bluuebunny/crossref_metadata_2025 huggingface dataset:
Phenology of Dent Corn and Popcorn. III. Improved Crop Development Models1
Authors: Stevens E. J. , Stevens S. J. , Flowerday A. D. , Gardner C. O. , Eskridge K. M.
Published: July 2010

Simple temperature‐dependent phenological regression models have been used for many years to predict seasonal development for dent corn (Zea mays L.) and sweet corn. However, only limited data are available for popcorn. More complex models have taken into account the effects of photoperiod but seldom planting date variation with respect to additional environmental variables. A recently established network of automated climate stations, reporting daily to centralized locations in the states of Nebraska, Kansas, Colorado, and South Dakota, has facilitated modeling corn phenology using hourly rather than daily data or long‐term temperature normals. Soil temperature data is also recorded by these weather stations. An interactive agroclimatology program and service (AGNET) offered by the University of Nebraska, Lincoln (UNL), utilizes some of these data as daily thermal units accumulated from the time of planting. The objectives of this research were to evaluate, and where necessary, modify models used by AGNET after studying the influence of (i) using hourly thermal units accumulated from 50% seedling emergence, (ii) photoperiod effects associated with variations in planting date and seedling emergence, and (iii) using a modified universal growth staging procedure and growth curve analysis. A 2‐yr phenology study incorporating three planting dates, one dent corn hybrid (B73 × Mo17), and three popcorn hybrids (P410, P609, and Iopop 12) was conducted in eastern Nebraska during 1982 and 1983. Statistically significant differences were detected among hybrids, among planting dates, and between years for regression coefficients derived from thermal and photoperiod/thermal regression models. Heat sums calculated over a range of temperatures between 5 and 28°C corrected for heat stress tended to be more consistent over the years than those calculated using a range of 10 to 30°C. The maturity rating of some corn hybrids was not constant across all planting dates modeled in terms of thermal units accumulated prior to the crop reaching a particular stage of phenological development. Iopop 12 matured proportionately earlier as planting date was delayed (i.e., fewer thermal units were accumulated prior to physiological maturity). As planting date was delayed the maturity rating of P41O remained unchanged while P609 matured later. The dent corn hybrid B73 × Mol7 first became earlier maturing then later maturing as the date of planting was delayed. A need to account for daylength at crop emergence as well as additional environmental variables associated with changing planting dates and the maturity rating of cultivars was demonstrated.
Evaluating the Genetic for Germination Salt Tolerance in Alfalfa Using a Sodium‐Chloride Gradient1
Authors: Robinson D. L. , Dobrenz A. K. , Smith S. E.
Published: July 2010

Progress made in breeding for salt tolerance at germination may be difficult to evaluate when only limited numbers of salinity levels are used for germplasm comparison. Patterns of response to salt stress may be better distinguished when seed is germinated at numerous osmotic potentials. A gradient of osmotic potentials can be easily created by making a series of small dilutions of a concentrated salt solution. Using this technique, alfalfa (Medicago sativa L.) seed from the cultivar Mesa‐Sirsa and a Cycle 7 syn‐1 experimental developed from Mesa‐Sirsa were planted in 37 concentrations of NaCl ranging from 0 to −2.87 MPa. Germination responses across the gradient were sigmoid shaped for both germplasm sources. Natural logarithmic transformations of the data revealed relatively similar and constant germination rates for the two populations at osmotic potentials between 0 and −0.75 MPa. Below these osmotic potentials, percent germination declined abruptly in Mesa‐Sirsa while in Cycle 7 syn‐1, a stable germination rate was maintained until the salt level reached −1.76 MPa, a threshold concentration more than 2.3 times that of Mesa‐Sirsa. At salinities greater than these threshold values, the two populations exhibited similar rates of decline in seed germination. Cycle 7 syn‐1 seed germinated more than twice as fast as Mesa‐Sirsa at −1.90 MPa. Selection for salt tolerance has both extended the germination range of alfalfa by 1 MPa and decreased the time required for seed to reach peak germination speed by 5 days. An osmotic gradient provides an excellent method for evaluating germplasm performance in a salt tolerance breeding program.
Alfalfa Establishment and Production on Soils with Different Drainage Characteristics1
Authors: Jones J. H. , Olsen F. J.
Published: July 2010

Alfalfa (Medicago sativa L.) production is reduced by poor drainage, moisture stress, and impervious soil horizons. This study was conducted to evaluate the establishment and production of alfalfa in relation to drainage characteristics. Four alfalfa cultivars, Cody, Spredor, Weevlchek, and WL‐307, were seeded on three soil series, a deep well‐drained Alford (fine‐silty, mixed, mesic Typic Hapludalf), a moderately well‐drained Hosmer (fine‐silty, mixed, mesic Typic Fragiudalf), and a nearly level, poorly drained Weir (fine, montmorillonitic, mesic Typic Ochraqualf). Soil moisture levels for the 0‐ to 0.90‐m depth for the three soil series varied according to rainfall and soil water recharge. Soil moisture depletion for the Alford series at the 0.90‐ to 1.80‐m depth was great due mostly to root proliferation. However, soil moisture depletion for Hosmer and Weir series at the 0.90‐ to 1.80‐m depth was much less than the Alford series, indicating little root proliferation into the fragipan and claypan at this depth. The highest dry matter yields were obtained on the well‐drained Alford site, whereas the lowest yields were generally obtained on the poorly drained Weir site. Alfalfa stands persisted for 7 yr on the well‐drained Alford series and the moderately well‐drained Hosmer series and for 5 yr on the poorly drained Weir series. The selection of a well‐drained soil site is essential for best alfalfa establishment, persistence, and high production. However, moderately well‐drained soils may be used for alfalfa production when well‐drained soils are unavailable.
Conservation Tillage and Irrigation Effects on Corn Root Development1
Authors: Newell R. L. , Wilhelm W. W.
Published: July 2010

The effects of conservation‐tillage practices on the root environment of corn (Zea mays L.) may differ with varying amounts of irrigation. Dryland, 50% irrigation, and 100% irrigation treatments were applied in combination with disc, no‐tillage, and a postemergence chisel treatment designed to allow rapid infiltration of irrigation water. The study was conducted during the 1980 growing season at the Nebraska Agricultural Experiment Station near Mead, NE, on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls). Root samples were taken to 1.50 m in 0.15‐m increments. Sampling was done at 60 (V8), 77 (V14), and 90 (R2) days after planting. Root length per soil volume as a function of depth from the soil surface was characterized using hybrid B73 × Mo17. Root length exhibited linear and often quadratic distribution over sampling depths at all sampling dates. The 100% irrigation treatment exhibited greatest total profile (0‐ to 1.5‐m) and surface (0‐ to 0.15‐m) root length at R2. Dryland and 50% irrigation treatments were associated with relatively greater root length proliferation deep in the soil profile. Differences in root length distribution were not as pronounced at stages V8 and V14. Chisel and no‐tillage treatments, with crop residues at the soil surface, resulted in greater surface (0‐ to 0.15‐m) and total profile root length than discing. Corn roots tended to explore the lower profile to a greater extent under water stress conditions. This phenomenon, in conjunction with soil water conservation by no‐tillage methods, may allow irrigators to increase water‐use efficiency by better use of stored soil moisture.
Quality Analysis of Summer‐Annual Forages. III. Prediction of Wet Silage In Vitro Dry Matter Disappearance from Chemical Constituents1
Authors: Fisher D. S. , Burns J. C.
Published: July 2010

Samples for the determination of silage quality are generally dried prior to analysis even though some silage constituents are lost during drying. The objectives of this study were to examine the prediction of wet silage in vitro dry matter disappearance (IVDMD) from analysis of dried samples using both oven‐dried and freeze‐dried fodder and silage. Frozen, wet silage was ground to pass a 1‐mm screen using liquid N as a cryostat. The IVDMD of ground, frozen silage (GFS) was found to be most closely related to the IVDMD of freeze‐dried fodder (FD), with GFS IVDMD = 24.7 + 0.99 (FD IVDMD) and r2 = 0.76**. Weaker relationships were found with freeze‐dried silage (FDS) (r2=0.46**), oven‐dried silage (ODS) (r2=0.35**), and oven‐dried fodder (OD) (r2=0.34**). The relationships between the IVDMD of GFS and fiber fractions of neutral detergent fiber (NDF), acid detergent fiber (ADF), permanganate lignin, apparent cellulose, apparent hemicellulose (NDF—ADF), and the ADF/lignin ratio as independent variables were examined using stepwise regression. Freeze‐dried fodder lignin (r2=0.44) and OD ADF (r2=0.37) were the two single fractions most closely related to wet silage IVDMD. Correlations from the Van Soest fractions alone in single variable regressions were not improved when using stepwise multiple regression analysis.
Precision and Bias of Various Soybean Dry Matter Sampling Techniques1
Authors: Hunt P. G. , Burnham K. P. , Matheny T. A.
Published: July 2010

A balance between sample sizes sufficient to detect real differences and resources necessary to obtain and process samples is a continual problem for scientists. In the first year, this study assessed the precision and bias associated With three subplot sampling techniques used for estimating soybean [Glycine max (L.) Merr.] shoot dry matter production: (a) random 1 m of row, (b) random 0.3 m of row, and (c) four randomly selected plants. The experimental design was a split‐split plot. Three cultivars (Braxton, Coker 338, and Davis) were the whole plots, and three sampling date plots were the subplots. Measurement of the total plant dry matter within the subplots as well as the dry weight obtained by three sampling methods constituted the four split‐split plots. When dry matter data were averaged over time and cultivar, the coefficients of variation (CV) for the sampling techniques (a), (b), and (c) were 0.187, 0.417, and 0.386, respectively. The CV was 0.088 when the 20‐m2 subplot (27 m of row) was measured. The 1‐m technique did not significantly overestimate dry matter production relative to the entire subplot measure, but the 0.3‐m and four‐plant (4‐P) techniques significantly overestimated dry matter production. Cultivar, date of sampling, and cultivar ✕ date‐of‐sampling interaction effects in the analysis of variance were significant at P ≤ 0.05 only when data from the entire subplot or 1‐m sampling technique were used. A second study in 1985 also showed that the 0.3‐m and 4‐P sample techniques were poor for both precision and accuracy. This second study also compared the precision and bias of 1‐ and 2‐m samplings as well as the precision and bias associated with different technicians. The 1‐ and 2‐m techniques gave equally unbiased results, but the 1‐m technique did not give equally good precision (CV). Comparison of techniques was not significantly affected by technicians. We concluded that adequate accuracy and precision were obtained by use of the 1‐m or 2‐m sampling technique, but not by the 0.3‐m or 4‐P techniques.
Modeling Long‐Term Crop Response to Fertilizer Phosphorus. I. The Model1
Authors: Wolf J. , de Wit C. T. , Janssen B. H. , Lathwell D. J.
Published: July 2010

Prediction of long‐term crop response to fertilizer P should result in more efficient use of this resource. To achieve this, a simple model designed to calculate the long‐term recovery of fertilizer P was developed and is presented here. In the model, both a labile and a stable P pool are distinguished. With time intervals of 1 yr, the model calculates the P transfers between the pools, the uptake of P by the crop, and the resulting pool sizes. Most input data required to operate the model can be obtained from ordinary one‐season fertilizer P trials. Input data, model parameters, and initial pools can be derived from field trials, and the model can be used to calculate long‐term recovery of fertilizer P. The sensitivity of the model is demonstrated by changing parameter values. The model can also be used to establish long‐term fertilizer recommendations for a certain target P uptake. Required rates of fertilizer P are calculated for different soils, fertilizer types, target uptakes, and periods of time.
Seeding Rates for Establishing Big Bluestem and Switchgrass with Preemergence Atrazine Applications1
Authors: Vogel Kenneth P.
Published: July 2010

The purpose of this study was to determine seeding rates for establishing switchgrass (Panicum virgatum L.) and debearded big bluestem (Andropogon gerardii Vitman) when atrazine |6‐chloro‐N‐ethyl‐ N'‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] is used as a preemergence herbicide. The high seed cost of these grasses makes it uneconomical to use higher seeding rates than necessary. The study was conducted on four eastern Nebraska sites during the period 1981 to 1985. The experimental design was a randomized complete block with six replications. Treatments were grasses (big bluestem and switchgrass) and seeding rates [107, 215, 325, and 430 pure live seeds (PLS) m−2] in a factorial arrangement. Plots were seeded in late spring with a plot seeder with double disk openers on a clean, firm seedbed, and broadcast sprayed with 2.2 or 3.0 kg ha−1 atrazine the day after seeding. Stands and forage yields were measured the first (Year 1) and second year (Year 2) following establishment. The 107 PLS m−2 seeding rate resulted in thinner, but still acceptable, stands (10–20 plants m−2) than the higher seeding rates in Year 1 and at two of the sites in Year 2. The stands from the higher rates, in general, did not differ within a site and were good to excellent ( >20 plants m−2). The lowest seeding rate produced lower forage yields than the other rates in Year 1, but these differences were significant at only one site. There were no differences for Year 1 yield for the other rates or for Year 2 yields for all rates.
Location, Year, Maturity, and Alfalfa Competition Effects on Mineral Element Concentrations in Smooth Bromegrass1
Authors: Casler M. D. , Collins Michael , Reich J. M.
Published: July 2010

Many environmental factors influence the level of herbage mineral elements and ratios, often to an extent potentially affecting ruminant performance. This study was conducted to estimate main effects and interaction effects of locations, years, stand types (pure stands vs. binary mixtures with alfalfa, Medicago sativa L.), and growth stages on the concentration of 11 mineral elements and three elemental ratios of smooth bromegrass (Bromus inermis Leyss.) herbage. Nine families of smooth bromegrass were grown in 2.7‐m2 plots, with and without alfalfa, at Hancock, WI (mixed, mesic, Typic Udipsamment soil) and Lancaster, WI (fine‐silty, mixed, mesic Typic Hapludalf soil). Plots were sampled for seven weekly intervals in 1982 and 1983, from the 17‐ to 22‐cm height stage to 7 days post‐anthesis. Stand types were whole‐plots in four randomized complete blocks; herbage samples were pairwise‐composited to provide two replicates. Samples were analyzed for P, K, Ca, Mg, S, Zn, Mn, Fe, and Cu by plasma emission spectroscopy and for N by micro‐Kjeldahl. Location, year, or stand type effects were significant for every element or ratio [Ca/P, N/S, and K/(Ca+Mg)]. The direction and magnitude of these effects varied considerably among elements and ratios. All three environmental effects (locations, years, and stand types) interacted strongly for most elements and ratios. All elements and ratios decreased with advancing maturity, except Ca/P, which increased. Relative changes over a 40‐day early May to mid‐June period were greatest for N (−97% of the overall mean) and smallest for Mn (−8% of the overall mean). Rate of change due to maturation for most elements tended to follow the pattern: 1982 > 1983, Hancock > Lancaster, and pure stands > mixed stands. For the diet of a moderately producing dairy cow (Bos spp.), smooth bromegrass herbage was severely deficient in P, Ca, Mg, S, Zn, Fe, and Cu at advanced stages of maturity, and excessive in K/(Ca+Mg) at all maturity stages. Although some of these deficiencies could be corrected by breeding, most would be more effectively corrected by fertilization or supplementation
Effects of Alfalfa Proportions and Clipping Frequencies on Timothy‐Alfalfa Mixtures. I. Competition and Yield Advantages1
Authors: Ta T. C. , Faris M. A.
Published: July 2010

Growing legumes in mixture with grasses has been of great interest to improve herbage production. The productivity of timothy‐ (Phleum pratense L.) alfalfa (Medicago sativa L.) mixtures at two plant density proportions (1:1 and 1:2) was compared with their component species grown in pure stands in the field (Manotick sandy loam soil, Typic Dystrochrett). In 1984 and 1985, the plots were harvested at the early, mid‐, and late‐bloom stages of alfalfa, which resulted in five, four, and three cuts per year, respectively. Results indicated that mix‐cropping timothy with alfalfa significantly increased both herbage and N concentration when compared to timothy grown in a pure stand. The magnitude of this increase correlated positively with the alfalfa proportion in the mixture. Although timothy had a dominant competitive ability over alfalfa in the first year (competitive ratio > 1), the situation was reversed in the second year at the higher alfalfa proportion. The land equivalent ratio of mixtures was always > 1 at different cuts under three harvest systems in both years, indicating the advantage of a timothy‐alfalfa mixture over a timothy pure stand, for herbage production. There was an indication that harvesting mixtures when alfalfa reached mid‐bloom (four cuts) increased total herbage and N concentration in both species when compared to harvesting at early (five cuts) or late (three cuts) bloom. Growing timothy in mixture at a high plant density‐proportion of alfalfa and harvesting when alfalfa reaches mid‐bloom stage provides high herbage and N yields of pasture.
Maleic Hydrazide Effects on Soybean Reproductive Development and Yield1
Authors: Helsel Zane R. , Ratcliff E. , Rudolph W.
Published: July 2010

Drift or misapplication of maleic hydrazide (MH) to tobacco (Nicotiana tabacum L.) sometimes effects neighboring soybean [Glycine max (L.) Merr.] fields. Our objective was to determine the effects of various rates and timings of MH application on soybean reproductive development and yield. Applications of 0.34 to 3.4 kg a.i. ha−1 were applied to soybean during the R3 to R6 growth stages. Significant (P<0.05) yield reductions from 30 to 100% occured when even low rates of MH were applied to soybean at growth stages R3 and R4. Yield losses occurred primarily as a result of decreased numbers of pods per plant. Injured soybean plants remained green until killing frosts. Plants treated with MH at the R5 and R6 stages experienced no yield loss and matured normally. Planting shorter‐season soybean cultivars early could result in soybean being past the sensitive stages when MH is applied, resulting in little or no injury if misapplication or drift occurs.
Tillage Effects on Soil Physical Properties and Wetland Rice Yield
Authors: Sharma P. K. , De Datta S. K. , Redulla C. A.
Published: July 2010

Puddling is the most common method of land preparation for wetland rice (Oryza sativa L.) in south and southeast Asia. While this method has certain advantages, it is time‐, energy‐, and capitalintensive. The objective of this study was to identify time‐, energy‐, and capital‐efficient tillage techniques for sustained productivity of wetland rice soils. The effects of different land preparation techniques on soil physical properties, root growth, and grain yield of wetland rice (cv. IR36) on two Philippine (IRRI) soils are reported. Bulk density, penetration resistance, and temperature of surface soil layers decreased with tillage intensity. In clay soil (Andaqueptic Haplaquoll with a water table of 0.30 m), the average daily water use (percolation + seepage + evapotranspiration) during a 90‐d irrigation period for zero tillage (dry‐seeded rice) was 37 mm d−1; zero tillage (transplanted rice), 35 mm d−1; minimum tillage, 34 mm d−1; and puddling, 30 mm d−1. The corresponding values for the clay loam (Typic Argiudoll with a water table > 1.2 m) were 393, 501, 263, and 164 mm d−1, respectively. Root‐length density (RLD) at the 0‐ to 0.10‐m depth at harvest was negatively correlated with soil bulk density at transplanting. On the other hand, grain yield was positively correlated with RLD, but negatively correlated with bulk density and soil penetration resistance and was less on zero‐tilled than on tilled plots. For the clay soil, grain yield (two‐season average) with minimum tillage was 26% higher than with zero tillage. for shallow puddling (one‐season data) and puddling, the figures were 33 and 28% higher. The corresponding values in clay loam soil were 36,66, and 56%, respectively. Zero and minimum tillage plots dried faster than puddled plots after they were drained at harvest; surface cracking was higher in puddled plots. In the clay soil and in both seasons, minimum tillage produced the same grain yield as puddling, and in such soil, minimum tillage may be an alternative to puddling, provided weeds are controlled.
Effects of Ozone and Water Stress on Canopy Temperature, Water Use, and Water Use Efficiency of Alfalfa
Authors: Temple Patrick J. , Benoit Larry F.
Published: July 2010

Ozone (O3) and soil water deficit are two environmental stresses that significantly affect the growth and yield of alfalfa (Medicago sativa L). However, little is known of the responses of field‐grown alfalfa to O3, and the effects of the interaction between O3 and water stress on canopy temperature and water relations of alfalfa have not been previously reported. The objective of this 2‐yr study was to determine the interactive effects of O3 and soil water deficits on canopy temperatures, water use, and water use efficiency (WUE) of alfalfa. Alfalfa (cv. WL‐514) was grown in 30‐3‐ by 5.5‐m plots on Wasco sandy loam (coarse‐loamy, mixed, nonacid, thermic Typic Torriorthents) in Shafter, CA, and was exposed in open‐top chambers to five levels of O3 for 12 h daily, from March to October of 1984 and 1985. Ozone treatments ranged from charcoal‐filtered air (CF) to twice ambient O3 concentrations. Each plot received either normal amounts of irrigation (NI) or 30% less than normal (WS). Canopy temperature‐air temperature differentials (Tc‐Ta) were significantly reduced by water stress an average of 27.9% in 1984 and 44.0% in 1985. Ozone also significantly reduced Tc ‐ Ta by 31% in NI and 37% in WS plots in 1984, but in 1985 O3 had no effect on Tc ‐ Ta. Water use, rate of soil water depletion, or depth of effective rooting zone were not affected by O3, hereas water stress significantly reduced all three. Water use efficiency was significantly reduced by O3, averaging 12% lower in nonfiltered compared with CF plots. The effects of O3 on WUE were attributed to premature senescence and abscission of older alfalfa leaves.
Influence of Chemical Drying Agent and Surfactant on Drying Time and Ruminal Nutrient Digestion of First‐Cutting Alfalfa Hay
Authors: Nocek James E. , Russell James B. , Fallon Janet B.
Published: July 2010

Drying agents and surfactants have been used to decrease field drying time of hay; however, little is known about their influence on ruminal digestion. This study was conducted to determine the effect of chemical drying agents (alkaline carbonates, 30 g L−1) or surfactant (actylphenoxypolyethoxyethanol, 0 to 0.164 ml L−1), or both, on field drying time and extent and rate of ruminal nutrient digestibility of alfalfa (Medicago sativa L.) hay. Untreated controls had longer drying times than treatments containing drying agent. Drying agent alone did not influence in situ dry matter (DM) or neutral detergent fiber (NDF) digestibility. Surfactant addition decreased the rate of DM and NDF digestion. Bacterial‐N contamination (fraction of residue N of bacterial origin) increased with time in the rumen for treatments receiving the highest surfactant concentrations. The rate of N digestion was faster when treatments contained drying agent plus surfactant. When examined with in vitro fermentation, surfactant concentrations greater than 0.0005 mL L−1 resulted in a greater than 80% reduction in digestion of filter paper. Surfactant had little effect on soluble starch fermentation, but there was an approximately 50% reduction both of ammonia production and cell protein, if protein hydrolyzate was the substrate. Amylolytic bacteria were less sensitive to the surfactant than cellulolytic species. The surfactant used in this study was inhibitory to rumen microorganisms and decreased the NDF digestion rate of alfalfa hay.
Trifluralin‐Substituted Amide Herbicide Interactions
Authors: Prosch S. D. , Weber J. B.
Published: July 2010

Substituted amide and dinitroaniline herbicides are used to selectively control annual grasses and certain broadleaf weeds in soybean [Glycine max (L.) Merr.]. Often, additional herbicide must be applied to control other broadleaf weed species. The objective of this study was to determine if combinations of selected soil‐applied herbicides could be used to control or suppress the growth in soybean of weeds that cannot be controlled with currently available herbicides. Field trials were conducted in 1982 and 1983 to evaluate the effects of two different application methods of trifluralin [2,6‐dinitro‐ N, N‐dipropyl‐4‐(trifluromethyl) benzenamine] and alachlor [2‐chloro‐ N‐(2,6‐diethylphenyl)‐N‐(methoxymethyl)acetamide] or metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐1 ‐methylethyl) acetamide] combinations for controlling broadleaf weeds, including morningglory (Ipomoea spp.) and jimsonweed (Datura stramonium L.), in soybean. No significant differences in the control of broadleaf weeds were found between a sequential application and a tank‐mix application of the two herbicides applied as a shallow incorporation. Both herbicide combinations provided good to excellent control of morningglory, and fair to good control of jimsonweed. The control of three Ipomoea species was not significantly different when combinations included either substituted amide. Greenhouse sand culture studies showed significant interaction effects of trifluralin plus alachlor combinations on the growth inhibition of soybean, hemp sesbania [Sesbania exaltata (Raf.) Rydb. ex A. W. Hill], morningglory, jimsonweed, velvetleaf (Abutilon theophrasti Medik), and sicklepod (Cassia obtusifolia L.). Soybean was much less sensitive to the herbicide interaction effects than were broadleaf weeds.
Nitrogen and Mineral Content of Selected Wild and Cultivated Genotypes of Jerusalem Artichoke
Authors: Seiler Gerald J.
Published: July 2010

Jerusalem artichoke (Helianthus tuberosus L.) can be a weed in pastures and crops or used as silage, but little is known about its N and mineral content and their contribution to forage quality. This study evaluated 19 wild and cultivated genotypes of perennial Jerusalem artichoke for protein and mineral concentrations at various stages of maturity, and compared these to an annual cultivated sunflower (H. annuus L.), ‘Hybrid 894’. The field experiment was conducted on Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll) at Bushland, TX. The 19 perennial genotypes and the commercial sunflower, Hybrid 894, were planted in pure stands. Leaves, stems, and whole plants were evaluated at vegetative, flowering, and fruiting stages to ascertain their nutritive value for ruminants. Crude protein (CP) concentrations of 140 g kg−1 and above occurred in leaves of 11 of 19 genotypes at the vegetative stage. Fifteen of the 19 genotypes had whole plant CP of 60 to 90 g kg−1 at all stages of maturity. Nutritionally adequate amounts of Ca (2− 8.6 g kg−1) were present in leaves, stems, and whole plants of all genotypes at all stages of maturity. Nutritionally adequate amounts of Mg (1 g kg−1) and K (6.5 g kg−1) were present in leaves and whole plants of most genotypes at all stages of maturity. Leaves, stems, and whole plants of most genotypes had suboptimal P (<2 g kg−1) levels for ruminants at all stages of maturity. Nutritionally adequate amounts of CP, Ca, Mg, and P were present in whole seeds of most genotypes. At varying maturity stages, nutrient levels of some artichoke genotypes are comparable to that of cultivated sunflower. Whether Jerusalem artichoke is mixed with other forbs or grasses in a pasture or hay, or whether it is used as silage, it appears to have the potential to provide a satisfactory nutrition level for ruminants.
A Field Technique to Study Root Growth in Peanut
Authors: Kvien C. S. , Schroeder J. , Banks P. A.
Published: July 2010

Traditional techniques for the field study of root growth usually require extensive monitoring devices and a large labor force. We have developed a simple field technique to study root growth using the carotene‐inhibiting herbicide, fluridone {1‐methyl‐3‐phenyl‐5‐[3‐(trifluoromethyl)phenyl]‐4(1H)‐pyridinone}. Underground bands (0‐ to 15‐, 20‐ to 35‐, or 40‐ to 55‐cm vertical depth, 5 cm in width) of fluridone were sprayed into location using fan nozzles mounted on a subsoil tine. The experiment was conducted near Tifton, GA, on a Tifton loamy sand (fine‐loamy, siliceous, thermic Plinthic Paleudults). Peanut (Arachis hypogaea L.) seed were hand planted in 3‐m‐long rows at a 23° angle to the band. The horizontal distance from row to fluridone band varied from 0 to 1.2 m. A root growth profile was generated by measuring, three times a week, the horizontal distance from the band to the farthest plant showing leaf bleaching. This technique provided a simple and accurate method for determining root growth patterns in peanut.
Crop Water Stress Index and Yield of Water‐Deficit‐Stressed Alfalfa
Authors: Hattendorf M. J. , Carlson R. E. , Halim R. A. , Buxton D. R.
Published: July 2010

The yield relationship of water‐deficit‐stressed alfalfa (Medicago sativa L.) with the Crop Water Stress Index (CWSI) may be dynamic over the alfalfa harvest period. This investigation was conducted to define the alfalfa yield‐CWSI relationship(s), to test possible advantages of using the CWSI over the canopy‐minus‐air temperature (Tc−Ta) differential, and to combine the yield‐CWSI relationship with a growth function. ‘Apollo II’ alfalfa was grown for 2 yr in 100‐L containers set into the ground and protected from rain by a movable shelter. The soil was a Nicollet silt loam topsoil (fine‐loamy, mixed, mesic Aquic Hapludoll). Treatments were irrigation levels of 112, 100, 88, 77, and 65% field capacity. Five harvests were taken at 7‐d intervals beginning 21 d after an initial clipping. Canopy temperatures were taken daily with an infrared thermometer. A series of exponential yield‐CWSI curves resulted from the sequential harvests. Yield reductions of about 10 and 20% resulted from mean CWSI of 0.05 and 0.10, respectively, over 42‐d periods. The Gompertz growth function was modified for water‐deficit‐stress by combining it with the exponential yield‐CWSI relationship. Vapor‐pressure deficit (VPD) effectively normalized the Tc−Ta data, allowing yield data of the 2 yr to be combined in the yield‐mean CWSI relationship. Yield and Tc−Ta data not normalized for VPD showed clear separation by year for slight VPD differences. Alfalfa yield response to water‐deficit‐stress over time appeared to be adequately described by the combined Gompertz function and the yield‐CWSI (Tc−Ta normalized for VPD) curves.
Germination Requirements of a Perennial Alysicarpus vaginalis Accession
Authors: Singer K. L. , Pitman W. D.
Published: July 2010

Germination of a perennial alyceclover [Alysicarpus vaginalis (L.) DC.] accession, which has potential value as a grazing‐tolerant pasture legume for peninsular Florida and some tropical locations, was evaluated for response to seed storage and scarification treatments. Both practical means of enhancing germination and characteristics of germination limitations were considered. A series of experiments evaluated responses to storage time, storage temperature, physical seed coat disruption with sandpaper, and exposure to steam, hot water, and dry heat. Freshly harvested seed failed to germinate regardless of seed treatment. Seed that had been stored for 3 to 8 yr produced rapid, essentially complete germination when scarified with sandpaper. A storage period of approximately 16 wk was sufficient for rapid germination regardless of storage temperature. At 4 wk of storage, a storage temperature of 7°C resulted in higher germination than storage at 24°C. Steam exposure times of from 40 min to 2 h or exposure to 80°C water for 5 to 10 min produced slow germination rates but greater than 60% germination after 56 d. Exposure to dry heat for 6 or 12 h produced poorer results (48% germination at 56 d) than steam or hot water. These heat treatments could have value either where mechanical scarification is not available or in situations where sporadic, early season rainfall creates high pasture establishment risks for seed lots that have been scarified to provide rapid, complete germination. Failure of scarified, imbibed, fresh seed to germinate indicates a physiological limitation to germination. Rapid, essentially complete germination of these seed lots after storage periods of from 16 wk to a number of years indicates that an afterripening period overcomes this limitation. Physical seed coat impermeability or hardseededness is demonstrated by the need for scarification even in seed that has been stored long enough to meet the after‐ripening requirement.
Persistence of Reed Canarygrass Clones in Binary Mixture with Alfalfa and Birdsfoot Trefoil
Authors: Jones T. A. , Carlson I. T. , Buxton D. R.
Published: July 2010

Competitive exclusion of one component of a binary perennial grass‐legume mixture by the other component is common, but the persistence of both components is desired. Fourteen reed canarygrass (Phalaris arundinacea L.) clones, exhibiting a range for drymatter yield (DMY), tiller density, and tiller weight, were grown in alternate‐plant binary mixture with ‘Olympic’ or ‘Baker’ alfalfa (Medicago sativa L.) or ‘Norcen’ or ‘Dawn’ birdsfoot trefoil (Lotus corniculatus L.) under a three‐cut‐per‐year management. The objectives were to determine if reed canarygrass clones and legume cultivars interact for DMY and legume concentration, to determine if the ranking of 14 reed canarygrass clones for legume concentration remained consistent across harvests, to compare the importance of tiller density and tiller weight to reed canarygrass DMY in legume mixtures, and to characterize the changing relationship between DMY of reed canarygrass and companion legumes over time. Alfalfa and birdsfoot trefoil concentrations increased from 266 and 159 g kg−1, respectively, at Harvest 1 (8 June 1983), to 937 and 856 g kg−1, respectively, at Harvest 7 (7 June 1985). Interaction between reed canarygrass clones and legume cultivars generally did not accompany significance of main effects, and ranks for legume concentration among reed canarygrass clonal mixtures stabilized by Harvest 2 (26 July 1983). Thus, it may be relatively easy to characterize reed canarygrass clones for legume compatibility. In mixtures, differences in tiller density among reed canarygrass clones usually accounted for more variation in reed canarygrass DMY than differences in tiller weight. A negative relationship between reed canarygrass DMY and legume DMY was always present. Though legumes increasingly dominated reed canarygrass over time, the rate of increase of their domination slowed as legume concentration increased.
In‐Office Retrieval of Literature with Microcomputers
Authors: Pawlak J. A. , Murray D. S. , Nofziger D. L. , Chun Sei , Reynolds D. B.
Published: July 2010

Current literature searches or retrieval systems generally require strict appointment schedules with operating personnel and are limited to articles published after 1968. A complete data base and a program for rapidly searching the data base in the convenience of one's office would increase literature retrieval efficiency. A searching program and complete data base for the journals Weeds, Weed Science, and Weed Technology, were developed and combined into a total system named WeedLit. The software requirements include the data base “Citation” and the retrieval program “Litsearch.” Hardware requirements include a computer capable of running MS‐DOS or PC‐DOS with a minimum of 512K bytes of RAM and a fixed disk with 4M bytes of free space for Citation. The data base contains all articles published in Weeds from 1952 to 1967, in Weed Science from 1968 to the present, and in Weed Technology from 1987 to the present. Each article in Citation consists of 10 fields containing information on the journal, author(s), title, year, volume, and page numbers, as well as crop(s), weed(s), pesticide(s), and keyword(s) that are pertinent to the content of the article. The LitSearch retrieval program was written in TurboPascal and is capable of rapidly searching the data base. Searches are conducted through the use of search units, which are composed of the field to be searched, a comparison operator, and the text to be searched for within the specified field. The LitSearch retrieval routine is capable of searching on any combination of up to 12 search units. Output options include three format types that can be directed to the screen, a printer, or an ASCII file. Retrieval times vary with complexity of the search as well as with computer model. Complex retrievals take approximately 6 min to complete on an IBM‐PC but can be conducted in less than 2 min with an AT‐type machine.
Seasonal Leaf Area‐Leaf Weight Relationships in the Cotton Canopy
Authors: Reddy V. R. , Acock B. , Baker D. N. , Acock M.
Published: July 2010

Specific leaf area (SLA), the ratio of leaf area to leaf dry weight, is used in crop simulation models to estimate total leaf area or dry weight. This experiment was designed to study changes in SLA in various parts of a cotton (Gossypium hirsutum L.) canopy throughout the growing season. The main stem of the cotton plant was divided into five‐node segments. Leaf area and leaf dry weight were measured for each segment throughout the growing season. The mean seasonal SLAs for the segments from the bottom to the top of the canopy were 26.2, 25.6, 20.9, 19.4, and 18.1 m2 kg−1. Except for the uppermost segment, SLA increased from 43 to 90 d after emergence (DAE) and declined from 100 DAE. The decline coincided with boll maturation but also with canopy defoliation. It was possible to account for 93% of the variation in SLA for all segments by plotting SLA against light flux density within the cotton canopy. Variations in SLA with time, growth stage, and leaf maturity were small to insignificant when variation due to light flux density was removed. Sampling for SLA should include leaves throughout the crop canopy. Modelers who use SLA to estimate total leaf area or dry weight should determine the relationship between SLA and light flux density for their particular crop.
An Electronic Meter Stick
Authors: Arkebauer T. J. , Norman J. M.
Published: July 2010

A simple device is described which facilitates the recording of repetitive length measurements in the field. The data are stored in a portable data logger for subsequent transfer to a microcomputer. A comparison between actual lengths, and lengths as measured and recorded with the device shows the error associated with this method to be less than 1%.
Corn‐Peanut Intercrop Performance in Relation to Component Crop Relative Planting Dates
Authors: Misbahulmunir M. Y. , Sammons D. J. , Weil R. R.
Published: July 2010

A two‐yr (1982 and 1983) field study was conducted to determine the vegetative and reproductive effects of three intercrop treatments on corn (Zea mays L.) SS 335 A hybrid and peanut (Arachis hypogaea L.) ‘Florunner’. Three planting time treatments of corn relative to peanut (2 or 3 wk before, simultaneous, and 2 or 3 wk after) were compared. Sole crops of each species were also established. Initial vegetative growth of peanut was greatest when intercropped with corn planted after peanut. Intercropped corn planted before peanut matured early but, after harvest, did not result in an environment favorable for peanut to compensate for early season growth reductions. Dry weights of intercropped peanut, regardless of relative time of corn planting, were reduced to half or less of those of sole‐crop peanut. Reproductive development of both species when intercropped was generally not affected by relative planting times. Grain yields of intercropped corn were 85 to 90% and 46 to 74% of sole‐crop yields in 1982 and 1983, respectively. Intercropped peanut yielded 33 to 37% and 47 to 49% of sole‐crop yield in 1982 and 1983, respectively. Land equivalent ratios for intercrop combinations were not significantly affected by relative planting times; they ranged from 1.20 to 1.25 and 0.96 to 1.26 in 1982 and 1983, respectively. Corn contributed 69 to 72% and 49 to 62% of total intercrop production in 1982 and 1983, respectively. The results suggest that greatest total productivity in a corn‐peanut intercrop will occur when corn is planted either simultaneously with or earlier than peanut. The highest intercrop peanut yields tended to occur when corn and peanut were planted simultaneously.
Grain Sorghum Yield and Susceptibility to Insects as Affected by Early Season Growth
Authors: Karlen D. L. , Sadler E. J. , Roach S. H.
Published: July 2010

Vigorous and uniform seedling emergence and growth are considered essential for profitable crop production. The objective of this note is to document the effect of nonuniform growth, apparently caused by differences in planting depth, on the susceptibility of grain sorghum [Sorghum bicolor, (L.) Moench] to Heliothis zea (Boddie) in a production environment. Observations were made within an 8‐ha field near Florence, SC, where differences in productivity among 17 soil map units representing seven soil series classified as Ultisols were being determined. The center two rows of each six‐row planting configuration grew more slowly than and reached the boot and bloom growth stage approximately 7 to 10 d after the outside rows. During early grainfill this delayed growth and development resulted in more than 90% infestation of the center rows by Heliothis zea compared with less than 10% infestation in the outside rows. Differential growth and subsequent Heliothis damage to the crop were similar across all soil map units. Average grain yield was reduced from 3110 to 1640 kg ha−1, apparently because deeper seed placement slowed plant growth and development enough that there was subsequent synchronization between a third generation Heliothis flight and flowering. This demonstrates that nonuniform plant growth and seasonal insect populations can reduce yield by nearly 50% in the Southeastern Coastal Plains.
Irrigation Effects on Water Use, and Production of Tap Roots and Starch of Buffalo Gourd
Authors: Nelson J. M. , Scheerens J. C. , Bucks D. A. , Berry J. W.
Published: July 2010

The buffalo gourd (Cucurbita foetidissima HBK) is a possible new root starch crop for semiarid regions. Information on water use relationships of this species is needed to determine its suitability for arid lands agriculture. The objective of this study was to assess the influence of water management on buffalo gourd tap root production and water use. Five irrigation levels were evaluated for an annual buffalo gourd crop in 1985 and 1986 at a 360‐m elevation field site on Casa Grande sandy loam (fine‐loamy, mixed, hyperthermic Typic Natrargid) using plant populations of 400 000 to 450 000 plants ha−1. Irrigating at 50% available soil water (ASW) content (I1) gave higher fresh tap root yields than irrigating at 75% ASW (I2) (27.8 vs. 24.1 Mg ha−1) in 1985 with identical starch yields. In 1986 the I2 treatment was higher than the I1 treatment in starch yield (3.1 vs. 2.1 Mg ha−1) and tap root starch concentration (47.5 vs. 38.1%). Vines of water stressed plants (I2) grew rapidly when irrigated. Consumptive water use was 649 and 487 mm in I1 and I2, respectively. Peak consumptive use rates were <6.5 mm d−1. As much as 48% of seasonal water use was from the 0 to 0.4 m soil depth. Water was extracted to a depth of 2.6 m. The I2 treatment had the highest wateruse efficiency (WUE), 4.9 kg m−3, for fresh root production. The WUE for starch production was higher for the I2 treatment (0.62 kg m−3) than the I1 treatment (0.42 kg m−3). Irrigation scheduling to provide moderate stress reduces buffalo gourd water use without reducing starch yield, increasing its potential as a semiarid starch crop.
A Pinpunch Apparatus for Quantifying the Growth Rate Distribution in Monocot Leaves
Authors: Arkebauer T. J. , Norman J. M.
Published: July 2010

The expansion of monocot leaves in the field is needed to understand the effects of various treatments on plant growth. A pinpunch method (sample destructive) is described that measures the growth rate distribution of the leaf. This method uses a surplus chart recorder, a linear potentiometer, and a data logger. Three sources of error are described in detail and data is presented that compares relative growth rate of plants with differing total water potentials. The relative growth rate as a function of distance from the node of the expanding leaf, can be determined.
Root and Herbage Growth Response of Birdsfoot Trefoil Entries to Subsoil Acidity
Authors: Alison M. W. , Hoveland C. S.
Published: July 2010

Stand productivity and longevity of legumes are often limited by subsoil acidity in the highly weathered soils of the eastern USA. This study was conducted to determine differences among four birdsfoot trefoil (Lotus corniculatus L.) entries for tolerance to acid subsoil. The entries were grown in the greenhouse in 13 ✕ 60 cm polyethylene tubes containing a representative profile of Appling sandy loam (clayey, kaolinitic, thermic Typic Hapludult) soil. The surface soil (0 to 15 cm) was limed to pH > 6.0. The subsurface soil (15 to 60 cm) was either limed (pH > 6.0) or not limed (pH < 4.9). All entries had similar root length in the surface and subsurface soil when subsurface soil was limed. Root length of GA 1, ‘Norcen’, and ‘Fergus’ in unlimed subsurface soil was 93, 52, and 35%, respectively, of the ‘AU Dewey’ root length. Root length of AU Dewey in the surface soil was nearly twice as much when the subsurface soil was not limed as when it was limed. Root length of the other entries was similar in the surface soil, regardless of the subsurface soil treatment. Herbage yield of AU Dewey was similar on limed and nonlimed soils, while herbage growth by the other entries was less when the subsurface soil was not limed. Relative herbage yields of AU Dewey, Norcen, GA 1, and Fergus with acid subsurface soil were 100, 68, 64, and 24%, respectively. These differences show that birdsfoot trefoil cultivar selection in acid soil environments is important and that breeding for acid soil tolerance may be possible.
Vehicle‐Mounted Hydraulic Sampler for Urban Soils
Authors: Hipp Billy W. , Graff Paul S.
Published: July 2010

Sampling soils in landscapes and research plots in urban settings is normally done by hand because motorized samplers lack the mobility and small size. To facilitate sampling urban soils, a vehicle‐mounted hydraulic sampler was constructed by making minor modifications to commercially available equipment. The unit consists of a hydraulic sampler with self‐contained engine and hydraulic pump mounted on the back of a turf utility vehicle. Soil cores are taken with a 32 mm diam. ✕ 0.46 m long slotted tube. Samples can be taken to 1.2 m depth.