and 1.2%, respectively. This technique is relatively rapid and can be used to measure plant root systems sampled by soil cores.
Effect of Acidity and N Source on the Growth and Thatch Accumulation of Tifgreen Bermudagrass and on Soil Nutrient Retention1
Authors: Sartain J. B.
Published: July 2010

Turfgrasses are commonly grown on a soil with a near neutral pH using synthetic organic slow‐release N sources which are more costly than soluble inorganic N materials. Acidic soil conditions slows nitrification and may decrease the long‐term leaching loss of inorganic NH+4 source fertilizers, thereby increasing the N efficiency of the fertilizer source. Specific studies evaluating the effects of soil acidity on N fertilizer efficiency and turfgrass growth and thatch accumulation have not been conducted; therefore this study was initiated with the following objectives: (a) to assess the influence of acidity and N source on the quality, growth rate, N uptake, and thatch accumulation of Tifgreen bermudagrass [Cynodon transvaalensis Burtt‐Davis ✕ C. dactylon (L.) Pers.] and (b) to evaluate the effects of acidity on the retention of selected nutrients by the soil. Treatments were applied in a randomized complete block design with four replications to a 5‐year‐old Tifgreen bermudagrass turf growing on a loamy fine sand (Typic Quartzipsamment). Three N sources (Ammonium sulfate [AS], Isobutylidene diurea [IBDU], and activated sewage sludge [SS]) were applied at two frequencies (5 g and 10 g N m−2) every 14 and 28 days, respectively. The bermudagrass was rated every 14 days, clippings were collected every 45 days for growth rate and N uptake estimates and cores for thatch accumulation estimates were collected after each of three growing seasons. Maximum growth rates occurred at pH less than 4.0. Overall turfgrass quality was not significantly influenced by N source or frequency of application. Acidity promoted thatch accumulation, except in the presence of applied Ca. Significantly lower levels of thatch accumulated on plots receiving IBDU. Application of 5 g N m−2 as AS every 14 days promoted the accumulation of more thatch than 10 g N m−2 applied every 28 days. Frequency of application had no effect on the thatch accumulation of plots receiving IBDU and SS. Mehlich I extractable nutrients (P, K, Ca, and Mg) in the top 5 cm of soil declined with increasing levels of acidity. Turfgrass growth rate was not reduced in the presence of a 100 to 1 soil extractable Ca to Mg ratio.
Effect of N, P, and S Fertilizers on Alfalfa Grown on Three Soil Types in Northeastern Saskatchewan. I. Yield and Soil Tests1
Authors: Nuttall W. F.
Published: July 2010

Experiments were conducted on three soil types to determine the effect of N, P, and S fertilizers on herbage yield of alfalfa (Medicago media Pers.) and on nutrients in soils over extended periods of time. Rates of 10,45, and 67 kg N ha−1 were applied in combination with 0,22, and 45 kg S ha−1 in the spring of each year. Twenty kilograms of P ha−1 was applied with these treatments. A control with no fertilizer yielded an average of 2.15 Mg ha−1 per cut Waitville loam (Wv 1, Typic Cryoboralf). An additional treatment (22 N, 0 P, and 26 S kg ha−1) yielded 3.01 Mg ha−1 per cut (avg. 10 cuts) which was the most economical treatment on Wv 1. Response to S fertilizer was significant on Wv 1, but only significant in 1 year on Whitefox fine sandy loam (Wf fsl, Typic Cryoboralf) which was Initially slightly lower in 0.01 M CaCl2 soluble‐S [18.4 vs. 16.5 S mg (4 kg)−1 soil]. Contrary to expectation, yield responses to S as much as 0.76 Mg ha−1 of herbage were obtained in 2 years on Melfort silty clay (M sic, Typic Cryoboroll), a soil initially containing a very high amount of So4‐S [46 mg (4 kg)−1 soil]. Results indicated that soils need to be tested every 4 to 5 years to provide a basis for adjusting S fertilizer rates. Regression analyses revealed that N significantly increased yield per cut on Wv 1 and Wf fsl soils and that S increased yield on Wv 1, averaged over 5 years. Because an expected response to S was not obtained on one site, tissue analyses should be investigated further as a method for determining availability of S.