bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Light Intensity, Temperature and Growing Period on the Growth, Chemical Composition and Digestibility of Culver and Tanverde Alfalfa Seedlings1
Authors: Garza T. Ricardo , Barnes R. F. , Mott G. O. , Rhykerd C. L.
Published: July 2010

Synopsis

Dry matter accumulation and cellulose content of two alfalfa varieties increased with advancing maturity and increasing light intensity while crude protein and in vitro digestibility decreased. Soluble carbohydrates were greatest under high light intensity with alternating day and night temperatures of 30° C. and 15° C., respectively. Dry matter accumulation was greatest under high temperature and high light intensity, but digestibility was lower as temperature increased.
Effects of Simulated Drought by Polyethylene Glycol Solutions on Corn (Zea mays L.) Germination and Seedling Development1
Authors: Parmar M. T. , Moore R. P.
Published: July 2010

Drought conditions were simulated in the laboratory by using aqueous solutions having osmotic pressures from 1 to 10 atmospheres. “Carbowax” polyethylene glycol 6000 was used as the solute. Germination percentages and subsequent seedling growth of two lots of corn, differing in embryo soundness, progressively decreased with increased osmotic pressures. The effects of the high osmotic pressures were more adverse in the low than in the high quality seed lot. Soundness of embryos as revealed by tetrazolium tests was closely related to growth performance. The germination of seed under simulated drought conditions offers possibilities for revealing seed weaknesses and predicting relative differences among seed lots in field emergence.
Effect of Corn Population on Yield, Evapotranspiration, and Water‐Use Efficiency in the Northwest Corn Belt1
Authors: Timmons D. R. , Holt R. F. , Moraghan J. T.
Published: July 2010

In 1963 and 1964, experiments were conducted in western Minnesota, eastern South Dakota, and south‐eastern North Dakota to study the effect of corn stand on yield, evapotranspiration, and water‐use efficiency at different stages of plant growth. Five corn populations, within the limits of 6,000 to 24,000 plants per acre, were planted in a Latin square design at 7 and 10 locations during 1963 and 1964, respectively.

Under adequate moisture conditions in 1963, yields ranged from 60 to 134 bushels per acre at optimum stands of 14,000 to 22,000 plants, whereas, yields of 1 to 75 bushels at stands of 6,000 to 12,000 plants per acre were produced under the limited moisture conditions in 1964.

Evapotranspiration from planting to maturity ranged from 13.5 to 20.6 inches and from 9.4 to 17.1 inches for 1963 and 1964, respectively. Except at 2 of the 17 locations, evapotranspiration was not affected significantly by stand at any growth stage during the 2‐year period.

Water‐use efficiency increased as corn yield increased and reached a maximum of 454 pounds (8.1 bushels) of corn per inch of evapotranspiration. No definite relation of water‐use efficiency to stand was found for grain yields since optimum corn stands were related to growing seasons. Forage production and water‐use efficiency generally increased with higher plant populations, so there was a close relationship between them during the 2‐year period.
Frost Heaving of Soil and Plants. I. Incidence of Frost Heaving of Forage Plants and Meteorological Relationships1
Authors: Portz H. L.
Published: July 2010

Frost‐heave ratings ranging from minimum to severe were determined from historical data on over‐wintering forage condition for a 50‐year period in Illinois. Field observations of both plant and dowel uplift were made on frost‐susceptible claypan soils in southern Illinois from 1958 to 1966. Associated meteorological and soil conditions were studied to better define and predict the frostheaving action. The 30 winters of moderate to severe winter damage to legumes in southern Illinois occurred on imperfectly drained claypan soils under conditions of high October to January precipitation accompanied by moderate winter temperatures. In central and northern Illinois, only 11 such winters were recorded. Alfalfa varieties differed in their frost‐heave susceptibility in 1958 to 1962, ranging from 1.5 cm to over 5 cm of uplift. Soil moisture under a bare‐cultivated surface treatment remained near or above field capacity throughout the winter; whereas under tall fescue, the soil moisture in the 15.2− and 30.5− cm layers was below 30% most of the winter. Dowel uplift was 3.3 cm and 0.3 cm in the respective plots. Movement of wooden dowels was compared to alfalfa and red clover seedlings with dowels averaging 2.36 cm and the legume plants 1.16 cm of frost heave. On soils susceptible to frost‐heaving antecedent precipitation (Oct. through Jan.) was found to be the major requisite for frost heave. When antecedent precipitation was less than the long‐term average, 32.61 cm (12.84 inches) at Mt. vernon, Ill., there were only 2 winters out of 50 in which severe frost heaving occurred. A final predictive index of antecedent precipitation multiplied by temperature factors gave the best indication of frost‐heaving incidence and could be used in assessing winter damage to certain forages in the absence of historical field records.
Effects of Defoliation on the Longevity of Stand, Dry Matter Yields and Forage Quality of Tall Wheatgrass, Agropyron elongatum (Host) Beauv.1
Authors: Stroh James R. , Law Alvin G.
Published: July 2010

Tall wheatgrass was subjected to three defoliation frequencies at three clipping heights to determine the degree of defoliation the grass would withstand under optimum fertility and supplemental irrigation.

At the most intense defoliation treatment (6‐week interval) yield and persistence were directly related to cutting height. At the less intense defoliation treatments (boot stage plus aftermath and flower stage) yield was highest at the 5‐cm stubble height the first 2 years, but by the third year density of the plants had declined to less than 50% of the original. The 5‐cm stubble height was too low for tall wheatgrass at three intensities of use. The 15‐cm cutting height was optimum at low cutting frequencies and the 25‐cm cutting height was optimum at high intensities. Harvesting tall wheatgrass at the boot stage was detrimental to the stand at all three cutting heights.

Forage quality, expressed in percentage crude protein, crude fiber, lignin, fat, and ash, was increased under high intensity defoliation. Production of total digestible nutrients (TDN) per hectare was directly proportional to the amount of dry matter produced under the several treatment levels. Frequency of defoliation had more effect on forage quality and production of TDN than did height of defoliation.
Castorbean Production as Related to Length of Growing Season I. Effect of Date of Plant Desiccation1
Authors: Kittock D. L. , Williams J. H.
Published: July 2010

Castorbean plants (Ricinus communis L.) were killed by chemical desiccant at weekly intervals during the fall in four tests in 2 years in Nebraska. Effects of desiccation on total yield and germination were determined. Yield, weight per 100 seeds, and germination were also determined for sequential racemes. Natural freeze was the check treatment. Yield increased at a uniform rate with delay of desiccation except in one test severely affected by Alternaria leaf spot disease. The average weekly increase in yield for the four tests was 199 kg per ha. Primary racemes were mature at the time of first treatments. The contribution of secondary, tertiary and quaternary racemes to yield increased during the entire course of the treatments.

Seed weight from secondary and tertiary racemes increased with maturity. Germination was positively and significantly correlated with seed weight. The highest percentage germination was obtained from late September and early October desiccation treatments. Freezing of immature seeds and weathering of mature seeds reduced germination. Drying of seed following plant desiccation required about 10 days and did not reduce germination. Yield loss from 10 days' growth prior to freeze was calculated to be 284 kg per ha. On basis of low seed germinations obtained in these tests, the feasibility of castorbean production for seed in Nebraska would be questioned.
Effect of Nitrogen on Winter Root Growth of Bentgrass1
Authors: Powell A. J. , Blaser R. E. , Schmidt R. E.
Published: July 2010

Effect of cool season N applications on root growth of bentgrass was studied under putting green conditions.

Roots grew rapidly during fall and spring. Winter root growth was highest when N had been applied in October, October‐December, or October‐December‐February. When N was not supplied or high rates were applied monthly, winter root growth was very low or even negative. It was suggested that the root growth reduction with the high rates of N fertilization could be associated with low carbohydrates since sugars needed for root growth were probably utilized in increased rates of N metabolism. Lack of winter root growth when N was not applied was associated with low metabolic activity.
Effects of Irrigation Intensity and Nitrogen Level on the Performance of Eight Varieties of Upland Cotton, Gossypium hirsutum L.1
Authors: Jackson E. B. , Tilt P. A.
Published: July 2010

The effects of four irrigation treatments and two levels of nitrogen on the performance of eight varieties of upland cotton were studied over a 3‐year period on Glendale silty clay loam at Yuma, Arizona.

The varieties (‘Acala 44‐10,’ ‘Deltapine Smooth Leaf,’ ‘DeKalb 220,’ ‘Stoneville 7‐A,’ California Strains A and A‐65, and Arizona Experimentals 221 and 6010) tended to respond similarly to the irrigation treatments. Highest yields were obtained from all varieties under irrigations spaced 14 to 21 days apart with totals of 102 to 119 cm of applied water per season. Much lower yields were obtained from the “dry” irrigation treatments which approached depletion of the available soil moisture before each irrigation, with totals of 84, 84, and 64 cm of applied water, respectively, for the 3 years. Irrigation every 7 days, in 1963 and 1964, with totals of 147 and 160 cm of applied water produced yields of seed cotton almost as low as those from the dry treatments.

Under the 14‐ and 21‐day irrigation schedules, application of ammonium sulfate at the rate of 224 kg N/ha, when compared with no applied nitrogen and with 84 kg N/ha, increased yields of seed cotton in all varieties. In 1963, application of 112 kg N/ha in midseason was equal to 224 kg N/ha applied before the first postemergence irrigation. Nitrogen level had no effect on yield under the dry 28‐day irrigation schedule. Under the wet 7‐day irrigation schedule, yields of Acala 44‐10 and Arizona Experimental 221 were reduced by high nitrogen while yields from the other varieties were unaffected or slightly increased.

There was no consistent treatment effect on lint percentage or fiber properties.
Phytotoxicity of Plant Materials on Seed Germination of Crownvetch, Coronilla varia L.1
Authors: Bieber G. L. , Hoveland C. S.
Published: July 2010

Phytotoxic potential of six crop and four weed species was determined on crownvetch. Water extracts of Virginia pepperweed, evening primrose, crabgrass, and crownvetch were most toxic to seed germination. Tall fescue and weeping lovegrass were least toxic. Extracts from aerial portions were more inhibitory than those from roots. Crown vetch was less tolerant of high osmotic pressure than was crimson clover, but this did not explain the strong inhibition of the former species by certain plant extracts. Pepperweed residues incorporated into soil for 10 weeks were toxic to crownvetch seed germination. Kobe lespedeza residues incorporated into soil did not affect percent germination but decreased seedling growth.

Pepperweed extract inhibited seed germination of tall fescue, ball clover, sericea, and Kobe lespedeza. It was toxic to crownvetch at a dilute concentration of 1:150 (w/v). The toxic substance occurred in all parts of the plant and was not affected by drying temperature. Pepperweed extract was toxic to five fungi. The phyto‐ and fungitoxicity of pepperweed may be of significance in competition with other plant species.
Effect of Cropping Systems on Soil Physical Properties and Irrigation Requirements
Authors: Carreker John R. , Bertrand Anson R. , Elkins Charles B. , Adams William E.
Published: July 2010

The irrigation requirements for the period May‐August were investigated in relation to some physical properties of Cecil soil as affected by eight cropping systems. These systems ranged from corn grown continuously with stalks removed to sod continuously. The cropping systems had no effect on particle size distribution and total porosity, but crust strength decreased and aggregate stability and infiltration rates increased as the quantity of plant material returned to the soil was increased. The increased water intake was offset by increased deep drainage from the root zone, so there was no change in subsequent irrigation requirements
Nitrate and Nutrient Accumulation in Two Varieties of Bermudagrass (Cynodon dactylon (L.) Pers.) as Influenced by Soil‐Applied Fertilizer Nutrients1
Authors: Lovelace Dale A. , Holt Ethan C. , Anderson W. B.
Published: July 2010

Two varieties of bermudagrass were grown in a green‐house to determine differences in nitrate‐nitrogen content due to soil texture, nitrogen fertilization, and various mineral nutrient treatments. Nitrate‐N content of ‘NK‐37’ bermudagrass was twice as high as that of ‘Coastal’ bermudagrass across all treatments. Soil texture influenced nitrate‐N levels within each variety more than did rate of N fertilization. Mineral nutrient application did not significantly alter nitrate‐N levels in the plant tissues. Dry matter yields were increased by nitrogen fertilization, but not by mineral nutrient application. Zinc was the only mineral nutrient which increased within the plant tissues due to mineral application. All nutrients were as high or higher in NK‐37 than in Coastal except for Mn.
Effects of Nitrogen and Potassium Fertilization, Irrigation, and Clipping Interval on Chemical Composition of Coastal Bermudagrass (Cynodon dactylon (L.) Pers.). I. Total Available Carbohydrates1
Authors: Hojjati S. M. , McCreery R. A. , Adams W. E.
Published: July 2010

‘Coastal’ bermudagras(Cynodon dactylon (L.) Pers.) with and without supplemental irrigation on Cecil sandy loam fertilized with seven N:K treatments (224:224, 224:112; 224:37, 672:672, 672:336, 672:112, 1120:560 kg/ha per year) was clipped at 2‐, 4‐, and 6‐week frequencies. Analyses of the forage for TAC (Total Available Carbohydrates) as measured by the soluble plus hydrolyzable (2% v/v H2SO4) carbohydrates, showed that irrigation and fertilization decreased the percentage TAC but increased the total TAC production per hectare due to higher yields. Extending the clipping interval increased both the percentage and yield per hectare of TAC.
Potassium Movement in Fallowed Soils1
Authors: Boswell Fred C. , Anderson O. E.
Published: July 2010

The rate and depth movement pattern of K, applied as KNO3, was studied on two widely different fallowed soils under field conditions. Results indicate: (a) 5 weeks after treatment, the applied K was in the top 15 cm of both the Davidson scl and the Marlboro ls after 4.6 and 3.3 cm of rainfall, respectively; (b) after 14 weeks and 43 cm of rainfall on the scl soil and 17 weeks and 26 cm of rainfall on the ls soil, virtually all of the applied K was found in the top 30 cm of both soils except for the high K‐rate on the loamy sand; (c) both soil texture and amount of rainfall influenced K movement; (d) the high rate of K tended to move faster and to greater depths as compared with the moderate rate; (e) irrespective of the application rate, the highest concentration of K was found in the 15 to 30 cm layer of both soils 76 weeks after application, even though above normal rainfall occurred; and (f) these data indicate that a normal application of K will not leach beyond the root zone in soils, similar to those used in these tests, during the growing season of most field crops.
Effect of Nitrogen, Phosphorus and Potassium Levels and Clipping Frequency on the Forage Yield and Protein, Carotene, and Xanthophyll Content of Coastal Bermudagrass1
Authors: Burton Glenn W. , Wilkinson W. S. , Carter R. L.
Published: July 2010

Omitting P and K from fertilizer that supplied 672 kg/ha of N to ‘Coastal’ bermudagrass (Cynodon dactylon (L.) Pers.) growing on a Tifton loamy sand of medium‐available P and low‐available K content reduced forage yield 45% without affecting the protein, carotene, and xanthophyll content of the grass. Increasing the ratio of P and K to N above a 4‐1‐2 (N‐P2O5‐K2O) fertilizer ratio failed to increase protein, carotene, and xanthophyll contents except at very high N rates (1,008 kg/ha). Excellent yields of carotene (4,838 g/ha) and xanthophyll (7,649 g/ha) were obtained from Coastal bermuda fertilized with 672 kg/ha of N with P2O5 and K2O to make a 4‐1‐2 ratio and cut at 21‐day intervals. This forage averaged 18.0% protein.
Nitrogen‐Sulfur Relationships in Wheat (Triticum aestivum L.), Corn (Zea mays), and Beans (Phaseolus vulgaris)1
Authors: Stewart B. A. , Porter L. K.
Published: July 2010

The nitrogen‐sulfur ratios in the tops and roots of wheat (Triticum aestivum), corn (Zea mays), and beans (Phaseolus vulgaris) were studied in relation to N and S supplies in soil. Greenhouse studies showed that when S became limiting, additional N did not affect either the yield or protein level of the plants, but the nonprotein N (nitrates, amides, and amino acids) increased. There was a close relationship between the amounts of N and S metabolized in the plants. The data indicated that one part sulfur was required for every 12 to 15 parts nitrogen to insure maximum production of both dry matter and protein. As the use of nitrogen fertilizers increases, the possibility that S may become limiting also increases, and adequate consideration of S becomes necessary. This is especially true in greenhouse studies, where S may become limiting very quickly.
Effect of Soil Moisture Regime and Row Spacing on Grain Sorghum Production1
Authors: Plaut Z. , Blum A. , Arnon I.
Published: July 2010

Effect of soil moisture regime and row spacing on grain yield of RS‐610 sorghum (Sorghum bicolor L. Moench.) was investigated under semi‐arid conditions in 1964 and 1965. Most grain resulted with three irrigations or with two irrigations when the second was applied between heading and milk stage. The latter gave highest water use efficiency. One irrigation, applied at heading, was better than a single application made earlier or later.

Main yield component affected by irrigation was the 1,000‐grain weight. One year this was significantly correlated with leaf area duration (LAD). Total evapotranspiration increased from 270 mm without irrigation to as much as 530 mm with three irrigations.

There was a sigmoid relationship between yield and total evapotranspiration. Total stover production per unit area increased linearly as evapotranspiration increased. Decreasing the number of irrigations increased water depletion by causing greater depth of root development.

Decreasing row spacing from 70 to 45 cm had hardly any positive effect on yield.
Defoliation Effects on Different Corn (Zea mays, L.) Hybrids as Influenced by Plant Population and Stage of Development1
Authors: Hanway J. J.
Published: July 2010

The effects of 50 and 100% defoliation at different stages of development of early, midseason, and late maturing corn hybrids grown at three plant populations were studied in a field experiment. The relative reduction in grain yield due to defoliation was different for hybrids, stages of development when defoliated, and degrees of defoliation, but was not influenced by differences in plant population density. Loss in grain yield due to defoliation was associated primarily with a reduced rate of dry matter accumulation in the grain during grain formation.
Vapor Losses Through Soil Mulch at Different Wind Velocities1
Authors: Acharya C. L. , Prihar S. S.
Published: July 2010

Rates of water vapor loss, E, through surfactant treated soil mulch of varying porosity and thickness were measured in pots exposed to various wind velocities under a wide range of evaporative demand. Empirical values of constant ‘BD’ obtained from the relation Eo/E = 1+BDZn (where Eo is the potential evaporation from the medium and Zn is the thickness of mulch) were expressed in terms of wind velocity (X1) and porosity mulch (X2). Multiple regression of the type BD = q + q1X1 + q2X2 was used to express BD as a function of wind velocity and porosity of mulch within the range of linearity of the relation Eo/E = f (Zn).
Zinc Seed Treatment as a Source of Zinc for Beans (Phaseolus vulgaris)1
Authors: Rasmussen P. E. , Boawn L. C.
Published: July 2010

Zinc uptake by bean plants from zinc materials applied to the seed coat was evaluated as a substitute for zinc fertilization and as a means of eliminating the temporary early season zinc deficiency which commonly occurs even after fields have received zinc fertifizafion.

Zinc seed treatment was not an effective substitute for zinc fertilization, since zinc uptake was insufficient to meet plant needs beyond the three‐compound‐leaf stage of growth even though the amount of zinc applied through seed treatment exceeded total zinc upake requirements for the entire growth cycle.

When used in conjunction with zinc fertilization, zinc seed treatment completely eliminated the temporary scattered zinc deficiency which occurred when beans received only a 11.2 kg Zn/ha soil application. However, no significant yield increase or hastened maturity occurred as a result of elimination of these early season zinc deficiency symptoms. The only apparent benefit of zinc seed treatment in this instance was promotion of more uniform maturity.

The zinc polyflavonoid was superior to ZnSO4 and ZnEDTA compounds when used as the zinc source in seed Treatment materials.
Effect of Crop Row Spacing on Erosion and Infiltration1
Authors: Mannering J.V. , Johnson C.B.
Published: July 2010

Simulated rain tests were applied during four cropstage periods to corn (Zea mays L.) row spacings of 51, 76, and 102 cm and to soybean (Glycine max (L). Merr.) row spacings of 18, 51, and 102 cm. Infiltration and soil loss were measured 2 to 3 weeks, 4 to 5 weeks, and 7 to 8 weeks after planting and after harvest. Corn row spacing had little effect on ground cover or erosion during the first 5 weeks after planting. At 7 to 8 weeks, ground cover was increased slightly and erosion was reduced 24% by the narrow row (51‐cm) spacings. Narrow row spacings (18 and 51 cm) for soybeans significantly increased ground cover as early as 3 to 4 weeks after planting. Major changes in infiltration and erosion resulting from narrow row soybeans, however, were largely restricted to the last half of the growing season. During this period, infiltration was 24% greater and soil loss 35% less from narrow rows (51‐cm) than from wide rows (102‐cm). From the erosion control standpoint, the use of narrow rows for soybeans would appear to be more beneficial than narrow row corn because of the comparatively greater soil‐loss reductions.
Relative Photosynthetic Potential for Grain Yield of Various Leaf Canopy Levels of Corn1
Authors: Pendleton J. W. , Hammond J. J.
Published: July 2010

Defoliation treatments were applied to individual plants of Zea mays L. surrounded by normal plants in the field at Urbana, Ill. over a 3‐year period to determine the Relative Photosynthetic Potential (RPP) of various leaf canopy levels and final grain yield. RPP was found to be approximately twice as high in leaves in the top third of the canopy as the middle leaves, and five times as high as leaves in the bottom third. There was also a linear decrease in RPP as defoliation treatments were applied at weekly intervals following tasseling. At extremely low plant populations (4,942 plants/ha), middle canopy areas were most important, whereas at intermediate or high plant populations the top canopy areas were the prime grain yield contributors. Defoliation comparisons of a tolerant vs. intolerant hybrid (at high plant populations) indicated great difference in RPP.
Distribution of Rhizobium japonicum Serogroups in Soybean Nodules as Affected by Planting Dates1
Authors: Caldwell B. E. , Weber D. F.
Published: July 2010

The soybean variety ‘Lee’ was planted at different dates for 3 successive years in Codorus silt loam soil containing an established population of Rhizobium japonicum. The soil was not reinoculated. Nodules were collected from each of the treatments and classified into the appropriate serogroup. The occurrence of specific serological groups was influenced by planting date. Serogroup c3 was greater in the late planting dates in 2 years and serogroup c2 increased the third year. Serogroup 110, and the composite serogroups 122 to 125 were at their maximum for the earliest planting dates. The serological distribution also differed when nodules were sampled from plants at different stages of development. The serological variation in planting date was attributed to the different soil and climatic environments and indicated the influence of the environments on the ecology of the Rhizobium.
Interaction of Gas Composition and Salinity upon Root Cell Division of Vicia faba L.1
Authors: Mohamed S. A. , Williamson R. E.
Published: July 2010

The responses of Vicia faba L. seedlings to treatments consisting of combinations of O2, CO2, and N2 gases in the root environment were determined by microscopic examination of root tips at several times during and after treatment. Superimposed on the gaseous treatments were three nutrien solution salinity levels of 2.95, 5.95, and 8.95 mmho/cm. The plants were grown in an artificially lighted, controlled environment room with roots in airtight chambers. Roots in the chambers were sprayed intermittently (1 min/5 min) with one of the nutrient solutions.

When roots were continually in air, the number of dividing cells in secondary root tips decreased linearly as the salinity level increased. The N2, treatment drastically reduced the number of dividing cells at all salinity levels; but during the recovery period, the numbers of dividing cells were 70, 80, and 100% of the controls at low, medium, and high salinity, respectively. Carbon dioxide levels of 3.5% and 6.0% with O2 at 17.5% and 15.0%, respectively, considerably reduced the number of dividing cells at a low salinity level and the number of dividing cells did not return to normal during recovery. At a medium salinity level 6.0% CO2 plus 15.0% O2 reduced the number of dividing cells, but 3.5% CO2 plus 17.5% O2 did not. During recovery following treatment with 6.0% CO2 plus 15% O2 at the medium salinity level, the number of dividing cells returned to that of the control. At the highest salinity level mitotic divisions in root tips were stimulated by CO2 treatments. These daa suggest that short periods of inundation or overirrigation may be less injurious to roots in saline than in nonsaline soil.
Evaluation of Reed Canarygrass and Tall Fescue as Spring‐Summer and Fall‐Saved Pasture1
Authors: Bryan W. B. , Wedin W. F. , Vetter R. L.
Published: July 2010

Dry matter (DM) digestibility and voluntary intake (VI) of reed canarygrass (RC) and tall fescue (TF) pastures were studied in June, late July, early October, early November, and late November. Three applications of nitrogen (N), totaling 314 kg/ha, were made. Relationships were established between fecal N and DM digestibility by feeding freshly cut forage to steers indoors. Chromic oxide was administered daily to grazing steers, feces were sward sampled, digestibility of grazed forage was predicted, and VI estimated. Data are also presented on yield, percentage DM, percentage and apparent digestibility of crude protein, and nutritive value.

In only one instance, early October, was TF superior to RC in VI, although TF was more digestible in all periods except June. In June, TF was more mature, and its digestibility and VI were less than RC. In late July, grazing steers consumed less TF in spite of its higher digestibility, compared with RC regrowth and wth first‐growth TF. In early November, TF was superior to RC in digestibility, VI, percentage crude protein, and yield. In late November, however, TF was lower than RC in VI and crude protein, findings difficult to explain. Dry matter digestibility and VI values were more closely related for RC than TF. Voluntary intake of steers grazing TF was more variable than the predicted digestibility. Thus, although digestibility is a good measure of nutritive value in RC, it does not seem so for TF.
Cation‐Anion Balance in Crops as a Factor in Determining the Effect of Nitrogen Fertilizers on Soil Acidity1
Authors: Pierre W. H. , Meisinger John , Birchett J. R.
Published: July 2010

The quantitative effect of crops on the acidity produced in soils from nitrification of NH4NO3 fertilizer was determined by growing oats and. buckwheat in the greenhouse and finding the amounts of CaCO3 necessary to bring the soils back to their original pH. Three crops of each plant species were grown, and the plants were analyzed for total N, nitrate‐N, and excess base. Determinations of pH were made both in 0.01 M CaCl2 and in H2O, with modifications to eliminate errors due to soluble salts.

The acidity developed from NH4NO3 in uncropped soil was almost equal to the theoretical amount that should be developed by nitrification. Without the removal of soluble salts erroneous values were obtained. The increase in acidity due to N4NO3 when oats was grown lower than the theoretical value in the absence of a crop by 27%, and the increase in acidity with buckwheat was higher than the theoretical value by 87%. Analyses of the crops showed that the deviations from the theoretical increase in soil acidity from NH4NO3 fertilizer was quantitatively explained by the numbers of chemical equivalents of N and excess bases taken up by the crops, excess base being defined as total cations (Ca++ Mg++, K+ and Na+) — total anions (C1‐, SO4‐, and H2PO4‐).
Management Effects on Forage Production and Digestibility of Yuchi Arrowleaf Clover (Trifolium vesiculosum Savi)1
Authors: Hoveland C. S. , Carden E. L. , Anthony W. B. , Cunningham J. P.
Published: July 2010

‘Yuchi’ arrowleaf clover (Trifolium vesiculosum Savi) produced more tillers and remained productive longer when cut at 1‐, 2‐, or 3‐week intervals than at 4‐, 5‐, or 6‐week intervals. Total yields were higher from less frequent cutting. Digestible dry matter (DDM) was high from December to maturity in June under all cutting frequencies. Stems of arrowleaf clover were higher in DDM than crimson clover (Trifolium incarnatum L.).
Herbicides and Nitrogen Fertilizer for the Establishment of Three Varieties of Spring‐sown Alfalfa1
Authors: Peters E. J. , Stritzke J. F.
Published: July 2010

We evaluated the effects of ammonium nitrate fertilizer on yields and stands of three varieties of seedling alfalfa (Medicago sativa L.) when these were treated and also not treated with preplant applications of 3.3 kg/ha of ethyl N,N‐dipropylthiocarbamate (EPTC). Alfalfa was sown in April. In two experiments we applied an overall treatment of 0.55 kg/ha of 4‐(2,4‐dichlorophenoxy)butric acid (2,4‐DB) to control broadleaf weeds. EPTC controlled weeds and increased yields of alfalfa, except when injury from EPTC occurred. Ammonium nitrate tended to reduce stands of alfalfa. Ammonium nitrate increased yields of Vernal and Du Puits, but not Ranger, when weeds were controlled with EPTC. Seedling alfalfa may not have fully responded to ammonium nitrate on EPTC plots because EPTC caused some injury to alfalfa and the fertilizer increased competition from broadleaf weeds.
Effect of Simazine on Protein Content of Rice Grain (Oryza sativa L.)
Authors: Vergara B. S. , Miller M. , Avelino E.
Published: July 2010

Although simazine application to flooded soil at flowering time increases the percent protein in the rice grain, it is accompanied by a decrease in grain yield which can be attributed to increased sterility. This decrease in grain yield consequently lowers the total grain protein production per crop.

Application of simazine to young rice plants grown in culture solution increased the nitrogen content of the blades, sheaths plus culms, and roots. The increase, however, is not the result of an increase in nitrogen uptake by the rice plant. The reduction in dry weight accounts for the increase in percent nitrogen.
Oxygen Diffusion in the Soil‐Plant System III. Oxygen Concentration Profiles, Respiration Rates, and the Significance of Plant Aeration Predicted for Maize Roots1
Authors: Luxmoore R. J. , Stolzy L. H. , Letey J.
Published: July 2010

Oxygen concentration profiles, mean respiration rates, and the percent plant aeration estimates (proportion of respired oxygen diffusing from the atmosphere via gas spaces in the plant) were obtained from an analysis of steady state oxygen diffusion in maize (Zea mays L.) root models under simulated field conditions.

An increase in root radius and in water film thickness as occurs after rainfall or irrigation induced a decrease in oxygen concentration within the root, a decrease in mean respiration rate, and an increase in percent plant aeration (PPA). An increase in root length reduced both mean respiration rate and PPA. The mean respiration rates calculated for the various models were about half of the maximum rate for mature root tissue, indicating that oxygen concentration is the main factor limiting respiration rate under the simulated field conditions.

Plant aeration increased markedly with increase in root porosity and this was accompanied by a higher oxygen concentration profile in the root and a small increase in mean respiration rate. Changes in the respiration or root wall permeability had minor effects on PPA.

Under conditions which simulate the growth of adventitious roots of maize (0.05‐cm root radius and 20‐cm root length), PPA is 34% for a well aerated soil (0.01‐cm water film) and 42% for a soil which is oxygen deficient (0.05‐cm water film). Plant aeration is thus predicted to be a significant factor in the oxygen relations of maize roots. For a given root system, the gas‐filled porosity and the thickness of the water film around the root have the greatest influence on this process. Soil aeration is important in the oxygen supply to the lower root and root tip regions and thus has a critical effect on continuing plant growth and development.
Sodium and Potassium Interactions in Increasing the Salt Tolerance of Atriplex halimus L.: II. Na+ and K+ Uptake Characteristics
Authors: Mozafar Ahmad , Goodin J. R. , Oertli J. J.
Published: July 2010

Absorption of Na+ and K+ by Atriplex halimus from solutions with varying concentrations of Na+, K+, or Na+ + K+ were studied. In contrast to most plants, Na+ absorption by A. halimus was not inhibited by high concentrations of K+ in the culture solution. On the other hand, K+ absorption was greatly reduced by excess Na+ in the growing medium. If Na+ and K+ were present at equal concentrations, Na+ uptake was twice as great as K+. A specific site for Na+ absorption which is not inhibited by excess K+ in A. halimus was postulated. The results of previously reported work, in which it was shown that the presence of equal parts of Na+ and K+ in the culture solution resulted in the tolerance of plants to lower external osmotic potential and also higher yield, was discussed in light of the presence of higher Na+ and K+ content of the leaves. The presence of a biochemical interaction between Na+ and K+ which becomes operative only when both ions are present in adequate amounts is postulated. Higher yields and tolerance to lower external osmotic potential are thought to be the final manifestation of such a biochemical interaction.
Influence of Temperature on the Yield and Chemical Composition of Five Forage Legume Species1
Authors: Smith Dale
Published: July 2010

One‐year‐old plants of ‘Vernal’ alfalfa, ‘Lakeland’ red clover, ‘Common’ alsike clover, ‘Empire’ birdsfoot trefoil, and ‘Goldtop’ biennial sweetclover were grown to first flower in four temperature regimes: (a) 32 C, day/27 C night, (b) 27/21 C, (c) 21/15 C, and (d) 15/10 C. Flowering was delayed as temperatures decreased, except for trefoil and sweetclover where flowering occurred first in (b). Herbage, root, and total plant dry matter yields increased as temperatures decreased, except for trefoil in (a) where maturity was delayed and yields were as large as in (d). Average shoot height of red and alsike clovers and sweetclover increased as temperatures decreased, but changed little with trefoil. Shoot height of alfalfa was greatest in (b). Numbers of shoots were not affected by temperature, except in alsike clover where they increased as temperature decreased. Influence of temperature on chemical composition of the herbage and on carbohydrate storage in the roots is discussed. It was noteworthy that K concentration was very low in the herbage grown at the coldest temperatures (d) where the average for all species was 1.4% as compared with 2.3% in the herbage from (b).
Differential Response of Rice Varieties to Timing of Mid‐season Nitrogen Applications1
Authors: Wells B. R. , Johnston T. H.
Published: July 2010

Field studies were conducted with rice (Oryza sativa L.) on Crowley silt loam soil using the important commercial cultivars ‘Bluebelle,’ ‘Nova 66,’ and ‘Starbonnet.’ We studied the effects of rate and timing of mid‐season N applications on grain yield, plant height, lodging, head‐rice yield, and grain weight (g/M) of varieties (cultivars) differing in maturity and plant type. All plots received 45 kg/ha of N as ammonium sulfate 15 days after seedling emergence, just before initial flooding. The remaining N needed to give total rates of 78, 112, or 146 kg/ha was applied to drained soil at specified intervals near midseason. Fifteen main stems, selected at random from the outside rows of each plot at the time of mid‐season N application, were used for determining internode lengths.

Maximum grain yields were associated with N applied at median internode lengths averaging 21.0, 58.5, and 5.0 mm for Bluebelle, Nova 66, and Starbonnet, respectively. Delaying mid‐season N applications until these respective stages of plant development, resulted in shorter plants and less lodging, accompanied by increased grain weight and head‐rice yields.

Variations in the median internode length at N fertilization, timed for a combination of maximum grain yield and minimum plant height and lodging, were closely associated with plant type. Starbonnet and Bluebelle, which have short, stiff straw and erect leaves, responded better to N applied at a shorter internode length than Nova 66, a taller, broader‐leaved variety. When N was applied too early, Nova 66 produced considerably more excessive vegetation than did Bluebelle and Starbonnet. Both Starbonnet and Bluebelle have plant types which approach the one currently favored by many plant breeders.
Sunflower Date of Planting and Chemical Composition at Various Growth Stages1
Authors: Robinson R. G.
Published: July 2010

Six sunflower (Helianthus annuus L.) varieties were planted at seven dates ranging from April 24 to June 28,1967 through 1969. Early May plantings produced highest seed yields, hectoliter weights, oil percentages, and large seed percentages. Days from planting to emergence and emergence to flowering decreased from early to late planting dates. Date of planting was the variable which most consistently affected seed yield. It overshadowed both varieties variation and the interaction of dates ✕ varieties.

Whole plant samples for N, S, P, K, Ca, Mg, Fe, Na, Sr, Zn, Cu, Mo, Mn, and B analyses were taken at 13 different growth stages and separated into root, stem‐leaves‐receptacle, and seed. Comparative data for seedling, heading, flowering, and maturing periods of growth showed concentrations of most elements declined with age in stems‐ leaves‐receptacle.

Variation in composition of stem‐leaves‐receptacle among growth stages was greater than among varieties, but this relationship was reversed in seed. Seed; stemleaves‐receptacle, and root differed in composition and in relative rank of the elements.
A Simple Turbidimetric Method of Determining Total Sulfur in Plant Materials1
Authors: Tabatabai M. A. , Bremner J. M.
Published: July 2010

A rapid method of determining total sulfur in plant materials is described. The plant material is digested in a volumetric flask with nitric and perchloric acid, and the sulfate content of an aliquot of the digest is determined turbidimetrically as BaSO4 by a barium chloride‐gelatin procedure. The method is simple and precise, and its results agree closely with those obtained by the Johnson‐Nishita method.
Mulches for Grass Establishment on Fill Slopes1
Authors: Dudeck A. E. , Swanson N. P. , Mielke L. N. , Dedrick A. R.
Published: July 2010

Eleven mulch treatments were evaluated during the fall of 1966 on a 2:1 northeast‐facing fill slope seeded to smooth bromegrass (Bromus inermis Leyss.). Mulch materials included wood cellulose fiber, excelsior, jute netting, emulsifiable asphalt used separately and as an anchorage for corncobs, woodchips, prairie hay, and fiberglass. Plots protected with an excelsior mat yielded the best seedling grass.

Eight mulch treatments were evaluated on a 2:1 east‐facing fill slope during the fall of 1967. Mulch materials included an emulsifiable polymer, compost, wood cellulose, jute netting, excelsior, and asphalt‐anchored mulches of excelsior, woodshavings, and bark dust. Plots protected with an excelsior mat or jute netting yielded the best seedling grass.
Nitrogen Metabolism in Atriplex polycarpa as Affected by Substrate Nitrogen and NaCl Salinity1
Authors: Chatterton N. Jerry , Goodin J. R. , Duncan Cameron
Published: July 2010

Nitrogen metabolism and growth responses of desert saltbush (Atriplex polycarpa) were studied using various combinations of nitrogen and sodium chloride in the growing medium. Plant yields were reduced with high levels of either N or NaCl and were further reduced when both N and NaCl were present at high concentrations. Nitrate accumulated in the plant tissues sufficient to be a problem for grazing animals only when the growth medium contained .045 M nitrogen. Total‐nitrogen and protein‐nitrogen were both relatively high, ranging from 2 to 8% (dry wt.) among the treatments. Although some non‐salt‐tolerant plant species accumulate non‐protein‐nitrogen when grown in a saline medium, we found no such increase in desert saltbush. We believe that salt tolerance in desert saltbush is the result of anatomical adaptations in combination with a high protein and low non‐protein‐nitrogen content.
N, P, and K Percentages in Soybean (Glycine max (L.) Merrill) Plant Parts1
Authors: Hanway J. J. , Weber C. R.
Published: July 2010

Field experiments were conducted with N fertilizer applications for nodulating and non‐nodulating soybean isolines, with P and K fertilizer applications for the nodulating isolines, and with 8 varieties. Percentages of N, P, and K in the plant parts at successive stages of plant development were determined. Composition of plant parts from different varieties usually were similar. N, P, and K concentrations in each plant part, except the seeds, usually decreased as the season progressed. Fertilizer applications resulted in increased concentrations of the fertilizer nutrient applied in all plant parts. N deficiency resulted in late‐season increased P concentrations, especially in leaves, petioles and seeds. Nutrient translocation to the developing seeds resulted in severe nutrient depletion in other plant parts irrespective of fertilizer applications.
Soil Temperature and Wheat Straw Mulch Effects on Wheat Plant Development and Nutrient Concentration1
Authors: Smika D. E. , Ellis R.
Published: July 2010

Hard red winter wheat (Triticum aestivum L.) was grown with and without wheat straw mulch on the soil surface both in a growth chamber with controlled soil temperatures and in the field where soil temperatures were measured at the crown depth. Concentrations of N, P, K, Ca, Mg, Fe, Zn, Mn, and Cu in the plant were determined at the end of tillering and at heading.

Wheat plants grown with soil temperatures below 10C for 50 days, whether in the growth chamber or in the field, had 2 to 3 fewer tillers per plant and 0.5 to 1.2 fewer heads per plant than plants grown with soil temperatures below 10C for only 15 days. Soil temperature seemed not to affect weight per head or total plant weight. Cooler temperatures reduced the concentrations of only K and Fe in the growth chamber at heading and N in the field at heading. When mulched and bare soil temperatures were identical, mulch did not reduce numbers of tillers or heads per plant, plant nutrient concentration, total uptake of any nutrient, or final grain yields in growth chamber or field. The concentration of all nutrients but Cu changed as the plant developed showing the necessity of knowing growth stages of plants if nutrient concentrations are to be compared.
Influence of Spring Mowing on Reseeding and Productivity of selected Annual Clovers in a Grass Sod1
Authors: Knight W. E.
Published: July 2010

In a 3‐year experiment, we studied the effects of three spring mowing treatments on reseeding of selected varieties of crimson, arrowleaf and subterranean clovers grown in a coastal bermudagrass (Cynodon dactylon (L.) Pers.) sod. Mowing on April 25 prevented satisfactory reseeding of crimson clover (Trifolium incarnatum L.) and greatly reduced reseeding of arrowleaf clover (Trifolium vesiculosum Savi.). Clipping on May 25 prevented effective reseeding of arrowleaf clover but provided best reseeding of crimson clover. Subclover (Trifolium subterraneum L.) reseeded well under all three spring mowing treatments. Careful grazing management of crimson and arrowleaf clovers will be required after April 1 if reseeding is desired. Under conditions of spring drought, overgrazing may reduce regrowth and seed production and cause stand failures in the succeeding year. Properly managed winter‐annual clovers not only produced forage of high quality in the winter and spring, but also increased production of the associated grass.
Factors Affecting the Spectral Properties of Leaves with Special Emphasis on Leaf Water Status1
Authors: Carlson Richard E. , Yarger Douglas N. , Shaw Robert H.
Published: July 2010

Leaf structure and water content constitute major factors affecting the interaction of radiant energy with leaves in the wavelength region from 800 to 2,600 mµ. Reflectivity, Rλ, and transmissivity, T», were measured in this wavelength region for leaves from three crop species (corn, Zea mays; soybean, Glycine max; sorghum, Sorghum bicolor). Absorptivity, Aλ, was calculated from measurements of Rλ and Tλ. The spectral responses (R», Tλ, or Aλ ) at six wavelengths (maxima and minima of the reflectivity curve) regressed on relative leaf water content (RWC) and specific leaf densities (mg/cm3) were highly correlated. A highly significant relationship between leaf RWC and the spectral response (RΔλ) over lour wide‐wavelength intervals is also reported.
A Method for Determining Aluminum Response of Barley in Nutrient Solution in Comparison to Response in Al‐Toxic Soil1
Authors: Reid David A. , Fleming A. L. , Foy C. D.
Published: July 2010

A method was developed to screen barley populations for Al response in nutrient cultures. Thirty varieties and selections were grown in tanks of nutrient solutions containing either O or 4 ppm Al at initial pH 4.8. Aluminum tolerance ratings obtained by this method were in good agreement with those obtained previously in pots of acid, Al‐toxic soils in the greenhouse and in field plots. In general, Al injury was characterized by an increase in the number of roots and a decrease in root length and root weight per plant. Highly significant (1% level) correlation coefficients were found between root length and weight (r=0.93); root weight and number of roots (r=−0.76); and root length and number of roots (r=−0.83). The correlation coefficient between root weight in solution and in soil (r=0.75) was also significant at the 1% level. The method presented is satisfactory for screening barley varieties for Al tolerance.