bluuebunny/crossref_metadata_2025 huggingface dataset:
Varietal Response of Burley Tobacco to Stage of Physiological Development when Topped1
Authors: Gupton C. L.
Published: July 2010

Little is known about the effects of stage of physiological development at which the plants are topped on early vs. late flowering cultivars of burley tobacco (Nicotiana tabacum L.). Four cultivars with a range of 18 days in flowering were topped at different stages of development to determine the optimum topping date for specific cultivats, whether discrimination would exist if all cultivars were topped simultaneously, and whether or not it would be feasible to use an extremely late‐flowering cultivar commercially.

Topping ‘MS Burley 37 × LS’ or ‘Burley 37’ earlier than full bloom, ‘Burley 49’ later than 50% bloom, or ‘Burley 64’ later than button stage did not increase yield significantly. Percent total N and percent total alkaloids in leaf from plots of the respective cultivars topped at these stages were within normally accepted ranges. Thus, all entries in a variety trial may be topped at the same time without creating undue bias of the estimates obtained. Maximum performance of Burley 64 was obtained when it was topped in the button stage. This indicates that a late flowering cultivar may be grown commercially if it is topped at an earlier stage of development but about the same date as early flowering cultivars.
Soil Nitrate Loss During Irrigation: Enhancement by Plant Roots1
Authors: Volz M. G. , Ardakani M. S. , Schulz R. K. , Stolzy L. H. , McLaren A. D.
Published: July 2010

Since roots can both absorb NO‐3 and supply organic matter for NO‐3 reduction by soil microbes, the influence of a root system on NO‐3 N loss from soil solution during irrigation was studied. Two Hanford sandy loam plots (Typic Xerorthent), one fallow, and the other planted to CM‐67 barley (Hordeum vulgare L.), were ponded for 44 hours with a solution containing 100 ppm N and 46 ppm CI‐ (tracer for NO‐3) as KNO3 and CaCl2, respectively. Nitrate — N, NO‐2‐N, NH+4‐N, and Cl‐ concentrations in soil solution were determined and related to N uptake by roots and microbial transformation of NO‐3.

During irrigation, concentrations of NO‐3‐N were lower in most soil solution samples from 0 to 60 cm under barley than in those from the fallow plots. However, Cl‐concentration profiles were identical in both plots to a depth of 45 cm. While nitrate uptake by barley in the top 15 cm led to some solution N loss, soil NO‐2 and NO‐2 reduction reactions are thought to have been responsible primarily, especially in deeper layers, after 26 hours. Data also indicate that, during irrigation, organic C is produced in the root zone of barley and that redox potentials in the planted plot decreased relative to those in the fallow plot. This organic C, percolating with NO‐3 solution, is thought to have facilitated NO‐3 loss both in, and below the root zone, by stimulating microbial activity and by decreasing redox potentials.
Chemical Composition and Quality of Penncross Creeping Bentgrass as Affected by Ammonium, Nitrate, and Several Fungicides1
Authors: Mazur A. R. , Hughes T. D.
Published: July 2010

Several fungicides that are widely used on turfgrasses have been shown to inhibit mineralization of N in soils. The fact that most fertilizer materials commonly used on turfgrasses supply N as urea or NH4+ promoted the present investigations.

Nutrient‐sand culture studies utilizing large volumes of nutrient solution with accurate control of pH and frequency and duration of wetting cycles were conducted in the greenhouse to determine the effect of NH4+ and NO3− on growth and chemical composition of ‘Penncross’ creeping bentgrass (Agrostis palustris Huds.) Greater amounts of growth were observed for plants receiving one‐half or all N as NO3−. Plants receiving NO3− as a sole source of N generally contained lesser amounts of soluble carbohydrate and greater amounts of total N than those receiving all N as NH4+.

Seasonal fluctuations in growth, soluble carbohydrates, and total N were observed. Growth generally decreased during the period from April to May through October to November. Soluble carbohydrates and total N decreased during the period April to May through July to August; and increased during the period July to August through the October to November. Low soluble carbohydrate levels during July to August were attributed to respirational losses and tended to emphasize the importance of carbohydrates in N assimilation.

Field studies on a Drummer silty clay loam (member of fine‐silty, mixed, mesic family of Typic Haplaquolls) did not show any differential effect of NH4+ and NO3− on turf quality or chemical composition of leaf tissue. The rapid conversion of NH4+ to NO3− undoubtedly accounted for the lack of differences under field conditions as compared to those observed in solution cultures. Fungicides were shown to influence both soluble carbohydrate levels and turf quality ratings in the field.
Effects of Narrow Row, Plant Population, and Nitrogen Application on Cotton Fiber Characteristics1
Authors: Koli Stephen E. , Morrill L. G.
Published: July 2010

Narrow row cotton (Gossypium hirsutum L.) has shown the potential for earlier maturity. This is especially significant in areas where season length is marginal. The effect of narrow row plantings has been similar to a reduced N application rate.

Studies were conducted on a Teller fine sandy loam (fine‐loamy, mixed, thermic, Udic Argiustolls) to relate the effects of N rates (0, 45, and 90 kg/ha), row spacing (25, 51, and 76 cm), and plant population (123,550 and 173,000 plants/ha) on cotton fiber characteristics. The effects of N‐row spacing and N‐population interactions were apparent. Finer fiber (decreased micronaire) resulted from high N with 25‐cm row width or high N and high population. But where no N as is applied, the 25‐cm row width produced coarser fibers. There were significant positive correlations between micronaire readings and lint and seed yields in both years.

N effects on uniformity index varied from year to year. Uniformity index tended to decrease for 25‐cm row width as plant population increased and at the low plant population as row spacing increased from 25 to 76 cm. In both years there were significant correlations between uniformity index and percent pulled lint, and between uniformity index and fiber fineness.

Increasing row spacing without increasing plant population, and vice versa, led to significantly lower fiber strength by 0‐inch gauge measurements in 1973. However, increasing row spacing from 25 to 76 cm produced a significant increase in fiber strength in 1974 by the 1/8‐in. gauge measurement. Fiber strength was negatively correlated with yield in 1974.

The major fiber properties of length, strength, and fineness were not consistently affected by the variables of N, row spacing, and population. Some of the interacting effects are of special interest and deserve further evaluation so that the influence of climatic differences can be placed in perspective in relation to the treatment variables.
Growth Responses of Tall Fescue and Bermudagrass to Leaf Applications of Ancymidol1
Authors: Nelson C. J. , Dunn J. H. , Coutts J. H.
Published: July 2010

Growth inhibitors are used for topgrowth control of turfgrasses, but little information exists on associated physiological responses or growth of other plant parts. Therefore, experiments were conducted with ancymidol and an analog to assess their potential as growth retardants and their effects on physiological processes associated with vigor and tolerance to environmental stress.

Tall fescue (Festuca arundinacea Schreb.) and bermudagrass [Cynodon dactylon (L.) Pers.] were grown under controlled environment conditions, and regrowth was measured for up to 32 days following application of foliar sprays of inhibitor. Topgrowth of bermudagrass was almost stopped at concentrations of ancymidol above 100 ppm, whereas tall fescue gave a quantitative growth response over the 200 to 600 ppm range. Root weight of treated bermudagrass was less than the control after a 21‐day regrowth period, but not when the growth period was 32 days. Root growth of tall fescue was not affected by treatment. Stubble weight of bermudagrass, which included leaf and stem tissue up to 6 cm above soil level, tended to be increased by treatment. Stubble weight of tall fescue was unaffected. Stolon number and weight were reduced about 50% by treatment of bermudagrass whereas tiller number of tall fescue was increased up to 30%.

Concentration of storage carbohydrate was reduced 10 to 20% in stubble and stolons of treated bermudagrass, and 25 to 40% in all tissue of treated tall fescue. This probably occurred because net CO2 exchange per pot was usually reduced by treatments due to decreased leaf area. Net CO2 uptake of both species on a leaf area basis was unaffected. Water use per pot per day was 20 to 25% lower in treated plants.

Results suggest that short‐term growth control may be feasible to reduce transpiration. Long term control, such as slowing growth in fall to increase frost resistance, may also be possible. However, in this study storage carbohydrate levels were lower than controls, and thus plants may not be vigorous enough to maintain themselves over long time intervals.
Accelerating the Germination of Common Bermudagrass for Hydroseeding1
Authors: Young James A. , Kay Burgess L. , Evans Raymonds A.
Published: July 2010

Our purpose was to obtain more rapid germination of common bermudagrass [Cynodon dactylon (L.) Pers.] for hydroseeding. Accelerated germination is especially valuable in hydroseeding where rapid germination is necessary to take advantage of the investments which are made in water, nutrients, and wood fiber to modify seedbed environments. Establishment may be improved by assuring germination soon after the initial application of these materails. Germination was determined for hulled seeds of common bermudagrass as affected by constant and alternating temperatures of 0, 2, and 5 C, and 5‐degree increments through 30 C, and at 40 C in the laboratory. Diurnal regimes consisted of 8 hours at the higher and 16 hours at the lower temperature. Phenological curves were developed for germination in relation to the optimum and near‐optimum temperature regimes. A 10/40 temperature regime produced high and rapid germination. Soaking of the seeds at this optimum temperature regime before hydroseeding would accelerate germination. Commercial application of presoaked seeds at 10/40 C would require refrigeration of the soaking liquid to reduce temperature to 10 C at night and heating to increase temperature to 40 C during the day. In addition, because of rapid germination at 10/40 C, in subsequent hydroseeding many seeds would have germinated exposing fragile radicles to turbulence of the pump action and relatively high nozzle velocities. A constant 30 C for 24 hours of preplant soaking is suggested as a practical alternative. We used 25 C for postsoaking incubation because it is a reasonable temperature existing at the time of most seeding. Maximum germination at 30 C required soaking in a solution of 1.0 mM potassium nitrate (KNO3) for triggering germination during the first 24 hours of incubation plus 0.035 mM gibberellin (GA) for accelerated germination and growth from 48 to 72 hours. Seedling growth through 96 hours was greatly enhanced by the further addition of 0.01 mM kinetin.
Soil Water‐Root Relations in Wheat: Water Extraction Rate of Wheat Roots that Developed under Dry and Moist Conditions1
Authors: Sharma R. B. , Ghildyal B. P.
Published: July 2010

Prior investigations have reported modifications of various root characters of plants grown under relatively dry soil conditions, but there is a lack of information on the effect of these modifications on the capacity of root systems to extract soil water. This study was therefore conducted to investigate whether the root systems of wheat (Triticum aestivum L.) grown under different soil water conditions differed in their capacity to extract water from the soil.

In a greenhouse experiment the water extraction rate per unit root volume was measured for two wheat (Triticum aestivum L.) genotypes grown for 60 days after sowing in pots maintained under three different soil water tension regimes of 0.3 to 0.8, 2.0 to 2.5, and 4.0 to 4.5 bars. The two genotypes under study were one gene dwarf Sonalika RR‐21 and three gene dwarf UP 301. The soil used was silty clay loam of the Mollisol order. Beginning on the 60th day after sowing the transpirational losses under different soil water tension regimes were measured for a period of 12 days by covering the pots with polyethylene sheet and weighing them intermittently. At the end of this 12‐day period volume, length, and dry weight of the roots were measured. The water extraction rate per unit root volume was calculated assuming that the transpirational loss was the amount of water extracted by the roots in a linear proportion to the root volume. The water extraction rate per unit root volume increased significantly with increasing soil water tension regimes. It varied from 7.91 cm3 H2O cm−3 root day−1 for UP 301 under the wettest regime of 0.3 to 0.8 bar to 9.11 cm3 H2O cm−3 root day−1 for Sonalika RR‐21 under the driest regime of 4.0 to 4.5 bar tensions. These findings suggest that root systems that developed under relatively dry soil conditions were capable of extracting greater amount of soil water on a unit root volume basis than those developed under moist conditions.
Physiological Development of Lehmann Lovegrass Seeds During the Initial Hours of Imbibition1
Authors: Haferkamp Marshall R. , Jordan Gilbert L. , Matsuda Kaoru
Published: July 2010

Data from both field and laboratory studies have suggested germination of Lehmann lovegrass (Eragrostis lehmanniana Nees.) caryopses (seeds) can be improved by various pre‐sowing seed treatments. Some of these treatments include moistening and drying, oven‐drying, scarification, and pre‐chilling on a moist substrate.

The objective of this study was to determine if exposure of dry Lehmann lovegrass seeds to high humidity conditions, or to moisture under low temperature could effect rapid and detectable changes in their metabolic state. Seeds were (a) imbibed in cold water at 10 C (Treatment low), (b) exposed to a water saturated atmosphere at 24 C (Treatment 24v), or (c) imbibed in water at 24 C (Treatment 24w). For studies on physiological development, samples were collected after 6, 18, 31, 48, and 60 hours of treatment. Seed moisture content, germination percentage, rate of respiration, and ATP, ADP, alcohol soluble sugars, and starch contents were measured at each collection interval. In addition, α‐amylase activity was determined in air dry seeds, 24w seeds after 18, 31, 48 and 60 hours, and 24v and 10w seeds after 60 hours of imbibition.

Physiological development of seeds was advanced in all treatments. Moisture content of the 24w, 24v, and 10w treated seeds increased 6.4, 3.0, and 5.1 fold, respectively. As the moisture content increased in the 24w seeds, the contents of ATP, ADP, and rate of respiration increased. The content of alcohol soluble sugars decreased from 1.88 to 1.20% during the initial 31 hours, but increased to 3.03% in the following 29 hours. This increase occurred with an increase in a‐amylase activity and subsequent active hydrolysis of starch. The 24v and low environments were unsuitable for germination, but ATP levels rose and starch and alcohol soluble sugars decreased slightly during the imbibition period. However, respiratory activity did not develop.
Germination of California Annual Range Plants in Response to a Summer Rain1
Authors: Raguse C. A. , Young J. A. , Evans R. A.
Published: July 2010

During the period 7 to 9 July, 1974 the northern half of California experienced an unusual summer rain of 40 to 150 mm. This once‐in‐a‐century occurrence provided an opportunity to observe germination responses of resistant annual grasses, legumes, and forbs. Annual plants which have evolved in a Mediterranean climate generally are assumed to have acquired mechanisms for resistance to summer germination, which ordinarily would result in catastrophic losses of seedlings.

Growth of resident and introduced annual range plants in response to the July rain was observed on grazed ranges at the University of California's Sierra Foothill Range Field Station, Browns Valley, Yuba Co. Transects were located on north‐ and south‐facing slopes consisting entirely of herbaceous vegetation. Square‐decimeter quadrats were sampled along the transects on 19 July, 30 August, and 18 October, and the seedlings found were counted and identified.

Seeds of only a few annual species germinated and few plants were established in response to the summer rain. Species found were principally Bromus mollis L. (soft chess), Erodium botrys (Cav.) Bertol. (broadleaf filaree), Trifolium hirtum L. (rose clover), and T. subterraneum L. (subterranean clover). Seedling densities were low compared with emergence under normal fall rainfall. Moderation of the Mediterranean climate summer temperature regime by soil surface irregularities or by litter cover favored germination and emergence. Emergence also was better on north‐facing aspects than on south‐facing aspects.

The data indicate that one characteristic of the many herbaceous annual species which have successfully invaded California since Gold Rush times is effective seed dormancy during summer. It is possible that this trait could prove useful in plant introduction screening.
Economic Optima and Price Sensitivity of N Fertilization for Six Perennial Grasses1
Authors: Colyer Dale , Alt F. L. , Balasko J. A. , Henderlong P. R. , Jung G. A. , Thang Vinh
Published: July 2010

Prices of both nitrogen fertilizers and forages have increased in recent years causing concern about the profitability of fertilizing forage grasses. Yield response functions, which permit computation of economic optima, were estimated using regression analysis for Kentucky bluegrass (Poa pratensis L.), tall fescue (Festuca arundinacea Schreb.) orchardgrass (Dactylis glomerata L.), reed canarygrass (Phalaris arundinacea L.), smooth bromegrass (Bromus inermis Leyss.), and timothy (Phleum pratense L.). Experimental data from 3 years, 1968, 1969, 1970, with N treatments of 0, 112, 224, and 448 kg/ha were used to estimate the regression equations. Economic analyses were made with 3 N prices, 44, 55, and 66 cents/kg, and 5 forage prices, 2.2, 3.3, 4.4, 5.5, and 6.6 cents/kg. The economically optimal N treatment varied by species and was sensitive to changes in N‐forage price ratio, declining as the N price rose or the forage price declined. Fertilization with N was found to be profitable for all but very unfavorable price ratios.
Relationships Among Cottonseed Vigor and Emergence1
Authors: Buxton D. R. , Melick P. J. , Patterson L. L. , Pegelow E. J.
Published: July 2010

Better predictive methods of field emergence of cotton (Gossypium spp.) seedlings are needed than are presently available. In this paper we report on two types of relationships for predicting seedling emergence. The first is the association between field emergence and a vigor term of germinating seedlings called % transfer (ratio of plant axis weight to total weight of seedlings). The second is the relationship between time to 50% total emergence (ET50) and total emergence. Seed of diverse origin were germinated in the laboratory at 15 C for 8 days or at 25 C for 4 days and % germination, and % transfer were determined. Several field plantings were made, and periodic counts were made as seedlings emerged. The time course of germination of two lines that responded differentially in germination and field studies was examined by taking weights and seedling axis lengths repeatedly for 4 days at 25 C and 14 days at 15 C. Germination at 15 C for 8 days did not consistently predict field emergence better than germination at 25 C for 4 days. Some improvement occurred when germination parameters were averaged for the two temperatures. Combining % transfer with % germination into a term called “germination index” did not consistently aid in predicting field emergence over use of % germination alone, apparently because seed with high viability generally produced vigorously germinating seedlings. Percent transfer was negatively correlated with ET30. Predictability of the germination parameters was improved by extending the length of the germination period. Total emergence decreased linearly with increase in ET50. The average decrease ranged from just under 2% per day of ET50 to over 4% when the test involved a salt‐affected soil. We conclude that incorporation of these seed vigor terms into seed testing will not aid in predicting potential for cottonseed emergence. The relationship between emergence and ET50 should serve as an aid in making early decisions about replanting, although the nature of the relationship will probably depend upon local soil conditions.
Cerrado Vegetation in Brazil: An Edaphic Gradient1
Authors: Lopes A. S. , Cox F. R.
Published: July 2010

The vegetation in central Brazil is a tropical savanna called “cerrado” that varies from pure grassland to a nearly closed canopy of medium height trees overlying grass. Since forest is the expected climax vegetation there, several theories have been given to explain the types of grassland present. The more promising of these involve differences in soil properties, but only a few sites have been used for evaluation. To study these relaships in more detail and yet cover the bulk of the region, 518 composite topsoil samples were collected from a 600,00 km2 area. Laboratory characterizations included pH, exchangeable A1, nutrient levels (including micronutrients), organic matter content, particle size distribution, and color. The relationships between type of vegetation and differences in soil properties were evaluated statistically, primarily by correlation and regression. A positive gradient was found between the density and height of woody vegetation and the following soil properties: pH (H2O), pH (KC1), exchangeable Ca, Mg, and K, and extractable P, Zn, Cu, and Mn. As the percent of A1 saturation increased there was a decrease in density and height of woody vegetation. Neither exchangeable Al, particle size distribution, nor organic matter content showed a consistent gradient with the vegetative measure. There was a tendency for more dense stands of vegetation to occur on dark, reddish brown topsoil; while less dense stands occurred on brown to dark brown topsoils. The results suggest that the types of vegetation present in the region may best be explained by differences in soil properties, and it is recommended that soil Al be expressed by percentage Al saturation, rather than by its absolute value, in these relationships.
Influence of Seed Weight on Germination, Growth, and Development of Tobacco1
Authors: Kasperbauer M. J. , Sutton T. G.
Published: July 2010

Seed size may influence germination rate and seedling vigor, which are important factors in innovative tobacco (Nicotiana tabacum L.) starting procedures such as seeding directly in the field or in transplantable containers. A study was conducted to determine relationships among tobacco seed weight, rate of germination, and seedling growth and development, including yield of cured leaf.

Tobacco seeds were separated into three weight groups of 76, 65, and 50 mg/1,000 seeds. Germination was tested at 20 C in light and in uninterrupted darkness. The heavy seeds germinated earlier, in higher percentages, and over a shorter period of time than did the light weight seeds. The medium seeds were intermediate in these responses.

Seeds from the three weight groups that germinated on the same date produced seedlings that did not differ significantly in size of transplants or in subsequent field growth and development, including leaf yield. However, seedlings from early and late germinating seeds within the same weight group differed significantly in size of transplants and in field performance. Even though the late seeds germinated only a few days after the early ones under optimal conditions, they produced seedlings that continued to lag in growth and development in the field and had a lower yield of cured leaf. Hence, heavy seeds that are light indifferent for germination should be used in tobacco starting procedures that require high germination percentages over a short period of time.
Effect of N Starvation of Soybean Plants at Various Stages of Growth on Seed Yield and N Concentration of Plant Parts at Maturity1
Authors: Streeter John G.
Published: July 2010

Estimates of the minimum N concentrations of vegetative soybean (Glycine max (L.) Merr.) plant parts are needed to assess the N supplying capacity of these tissues during seed development. Also, little is known about how the plant responds to severe N stress during reproductive growth in terms of redistribution of N among plant parts and in terms of leaf senescence. The purpose of this experiment was to determine the effect of N starvation of soybean plants at various stages of growth on seed yield and N concentration of plant parts at maturity. Non‐nodulated soybean plants were grown in sand culture with a nutrient solution containing 100 mg N/liter and adequate levels of other major and minor elements. Nitrogen was withdrawn from the solution near the end of the flowering period or during rapid pod formation or during rapid seed formation; these withdrawal times were 65, 76, or 87 days after planting (DAP), respectively. The shortest period of N stress (withdrawal 87 DAP) resulted in marked decreases in individual seed weight and N concentration but did not result in premature leaf senescence or in a decline in N concentration of vegetative organs or a decline in the number of fruits and seeds per plant. Longer periods of N stress (N withdrawal 65 and 76 DAP) caused major reductions in pod and seed numbers as well as further decreases in seed weight and in N concentrations in seeds and vegetative organs. Concentrations of 1.0% N in leaves, 0.5%, N in stems, and 1.3% N in roots (dry basis), observed under conditions of extreme N stress, are estimates of the lower limits of N in these soybean tissues after maximum export of N. However, these lower limits were not reached until the amount of N stored in seeds was reduced by greater than 50%.
Nutrient Uptake by Grass and Leaching Losses from Soluble and S‐Coated Urea and KCl1
Authors: Allen S. E. , Terman G. L. , Kennedy H. G.
Published: July 2010

Slow‐release fertilizers should provide for more efficient nutrient use by the crop as well as reduce leaching losses. This study was conducted to measure crop response to N or K in uncoated urea, ammonium nitrate (AN), S‐coated urea (SCU), KCl, and S‐coated KCl (SCK) and to relate leaching losses to NO3‐Nan and cations. In one series, granular N sources to supply 200 or 400 kg of N/surface ha were mixed with the upper 20 cm of a 1:1 mixture of Norfolk s1 (Typic Paleudult) and builders sand contained in 15‐ ✕ 120‐cm columns. A second series was similarly fertilized with K sources to supply 100 or 200 kg of K/surface ha.

Soil columns were left fallow or planted to tall fescue (Festuca arundinacea Shreb. ‘Kentucky 31’) which was harvested six times at 4‐week intervals. Following the sixth harvest of fescue, stubble and roots were incorporated into the soil along with a second application of N or K and cultures were planted to sorghum‐sudangrass (Sorghum bicolor ✕ Moench Sorghum vulgare sudanense ‘Green M’), which was harevsted four times at 4‐week intervals. Water was applied as required for crop growth and once during each growth period all columns (including fallow) were heavily watered to collect liters (10 cm) of leachate from each.

Total recovery of N by both crops was in the order: SCU‐12 > split‐AN > SCU‐20 > urea > AN > no N. With cropping, 0 to 11% of applied N was found in drainage water. Under fallow, losses of N were much higher (29 to 72%) and were in the order: split‐AN > SCU‐12 = SCU‐20 > AN = urea > no N. These results support the premise that slow‐release fertilizers supply more N for crop response, but may not reduce leaching losses. Leaching of cations was well correlated with loss of NO3‐N (r = 0.83 to 0.90) under fallow, but was less correlated (r = 0.33 to 0.74) under grass.

Recovery of K by both crops was near 100%. Applied K decreased loss of NO3‐N, Ca, and Mg under cropping and increased losses under fallow. Leaching of NO3‐N and cations was highly correlated. Applied N and oxidation of S in S‐coated products both contributed to acidification of the soil, which intensified leaching of Ca and Mg.
Effect of Slow Release Fertilizer on Fertilizer Residues and on Yield and Composition of Flue‐cured Tobacco1
Authors: San Valentin G. O. , Robertson W. K. , Johnson J. T. , Weeks W. W.
Published: July 2010

Many of the fine soils on which tobacco (Nicotiana tobacum L.) is grown do not retain applied K following irrigation or rainfall long enough to satisfy plant requirements. Losses should be reduced by the use of materials that restrict K solubility or by split application.

Tobacco was grown for 5 years on Lakeland fine sandy soil (Typic Quartzipsamment), a soil which retains very little K. Split applications of K2SO4 were compared to single applications of K2SO4 and resin‐ polyvinyl‐, and S‐coated K materials. Yields and chemical composition of tobacco leaves and soil were used to measure the relative effectiveness of K treatments.

Yields and K contents of tobacco leaves were increased by K fertilization. Split applications of K2SO4 were more effective than single applications at planting. In years with heavy rainfall, applying slowly‐soluble sources all at planting was better than applying K2SO4 in split application. Potassium from slowly soluble materials was less readily leached than from K2SO4, resulting in higher concentration of K within 60 cm of the surface at the time of tobacco flowering. When various thickness of S were applied to give a range of K release, the thicker coatings gave higher yields. Treatments that provided higher K contents increased total alkaloids and decreased reducing sugars in the first of the two years that they were measured. Application of K fertilizers with reduced solubility should assure good yields, quality, and a high level of K in tobacco.
Forage Yield and Fertilizer Recovery by Three Irrigated Perennial Grasses as Affected by N Fertilization1
Authors: Hanson C. L. , Power J. F. , Erickson C. J.
Published: July 2010

In many locations in the United States the livestock industry uses irrigated grasses for hay production. The purpose of this study, conducted in western South Dakota on heavy clay soils (Ustertic camborthids), was to determine forage yield responses and N recovery of three irrigated grasses‐reed canarygrass (Phalaris arundinacea), garrison creeping foxtail (Alopecurus arundinaceus), and smooth brome (Bromus inermis)—to single and split N applications. Single N treatments consisted of 0, 56, 112, 224, or 448 kg N/ha applied in March. For the split N applications, these same rates were applied both in March and again after the first hay cutting. Forage yields were maximum when the grasses were fertilized with 224 kg N/ha in the split applications. Maximum forage yields ranged between 8,899 kg/ha (air‐dried) for garrison creeping foxtail and 11,802 kg/ha for smooth brome. Split applications did not benefit total production at the 56 kg N/ha rate.

First cutting forage N percentages varied between 0.8 and 1.3 for N rates of 56 to 224 kg N/ha and between 1.3 and 2.3 for N rates of 224 and above. The percentage of N was highest, frequently over 3%, in second cutting forage from treatments receiving split fertilizer applications.

Percent total N recovered increased as fertilizer rate increased when all N was applied in March, but recovery was highest for the split application of 224 kg N/ha. Recovery by smooth brome forage was highest with split applications (up to 50% recovery), but was highest for the other grass species for single annual (March) applications.
Beta‐Nitropropionic Acid Concentration of Crownvetch Plant Parts as Affected by Growth‐Temperature‐Maturation Variables1
Authors: Faix J. J. , Gustine D. L. , Wright M. J.
Published: July 2010

Early meadow vole (Microtus pennsylvanicus) dietary trials on crownvetch indicated the presence of an adverse substance in the forage. Vole performance appeared to be related to forage source or to the effect of plant environment on the concentration of a deleterious substance. Betanitropropionic acid (BNPA) has since been identified in crownvetch as the deleterious compound. The objective of this study was to determine the influence of growth temperature on BNPA concentration in various plant parts of crownvetch forage. In this growth chamber study, BNPA concentration in crownvetch forage increased with increasing growth temperature. The most consistent increase in BNPA concentration occurred in the stem tips and leaflets, and the concentration in these parts averaged nearly twice that of the other parts. From this study it can be concluded that higher growth temperature can increase BNPA concentration in crownvetch forage and overall concentration can be influenced by the leafiness of the forage.
Effect of Day and Night Temperatures During Floral Induction on Morphology of Soybeans1
Authors: Thomas Judith F. , Raper C. David
Published: July 2010

Temperature affects the vegetative and reproductive morphology of soybeans [Glycine max (L.) Merrill]. Descriptive information of the effects of temperature will assist in development of a dynamic simulation model. The purpose of this study was to determine the effects of day and night temperatures on growth and development of the determinate soybean cultivar ‘Ransom’. Seedlings were grown under a long‐day (non‐inductive) photoperiod at 26/22 C day/night temperatures in a temperature controlled greenhouse until the expansion of the first trifoliolate leaf. Plants then were moved into five controlled‐environment chambers programmed for 9‐hour photoperiods with temperature regimes of 14/10, 18/14, 22/18, 26/22, and 30/26 C. At the beginning of each night, groups of plants were moved from the five day temperatures to each of the five night temperatures to obtain a total of 25 day/night temperature combinations. Significant interactions between day and night temperatures for all measured characteristics except branch internode length made general evaluations of simple effects of day and night temperatures difficult. Instead, responses to the specific combinations of day/night temperature were considered. At the conclusion of 50 consecutive short days, area per leaf and vegetative dry weight were greatest at 26/10 C temperatures while pod dry weight was greatest at the higher night temperature combination of 26/22 C. The lowest net carbon dioxide exchange rate was obtained at temperatures of 14/26 C, and the highest rates at 26/14 and 26/18 C. The extent of apical dominance, given as the ratio between main stem height and total branch length, was greatest for plants from either warm day and warm night or cool day and cool night combinations. Warm night temperatures, in conjunction with any of the day temperatures, shortened the time from first exposure to inductive photoperiod to anthesis. At the four coolest day/night temperature combinations (14/10, 14/14, 18/10, and 18/14 C) pods were not formed even though floral initiation had occurred
Differential Response of Maize Inbreds to Zn1
Authors: Clark R. B.
Published: July 2010

Maize (Zea mays L.) inbreds differ in their ability to take up and use Zn and these differences could be important for development and adaptation of plants to low Zn conditions. In pursuing the need for such information growth measurements and mineral element analysis were made on the inbreds A635 and H84 which showed differential Zn deficiency when grown with varied Zn in nutrient solutions. H84 was more “Zn‐efficient” than A645. H84 produced more total dry matter and more dry matter per unit Zn, developed fewer Zn deficiency symptoms, had more Zn in the tops compared to roots, and had fewer imbalances of other mineral elements when both were grown at low levels of Zn. At higher Zn levels, A635 produced as much as or more dry matter and had similar mineral element balances as H84. H84 also grew better than A635 when the two inbreds were grown together in the same low Zn solution. A635 showed greater changes in P, Ca, Mg, Mn, and Fe than H84 as Zn varied in solution. Differential responses between these two inbreds for Zn appeared to be caused by differences in the inbreds for translocation, requirements, and utilization of Zn, and for accumulation of imbalanced amounts of mineral elements which interact with Zn.
Effect of Plant Population on Yield and Height Characteristics in Determinate Soybeans1
Authors: Hoggard A. L. , Shannon J. Grover , Johnson D. R.
Published: July 2010

Lodging resistance may be an important factor in determining how soybean [Glycine max (L.) Merr.] cultivars respond to high populations. Therefore, the effects of plant population on yield, lodging, pod number, height, internode number, and average internode length for the lower, center and upper main stem internode regions, in determinate soybean cultivars differing in lodging resistance were studied in a field experiment on a typic Arguidoll soil. Group V cultivars, ‘Essex’ (most lodging resistant); ‘Forrest’ (intermediate lodging resistant); and ‘Mack’ (least lodging resistant); were evaluated in rows 97‐cm wide over a 2‐year period at populations of 23, 33, 43, and 53 plants/m of linear row (240,000; 340,000, 440,000; and 540,000 plants/ha). Lodging was moderate and increased as planting rate increased. Although yields were highest at the lowest plant density in all varieties, Essex did not respond to plant population as did the other two cultivars. Yield of Forrest at 23 plants/m was significantly greater than at 43 and 53 plants/m. Yield of Mack at 23 plants/m was higher than at the other populations. Pods per plant decreased as plant density increased. Forrest averaged significantly more pods per plant for all populations than Essex or Mack. Internode number in Essex was unaffected by population and was significantly less than in Forrest or Mack. Length of lower and central internodes increased and internode number declined as population increased in Forrest and Mack. Internode number and length offset each other resulting in similar heights across populations in Forrest and Mack while Essex was slightly taller with increasing populations. Essex which averaged 72 cm tall was significantly shorter than Forrest (93 cm tall) or Mack (90 cm tall) because of fewer and shorter internodes. However, yield of Essex was comparable to Forrest and better than Mack indicating that cultivars of short stature and improved lodging resistance can be grown without lowering yield. Yield stability across populations in lodging resistant Essex compared to significant yield reductions at the higher seeding rates in the more lodging susceptible cultivars, Forrest and Mack, indicates that lodging resistance is an important factor in determining how a soybean variety will respond to higher populations. Thus, lodging resistance is an important consideration in determining the optimum seeding rate of varieties best adapted to a particular area for maximizing yield, even in environments where lodging is only moderate.
Performance of Triticale in Comparison with Wheat, Oats, Barley, and Rye1
Authors: Morey Darrell D.
Published: July 2010

Triticale (X Triticosecale Wittmack) is a relatively new cereal crop of interest for forage, food and feed grain production. The experiments reported here were conducted at Plains and Tifton, Georgia, to compare grain yields, test weight, height, lodging, disease reaction and protein production of triticale cultivars in comparison with the best adapted cultivars of wheat (Triticum aestivum L.), oata (Avena sativa L.), barley (Hordeum vulgare L.), and rye (Secale cereale L.). At Plains, ‘Volbar’ barley and ‘Coker 227’ oats tended to yield more grain than ‘Holley’ wheat, ‘Weser’ rye and 4 ‘Fasgro’ triticale cultivars during 5 years of testing. No differences in total protein production were noted for the 5 grain species at Plains.

At Tifton, 5 years of testing showed no differences in grain yields of wheat, oats, barley, rye or the ‘Fasgro’ triticales. ‘Coker 227’ oats gave a higher percentage of protein than other grains but no differences in total protein production were obtained when all grains were considered. The newer triticale cultivar ‘6TA 227’ led the yield test in a 3 year comparison at Tifton, followed closely by ‘6TA 571’ and ‘6TA 579’.
Analytical Description of a Soybean Canopy1
Authors: Hommertzheim D. L.
Published: July 2010

One of the crucial components of a plant simulation model is the light distribution within the crop canopy. But in order to calculate the light distribution, the model must have knowledge of the leaf area distribution. This article describes an analytical procedure for calculating the leaf area distribution within a community of soybean plants arranged in a row configuration.

The procedure has three main steps: 1) describe the plant analytically (i.e., size, shape, and spatial position of each leaf), 2) determine for a single plant the leaf area distributions as a function of height and distance from the center of the plant, and 3) combine the leaf area distributions of plants into a distribution for a community of plants in a row.

The calculated leaf area distributions are sensitive to the distance between plants in a row, the leaf length to width ratios, leaf angles, plant growth stage, petiole lengths, and insect damage. The procedure can also be extended to other plant types, interspersing of weeds in the crop rows, and non‐wide row crop arrangements.
Split Root Observation System for Glass Root Dynamics Studies1
Authors: Lonkerd W. E. , Ritchie J. T.
Published: July 2010

A split root observation system was designed to provide accurate values of root lengths and water‐uptake rates for use in establishing principles of estimating water uptake from field soil.

The system consists of four independent glass‐bottom root observation boxes, each suspended from a load cell mounted on a support structure. The boxes have a 5° lengthwise downward slope from the plant location and contain a shallow layer of soil about 2 cm deep A plant is supported and weighed by a fifth load cell. Using a voltmeter with a 1‐µv resolution, an overall system accuracy of ±2.0 g is possible for observation box weights and ±0.4 g for the plant weight. Root growth is recorded using time‐lapse photography. Photographic slides are projected on a screen and root lengths are estimated using a line‐intercept method.

A sorghum (Sorghum bicolor (L.) Moench) plant was used to evaluate the system. A seedling was grown in nutrient solution until eight adventitious roots had lengths at least 25 cm long. Two roots were then planted into each observation box. System performance tests illustrated how hourly, daily, and long‐term data can be used to relate plant weight, leaf area, root length, and water uptake. Split root observation systems of this type provide quantitative information on how different root zone conditions of a single plant affect root growth, water uptake, and top growth.
Nitrogen and Aerification Influence on Putting Green Thatch and Soil1
Authors: Smith G. S.
Published: July 2010

‘Tifdwarf’ bermudagrass, (Cynodon dactylon (L.) Pers. ✕ C. transvaalensis Davy.), forms excessive thatch under intensive golf course management. Retarding thatch buildup or increasing its decomposition need study. This experiment was conducted 1) to determine the effects of ammoniacal and nitrate‐N on turf growth and thatch production, and 2) to study the thatch‐soil environment as affected by fertilization aerification, and liming. An established Tifdwarf putting green was aerified at three frequencies (twice yearly, monthly, and biweekly) and fertilized with biweekly or weekly N at 0.48 kg/l00 m2 from ammonium sulfate or calcium nitrate. Lime was applied to neutralize acidity, and soil topdressing was evaluated. Thatch thickness and weight and N content of organic‐matter fractions were measured over time. Subthatch soil cores were analyzed for pH, K, Ca, Mg, and P. Bermudagrass root weights were also determined. Thatch thickness was extremely variable; maximum depth was observed under biweekly fertilization with ammonium sulfate combined with semiyearly aerification. Weight of thatch size fractions, though more difficult to obtain, proved a good indicator of thatch accumulation. Weight measurements supported thickness measurements. Ammonium sulfate produced maximum thatch weight, while increasing aerification frequency decreased weight of organic fractions collected. Ammoniacal‐N did, however, produce excellent quality turf and 50% greater root weight was measured under ammonium sulfate fertilization. Soil levels of Mg and P were unaffected by treatments. Ammonium sulfate significantly reduced soil pH, Ca, and K as compared to calcium nitrate. Surface liming was not effective in retarding acidulation. No changes in thatch weight or N content could be measured. Thatch accumulation was not adequately controlled by combinations of aerification, selective N sources, liming or soil topdressing. Measuring thatch proved difficult, as did correlating thatch with turfgrass quality and growth.
Yield Potential of Interplanted Annual Food Crops in Southeastern U. S.1
Authors: Cordero Alvaro , McCollum R. E.
Published: July 2010

Intercropping may be one way to increase the productivity of land. If so, it is of scientific as well as practical interest to know how the increase is achieved and devise methodologies which will exploit such systems to the fullest. This report compares the productivity of two component intercrops with that of their respective monocultures under differing nitrogen regimes.

Two soil conditions were tested in each of 2 years—a poorly drained Portsmouth fsl (Typic Umbraquult, fine‐loamy, mixed, thermic) and a well drained Orangeburg sl (Typic Paleudult, fine‐loamy, silicious, thermic). Treatment variables were cropping system (intercrops vs. monocultures), row arrangement, and N rates from zero to 270 kg/ha. Corn (Zea mays L.) was used as the overstory crop and soybeans (Glycine max L. Merr.), snapbeans (Phaseolus vulgaris L.), or sweet potatoes (Ipomea batatas Lam) as the interplanted understory species. All interplanted species were at the same population as their monoculture checks.

With adequate N, monoculture corn in conventional rows (97 un) averaged 9,400 kg/ha. Planting monoculture corn in paired 46‐cm rows, with 147 cm between row pairs, caused a 12% reduction in yield. An additional reduction of 5 to 10% resulted when soybeans or snapbeans were interplanted into corn in the 147‐cm space between row pairs. Monoculture soybeans yielded 2,750 kg/ha with only minor variations among sites. Interplanted soybean yields were site and year dependent, however, and varied from 33 to 55% of their respective monocultures. Intercrop soybean yields were inversely related to the amount of N applied to corn. Yields of spring‐planted monoculture snapbeans ranged from 7,000 to 15,500 kg of fresh pods/ha. Regardless of yield level, however, interplanted snapbeans yielded 48% of the monoculture check. Fall snapbeans, relay interplanted into maturing corn in mid‐August, also produced about 50% of a crop. Land equivalent ratios (LER) of 1.20 to 1.40 thus suggest a 20 to 40% increase in total productivity during one 200‐day season by intercropping. Higher production by intercrops was most easily interpreted in terms of total leaf exposure. Monoculture corn had a leaf‐area duration (LAD) of 150 days; but when soybeans were interplanted into corn, LAD of the intercrop exceeded 300 days.