bluuebunny/crossref_metadata_2025 huggingface dataset:
Yield and Quality of Cicer Milkvetch Forage as Influenced by Cutting Frequency1
Authors: Townsend C. E. , Christensen D. K. , Dotzenko A. D.
Published: July 2010

Cicer milkvetch (Astragalus cicer L.) is a potentially valuable forage crop for irrigated pastures, but little information is available concerning the effects of management practices on forage production. Therefore, the objective of this field study was to evaluate the effect of six harvest treatments on yield, forage quality, weed invasion, and persistence of stand. The study was conducted under irrigation on a Nunn clay loam soil (aridic Argiustoll). The treatments consisted of clipping the forage two, three, four, five, six, and seven times annually for 3 years to a height of 7.5 cm. Forage yields and weed counts were taken for 3 years, and seven quality factors and four mineral elements were evaluated for 2 years. Total nonstructural carbohydrates in the rhizomes were measured at the end of the 3rd harvest year. There were significant differences in yield among harvest treatments in 2 of 3 years and for the 3‐year average. In general, the two‐ and three‐cut treatments were the most productive with 3‐year average yields of 10.5 and 10.7 metric tons/ha, respectively. Considerably more weeds were present in the five‐, six‐, and seven‐cut treatments than in the two‐, three‐, and four‐cut treatments. Annual weeds were most prevalent during the first 2 years, but by the 3rd year dandeloins (Taraxacum spp.) were the most common. Although there were significant differences among treatments for total nonstructural carbohydrates in the rhizomes, the differences were not associated with persistence because persistence of stands was excellent for all treatments. In vitro dry matter digestibility (IVDMD) and all chemical constituents evaluated, with the exception of magnesium and potassium, differed significantly among treatments each year. In general, cell wall constituents (CWC) and cellulose decreased with an increase in the frequency of cutting. Protein, IVDMD, and phosphorus increased as the number of cuttings increased. Lignin, hemicellulose, silica, calcium, magnesium, and potassium varied among cutting treatments. The quality of cicer milkvetch forage was high for all cutting treatments. Based on yield, quality, and stand persistence cicer milkvetch has the attributes of a desirable forage species.
Seasonal Changes in Reflectance of Two Wheat Cultivars1
Authors: Leamer R. W. , Noriega J. R. , Wiegand C. L.
Published: July 2010

Accurate crop identification from remote sensing signals is dependent on a knowledge of differences in characteristics of reflectance from various crop canopies. The objective of the present work was to follow changes in the reflectance of two dissimilar wheat [Triticum aestivum (L.)] cultivars through a growing season to determine which reflectance characteristics were suitable for use in the analysis and interpretation of spectral reflectance curves. Reflectance over the wavelength interval of 0.45 to 2.50 μm was measured with a ground‐based spectroradiometer on nine cloud‐free days between planting and maturity of wheat planted on Hidalgo sandy clay loam (Typic Calculstols) soil. Seeding rate affected the rate of ground cover, but not the spectral reflectance of either a winter or a spring wheat once about 25% of the area was covered by vegetation. All reflectance curves had the characteristic shape for vegetated surfaces by 4 weeks after emergence. The proportion of the ground covered by plants was more important than development stages of the plants in determining spectral responses, except at the end of the season when the plants senesced and lost pigmentation. Through the season soil was much less reflective than green vegetation at 0.75, 0.90, and 1.10 μm and much more reflective at 1.65 and 2.20 μm, making these wavelengths valuable for distinguishing vegetation from soil background and for assessing vegetation cover or density.
Bayes Least Significant Difference: A Review and Comparison1
Authors: Smith C. Wayne
Published: July 2010

The Bayesian approach to mean separation overcomes the objections to previous least significant difference (LSD) procedures by having a direct dependence upon the calculated F value. This procedure has the power of a comparisonwise approach when F is moderate to large in size and is conservative at F values less than about 3.0. The Bayes LSD has the same form as the Fisher LSD, i.e., LSD = sdt, where the Bayes t is not to be confused with Student's t. In the example cited, the Bayes LSD was found to be a more powerful test than the Fisher LSD, Tukey's honest significant difference (HSD), or the Duncan new multiple range (DMR) when F = 45.36, moderate in size and comparative to the Fisher LSD and the DMR when F = 4.43, and conservative and comparable to Tukey's HSD when F = 1.4. The use of BLSD rather than LSD to designate the Bayes Least Significant Difference procedure is suggested.
Response of Soybeans to Commercial Soil‐Applied Inoculants1
Authors: Nelson D. W. , Swearingin M. L. , Beckham L. S.
Published: July 2010

Recent development of soil‐applied inoculants, which have been advertised in midwestern states as increasing yields by an average of 10%, has stimulated a great deal of interest among soybean (Glycine max (L.) Merr.) producers. Field studies with two soybean varieties were conducted over 2 years (three different cultivars were used), to evaluate crop response to application of commercial soil‐applied Rhizobium japonicum inoculants. Conventional seed‐applied inoculants were also studied for comparison of effectiveness. Plots were established on a highly productive silty clay loam soil which had not been cropped to soybeans for more than 15 years (the native population of rhizobia was assumed to be low). Grain yields, nodulation, and leaf and grain composition were measured. Inoculation of soil or seeds with commercial inocultants did not increase yield, nodule mass per plant, or leaf and grain N concentration. Small, but inconsistent, changes in total P concentration of grain were obtained from inoculation. Soil inoculants were not superior to seed‐applied inoculants for soybeans. These results combined with recent findings of other investigators (personal) communications from G. E. Ham and R. E. Smith) suggests that yield responses to soil or seed inoculants are unlikely in Cornbelt soils where soybeans are grown with some regularity because of a sufficient population of “native” rhizobia. There appears to be little justification for recommending in oculation of soybeans except where soybeans are to be planted in a field for the first time or where a previous crop was poorly nodulated.
Effect of Leaf Shape and Plant Population on Rate of Fruiting Position Appearance in Cotton1
Authors: Kerby T. A. , Buxton D. R.
Published: July 2010

Rate of appearance of fruiting positions in cotton (Gossypium hirsutum L.) is an important component of earliness. The objective of this research was to evaluate the influence of leaf type (size) and population density on rate of fruiting position appearance along branches of individual plants. Normal, okra, and superokra leaf cotton plants were grown in rows 51 cm apart in irrigated basins at 11.2 and 18.5 plants/m2 in 1973, and 10.0 and 20.0 plants/m2 in 1974. Fruiting positions reaching anthesis were tagged daily. Rate of appearance was determined by observing the number of days between successive fruiting branches (sympodial plastochron) and the number of days between first fruiting positions of successive fruiting branches (monopodial plastochron). Plants grown in high population densities generally had larger sympodial and monopodial plastochrons (longer time intervals between appearance of fruiting positions) than plants in the low population. Okra and superokra plants had smaller monopodial plastochron and larger ratios of sympodial to monopodial plastochrons than normal leaf plants. Sympodial plastochron increased from early to mid‐season and then declined. Monopodial plastochrons increased from early season to plateau values at mid‐season. The seasonal changes in plasto‐chrons did not appear to be related to changes in temperature. This study shows that both leaf type and population density affect rate of fruiting position appearance and earliness in cotton but changes in temperature found in fields may have little effect on plastochrons.
Influence of Rhizobium japonicum Strains and Inoculation Methods on Soybeans Grown in Rhizobia‐populated Soil1
Authors: Boonkerd Nantakorn , Weber D. F. , Bezdicek D. F.
Published: July 2010

Indigenous rhizobia in field soils previously planted to soybeans (Glycine max L. Merr.) usually preclude the nodulation by rhizobia applied as inoculants. However, the introduction of superior N fixing strains is still considered an important management goal. This study was conducted in a rhizobia‐populated field soil (Fluvaquentic dystrochpepts) using three strains of R. japonicum (62, 76, and 110). Each strain was used at 1× and 10 × rates of peat inoculum applied to the seed and at 1×, 10× and 100× rates of liquid inoculum applied over the seeds in the row. The objective was to determine if applied strains could compete with indigenous rhizobia for nodule sites and enhance N fixation. Inoculation by either method or with any rate or strain did not effect nodulation or plant growth. However, when the level of strains 62 and 110 in broth was increased 10 and 100 times the initial rate, the recovery of applied strains increased. Peat inoculum applied at 10 times the initial rate did not appreciably change the serogroup distribution in nodules. Strain 76 did not form an appreciable percentage of the nodules at any rate or method of inoculation because it was less competitive than the predominant strains in the field soil. Increased inoculum rates applied by different methods, while only partially successful in displacing indigenous soil rhizobia, demonstrate the need for continued evaluation of innovative methods of applying efficient rhizobia which can compete for nodule sites in the field.
In situ Root Studies Using Neutron Radiography1
Authors: Willatt S. T. , Struss R. G. , Taylor H. M.
Published: July 2010

Most studies of plant roots growing in soil involve destructive sampling or involve estimates of root growth only at a soil‐viewing surface interface where growth conditions are different from those in bulk soil. This research tested the feasibility of using preferential attenuation of thermal neutrons by roots to overcome these two disadvantages of current methods. Radiographs were obtained of soybean [Glycine max (L.) Merr.] and corn (Zea mays L.) roots growing through bulk samples of unsaturated soil.

Plants were grown at 22 C in loamy sand soil wetted to 9% volumetric water content. The soil was contained in either 2.5‐ or 5.0‐cm thick aluminum boxes. At irregular intervals, the sample containers were transferred into a 6° diverging 0.04eV (thermal) energy neutron beam obtained from the Ames Laboratory Research Reactor, U. S. Energy Research and Development Administration, Iowa State University, Ames, Iowa. The samples were exposed to the neutron beam for 8 to 10 min. This exposure allowed about 5 × 109 neutrons/cm2 to strike an indium collector plate attached to the rear of the container. After the collector plate was removed from the neutron beam, photographic film was attached to the collector plate for 1 ½ hours; then the film was processed.

The preferential neutron scattering by the roots allowed elongation rates of soybean radicles or seminal roots of corn to be determined easily through either 2.5‐ or 5‐cm thick soil samples. Small lateral roots of either species were less clearly distinguishable and resolution must be improved before elongation rates can be measured for laterals with a diameter smaller than 0.33 mm. Plants were not harmed visibly by the thermal neutron fluxes used in these experiments.
Accumulation and Redistribution Pattern of Dry Matter and N in Triticale and Wheat Varieties under Water Stress Condition1
Authors: Lal Pyare , Reddy G. G. , Modi M. S.
Published: July 2010

Accumulation of dry matter and N in a cereal plant indicates its potentiality for yield, but its mobilization to the reproductive sink is important for higher economic yield. We studied this mobilization in triticale (Triticale hexaploide Lar.)), a recently developed crop which might compete with wheat (Triticum aestivum L.). The objective was to screen varieties of triticale relative to wheat for their high translocation ability and N utilization efficiency.

A field experiment was conducted on silt loam soil (Typic Hapludoll) during 1973–74 at Pantnagar, India. Treatments consisting of five varieties each of triticale (‘Bronco 90’, ‘Armadillo PM 112’, ‘Armadillo PM 113’, ‘Armadillo PM 114’, and ‘Armadillo PPV 13’) and wheat (‘C 306’, ‘K 65’, ‘K 68’, ‘Kalyansona’, and ‘Sonalika’) were arranged in a randomized block design with five replications. Plant samples were collected from a 0.125‐m2 area for dry matter and N content studies in culm, lower leaf, flag leaf, spike chaff, and grain at successive stages. The loss of dry matter from different plant parts was assumed to be translocated to the grains.

Both triticale and wheat cultivars differed greatly in their capacity to accumulate and redistribute dry matter and N. Bronco 90 and Armadillo PM 112 triticale cultivars, and C 306 and K 65 wheat cultivars, accumulated greater amounts of dry matter and N than the other varieties. The dry matter losses, presumably because of translocation to kernels, varied from 12.9% (Armadillo PM 113) to 36.9% (Armadillo PM 112) in triticale, and from 19.2% (C 306) to 31.6% (K 68) in wheat. In translocation of N to grain, Bronco 90 (58.4%) and Kalyansona (61%) were the most efficient cultivars of triticale and wheat, respectively. Such cultivars should be selected for further improvement in yield. Armadillo PM 112 and C 306, the top yielding cultivars in respect of grain, removed the largest quantities of N (75.7 and 5.93 kg N/ha). On an average, triticale cultivars removed larger amounts of N than the wheat. Selecting varieties that are more efficient in use of N would help in economizing N fertilizer, which is urgent in today's crop production.
Seasonal Production, Perloline Content, and Quality of Fescue After N Fertilization1
Authors: Fribourg Henry A. , Loveland Richard W.
Published: July 2010

The already great importance of tall fescue (Festuca arundinacea Schreb.) as a forage grass could be enhanced if its yield and quality during summer, fall, and winter could be increased. The effects of several rates (from 50 to 700 kg/ha) and times (March, May, July, September, October, November—singly or in different combinations) of N fertilizer application on tall fescue seasonality of production and quality were evaluated over a 3‐year period. Herbage was removed at a 5‐cm stubble whenever growth reached 8 to 10 cm. Variables measured included dry matter production in vitro digestible dry matter (IVDDM), and contents of perloline, and total and nitrate N. Nitrogen fertilizer increased yield and total N, NO3‐N and perloline in harvested forage. Season affected IVDDM more than N fertilization, although the higher or more frequent N rates increased IVDDM indirectly. Increases in total N, NO3‐N and perloline were evident in individual harvests soon after N applications, but yield increases were not observed until precipitation occurred. Summer N fertilization to increase yield is therefore questionable unless soil moisture is present, and it may result in higher NO3‐N and perloline contents than are desirable for quality forage. Applying more than 50 kg N/ha in September did not increase appreciably quality and quantity of fall forage. Late fall N fertilization did not increase measurable winter forage production, but it did increase earliness and yield the following spring.
Use of Methanol‐Water Solutions for Freeze Protection of Tensiometers1
Authors: Wendt C. W. , Wilke O. C. , New L. L.
Published: July 2010

The use of tensiometers to schedule irrigations has teen limited primarily to summer crops because of water freezing in the tensiometers during the winter months. Since methanol‐water mixtures have lower freezing points than water, a greenhouse study was conducted using an Olton loam soil (Acridic Paleustolls) to determine the effect of a methanol‐water mixture (30% methanol by volume) on tensiometer readings and plant growth. No major effects of tensiometer readings or plant growth Mere noted. Results from a field demonstration on irrigated winter wheat (Triticum aestivum L.) indicate that tensiometers with such mixtures can be used to estimate soil water tension changes at atmospheric temperatures down to −18.8 C.
A New Fiber Optic Technique for Measuring Root Growth of Soybeans Under Field Conditions1
Authors: Sanders J. L. , Brown D. A.
Published: July 2010

An experimental procedure, described in this paper, involved the use of a highly refined fiber optic duodenoscope for observing and photographing root development patterns within a soil profile. The root was monitored by inserting the unit into a transparent Plexiglas tube imbedded within the root zone. This technique permitted the observation and quantitative characterization of the root system throughout the entire growing season, which, until this time, has been excessively expensive, laborious, time consuming, and nonreproducible. Root lengths for soybeans [Glycine max (L.) Merr. ‘Lee‐68’] at the R‐7 stage of maturity were calculated and compared by the duodenoscope and the Newman‐Core methods at four depth‐intervals. The depth intervals were reported as 0–18, 18–36, 36–54, and 54–72 cm in a Peridge silt loam (Typic Paleudalf; fine silty, mixed, mesic). Total root lengths estimated by the Newman‐Core method for the 0 to 72 cm depth‐intervals was 56.36 m, while the estimate by the scope was 52.84 m. Although both methods gave similar results, the scope tended to estimate a greater root length than did the soil cores at all depths except the 0 to 18 cm. Both methods showed that the majority of the root system was in the 0 to 18 cm depth; 68% for the soil cores and 47% for the scope. Root density (cm/cm3) decreased with soil depth from 10.58 to 1.52 by the soil core method and from 6.77 to 2.83 for the scope measurement. The coefficient of variation was 52.64 and 14.10 percent for the core and scope measurements, respectively. The study indicated that the duodenoscope method can be used as a nondestructive technique for quantitatively measuring soybean root systems throughout the growing season.
Seedlings Stage Drought Response in Rice1
Authors: O'Toole J. C. , Aquino R. S. , Alluri K.
Published: July 2010

Drought‐related problems of crop establishment occur in many of the world's rainfed rice (Oryza sativa L.) growing areas. Little effort has been made to breed improved cultivars for these chronically drought‐prone areas. In this note, we report investigations on the feasibility of controlled‐environment evaluation of seedling stage drought resistance among rice cultivars. Rice cultivars were grown in a glasshouse to the three leaf stage and then placed in a growth chamber with programmed diurnal changes in light, temperature, and humidity. After a 10‐day exposure to growth chamber conditions without irrigation, the trays were moved back to the glasshouse, watered, and after 3 days the seedling survival percentage determined. A wide spectrum of seedling survival percentages was found among the 206 rice cultivars screened by this method. The technique illustrated its capability to identify well‐adapted, traditional cultivars from areas where seedling stage drought is a chronic problem. Thus the technique can identify donors of this trait for hybridization purposes and can monitor the trait through a varietal improvement process.
A Comparison of Osmotic Potential, Elastic Modulus, and Apoplastic Water in Leaves of Dryland Winter Wheat1
Authors: Campbell G. S. , Papendick R. I. , Rabie E. , Shayo‐Ngowi A. J.
Published: July 2010

Previous models which describe the water‐content potential relationship for plant tissue do not account for die presence of apoplastic water in the tissue and its variation with water potential. This could cause errors in determination of tissue water parameters which are sensitive to plant water deficits. The theory was modified to account for apoplastic water fraction and used to determine the osmotic potential at full and zero turgor and tissue elastic modulus from moisture release curves for leaves of three winter wheat (Triticum aestivum L.) cultivars grown under moderately high and low stress environments in eastern Washington. Moisture release curves for individual leaves were obtained using a pressure chamber. Apoplastic water content was obtained independently from moisture release curves of frozen leaves using a hydraulic press. Osmotic potential at full and zero turgor showed significant responses to environment with leaves from the drier location having osmotic potentials 5 bars or more lower than leaves from the more moist site. Shifts in osmotic potential from wet to dry portions of the season were also about 5 bars. Apoplastic water fraction and elastic modulus were relatively insensitive to environment, averaging around 0.3 and 200 bars, respectively. Significant cultivar differences were found in tissue osmotic potential, but these did not correlate with performance of the cultivars in droughty environments. The study showed that apoplastic water in tissue, if not corrected for, markedly influences osmotic potential measurements using expressed cell sap since this water, which is essentially solute‐free, dilutes the cell sap when the membranes are destroyed. The tissue water parameters studied provide further insight on physiological factors important in plant resistance to moisture stress.
Grain Yields and Land Equivalent Ratios from Intercropping Corn and Soybeans in Minnesota1
Authors: Crookston R. Kent , Hill David S.
Published: July 2010

Intercropping, or growing two or more crops simultaneously on the same field, is a farming practice that has recently received attention from agronomic scientists as a means of improving land usage. The objective of this study was to determine whether present‐day corn (Zea mays L.) hybrids intercropped with soybean (Glycine max L. Merrill) at conventional row spacings would increase land usage in Minnesota.

Two different intercropping patterns were examined, each under three environments. The first pattern consisted of growing the two crops in combinations of alternating 76‐cm spaced rows. The patterns were: single alternate rows, three rows of each crop alternated, six rows of each crop alternated, and twelve rows of each crop alternated. Both crops were planted on the same day. In the second pattern, the two crops were grown in single, alternating, 38‐cm rows, with corn maturity rating, population, and planting date as variables

Although corn yields were significantly improved in some combinations of the first pattern, accompanying soybean yields were always reduced to the extent that none of the combinations made significantly different use of the land than did sole cropping. In many combinations of the second pattern, both corn and soybean yields decreased and land usage was thereby significantly reduced. In the other combinations of the second pattern land usage was unaffected. Minnesota land use efficiency was thus not improved by intercropping corn and soybeans in a variety of management combinations. Management approaches that might be expected to result in improved land usage are postulated.
No‐Tillage Maize Production in Chemically Suppressed Grass Sod1
Authors: Elkins D. M. , Vandeventer J. W. , Kapusta G. , Anderson M. R.
Published: July 2010

For no‐tillage maize (Zea mays L.) planted in sod, production usually involves the use of a contact herbicide to chemically mow or kill the grass sod. Such a procedure often necessitates costly forage reestablishment and subjects the land to water and wind erosion hazards during noncrop periods. Substantial acreage of rolling, erosive land presently is being row cropped. Field studies on different soil types were designed to investigate: a) the feasibility of chemically suppressing the grass sod for maize production; b) maintaining a sod cover for erosion control; c) providing sufficient forage for fall and winter animal grazing.

More than 20 treatments involving growth retardants and sublethal herbicide rates were evaluated for maize production in tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.) sods at two southern Illinois locations from 1975 to 1977.

The growth retardants which resulted in the best combination of maize yield and grass production in these experiments were maleic hydrazide (1,2‐dihydro‐3,6‐pyridazinedione), fluridamid (N‐[3‐[1,1,1‐trifluoro methylsulfonyl) amino]‐4 methylphenyl]acetamide), and mefluidide (N‐[2,4‐dimethyl‐5[[(trifluoromethyl) sulfonyl]amino]phenyl] acetamide.

The herbicides which most nearly met experimental objectives were glyphosate (N‐(phosphonomethyl)glycine), glyphosate plus atrazine (2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine), metolachlor (2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐l‐methylethyl) acetamide), metolachlor plus atrazine, and dalapon (2,2‐dichloropropionic acid). In most instances, it was necessary to apply a band of paraquat (1,1′‐dimethyl‐4,4′‐bipyridiniumion) over each row for acceptable maize yield.

In these experiments, it was possible to obtain good maize yields while maintaining at least 50% of the grass sod with little or no erosion observed. This method offers the potential for a combination of maize production and grazing on erosive land.
Influence of Nitrogen Fertility Level and Topping Method on Yield, Quality, and Storage Losses in Sugarbeets1
Authors: Akeson W. R. , Westfall D. G. , Henson M. A. , Stout E. L.
Published: July 2010

The recovery of sucrose from sugarbeets (Beta vulgaris L) has decreased in recent years while root yield has increased. Our objective was to determine the effect of N application rate and topping method on root yield and on the factors affecting recovery of sucrose‐sucrose content, purity, and storage loss.

The effect of five N fertility levels (0, 67, 134, 202, and 269 kg/ha) on sugarbeet root yield, quality (percent sucrose and percent purity) and crown tissue size was investigated from 1975‐1977 in 10 field experiments in Colorado, Kansas, and Nebraska. Crown tissue, the portion of the sugarbeet above the lowest leaf scar, increased from 10.64 to 16.03% of the total root weight as the N application rate increased from 0 to 260 kg/ha. Total root yield increased from 45.2 to 54.4 metric tons/ha over the same N range, but much of the yield increase was due to increase in crown size. Sucrose content and clarified juice purity (CJP) decreased 1.42 and 1.97% units, respectivdy, as the N application went from 0 to 269 kg/ha. The decrease in quality offset the increase in yield so that increasing rates of N had no significant effect upon yield of recoverable sucrose per ha. The extractable sucrose per metric ton of beets was reduced from 144.5 kg/ton for the 67 kg N/ha application to 128.6 kg/ton for the 269 kg N/ha application. Crown removal significantly reduced yield of recoverable sucrose per hectare but only increased extractable sucrose per ton from 136.7 to 140.0 kg/ton.

Quality (sucrose and CJP) was improved both by proper topping and by N management, however, N management has a more dramatic effect upon quality. Total sucrose yield is reduced by topping, but not significantly affected by N application rate.

Three N fertility levels (0, 134, and 269 kg/ha) and three topping methods (flailed, half‐topped, and topped) were evaluated for their effect on sucrose and quality changes in sugarbeet roots during storage in nine experiments. Failed beets had 27.4 and 25.5% less gross sucrose and recoverable sucrose losses than regular topped beets and 17.3 and 15.7% less gross suaose and recoverable sucrose lass than half‐topped beets. Method of topping had a significant effect upon sucrose losses in beets grown in all Iri levels. Nitrogen application rate had no significant effect upon gross sucrose or recoverable sucrose losses.

Beet quality (extractable sucrose per metric ton) was higher in topped beets than flailed beets at harvest, but no difference existed between topping treatments after storage. Sucrose production per acre and beet quality was maximized with the low fertility, flailed treatments before and after storage.
Root Distribution Patterns of Two Hybrid Grain Sorghums Under Field Conditions1
Authors: Zartman R. E. , Woyewodzic R. T.
Published: July 2010

Senscence is sorghum [Sorghum bicolor (L.) Moench] is manifested as pre‐mature shedding of the lower plant leaves. This process occurs during grain filling and is much more pronounced in senescent than in nonsenescent cultivars. Since roots are the plant organs responsible for water and nutrient accumulation, it is important to understand their relationship to total plant development. The root development of a senescent and a nonsenescent hybrid grain sorghum was investigated in the field. The purpose of this investigation was to determine the influence of senescence on root distribution of two grain sorghum hybrids.

Root samples were collected on approximately biweekly bases to measure their rate of growth and extent of distribution. Samples were collected on both sides of, and perpendicular to the row at 5‐, 15‐, 22.5‐, and 30‐cm intervals to a depth of 105 cm. Root distribution and density were similar for each hybrid 3 weeks after planting (3 June). The nonsenescent hybrid, represented by ‘ Pioneer 42004’, established its aventitious root system earlier than did the senescent hybrid, represented by ‘Pioneer 22516’. Differences were based on visual inspection of the roots and root diameter measurements. Root density of both hybrids increased until grain filling with the senescent cultivars generally exhibiting greater root density. From week 11 (5 August) to week 13 (19 August), both hybrids decreased in root density with a greater decrease noted for the senescent hybrid. The more dramatic decrease in density for the senescent hybrid was also reflected in a lesser grain yield.
Comparison of Diurnal Drought Response of Selected Wheat Cultivars1
Authors: Sojka R. E. , Stolzy L. H. , Fischer R. A.
Published: July 2010

In a 2‐year field study in Sonora, Mexico, irrigated and water‐stressed wheat (Triticum aestivum and T. durum) was grown to test the hypothesis of the existence of a substantial physiological response plateau at midday, and to assess several water‐stress characterizing techniques for field comparison of cultivars. Cultivars used were: ‘Yecora 70’, ‘Gabo’, ‘Sonora 64’, ‘Cajeme 71’ (bread wheats), and ‘Cocorit 71’ (a spring durum). Parameters examined included xylem pressure potential (ψχ), diffusive resistance (Rs), leaf osmotic potential (ψπ), and relative turgidity (RT).

Diurnal studies indicate ψχ of midday (maximum stress) observations do not change statistically from 1100 to 1600 hours under the conditions studied. Thus with sufficient replication and random sequence of sampling, large numbers of cultivars can be compared daily and seasonally for their response to water stress at midday.

Studies of technique indicated that pressure chamber temperature rose only 5 C when pressurizing to 20.7 bar in 10 sec and only 3 C when pressurizing in 105 sec. ψχ of plant samples tended to drop when stored in moist plastic bags after as little as 5 min. Rapid pressure increase rates resulted in statistically lower observed ψχ in one comparison (−23.5 bars in 1 min vs. − 23.2 bars in 4 min). Diffusive resistances (Rs) of abaxial leaf surfaces were larger and more variable than those observed on adaxial surfaces.

Diurnal observations of ψχ, ψπ and RT showed a high degree of correlation between ψπ, RT, and ψχ, pointing to ψχ as a good overall indicator of plant water status. Data indicate there may be a significant potential gradient between the terminal stem node and the flag leaf and/head.
Adhesive Increases Inoculation efficiency in White Clover1
Authors: Waggoner J. A. , Evers G. W. , Weaver R. W.
Published: July 2010

Relatively few fields in the southern USA contain sufficient numbers of Rhizobium trifolii to nodulate Trifolium species adequately. Thus, it is essential to know the extent to which current inoculation practices provide rhizobia for adequate nodulation. The nodulation of white clover (T. repens L.) grown from seed inoculated with a peat base inoculant using water or gum arabic as the adhesive was compared. The clover was sown in a Crowley sandy loam having a pH of 6.4. This soil contained fewer than 100 R. trifolii/g. Adequacy of inoculation was evaluated by determining plant dry matter production, percentage protein, nodule number and weight, and acetylene reduction. Inoculation with enough peat to supply 600 rhizobia/seed was adequate when applied with gum arabic, but not with water. Inoculation procedures normally supply approximately 200 rhizobia per seed. There was no significant difference between the uninoculated treatment and the inoculant treatment applied with water for any of the parameters used except for nodule weight at an early sampling date. When gum arabic was used, increasing the number of rhizobia from 600 to 3,000/seed did not significantly increase any parameter. Clover growth was nearly doubled by good inoculation.
Effect of Plant Arrangements and Densities on Yields of Dry Beans1
Authors: Kueneman E. A. , Sandsted R. F. , Wallace D. H. , Bravo A. , Wien H. C.
Published: July 2010

Dry beans, Phaseolus vulgaris L., are commonly sown in wide rows (75 to 90 cm) because many of the mechanical planters and cultivars in use were designed or adjusted for maize (Zea mays L.) culture. More importantly, effective herbicides for weed control and machinery for harvesting beans grown in narrow rows have not been available until recently. New developments in herbicides and prospects of more flexible harvesting machinery being marketed warrant investigations to determine yield responses of dry beans to plant spacings.

Eleven field experiments were conducted in New York State from 1966 to 1977 to determine effects of plant arrangements and densities on yields of dry beans. These experiments were at Aurora, N.Y., on soils of type Glossoboric hapludalfs, or at Ithaca, N.Y., on either Dystic flurentic entrochrepts or Typic dystrochrepts. Between row spacing effects were evaluated in nine experiments; narrow rows conditioned significantly higher (7% to 48%) yields in seven of the nine experiments. At a given density, plants in more equidistant arrangements significantly outyielded those in more rectangular arrangements. For example, plants spaced at 25✕25 cm yielded more than those at 76✕8 cm by 13%, plants spaced at 20✕20 cm yielded more than those at 76✕5 cm by 12% and yields averaged across five genotypes at 30✕10 cm were 48% larger than those at 60✕5 cm.

Results of an on‐farm trial indicated that difficulty in harvesting beans grown in narrow rows is a major constraint to adoption by farmers of narrow‐row culture. Suggestions for further research include: 1) modification of bean pullers or direct harvesters to accommodate beans grown in narrow rows; 3) determination of the yield advantage associated with alternating between several narrow rows and a wide row to enable passage of a tractor through the field for the purpose of cultivating, spraying, and harvesting; 3) selection of bean cultivars that will maximize the yield advantage of narrow‐row culture.
Dry Matter and Nitrogen Accumulation in Male‐Sterile and Male‐Fertile Soybeans1
Authors: Burton J. W. , Wilson R. F. , Brim C. A.
Published: July 2010

One explanation for the rapid decline in N fixation of soybeans [Glycine max (L.) Merr.] during pod‐fill, is that deveioping seeds compete so strongly for photosynthate that inadequate amounts are available to nodules. Nitrogen fixation by nodulated legumes may be enhanced during the pod‐filling period by increased photosynthate supply to the root system. A reduced number of pod sinks presumably would allow more of the available photosynthate to be translocated to the root system and nodules. In the field, genetic male‐sterile (ms1) soybean plants naturally produce between 80% and 90% fewer pods than their fertile siblings. In addition, their leaves remain green until a killing frost which occurs usually well after their fertile siblings have completey matured. The objective of this study was to determine if these secondary effects of male sterility are also associated with dry matter and N accumulation patterns which are different from those of male‐fertile plants.

Sterile and fertile plants from a population of the male‐sterile (ms1) maintainer line, N69‐2774, were sampled in a replicated experiment at 10day intervals from flowering to maturity. Dry weights and Kjeldahl N determinations were made on stems plus petioles, leaf blades, and pods.

We found patterns of dry matter and N accumulation in sterile plants indicating that with reduced pod set, leaves, stems, and roots were sinks for N and photosynthate during the pod‐filling period. At peak N accumulation, 130 days after emergence (DAE), 70y0 of the total N in the aboveground portion of fertile plants was in the pods, 8% in stems plus petioles, and 22y0 in leaf blades. In sterile plants at 130 DAE, 11% of the N was in pods, 390/, in stems plus petioles, and 50y0 in leaf blades.

Although the sterile plants had 87% fewer pods per plant than the fertile plants and did not show leaf yellowing, sterile and fertile plants showed little difference in the rate of dry matter accumuation per pod or in the total accumulation of plant dry matter. These genotypes also contained similar amounts of total N throughout the pod‐filling period. The results suggest that the retention of green leaves and increased carbohydrate supply to the roots may not increase N2 fixation in the absence of a strong seed sink.
Irrigation and Tillage Effects on Soybean Yield in a Coastal Plain Soil1
Authors: Martin C. K. , Cassel D. K. , Kamprath E. J.
Published: July 2010

Tillage‐induced pans in many Atlantic Coastal Plain soils restrict soybean (Glycine max L. Merr.) rooting. Consequently, one or more drought periods may reduce soybean yields. This study determined tillage and irrigation effects on soybean yields in one of these soils in a dry year.

‘Ransom’ soybeans were planted on 19 May 1977 on Wagram loamy sand (Arenic Paleudult) which has a traffic induced pan at 25 cm. One half of each plot was conventionally tilled (moldboard plus three diskings); the other half was subsoiled to 45 cm and bedded. The date at which irrigation began was considered the whole plot and was replicated four times in a randomized block design. Irrigations were scheduled using tensiometers whenever the soil moisture tension in the 15 to 30‐cm depth reached 0.8 bars. A gradient with respect to the amount of water applied was established across each plot; no irrigation water reached the far side of the plots. Dates at which irrigation began were 23 June (early), 29 July (after flowering began), and 1 September (after pod set started). Once irrigation was initiated, each treatment was irrigated as needed throughout the growing season.

Yields of conventionally tilled soybeans were 1,728, 2,063, 2,124, and 1,686 kg/ha for no irrigation and for full irrigation initiated on 23 June, 29 July, and 29 September, respectively. No significant yield increase or decrease was observed for the irrigated, subsoiled plots, regardless of the date irrigation began. Average yield of the subsoiled treatment was 37% higber than the 1,802 kg/ha overall average yield for conventionally tilled soybeans.

The fact that the irrigated, conventionally tilled treatments did not achieve yields equal to those of the nonirrigated, subsoiled treatment suggest that some other benefit(s) accrue from the subsoil and bedding operation in addition to increasing water availability.
Effects of Small Grain Stubble Height and Mulch on No‐Tillage Soybean Production1
Authors: Hovermale C. H. , Camper H. M. , Alexander M. W.
Published: July 2010

Little data are available on the increasing popular practice of no‐tillage planting soybeans (Glycine max L. Merr.) in small grain stubble. To determine the effects of three small grain stubble heights and three straw mulch rates in branching height, plant height, lodging, population, and yield of no‐till planted soybeans, field studies were conducted at Warsaw and Suffolk, Va. for 3 years. Straw mulch treatments were normal amount (✕), twice the normal amount (2✕), and all straw removed (0). The three stubble heights were “Low” (10.2 cm), “Medium” (20.3 cm), and “High” (35.6 cm at Warsaw and 40.6 cm at Suffolk). Neither mulch rate nor stubble height affected final plant stand significantly, but there was a tendency toward fewer plants in the heaviest mulch rate. Mature plants at Warsaw were tallest in the high stubble with no difference between the low and medium stubble; the same trend was shown at Suffolk. Soybean plants grown in the ✕ and 2✕ mulch at Warsaw and the ✕ mulch at Suffolk were taller than those grown in the other mulch treatments. Lodging and pod height followed the same trend as plant height. Seed yield was highest in the medium stubble and ✕ mulch rate.

It is concluded that harvesting small grain to leave a 20‐cm stubble produces optimum soybean yields and the addition of mulch shows no benefit.
Greenhouse Alfalfa Yields with Single and Split Applications of Deproteinized Alfalfa Juice1
Authors: Volenec Jeff , Smith Dale , Soberalske R. M. , Ream H. W.
Published: July 2010

A greenhouse study was initiated to observe the response of alfalfa (Medicago sativa L.) to single and split applications of deproteinized alfalfa juice (DAJ) at surface depths of 1.25, 1.88, and 2.30 cm in a Piano silt loam (Typic Argiudoll) soil mixture containing 20% sand. Total alfalfa herbage yields (three harvests) increased significantly over the control with single applications of 1.25 cm of DAJ; were similar to the control with 1.88 cm of DAJ; and were reduced significantly below the control with 2.50 cm of DAJ where plants were killed. Total herbage yields were higher with split than single DAJ applications, but significantly higher only with 1.88 and 2.50 cm. The highest total herbage yields were obtained with split applications at 1.25 and 1.88 cm. It is concluded that above 1.25 cm, DAJ should be applied to alfalfa in split rather than in single applications.
Optimum Crown Temperatures for Maximum Alfalfa Growth1
Authors: Evenson P. D.
Published: July 2010

Reported effects of soil or root zone temperatures on alfalfa growth have not separated the temperature effects on roots and crowns. The optimum crown temperature for maximum top, crown, and root growth was determined in this investigation. Alfalfa growth was measured at various crown temperatures while root and shoot temperatures were held constant.

Two similar growth chamber experiments were conducted on ‘Vernal’ alfalfa. In the first experiment, crown temperatures of 25, 28, 34, and 36 C were used. Maximum predicted top growth occurred at a 32 C crown temperature. Average shoot length and number of trifoliate leaves per plant were the major variables that correlated with topgrowth.

Top and root growth were influenced in an opposite manner (r = —0.51) by crown temperatures of 23, 31, 36, and 40 C in the second experiment. Crown weights were not significantly influenced by these temperatures. Therefore, total plant weights were evaluated. The maximum predicted‐ and actual‐total‐plant weight was at 36 C. The most topgrowth and least root growth occurred at 40 C. However, topgrowth was abnormal in appearance, and cortical cells had collapsed hi the roots. Excluding results at 40 C, the maximum top growth occurred at 31C.

Optimum crown temperature is much higher than the reported‐optimum‐root temperatures for maximum alfalfa growth.
Photosynthesis of Peanut Canopies as Affected by Leafspot and Artificial Defoliation1
Authors: Boote K. J. , Jones J. W. , Smerage G. H. , Barfield C. S. , Berger R. D.
Published: July 2010

Cercospora sp. leafspot and defoliating arthropods are major pests which reduce the yield of peanuts (Arachis hypogaea L.) in the southeastern United States by decreasing the amount and effectiveness of photosynthetic surfaces. Nevertheless, in the past, yield reductions have been empirically predicted from season‐end yields without considering the intermediate effects of leafspot or defoliation on canopy photosynthesis. Information on short and long term responses of crop growth processes to these pests is vital to the development of croppest management models which dynamically simulate crop and insect interaction. Our objective was to determine canopy photosynthesis and characteristics of peanut foliage layers in response to leafspot, defoliation, and combinations of disease and defoliation. Measurements from a field experiment included canopy C exchange rate (CER), photosynthetic uptake of 14CO2, leaf area, and light interception by leaves in three canopy layers.

The upper 42% of the canopy leaf area intercepted 74% of the light and fixed 63% of the total 14CO2 taken up by intact canopies. Removal of 25% of the total leaf area, primarily from the upper half of the canopy, reduced 14CO2 uptake by 30% and canopy CER by 35%. In 1977, severe leafspot damage reduced leaf area index (LAI) by 80%, 14CO2 uptake by 85%, and canopy CER by 93%. Canopy CER values measured in 1978 were reduced 35 and 65% for medium and high leafspot damage treatments, respectively. Photosynthesis of diseased canopies was reduced not only by loss of leaves which abscissed as a result of infection, but also because diseased leaves which remained on the plants were less efficient in fixing CO2.

Modeling the effects of insect defoliation and leafspot on peanut plant growth will require the fraction of LAI lost relative to LAI of 3 or 4, as well as the location and photosynthetic rate of the leaves remaining after insect defoliation or disease.
Steer Performance on AP‐2 Phalaris and ‘Kentucky 31’ Tall Fescue Pasture1
Authors: Hoveland C. S. , Haaland R. L. , King C. C. , Anthony W. B. , McGuire J. A. , Smith L. A. , Grimes H. W. , Holliman J. L.
Published: July 2010

Steer performance on tall fescue (Festuca arundinaca Schreb.) pasture without supplemental feeding has generally been poor. The new Auburn Univ. experimental phalaris (Phalaris aquatica L.) cultivar, ‘AP‐2,’ appeared promising in preliminary clipping tests but no information was available on animal performance. The objective of this study was to determine steer performance on pastures of ‘Kentucky 31’ tall fescue and AP‐2 phalaris. The two grass species were grown in west central Alabama on replicated 1.2 ha paddocks containing two calcareous soils, Sumter clay (Rendolic Eutrochrept, fine silty, carbonatic, thermic) and Houston clay (Typic Chromudert, very fine montmorillonitic, thermic). They were fertilized annually with 224 kg N/ha and grazed with yearling steers from 17 October to 26 December and 7 March to 19 June for 3 consecutive years. Tall fescue furnished 602 animal days/ha, produced 488 kg gain/ha, and an average daily gain (ADG) of 0.81 kg. Phalaris furnished 499 animal days/ha, 389 kg gain/ha, and ADG of 0.78 kg. Carrying capacity was higher on tall fescue than on phalaris, 3.53 and 3.15 steers/ha respectively. Steers had excellent appearance from the standpoint of hair coat and degree of finish at end of each grazing season. Dry matter digestibility of both grasses averaged 59% for the season. Calcium content of tall fescue herbage was higher than for phalaris, 0.72% and 0.58% respectively. The ADG of steers on both tall fescue and phalaris was similar to that on small grain pastures and much higher than usually obtained on tall fescue in other experiments. These results suggest that tall fescue has the potential for excellent animal performance which is not now being generally realized in the southeastern U.S. Phalaris furnished relatively high ADG but had a lower carrying capacity and was less persistent under grazing than tall fescue.