bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrate Uptake Effectiveness of Different Cultivars of Triticale, Wheat, and Rye1
Authors: Mugwira L. M. , Elgawhary S. M. , Allen A. E.
Published: July 2010

abstract

Nitrate absorption and utilization vary among plant species and varieties but there is little information on the nitrate uptake effectiveness of triticale (X Triticose. cale, Wittmack), wheat (Triticum aestivum L.), and rye (Secale cereale L.). The nitrate uptake effectiveness of different cultivars of triticale, wheat, and rye were investigated in a growth chamber, using nutrient solutions. Plants were grown in pots containing the same base solution for 28 days before being transferred to solutions containing different nitrate concentrations. The solutions contained 0.1, 1.0, 2.5, 5.0, and 10.0 mM nitrate. Increasing nitrate concentration from 0.1 to 2.5 mM increased plant dry matter and N uptake. Few significant differences were observed at nitrate concentrations greater than 2.5 mM. Root uptake coefficients decreased with increasing nitrate concentration. Triticale '6TA 385', 'Arthur' wheat, and 'Abruzzi' rye showed higher effectiveness than triticale '6TA 203', 'Atlas 66' wheat, and 'Vitagraze' rye in the uptake of nitrate at 0.1 and 1.0 mM nitrate concentrations but these differences were not obtained at higher nitrate concentrations. Varietal differences within species indicated that triticale, wheat, and rye had similar nitrate uptake effectiveness.
Response of Winter Wheat to Inhibiting Nitrification of Fall‐Applied Nitrogen1
Authors: Huber D. M. , Warren H. L. , Nelson D. W. , Tsai C. Y. , Shaner G. E.
Published: July 2010

Large overwinter leaching and denitrification losses of fall‐applied N are common in many Corn Belt soils cropped to wheat (Triticum aeslivum L.). These losses decrease the utilization efficiency of N fertilizers, lower crop yields and quality, necessitate multiple fertilizer applications, and predispose wheat to several soil‐borne diseases. This study was conducted to determine if inhibiting nitrification of fall‐applied ammoniacal fertilizers would reduce N losses and be a practical alternative to multiple fertilizer applications in maintaining crop yield, quality, and tolerance to disease. We tested the effectiveness of a specific nitrification inhibitor, Z‐chloro‐6(trichloromethyl)‐pyridine (nitrapyrin), in reducing losses of fall‐applied NH4+ sources of N in four Indiana soils of varying texture. The field experiment was conducted over a 5‐year period by comparing the growth, disease incidence, grain protein, and yield of wheat in field plots receiving anhydrous ammonia, urea, or ammonium sulfate plus nitrapyrin with wheat production in plots treated with these N sources without the inhibitor. Calcium nitrate was used in some studies to provide a source of N exhibiting high potential for loss.

Inorganic N analyses of soil showed that severe loss of N frequently occurring as a result of fall application of N may be markedly reduced by using a nitrification inhibitor. Wheat yields were increased as much as 40% (average increase was 14.7%) as a result of applying 0.55 kg of nitrapyrin/ha with fall‐applied NH4+ fertilizers. Yields obtained with fall‐applied N plus nitrapyrin were similar to those observed with a split‐application (25% fall—75% spring) of N without the inhibitor. Fall application at 44 kg N/ha plus nitrapyrin resulted in yield similar to those with 88 kg N/ha without the inhibitor. Inhibition of nitrification of fall‐applied NH4+ also increased protein content, minimized N loss from the up per soil profile, and reduced the severity of fungal root and crown rots. Nitrification inhibitors added to fall‐applied NH4+ should provide a practical alternative to multiple fertilizer applications for maintaining the yield, quality, and disease tolerance of wheat grown in the Corn Belt.
Field Drying of Rough Rice: Effect on Grain Yield, Milling Quality, and Energy Saved1
Authors: Calderwood D. L. , Bollich C. N. , Scott J. E.
Published: July 2010

Harvesting rough rice (Oryza saliva L.) at a low moisture content is one method of reducing energy needs for drying. The objectives of energy‐related research were to: 1) determine the economic feasibility of harvesting rice at a low moisture content; 2) identify the harvest moisture level at which head rice yield drops sharply; 3) identify rice cultivars adaptable for field drying; and 4) estimate energy savings to be gained by harvesting at particular moisture levels.

Rough rice initially at 25% moisture content was harvested at 11 intervals during a time span of 30 to 36 days to determine the amount of drying in the field and the effect of field drying on grain yield, milling yield, germination, and test weight. Ten tests were run during four harvest seasons. Long‐grain cultivars, ‘Labelle’ and ‘Lebonnet’, and medium‐grain cultivars, ‘Brazos’ and ‘Nato’, were included in the tests. During each of the tests, rice moisture content dropped steadily during dry weather, but rain and dew caused unpredictable amounts of rewetting. Rice eventually dried to near 16% moisture content in all 10 tests and to 14% moisture content or lower in five of the tests.

Grain yields were not greatly affected by delayed harvesting, but tended to decrease before the tests were concluded. The percentage of total milled rice (whole and broken kernels combined) increased with delays in harvest date, but the percentage of head rice (whole kernels of milled rice) reached a maximum at an intermediate harvest date, then declined rapidly with delays in harvesting. Both Brazos and Lebonnet cultivars required harvesting at a higher moisture content than did Labelle and Nato cultivars to maintain a high percentage of head rice. Neither germination nor test weight was adversely affected by delays in harvest dates. Energy for drying may be reduced about 50% by harvesting rice at 16% rather than at 22% moisture content.
Adaptation of Cotton Genotypes to an Acid, Aluminum Toxic Soil1
Authors: Foy C. D. , Jones J. E. , Webb H. W.
Published: July 2010

Aluminum toxicity, associated with subsoil acidity, limits rooting depth of cotton (Gossypium hirsutum L.) in certain soils of the southern U.S. Shallow rooting means greater susceptibility to drought and less effective use of subsoil nutrients. Liming subsoil to detoxify Al is difficult and often not economically feasible. An alternative or supplemental approach is to select or breed cotton genotypes with greater Al tolerance.

Fifty‐four cotton genotypes were screened for Al tolerance in greenhouse pots of an acid, Al‐toxic Tatum subsoil (clayey, mixed, thermic, typic Hapludult) treated with 375 µg/g CaCO3 (pH 4.7 to 4.9) or 3,000 µg/g CaCO3 (pH 5.3 to 5.4). Aluminum tolerance was measured by relative growth, which is defined as the dry weight of tops or roots at low pH (4.7 or 4.9) expressed as a percentage of that at the higher pH (5.3 to 5.4). In one experiment, relative yields of genotypes (pH 4.7 compared with 5.3) varied from 50 to 25% for tops and from 78 to 35% for roots. In a second experiment, relative yields (pH 4.9 compared with pH 5.4) ranged from 29 to 10% for tops, and from 51 to 12% for roots. Genotypes showing greatest tolerance to the acid subsoil included Pima S‐2, Acala 4‐42, LaDASS 5194, LaDASS 5187, Stoneville 213, Delcot 277, McNair 612, and Dixie King 3. Three Coker genotypes had tolerance approaching that of Stoneville 213; these were C‐Misc,73‐110, C‐Misc,73‐113 and C‐Sgs,71‐704. More sensitive genotypes were Auburn 56, Coker 201, Deltapine 16 and several experimental lines, including LaDSI 19979, C‐Misc,73‐114, C‐8103, 71‐106, and C‐7105‐73‐319.

Acid soil tolerant and sensitive genotypes did not generally differ significantly in concentrations of Al, Mn, Ca, or P in whole plant tops. However, Al and Ca concentrations tended to be higher in chlorotic and/or cupped leaves than in normal leaves of selected genotypes.

Results indicated that cotton genotypes vary significantly in Al tolerance and that further improvement may be made through plant selection and breeding. This approach has the potential to alleviate the shallow rooting problem of cotton in strongly acid subsoils. Very high correlation (0.001 level) between top and root yields (r = 0.968 and r = 0.979) in two experiments on the acid Tatum subsoil (pH 4.7 to 4.9) indicated that measurement of either component may be adequate in screening populations for Al tolerance.
Photoassimilate Distribution in Spartina alterniflora Loisel. II. Autumn and Winter Storage and Spring Regrowth1
Authors: Lytle R. W. , Hull R. J.
Published: July 2010

Vegetative regeneration of natural Spartina alterniflora Loisel. stands is critical to the stability and sustained productivity of Atlantic tidal salt marshes. Environmental conditions and human activity may limit the seasonal regeneration of energy reserves in perennial vegetative organs. Therefore, the use of energy stored in overwintering organs for vegetative growth in the spring was investigated. Leaf blades of mature flowering culms were exposed to 14CO2 during October. Entire plants were harvested during the ensuing winter and growing season. Distribution of 14C‐photosynthate in plants was measured by radioassay and radioautographic techniques. Approximately 50% of the late‐season photosynthate recovered from the plants had been translocated to basal organs, with rhizomes and tillers serving as major accumulation sites. During spring growth, almost half of the remaining stored 14C was translocated into tillers and plants emerging from rhizome buds. Shoots drew heavily upon stored energy sources through the fourth to fifth leaf stages of development. In mid‐summer, new rhizomes were regenerated largely by using energy stored in overwintered rhizomes. In S. alterniflora, energy transferred from one season to the next was utilized in suppport of early shoot growth and to produce organs which would serve as current season storage.
Annual Carbohydrate Variation in Culms and Rhizomes of Smooth Cordgrass (Spartina alterniflora Loisel.)1
Authors: Lytle R. W. , Hull R. J.
Published: July 2010

The productivity and stability of northeastern Atlantic tidal salt marshes depend largely upon the growth and persistence of the tall and short ecophenes of smooth cordgrass (Spartina alterniflora Loisel.). While the annual energy balance upon which perennial grass persistence depends has been studied in the tall form, no such information is available for the short form. The seasonal energy relations of the two morphological forms were compared based upon changes in the nonstructural carbohydrate content of rhizomes and culm tissues. Grass stands growing on a tidal marsh composed of sandy sulfaquents with occasional histic epipedons were sampled at 2‐week intervals during 3 years. Lipids, sample sugars, long chain fructosans, and starch were extracted in chloroform, ethanol, water, and perchloric acid, respectively. Carbohydrates were quantified by standard spectrophometric methods. Sucrose was the major carbohydrate extracted from culms and rhizomes throughout the year. Rhizomes never contained more than 4% starch while ethanol extractable sugars were 20% of dry weight in early spring and autumn. Almost no fructosans were detected in these tissues. During flowering and gram filling in August, the simple sugar content of tall culms was about 10% of dry weight but declined sharply between September and October which was coincident with carbohydrate accumulation in rhizomes. Short plants flowered less and continued Vegetative growth into autumn. Culm tissues of short plants retained a relatively high simple sugar content through October and rhizome carbohydrate levels increased gradually during autumn and early winter. It is proposed that the persistent vegetative growth of the short ecophene may result in less annual rhizome turnover than occurs in the tall form.
Osmoconditioning of Soybean Seeds to Improve Performance at Suboptimal Temperatures1
Authors: Knypl J. S. , Khan A. A.
Published: July 2010

The use of osmotic treatment or osmoconditioning (OC) to improve the performance of soybeans (Glycine (L.) Merrill cv. ‘Traverse’) was explored. The aim of this investigation was to examine in detail the optimum conditions needed for OC of soybean seeds for germination and soil emergence at suboptimal temperatures. Such a study is necessary if soybeans are to be planted early in the season when the soil is moist and cold. Osmotic treatment consisted of treating seeds with various concentrations of polyethylene glycol‐6000 (PEG) solutions at 15 C. Following osmotic treatment, seeds were germinated either on filter paper soaked with water or in a soil medium. The treatment improved the performance of soybean seeds as shown by axvancement in the time of germination and an increase in the rate of germination and emergence at suboptimal temperatures (8 or 15 C). The optimum time period of 06 at 15 C was in the range of 4 to 8 days, and the most favorable range of PEG concentration for OC was 25 to 30 g/100 ml of water (−8.6 to −11.9 bars). Following OC, drying the seeds to the original air dry weight did not remove the germination advantage gained by OC. Although 0.20/, thiram added to PEG solution improved the appearance of the seedling, it did not affect OC. These studies suggest that it might be possible to plant osmoconditioned seeds in moist, cold soil to extend the planting Season and/or to improve the uniformity of seedling stand.
Fungal Effects on Rhizobium japonicum‐Soybean Symbiosis1
Authors: Angle J. S. , Pugashetti B. K. , Wagner G. H.
Published: July 2010

Soil fungi are known to produce mycotoxins which could inhibit growth and activity of other microorganisms in the soil. This study was undertaken to examine antagonistic effects of mycotoxins on growth of Rhizobium japonicum and on nodulation and growth of soybeans [Glycine max (L.)].

Seventeen common fungi were isolated from the surface horizon of an Udollic ochraqualf and examined in laboratory and growth chamber studies to determine effects of these fungi on Rhizobium japonicum strains USDA 110 and 138. Several fungi were found to be antagonistic towards rhizobia due to mycotoxins which were exuded from the mycelia into the surrounding environment. During preliminary screening experiments Trichoderma viride, Rhizopus nigricans, and Mucor vesiculosis were observed to be consistently antagonistic to R. japonicum. Subsequently, these three fungi were inoculated simultaneously with rhizobia into perlite which was seeded to soybeans. The effect of each fungus on nodulation and growth of the soybeans during culture for 9 weeks was determined. The nodulation of soybeans by strains 110 and 138 was reduced by Trichoderma viride. Nodules per plant for strain 138 were reduced from a control value of 54 to 34. Total nodule weight and N2(C2H2) reduction also decreased, however, no changes were observed in plant shoot and root weight or in total N. Mucor vesiculosis increased nodulation and plant growth, while Rhizopus nigricans had no effect.

In non‐sterile soil, Trichoderma viride was the only fungal isolate capable of reducing the R. japonicum population. The population was reduced to one tenth that of the control soil. Trichoderma viride also decreased nodule number which was accompanied by a decrease in N2(C2H2) reduction per soybean plant from a control value of 1.07 to 0.65 µmoles/hour. The antagonistic effects of Trichoderma viride on rhizobia1 activity were paralled by decreases in plant root and shoot weights. These plant parameters were similarly decreased, although not as severely, by Mucor vesiculosus and Rhizopus nigricans
Water Deficit Effects on Water Potential, Yield, and Water Use of Cowpeas1
Authors: Shouse Peter , Dasberg Samuel , Jury W. A. , Stolzy L. H.
Published: July 2010

Previous studies report conflicting results regarding the sensitivity of cowpeas to growth stage water deficits. Our 2‐year field study was designed to monitor the effects of water deficit imposed at three growth stages on the yield and water use of cowpeas (Vigna ungiculata (L.) Walp.). Six irrigation treatments were used to impose the water deficit including a well watered control treatment (WWW) and five deficit treatments (DWW, WDW, WWD, DWD, WDD). Cowpeas were grown on a sandy loam soil (coarse‐loamy, mixed thermic Haplic Durixeralf) on the experimental farm in Riverside, California.

The pre‐dawn leaf water potential, as measured by the pressure bomb technique, was a better indicator of crop water stress than was the midday leaf water potential. The pre‐dawn leaf water potential at any growth stage progressively decreased with time following cessation of irrigation, but completely recovered after soil water storage was recharged by irrigation or rain.

The most sensitive growth stages to drought were flowering and podfilling, with yield reduction from 35 to 69% depending on the timing and length of the drought treatment. A soil water deficit during the vegetative stage had the least effect on crop yield. This, coupled with decreased evaporation, resulted in a water‐use efficiency which was greater than that of the control treatment, which was adequately watered throughout the season. The water‐use efficiencies of the other stage deficit treatments were decreased below that of the control because of large decreases in crop yield.

Seed yield of cowpeas was found to be linearly related to an integrated water stress indicator based on the predawn measurement of leaf water potential.

We found that the relative dry matter yield was linearly related to crop transpiration as determined by the difference between a water balance measurement of ET and modeled evaporation (T = ET meas. ‐ Emodeled).
Freezing Cold‐tolerant Parental Clones of Sugarcane1
Authors: Tai P. Y. P.
Published: July 2010

Sugarcane (a complex hybrid of Saccharum spp.) deteriorates after freezing damage. Efforts have been made to introduce the cold tolerance of S. spontaneum L. into commercial types. Six cold‐tolerant clones of F1 (commercial cultivar ✕ S. spontaneum) and BC1 progenies were used to evaluate the deterioration of Sugarcane after artificial freezing and to compare the deterioration characteristics of their crusher juice quality with those of two commercial cultivars. The characteristics of juice quality studied were pH, titratable acidity, percent sucrose, percent purity, and kg of sugar per metric ton of cane. Stalks were exposed to −4.4 to −5.0 C for 6 hours. Samples were ground at Week 0 (immediately after harvest) and at 1, 2, and 3 weeks after freezing. The juice of fresh cane, Week 0, of the six cold‐tolerant clones had higher pH and titratable acidity and lower percent sucrose, percent jurity, and kg of sugar per metric ton of cane than did that of either commercial cultivar (‘CP 57‐526’ or ‘CP 63‐588’). Low positive correlations between titratable acidity measurements made at the start and end of various time periods after freezing of sugarcane stalk samples indicate that the deterioration hi titratable acidity between sampling dates was either independent or associated in a loose manner. Titratable acidity for all six cold‐tolerant clones increased relatively slowly during the first 2 weeks after freezing. Titratable acidity after freezing is more indicative of cold damage than is percent sucrose, and selecton of clones for cold tolerance might be made more rapidly if titratable acidity were used as the selection criterion.
Day and Night Temperature Effects on Nitrogen and Soluble Carbohydrate Allocation During Early Reproductive Growth in Soybeans1
Authors: Thomas Judith F. , Raper C. David , Weeks Willard W.
Published: July 2010

By altering the timing of reproductive events, temperatures may affect allocation of N and C within soybean [Glycine max (L.) Merrill]. The objective of this study was to determine the changes in partitioning associated with early development of the reproductive sinks. Plants of the determinate cultivar ‘Ransom’ growing in controlled environments were transferred to inductive shortday photoperiods at the V3 stage and grown under 25 combinations of day/night temperatures over a range of day temperatures of 14 to 30 C and night temperatures of 10 to 26 C. Plants from each combination were sampled at 0, 20, 30, and 50 days after the first inductive photoperiod. Plants were separated into leaves, stems, and pods, freeze‐dried, and analyzed for total N and soluble carbohydrates.

During the first 20 days after plants were transferred to short days and before pods appeared, increases in rates of accumulation of dry matter, N and soluble carbohydrates in leaves and stems were related to increases in both day and night temperatures. Time of pod appearance was inversely related to temperature. As pod growth became an active sink, accumulation rates of dry matter, N and soluble carbohydrates decreased in leaves and stems, but even at higher temperatures with the greatest rates of pod development, net accumulation of dry matter and N (and soluble carbohydrates in some instances) were measured during the final sampling interval. The most advanced plants at Day 50 were approaching full seed (R6) development stage. Nitrogen and soluble carbohydrate concentrations in leaves and stems were different among temperature treatments at the initial sampling on 20 days after treatments were imposed and before pods had appeared. During the subsequent growth intervals, there were no further variations of N concentration in leaves and stems within temperature treatments in association with stage of pod development through R6. However, concentrations of soluble carbohydrates had begun to decline as the stage of pod development approached R6. These results indicate that until the stage of seed fill, the greatest effect of reproductive growth on N reserves in vegetative tissues may be in limiting the amount of vegetative tissues rather than in net remobilization from these pools.
Effects of Turfgrass on the Establishment of Woody Plants1
Authors: Fales S. L. , Wakefield R. C.
Published: July 2010

Suppression of woody plants by grasses has been widely reported; but few studies have investigated the factors responsible for the reduced growth and poor appearance often shown by ornamental trees and shrubs planted in association with turfgrass. This research was undertaken to determine the major factors responsible for this phenomenon.

A field study, conducted over two growing seasons, evaluated the growth of flowering dogwood (Cornus florida L.) and forsythia (Forsythia intermedia Spaeth.) planted in established sod (Enfield silt loam soil, Typic Dystrochrept). Treatments included different sized areas of turf‐free space (0.3m2, 0.7m2, and 23.7m2), surface and subsurface placement of fertilizer and irrigation, and two mowing heights (10 cm and 4 cm). Turfgrass significantly reduced the growth of both woody species. Although supplementary fertilizer, applied as a topdressing, failed to benefit the ornamentals, subsurface treatments resulted in considerable increases in growth. Competition for moisture did not appear to be responsible for the observed differences in growth, since maintaining a high level of soil moisture failed to overcome the inhibitory effects of the turfgrass. Competition for N, however, was indicated by results of leaf tissue analysis.

A bioassay experiment tested the hypothesis that the competitive nature of turfgrasses involves an allelopathic mechanism. Aqueous leachates of the roots of perennial ryegrass (Lolium perenne L.), red fescue (Festuca rubra L.), and Kentucky bluegrass (Poa pratensis L.) were applied to rooted cuttings of forsythia. Top growth of the forsythia was inhibited by leachates from all three turfgrass species. Root growth was suppressed by ryegrass and red fescue leachates.

Results of these experiments indicate that the suppression of woody plants by turfgrasses may involve chemical inhibition as well as direct competition for available N.
Protein and Oil Content of Winged Bean Seeds as Measured by Near‐Infrared Light Reflectance1
Authors: Hildebrand D. F. , Chaven C. , Hymowitz T. , Bryan H. H. , Duncan A. A.
Published: July 2010

Grain analyzers are being utilized by plant breeders to estimate the protein and oil content of various agricultural commodities. The method is rapid and inexpensive. Its potential use for the analysis of winged bean [Psophocarpus tetragonolobus (L.) DC.] seed meal was investigated in this study. Simultaneous estimations of protein and oil concentrations in winged bean seed meals made by a near‐infrared light reflectance instrument coupled to an analog computer (grain analyzer) were compared to protein and oil determinations by Kjeldahl and Soxhlet extraction procedures. The correlation between Kjeldahl protein and the grain analyzer values was 0.998. The correlation between Soxhlet extracted oil and the grain analyzer values was 0.995.

The 240 winged bean accessions evaluated in this study were obtained from 16 countries. The seed protein contents ranged from 20.7 to 45.9%. The seed oil contents ranged from 7.2 to 21.5%.

A centrally located grain analyzer facility should be able to monitor the protein and oil values in winged bean cultivar and breeding trials carried out anywhere in the world.
Forage Production of a Tall Fescue Sod Intercropped with Sorghum ✕ Sudangrass and Rye1
Authors: Belesky D. P. , Wilkinson S. R. , Dawson R. N. , Elsner J. E.
Published: July 2010

A multispecies no‐tillage system was designed to produce supplemental forage for year‐round grazing while maintaining a viable tall fescue sod for erosion control. This system offers the potential to improve forage quantity and quality for low yielding tall fescue (Festuca arundinacea Schreb.) pastures in the South. Sorghum ✕ sudangrass hybrid, cv. ‘Pennington's summergrazer’ (Sorghum bicolor L. Moench ✕ Sorghum bicolor L. Moench) (SS hybrid), was seeded into tall fescue sod after the flush of spring growth, and rye (Secale cereale L.) seeded in early October after the end of the summer growing season for 3 consecutive years. Tall fescue sod kill treatments of no kill, 25, 50, and 100% of the surface area were obtained with 0.28 and 0.56 kg paraquat (1, 1'‐dimethyl‐4, 4'bipyridimium ion) per ha. Nine treatments were applied in a randomized block design replicated four times on Cecil sandy loam (Typic Hapludult, clayey, kaolinitic thermic). Phosphorus and K fertilizer was applied to satisfy soil test recommendations, while N fertilizer was applied in split applications across all treatments. Summer forage was harvested and separated by cutting height into tall fescue and SS hybrid, while winter yield was represented by tall fescue or tall fescue plus rye. The higher rate of paraquat gave no significant yield advantage to sod‐seeded species at a given level of tall fescue sod control. A tall fescue sod monoculture yielded 7,405 kg dry matter/ha annually (3‐year average). Inclusion of SS hybrid and rye in the tall fescue system with 50% sod kill increased total average forage yield to 11,115 kg/ha and improved distribution of yield over the year. Sorghum ✕ sudangrass hybrid accounted for 48%, (5,283 kg dry matter/ha) of the average yearly total yield for 50% sod kill. Yearly total forage yields were not significantly different far 50 and 100% levels of tall fescue sod kill seeded with both SS hybrid and rye.

Thus, it was feasible to increase and improve distribution of forage yield and provide species diversity, while maintaining tall fescue sod as an integral part of the system.
Estimating Development Stages of Corn from Spectral Data — An Initial Model1
Authors: Badhwar G. D. , Henderson K. E.
Published: July 2010

When applying remote sensing technology to crop area estimation or crop condition assessment, a knowledge of the crop development stage at the time the remotely sensed data is acquired is important. In addition to historical statistics and weather driven development stage models, remotely sensed spectral data provides a potential tool for estimation of crop development stage. A model based upon spectral data should also provide advantages in terms of simplicity, timeliness, and applicability to areas as small as individual fields.

In this investigation, a model for determining development stage of corn (Zea mays L.) from spectral measurements in the four Landsat bands of 0.5 to 0.6, 0.6 to 0.7, 0.7, to 0.8, and 0.8 to 0.11 <m is proposed.

Estimated corn development stages using the model were determined from Landsat data acquired over sample areas 01 the U.S. Corn Belt as well as agricultural research plots at the Purdue University Agronomy Farm, West Lafayette, Indiana. The estimated corn development stage using the model was compared to ground observations made with the Hanway scale (1966).

Corn development stage estimates made from Landsat data had a correlation of R2 = 0.964 with the ground observed stages, being most accurate at stages earlier than Hanway Stage 6.0 (blister). Analysis of spectral data obtained from corn research plots at Purdue Agronomy Farm revealed that the model worked well with variation in plant population and soil background differences as well as arbitrary division into grain yield levels due to various experimental conditions. For all treatment variations of soil type and plant population and yield groupings, the R2 of calculated vs. observed development stage exceeded 0.95. This model's advantage for remote sensing is that it uses only spectral data and does not require meteorological data such as temperature, precipitation, and daylength. The model can be applied to individual corn fields rather than a general application to a region as large as crop reporting districts (or a state) and was found to work well for fields sampled over a large geographic area.
Date of Planting and Row Spacing Effects on Four Soybean Cultivars1
Authors: Parker M. B. , Marchant W. H. , Mullinix B. J.
Published: July 2010

Soil moisture conditions favor April planting of soybeans [Glycine may (L.) Merr.] in the southern USA, but reports have indicated that soybean cultivars were not adapted to April planting. Data are not available on the response of newer cultivars to early and late plantings. Also, reports from the north central USA have indicated that soybeans yield more when planted in narrow (46 cm or less) than in wide (92 cm or greater) rows, but there are conflicting data regarding row width from the southern USA.

A 3‐year study was conducted on a Tifton silt loam (fine‐loamy, siliceous, thermic, Plinthic Paleudult) at Tifton, Georgia (31° 28‘ N). ‘Essex’, ‘Davis’, ‘Bragg’, and ‘Hutton’, maturity groups V through VIII, respectively, were planted in narrow (46 cm) and wide (92 cm) rows at 15day intervals from early April to early July.

The interval from planting to flowering decreased for Essex and Davis as the planting date was delayed from early April through early July. This relationship occurred for Bragg and Hutton after early May planting. Essex was the earliest flowering and produced the shortest plants among all cultivars within each planting date. Essex was too short for efficient combining.

The overall effect of narrow rows vs. wide rows was a yield inuease of 1.2 quintals/ha or 4.2%, but yield response to narrow row planting was not affected by cultivars or planting dates.

Highest yields of Essex were obtained from early May planting. The other three cultivars yielded equally well when planted from late April through early June. Yields of all cultivars were lower for early April and early July plantings than for May and early June plantings.

May to early June was the optimum planting period for Davis, Bragg, and Hutton for the combined factors of yield, plant height, and seed quality, and none of the cultivars performed well in April planting. However, the late flowering characteristics of Davis, which apparently is responsible for relatively tall plants in April plantings, offers possibilities for use in breeding programs to develop desirable cultivars for April plantings but improved seed quality needs to be combined with other desirable traits.
Effects of N Fertilization and Cutting Schedules on Stockpiled Tall Fescue. I. Forage Yield1
Authors: Collins Michael , Balasko J. A.
Published: July 2010

Forage stockpiled in situ for winter use provides pasturage during a period of low forage production in midlatitude states of the midwestern and eastern United States. Two experiments were conducted to study the effects of harvest management and N fertilization rates on spring‐summer and autumn‐winter production of tall fescue (Festuca arundinacea Schreb.) forage. Treatments in Exp. I included four N rates; 0, 60, 120, and 180 kg/ha applied as NH4NO3 in split applications of one‐half in March and one‐half in August; three spring‐summer cutting schedules (1) mid‐June only, (2) mid‐May and early July, and (3) early June and mid‐July; and three autumnwinter harvest dates (1) mid‐December, (2) mid‐January, and (3) mid‐February. The soil was a moderately welldrained Lily loam (Typic Hapludults). Regression analysis indicated that the yield of forage available during winter increased as annual N application increased up to 137 kg/ha and 126 kg/ha for mid‐June stockpiling initiation in 1973–1974 and 1974–1975, respectively. The optimum annual N application rate for forage stockpiled beginning in early‐July was calculated to be 197 kg/ha in 1973–1974 and 136 kg/ha in 1974–1975.

Stockpiled forage yields decreased from 2.50 metric tons/ha to 2.24 metric tons/ha between December and February averaged over the 2 years of the study. Winter in vitro digestible dry matter yield (IVDDM) decreased during winter.

In Exp. II, treatments included four N rates: 0, 75, 150, and 225 kg/ha applied as NH4NO3 at the time of the last summer or autumn cutting which occurred in either early September, mid‐September, or early October. The soil was a Clarksburg silt loam (member of the fine‐loamy, mixed, mesic family of Typic Fragiudalfs). All forage was harvested in late winter. Forage yields during spring and summer increased up to the highest rate of N applied in both seasons. Any delay in initiation of stockpiling in Exp. II resulted in reduced winter yield. Winter yields increased in response to N application. Cutting date in autumn had little influence on forage yields the following spring, but rate of N fertilization did influence spring yield. Increasing autumn N application from 0 to 225 kg/ha increased spring forage production by an average of 2.40 metric tons/ha.
Combined Nitrogen and Vegetative Regrowth of Symbiotically‐grown Alfalfa1
Authors: Fishbeck Kathleen A. , Phillips Donald A.
Published: July 2010

Few studies clearly compare N source effects on herbage yield of alfalfa (Medicago sativa L.) grown with Rhizobium over several harvest cycles. Therefore, the effects of combined N on nodulation, growth, N accumulation, and development of alfalfa were studied over four harvest/regrowth cycles with a genotype cloned from the nondormant cv. ‘Dohfari.’ Ramets inoculated with Rhizobium meliloti Dang. strain 102F28 and irrigated with 0,2,8, or 16 mM N provided as NH4NO3, NO3‐, or NH4+ were grown in vermiculite in a naturally illuminated greenhouse in two replicate experiments from March through June and July through October. All combined N treatments enhanced herbage dry weight and total crude protein above the nil N control during the first growth period. The promotive effect of combined N decreased with each harvest until during the fourth regrowth, plants totally dependent on Rhizobium for reduced N produced herbage and crude protein yields equivalent to plants supplied 8 or 16 mM N as NH4NO3. Plants grown with 2mM N, a more reasonable N concentration for the soil solution, were more productive than nil N plants during the first two growth cycles but had no advantage during the third and fourth cycles regardless of the form of combined N used. Nitrate suppressed nodule development more than either NH4NO3 or NH4+. Greater availability of combined N increased the soluble sugar:starch ratio in the root and crown tissues. No significant differences were observed between the two experiments except that plants grown later in the year (July to October) took longer to flower during each regrowth cycle.

The data indicate that the Rhizobium symbiosis cannot produce sufficient reduced N for optimum alfalfa growth during the first few harvest/regrowth cycles. During subsequent regrowth cycles, however, plants totally dependent on Rhizobium for N compounds had overcome the period of N‐limited growth and produced as much herbage and crude protein as plants grown with levels of combined N that might be expected under normal field conditions.
IVDMD, Total Sugars, and Lignin Measurements on Normal and Brown Midrib (bmr) Sorghums at Various Stages of Development1
Authors: Hanna Wayne W. , Monson Warren G. , Gaines T. Powell
Published: July 2010

Reduced lignin concentrations found in brown midrib (bmr) mutants of sorghum, Sorghum bicolor (L.) Moench., have great potential for increasing the in vitro dry matter digestibility (IVDMD) of sorghum forage. The objective of this study was to determine the effects of five bmr mutants on IVDMD, lignin concentration and total sugars of young vegetative forage that would be used for grazing or hay.

Forage from bmr 12 and bmr 18 harvested 4 weeks after planting was significantly higher in IVDMD than their normal counterparts in each of the 3 years tested. Three other mutants were not consistently higher in IVDMD indicating a possible environmental interaction. Total reducing and non‐reducing sugars were not related to IVDMD and the bmr mutants did not have a significantly different total sugar concentration than normal types. Four weeks after planting, IVDMD of bmr 12 forage was 7.2 and 5.6 percentage units higher than normal forage for leaves and stems, respectively. The differences observed for the bmr gene should lead to significant improvement in animal performance.
Chloride Effects on Water Potentials and Yield of Winter Wheat Infected with Take‐all Root Rot1
Authors: Christensen N. W. , Taylor R. G. , Jackson T. L. , Mitchell B. L.
Published: July 2010

Severity of take‐all root rot (caused by Gaeumannomyces graminis var. tritici) of winter wheat (Triticum aestivum L.) has been decreased in the Willamette Valley of western Oregon by applying Cl containing fertilizers. Apparent increases in leaf turgor of field grown wheat following spring topdressing with NH4Cl fertilizer suggested that Cl salts affect plant water potential components. Since the growth rate of G. graminis tritici declines with declining water potential, changes in plant water potential could influence the rate of host colonization by the pathogen. Leaf water (Ψ), osmotic (π), and turgor (P) potentials of winter wheat grown in replicated field trials on an Argiaquic Xeric Argialboll, an Aquultic Argixeroll, and a Pachic Ultic Argixeroll fertilized in March with 135 to 140 kg N/ha as (NH4)2SO4 or NH4Cl were measured in May and June to ascertain whether application of Cl salts influences water potential components in wheat. Fresh plant weight at milky ripe stage, grain yield, and grain kernel weight were measured to evaluate treatment effects on yield of wheat infected with take‐all root rot.

Applying 342 and 355 kg Cl/ha as NH4Cl reduced π in ‘Yamhill’ and ‘Stephens’ winter wheat leaves measured in May by 4 and 2 bars, respectively. Chloride treatment effects on π generally persisted through June. The slope of the regression of π on percent Cl in leaf tissue at one site was the same as that predicted by the van't Hoff equation indicating that increased symplasm Cl concentration probably accounted for the measured change in π. Leaf water and turgor potentials tended to be lower and higher, respectively, when these parameters were influenced by Cl treatment.

Use of NH4Cl fertilizer increased grain yields from 770 to 2,150 kg/ha (11 to 40%) over those obtained with (NH4)2SO4. Fresh weight yield and kernel weight were also increased with NH4Cl fertilization. Application of (NH4)2SO4 plus KCl or NaCl (101, kg Cl/ha) at one site increased grain yield and kernel weights over those obtained with (NH4)2SO4 alone.

Results of this study suggest that the susceptibility of winter wheat plants to G. graminis tritici colonization may be reduced by lowering the chemical potential of water in the plant. Because the osmotic potential in wheat plants changes readily with Cl application, fertilization with Cl salts provides an opportunity to actively manage plant water potential components for the express purpose of take‐all root rot suppression.
Aflatoxin Production on Various Popcorn Genotypes1,2
Authors: McMillian W. W. , Widstrom N. W. , Wilson D. M.
Published: July 2010

Aflatoxin, a metabolite of the ubiquitous fungus, Aspergillus flavus Link, is a chronic contaminant of preharvest corn (Zea mays L.) produced in some areas of the USA. Growing hybrids that sustain relatively low levels of toxin has been suggested as a method of minimizing this potentially serious threat to animal and human health. The purpose of this 3‐year study was to evaluate ears of selected popcorn genotypes for corn earworm, Heliothis zea (Boddie), damage, incidence of greenish‐yellow fungus (GYF) sporulation characteristic of A. flavus Link infections, and aflatoxin contamination levels in the grain. Evaluations were conducted under field conditions in Tifton loamy sand (Thermic, Plinthic Paleudult) and involved 17 popcorn genotypes. Results demonstrated significant differences among popcorns for levels of aflatoxin contamination, fungal infection, and corn earworm damage. A significant interaction between genotypes and years indicated that information from a single year cannot be relied upon to accurately identify host plant genotypes with consistent low aflatoxin levels.
Carbohydrate Quantification and Relationships with N Nutrition in Cool‐Season Turfgrasses1
Authors: Westhafer M. A. , Law J. T. , Duff D. T.
Published: July 2010

Abastract

Environmental and cultural variables are known to influence the carbohydrate status of cool‐season turfgrasses. This greenhouse study was conducted to 1) develop a technique utilizing standard analytical procedures which would simplify carbohydrate analysis of plant tissue while increasing specificity and sensitivity, and 2) to use these methods to determine if any one carbohydrate fraction in leaf, stem, or root tissue of three turfgrass species is more sensitive than another to applied N treatments.

A single aqueous extraction was required for quantification of glucose, fructose, sucrose, and fructans using glucose oxidase and invertase coupled with two standard colorimetric tests. Data analysis showed that the portion of the error term which could be directly attributed to the analytical technique across the three turf species was 1.19%. The procedure was precise, simple, and highly efficient.

‘Baron’ Kentucky bluegrass (Poa pratensis L.), ‘Penncross’ creeping bentgrass (Agrostis palustris Huds.), and annual bluegrass (Poa annua L.) were grown in a greenhouse at 5 and 10 mM NO‐3‐N levels. Total carbohydrate (reducing sugars, sucrose, and fructans) concentrations in root, stem, and leaf tissue of each species were lower in plants grown at the 10 mM NO‐3 level than those plants grown at the 5 mM NO‐3 level. On a whole plant basis, Kentucky bluegrass, creeping bentgrass, and annual bluegrass had 58%, 58%, and 49% lower total carbohydrate concentrations when grown at the 10 mM NO‐3 level. Fructose and glucose concentrations were usually, but not always lower in plants grown with 10 mM NO‐3‐N. Comparison of the carbohydrate concentrations between treatments and tissue fractions shows sucrose levels in root tissue to have the most dramatic response to N treatment. The ratio of total carbohydrates between the low to high N treatment was lower than the ratios of either sucrose in root tissues or fructans in stem tissues, indicating total carbohydrate analysis to be a less sensitive measure of the carbohydrate concentration changes between N treatments.
Composition and Digestibility of Smooth Bromegrass Clones Selected for High and Low IVDMD1
Authors: Collins Michael , Drolsom Paul N.
Published: July 2010

Improvement of the digestibility of forage grasses through breeding has received considerable attention. The objective of this experiment was to evaluate differences in composition and digestibility among smooth bromegrass (Bromus inermis Leyss.) clones selected for high and low in vitro dry matter disappearance (IVDMD). Thirty‐five clones of smooth bromegrass from a nursery (Piano silt loam, Typic Argiudoll) established near Madison were analyzed for IVDMD.

In vitro cell wall disappearance (IVCWD), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose, hemicellulose and lignin. The 35 clones consisted of 18 clones selected for high IVDMD and 17 selected for low IVDMD. In vitro dry matter disappearance ranged from 54.9% to 66.5%. High IVDMD clones averaged 63.2% IVDMD compared with 59.6% for low IVDMD clones. Neutral detergent fiber concentration in high IVDMD clones was reduced significantly compared with low IVDMD clones. The potential impact of such a reduction of cell wall concentration on forage intake should be evaluated with livestock.

A high negative correlation r = −0.76 was found between lignin concentration in the cell wall and the rate of IVCWD as measured by ending fermentation after 12 hours. This indicates that lignin concentration in the cell wall influenced initial IVCWD. The percentage of final cell wall disappearance after 12 hours of incubation in an in vitro system ranged from 22.4% (6.3% lignin in the cell wall) to 41.6% (3.7% lignin in the cell wall). The possible influence of the rate of cell wall disappearance on forage consumption of smooth bromegrass should be studied.

Lignin concentration in the cell wall component was found to be poorly correlated with the extent of IVCWD after 48 hours. No difference existed in the mean IVCWD (48‐hr) of high and low IVDMD clones even though high IVDMD clones had a lower lignin concentration in the cell wall (4.1%) compared with low IVDMD clones (5.4%).
No‐tillage Advantages for Soybean Seed Quality During Drought Stress1
Authors: Tyler Donald D. , Overton Joseph R.
Published: July 2010

Seed quality can be affected by soil and climatic conditions. The availability of soil water can be enhanced under no‐tillage. Under drought stress this can result in a more vigorous plant and production of higher quality seed.

Soybean [Glycine max (L.) Merr. ‘Forrest’] seed quality was evaluated in an experiment comparing no‐tillage, and five conventional tillage methods ranging from disking 10 cm deep to under‐row subsoiling 25 cm deep. The methods were studied on a Lexington silt loam (fine‐silty, mixed, thermic, Typic Paleundalfs) in 1979 and 1980.

No‐tillage soybeans were of higher quality in the dry season of 1980 as compared to conventional methods. Seed from no‐tillage had significantly less purple stain [Cercospora kikuchii (T. Matsu. and Tomoyaso) Chupp.] and wrinkled seed coats. Seed germination, weight, density, and yield were also superior in no‐tillage as compared to conventional methods. Soil water availability was also higher in notillage due to water conservation by the surface mulch.

Higher seed quality in no‐tillage could have resulted from greater soil water availability and reduced soil splash of purple stain organisms.