bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Temperature and Methyl Parathion on Vegetative Development and Fruiting of the Cotton Plant1
Authors: Gipson Jack R.
Published: July 2010

In the northern areas of the Cotton Belt, suboptimum temperatures are rather common during the very early stages of growth and during the latter stages of boll development of cotton (Gossypium hirsutum). The effects of low temperature on boll development have been well defined, but little is known of the early season effects on plant fruiting and development. Thus, the purpose of this research was to determine how temperature influences early fruiting and vegetative development in cotton and to what extent the action of a chemical known to effect fruiting may be modified by temperature. Two diverse cotton cultivars, ‘Gregg 35’ and ‘Deltapine 16,’ were grown in field growth chambers under night temperature regimes of 10, 15, 20, and 25 C from the day of seedling emergence until frost. Methyl parathion was sprayed on half the plants of each cultivar at 10, 12, and 13 days after planting to assess the temperature chemical interaction. The observed effects, in the order of their magnitude were temperature > cultivar > chemical. Temperature‐cuitivar and temperature‐chemical effects were apparent in some cases. Earliness of fruiting as measured by days from emergence to first square, and bloom was most timely at 20 and 25 C. As temperature decreased below 20 C, however, there was a marked increase in both days to first square and days to first bloom. Nodal positions of first squares and blooms were essentially the same at 15 and 20 C, but either a reduction to 10 C or an increase to 25 C resulted in a significantly higher nodal position of these forms. The total number of limbs per plant was relatively constant across cultivars and treatments, but the ratio changed between vegetative and fruiting limbs. At 10 and 25 C the number of vegetative limbs increased at the expense of fruiting limbs. Number of bolls per plant and seed cotton yield were drastically retarded at 10 C for both cultivars. Maximum boll production was achieved at 15 C for Gregg and 20 C for Deltapine. Maximum yields were attained for both cuitivars at 20 and 25 C.
Ammonia Volatilization from Soils1
Authors: Mills Harry A. , Barker Allen V. , Maynard Donald N.
Published: July 2010

If NH4+‐N fertilizers are used, most agronomic crops grow best if the soil reaction is near neutrality. Previous studies have shown that if the soil pH becomes alkaline, NH3 volatilization losses of N occurs. The objective of this study was to determine whether or not a rapidly growing crop could reduce the volatilization losses of N, especially from soils above pH 7 to which large applications of NH4+‐N fertilizers were made. This study was conducted in a greenhouse using a closed system in which all NH3 evolved from the soil was swept away by a stream of air and collected. The amount of NH3‐N evolved from the soils was measured as a function of time, soil pH, amount of N application, and presence or absence of corn (Zea mays indentata Bailey) seedlings. Ammonia losses with or without plants in the system increased as the soil reaction and amount of NH4+‐N application increased. A sharp upward inflection in NH3‐N loss occurred at pH 7.2. Plants reduced NH3‐N losses by atleast 60% in the alkaline soils and by lesser amounts in the acidic and neutral soils. Rapid absorption of NH4+‐N by plant roots appeared to account for the conservation of N.
Effects of Germination on Cotyledon Nitrogen, Starch, Reducing Sugar, and Growth of Lima Seedlings
Authors: Hegwood D. A. , Gaines T. P.
Published: July 2010

Poor seedling establishment which frequently reduces stands and causes uneven seedling growth in lima bean (Phaseolus lunatus L.) plantings points up the need for research to identify those changes occuring during the seedling establishment phase. This research is needed to show how these changes are associated with early seedling growth. Accordingly, cotyledons from seedlings of two lima bean cultivars, ‘Nemagreen and Jackson Wonder,’ were compared during pre‐ and postemergence for changes in total N, protein N, nonprotein N, starch, reducing sugars, and seedling growth.

Cotyledons of Jackson Wonder were significantly higher in total N than Nemagreen because of the protein N fraction. The nonprotein N fraction did not differ between cultivars.

The protein:nonprotein N in Nemagreen approached 1 on the sixth, seventh, eighth, and ninth day after planting. Maximum decrease of protein N and a corresponding maximum increase of nonprotein N occurred on the fourth, fifth, sixth, and seventh day for each cultivar. A net decrease in total N in cotyledons occurred during postemergence.

Reducing sugars were present in cotyledons of resting seed and developing seedlings but did not differ in amount between cultivars.

The period of most rapid starch depletion and cotyledon weight loss occurred during postemergence and was accompanied by rapid increases in top dry weight.
Seed Yield Coronilla Varia L.1
Authors: Al‐Tikrity Wail , McKee G. W. , Clarke W. W. , Peiffer R. A. , Risius M. L.
Published: July 2010

Although average seed yields of crownvetch (Coronilla varia L.) are low, there are to our knowledge no published data on potential yields and on losses incurred during harvest. To secure such information, samples of crownvetch forage and the contained seed were hand harvested in 1970 and 1971 from a 24‐ha commercial seed field of the variety ‘Penngift.’ The seed was hand‐hulled and cleaned to certified standards. The mean yield of handharvested seed in 1970, a year of above‐normal precipitation and very heavy forage growth, was 257 kg/ha. In 1971, with precipitation slightly below normal, the mean yield was 530 kg/ha. Field losses during commercial harvest were about 61% in 1970 and 58% in 1971. Seed harvest in crownvetch is complicated by uneven maturity caused by an indeterminate flowering habit and by a tendency for the seedpod or loment to shatter readily when disturbed. In addition, a dense growth of foliage must be combined to recover the seeds.
Nitrogen Fertilization of Corn and Sorghum Grown in Oxisols and Ultisols in Puerto Rico1
Authors: Fox R. H. , Talleyrand H. , Bouldin D. R.
Published: July 2010

The requirement of fertilizer N for high yields, its generally high price, and the ever‐present possibility of large leaching losses of inorganic N makes it essential that fertilizer N be managed as efficiently as possible in the humid tropics. Three rates and 2 times of application of fertilizer N were applied to 15 corn (Zea mays L.) and 3 sorghum (Sorghum bicolor Moench) crops on 2 Ultisols and 3 Oxisols during 5 successive growing seasons in Puerto Rico to determine the most effective means of applying fertilizer N to these crops. Additional objectives were to determine the apparent recovery of fertilizer N by the crops; the interrelationships between crop yield, N fertilization and soil inorganic N content; and the effectiveness of slow‐release sulfur‐coated urea as a source of fertilizer N for corn and sorghum. All soils had been under cultivation for at least 50 years and received relatively high rates of fertilizer for the last 20 years.

The results indicated that: 1) postplant sidedress applications of fertilizer N resulted on the average in higher yields and plant recovery of fertilizer N than preplant applications; 2) when there were no limiting factors of climate or disease, and there was a response to N, the recovery of postplant applied N was comparable to that observed in temperate areas; 3) maximum corn grain yields were approximately 6.3 metric tons/ha; near‐maximum corn grain yields were obtained with 67 kg/ha of postplant‐applied N; 5) preplant‐applied sulfur‐coated urea was no more effective than preplant urea in increasing yields or N recovery; 6) soil inorganic N content was generally not a good index of soil N supplying power in these soils; 7) drought and disease frequently reduced yields; 8) there was very little residual effect of the fertilizer N applied in this experiment; and 9) the clayey Oxisols and Ultisols in Puerto Rico had a relatively high N‐supplying power.
Plant Height, Grain Yield, and Yield Component Relationships in Spring Wheat1
Authors: McNeal F. H. , Smith E. P. , Berg M. A.
Published: July 2010

The relationships of grain yield to plant height and yield components in spring wheat (Triticum aestivum L.) were studied in two yield nurseries in 1971 and 1972 at Bozeman, Montana, in order to determine if selection should be directed at yield, or at yield components. Genetic and environmental effects were separated by correlation analysis and analysis of variance.

Correlation coefficients computed with various combinations of replications, years, and cultivars or selections (genotypes) showed that cultivars account for most of the variation among both plant height and yield component comparisons. Simple correlation coefficients showed that grain yield was more closely related to heads/4.9 m than with kernels/head or kernel weight. A multiple correlation analysis between grain yield and yield components was found to be significant for only one of the two nurseries. Simple correlations among the three yield components were either negative or of a nonsignificantly positive value.

We were unable to determine whether selection should be based on grain yield or on one or more of the yield components. However, the r values among yield components provided very small R2 values, suggesting that compensating effects among yield components were small in this study.
Water Relations of Cotton. I. Root Growth and Water Use as Related to Top Growth and Soil Water Content1
Authors: Taylor Howard M. , Klepper Betty
Published: July 2010

Many experiments have evaluated the effects of decreasing soil water contents on top growth and yield of plants, but few experiments simultaneously have evaluated root growth.

An experiment was conducted to determine the response of cotton (Gossypium hirsutum L. ‘Auburn 623b’) roots and tops to decreasing soil water content. Plants were grown m rhizotron compartments with rainfall excluded by metal covers over the soil. Soil profile or irrigation schedule treatments provided different levels of soil and plant water potentials. Soil water content was determined with a neutron probe; rooting density, from measurements of roots on the glass viewing surface of each compartment. Plant water potential was determined with a pressure chamber apparatus, and top growth was evaluated by plant height.

At the same time that total root length stopped increasing plant top growth slowed or ceased, and plant water potential near sunrise decreased. Root length ceased to increase when the soil water content of any layer decreased to about 0.06 to 0.07 cm3/cm3, which corresponds to a soil water potential slightly wetter than −1 bar or a hydraulic conductivity of about 2 ✕ 10−4 cm/day. Thus, for conditions of this experiment, cotton root growth was correlated with decreases both in plant water potential and in soil water content.
Comparison of Different Phosphorus Extractants in Soils of the Western State of Nigeria1
Authors: Oko Bernard F. D. , Agboola Akinola A.
Published: July 2010

Researchers in Western Nigeria have a problem in choosing a universally accepted extractant for soil test correlations. Many P extractants that are in use today have been adopted without sufficient investigation.

In the present study, 8 different P extractants were used in extracting P from 90 surface soil samples taken from 2 different ecological zones of the Western State of Nigeria. Soil P values for the different extractants before the first crop of rice (Oryxa saliva var. ‘OS6’ upland rice) were correlated with P uptake of the first crop, cumulative P uptake (P uptake for two croppings of 8 weeks each), and with cumulative yield (dry matter for two croppings). Soil P values after first crop were correlated with P uptake of the second crop.

Results suggested that different ecological zones may require different extractants, viz. Bray No. 2 (0.03 N NH4F + 0.1 N HC1) (r = 0.433*) for the swamp soils; Bray No. 4 (0.5 N NH4F + 0.1 N HC1) (r = 0.491**) for the Ikenne soils, and Bray No. 1 (0.03 N NH4F + 0.025 N HC1) (r = 0.383*) for the Ilora soils, but the general purpose extractant for rice in soils of the Western State was Bray No. 1 (r = 0.372***).

With the swamp soils, there was a negative correlation when soil P after first crop was correlated with second P uptake. The North Carolina extractant (0.05 N HC1 + 0.025 N H2SO4) (r = 0.462**) gave the best reliability for Ikenne soil. The Bray Nos. 1 and 2 were equally useful in both correlations for the above, as well as initial soil P with first P uptake although there was a slight preference in the former for the Bray No. 2 (r = 0.513**) over Bray No. 1 (r = 0.396*). For the 90 soil samples, Bray No. 2 (r = 0.279**) gave better correlation between soil P after first planting with second P uptake.

Correlation of initial soil P with one cropping of 8 weeks was better for swamp soils, whereas in Ikenne soils more confidence could be placed on correlations with second cropping and cumulative P uptake. For the Ilora soils and with a combined group (consisting of 90 soil samples) there was little or no significant difference in using either.
Effect of Simazine and Diuron on the Nitrogen Content and Dry Weight of Wheat and Sorghum1
Authors: Rottman G. A. , Tweedy J. A. , Kapusta George
Published: July 2010

Studies were conducted to determine if 2‐chloro‐4,6‐bls‐(ethylamlno‐s‐triazine (simazine) or 3‐(3,4‐dichlorophenyl)‐l,l‐dimethylurea (diuron) increased the nitrate or Kjeldahl N content in the shoots or roots of wheat (Triticum aestivum L.) or soghum (Sorghum blcolor (L.) Moench)plants. Wheat and sorghum plants were grown in nutrient solutions containing several concentrations of these two herbicides for various time intervals. Nitrate N and Kjeldahl N were determined in shoots and roots and expressed as totals per plant.

Simazine‐ and diuron‐treated wheat plants had a higher nitrate N content and lower dry weight than control 6 days after treatment. The Kjeldahl N per six plants was reduced by diuron and was not affected by simazine. Diuron at 0.25 ppm was phytotoxic to wheat. An increase in nitrate was usually accompanied by a decrease in dry weight.
Corn Cob Hemicellulose Composition of Corn Isolines Involving Several Mutant Genes1
Authors: Helm J. L. , Donnelly B. J. , Glover D. V.
Published: July 2010

All economically successful xylose production procedures require a carbohydrate source rich in hemicellulose and with a minimum content of other pentose sugars. Mature corn (Zea mays L.) cobs are a good source of hemicellulose. However, birchwood sulphite liquor has been a more economical raw material for xylose production in recent years. A strong pleiotropic or linkage relationship between genes used in today's specialty corn programs and increased hemicellulose content or improved composition would facilitate a program to purchase corn cobs of known genotype. The inbred line Oh43 and its isogenic counterparts homozygous for the recessive endosperm genes wx, su1; du, su2, o2 and ae were tested tor hemicellulose content and composition. The results indicate no relationship between composition of mature cobs and any of the six recessive endosperm genes either in a pleiotropic or linkage sense. Additional visual marker genes should be evaluated so that corn cobs could be used as an economically suitable raw material in a xylose production program.
Multiple Assignment Tester Animals for Pasture‐Animal Systems1
Authors: Matches A. G. , Martz F. A. , Thompson G. B.
Published: July 2010

Different forages or management practices are often evaluated as separate entities in conventional grazing trials. A more meaningful approach is to evaluate “pasture systems” for season‐long grazing, whereby separate pastures of different forages or managements comprise a pasture system, and each component is grazed at different periods during the season. The purpose of this paper is to stress the need for the evaluation of different forages or management practices within the framework of a total system and to suggest two practical experimental designs for pasture‐animal system experiments.

Two types of pasture systems using multiple assignment testers are proposed: 1) systems with separate pastures and 2) systems with common pastures. With multiple assignment testers and common pastures, several pasture systems may be compared simultaneously, but require fewer pastures per replication. For example, only 6 pastures are needed for a 3 ✕3 system trial with common pasture, as compared to 18 pastures per replication for system trials with separate pastures. Animal and pasture production may be compiled for the total system and for each component of the system. Multiple assignment tester animals are defined as tester animals assigned to graze two or more components comprising a pasture system.

In evaluation of the concept of pasture systems, experimental errors for measuring beef cattle gain per hectare and average daily gain per animal were nearly the same for grazing trials analyzed as a conventional trial and as a system trial with common pastures. The season‐long pasture system approach in grazing research provides the cattle producer with more realistic information on which to plan his pasture program.
Field Use of Microwatersheds with Vertical Mulch1
Authors: Fairbourn Merle L. , Gardner H. R.
Published: July 2010

Microwatersheds and vertical mulch were tested at the Central Great Plains Field Station, Arkon, Colorado, to determine if their effects on storage and use of soil water in the field were similar to responses obtained in the laboratory. Treatments consisted of microwatersheds with vertical mulch, microwatersheds without mulch, and a flat surface control. Each treatment was replicated twice on both crop and fallow plots. All microwatershed plots had slopes treated with a hydrophobe to increase water runoff and check dams placed at uniform intervals across row areas to keep the water on the plots. Biweekly soil water measurements were made during each growing season by gravimetric analysis in 1972 and by the neutron method in 1973. Grain sorghum [Sorghum bicolor (L.) Moench] was grown and plant harvests were made at the end of each crop season. Soil water evaporation was lowest on the microwatershed with vertical mulch treatment as a result of concentration and deep infiltration of precipitation. Increased soil water storage was the major factor responsible for an increase in grain sorghum yield on the vertical mulched microwatershed ranging from 37 to 150% above the control treatment. The vertical mulched microwatersheds seem to have the potential for increasing and stabilizing annual yields in semiarid regions.
Effects of Nitrogen Rate, Source, and Various Anions and Cations on NO3 Accumulation and Nutrient Constituents of Table Beets1
Authors: Cantliffe D. J. , Goodwin P. R.
Published: July 2010

Excessive N fertilization of table beets (Beta vulgaris L.) can be expensive and can be detrimental to quality of the processed product. The type of N fertilizer applied can lead to differential absorption of N, NO3‐N and other plant constituents. The objectives of the present study were to apply various N fertilizer sources, rates, and supplemental anion‐cation fertilizers to table beets to determine their effect on yield and tissue concentrations of NO3‐N, total N, and other nutrient constituents. Nitrogen as NaNO3, KNO3, NH4C1, (NH4)2SO4, and NH4NO3 was broadcast at rates of 0, 112, and 224 kg N/ha to table beets grown on a fine sandy loam soil. Sodium as NaC1 and Na2SO4 and K as KCI and K2SO4 at rates of 224 kg Na or K/ha were applied to plants receiving 0, 112, or 224 kg N/ha from NH4NO3. Nitrate‐N, total N, P, K, Ca, Mg, Na, C1, Zn, Mn, and Fe were determined on freezedried table beet leaf blades, petioles and roots.

Yield of roots as metric tons/ha or $/ha (graded) was significantly increased by each increment of N fertilizer. Although there were no significant differences between N sources used, yields were consistently higher from the NO3 sources. The addition of Na, K, Cl, and SO4 fertilizers had no significant influence on yield.

The NO3‐N concentration in beet blades, petioles, and roots were significantly increased by increased amounts of N fertilizer. Nitrate concentrations were lowest in plants receiving NH4 and highest in those receiving NO3 fertilizers. The total N concentration in the plants was increased by N fertilizer. Total N was higher in roots receiving NO3 than those receiving NH4 fertilizer and was lowered below controls not receiving N fertilizer by Na or K. In the blades, these trends were reversed.

Nitrogen rates and sources, and cation sources had a varied effect on the tissue concentrations of the other elements that were examined depending on the plant part tested.
Planting Date Effects on Yield, Height, and Stem Diameter of Kenaf1
Authors: Massey John H.
Published: July 2010

‘Everglades 71’, ‘Guatemala 4’, ‘Guatemala 45,’ and ‘SH/15R’ kenaf (Hibiscus cannabinus L.) were planted at four 2‐week intervals in 1970–1972, to determine differential response to planting date. There was no planting date ✕ cultivar interaction for yield or plant height in any year, nor for stem diameter in 1970. In 1971, yield tended to decrease with successively later planting dates and was 66% lower at the last as compared with the first planting, but in 1970 and 1972 planting date did not affect yield. Stem diameter and plant height also were reduced by later planting in 1971. Everglades 71 in 1971 and SH/15R in 1972 produced higher yields than the other cultivars. Basal stem diameter of SH/15R was greater than that of other cultivars in 2 of 3 years. Generally, cultivars did not differ in plant height in any year. Results indicate that there was no advantage of one cultivar or planting date over the others tested.
Effect of Preplant‐Only Irrigation on Cotton Yields1
Authors: Bilbro J. D.
Published: July 2010

Irrigation practices for cotton (Gossypium hirsutum L.) are changing on the Texas High Plains because the irrigation water supply is declining. The objectives of this study were to calculate yield probabilities for cotton planted on both early and late dates and grown with only a preplant irrigation, and then to compare these yield probabilities with those previously calculated for dryland conditions. Yields from early and late plantings that had received only a preplant irrigation for the period 1960 through 1971 were used for calculating probabilities for various yield levels.

The expected average yields (50% probability) of the early and late plantings of preplant‐irrigated cotton are 530 and 503 kg/ha, respectively; and about 70% of the time the respective yields will differ by less than 50 kg/ ha. Thus, the yield potential of preplant‐irrigated cotton was not greatly affected by a wide range of planting dates. Also, 50% of the time preplant‐irrigated land can be expected to yield about twice as much as comparable dryland and to vary much less in year‐to‐year yields.
Residual Fertility in Soil Continuously Field Cropped to Corn by Conventional Tillage and No‐Tillage Methods1
Authors: Moschler W. W. , Martens D. C. , Shear G. M.
Published: July 2010

The increasing importance of no‐tillage crop culture merits investigation of its many aspects. Reports to date on no‐tillage corn (Zea mays L.) fertilization or liming have not fully clarified the requirements, especially with respect to effective utilization of the nutrient elements, which must necessarily include residual supplies left in the soil.

This paper reports comparative residual nutrient elements in the 0 to 20, and 20 to 40 cm soil layers after 11 consecutive years of corn grown in the field by no‐tillage and conventional tillage methods. Corn grown by both methods had received the same amounts of calcitic limestone and fertilizer. The data on residual fertility were obtained by repeated greenhouse cropping without lime or fertilizer, followed by testing the soil for pH and acid‐extractable nutrient elements. Greenhouse recovery of residual nutrient elements, coupled with residual soil supplies, were used to draw conclusions.

Considerably more P and slightly more N were recovered in the greenhouse corn at the 0 to 20 cm soil depth when no‐tillage corn had been grown than where conventionally tilled soil had been grown. Acid extractable P and Ca, after greenhouse cropping, were higher in no‐tillage soil than in conventionally tilled soil.

More Mg and less K were recovered in the greenhouse corn from no‐tillage soil than from conventionally tilled soil at the 20 to 40 em depth. Soil pH and acid extractable P were higher and Mg was lower, after greenhouse cropping, in no‐tillage soil when compared to conventionally‐tilled soil.

The increases in soil pH and extractable P at the lower soil depth that were found in no‐tillage soil were assumed to be from chemical or biological causes, or probably a combination of the two.

The results of the study should be of considerable economic benefit for maintaining a more permanent soil productivity as well as of scientific interest in soil fertility behavior.
Yield and Botanical Composition of an Irrigated Grass‐Legume Pasture as Influenced by Fertilization1
Authors: Rehm G. W. , Nichols J. T. , Sorensen R. C. , Moline W. J.
Published: July 2010

Irrigated pastures are becoming more important for animal production in several Great Plains and Western states. The majority of fertilization studies have been conducted at sites where surface irrigation practices were used on medium to fine textured soils. This study was designed to evaluate the effect of N, P, and K fertilization on forage production and grass‐legume composition of an irrigated pasture containing bromegrass (Bromus inermis Leys.), orchardgrass (Dactylis glomerata L.) and alfalfa (Medicago sativa L.) on sandy soils irrigated with automated sprinkler systems.

Forage yields were recorded for 3 years at two sites and plant separations to determine the grass‐alfalfa composition were made at one of the two sites. The response to increasing levels of N was curvilinear at both sites throughout the 3‐year period. The application of 252 kg N/ha produced maximum yields at the Holt County site, whereas the use of 560 kg N/ha produced the maximum yields at the North Platte site. These N rates produced increases of 4.7 and 7.0 metric tons/ha, respectively. The response to applied P was linear at the Holt County site but had little influence on yields at the North Platte site. Applied K had no influence on forage yields at either site.

Fertilization influenced the grass‐legume composition at the Holt County site to some extent, but trends were not consistent for the 2 years. The data show that N rates in excess of 252 kg/ha decreased the percentage of grass in the mixture while increasing the percentage of alfalfa. Since clipping frequency may have had some influence on grass‐legume composition, changes in the percentage of grass and alfalfa in the mixture cannot be entirely attributed to fertilization.
Relation of Hydrocyanic Acid Potential to Morphological Characteristics and Dry Matter Percentage of Sorghum1
Authors: James John H. , Gray Elmer
Published: July 2010

All Sorghum species are believed to have the potential of producing hydrocyanic acid, and thus, the common usage of Sorghum as a forage results in the threat of poisoning to cattle. Since the determination of hydrocyanic acid potential (HCN‐p) is laborious, we sought to ascertain whether it is possible to predict HCN‐p from other more easily measured plant characteristics.

The relationships of HCN‐p to various morphological plant characteristics and dry matter percentage of six sorghum types were studied in 1970 and 1971. Significant differences among the cultivars were found both years for all the plant characteristics—height, diameter of culm, length of stem, number of leaves, width and length of third leaf, dry matter percentage, and HCN‐p. Most of the correlation coefficients between HCN‐p and the morphological characteristics of the cultivars were not significant. Correlation coefficients between HCN‐p and dry matter percentage were all negative, and most were highly significant. It was not possible to predict HCN‐p from measurements of the morphological characters. Although dry matter percentages were influenced by genotype and stage of development, relative differences in dry matter percentages were indicative of relative differences in HCN‐p.
Fertilization of Native Grass and Weeping Lovegrass1
Authors: McMurphy W. E. , Denman C. E. , Tucker B. B.
Published: July 2010

Yield responses by native range to fertilization has often been disappointing in the tall grass prairie, and the results were confounded by changes in species composition. This study evaluated the response to N and P fertilizer by monocultures of three native species ‘Kaw’ big bluestem (Andropogun gerardi Vitman), ‘Caddo’ switchgrass (Panicum virgatum L.), and indiangrass [Sorghastrum nutans (L.) Nash] and an introduced grass, weeping lovegrass [Eragrostis curvula (Shrad.) Ness].

Rates of N fertilizer were 0, 45, 90, and 180 kg/ha in all combinations with P at 0 and 40 kg/ha. Forage production, crude protein, fertilizer N recovery, stand longevity, and soil fertility changes were evaluated.

Excellent forage yield responses to N fertilization were obtained from the native species in monoculture. Switchgrass and weeping lovegrass were the most productive species at 180 kg N − 40 kg P/ha, but had different seasonal production. All native grasses produced one flush of growth and very limited regrowth when compared with weeping lovegrass. Indiangrass had significant reductions in stand at 90 kg N and 180 kg N/ha and was the first species each year to show visual symptoms of drought stress. Severe lodging of big bluestem at 180 kg N/ha limited its potential. Fertilizer N recovery of all species was most efficient at the 90 kg N − 40 kg P/ha treatment being 52 to 66% for native grasses and 84% for weeping lovegrass. Soil tests revealed P accumulations with P fertilization, decreased soil pH associated with N fertilizer and soil K changes in relation to forage removal.

The native species have some characteristics which limit their potential for use in fertilized meadows.
Responses of Dry Beans to Varying Nitrogen Levels1
Authors: Edje O. T. , Mughogho L. K. , Ayonoadu U. W. U.
Published: July 2010

Dry beans (Phaseolus vulgaris L.) are poor nitrogen fixers; therefore, nitrogen fertilizers are recommended for even reasonable production. We studied the effects of six levels of nitrogen (0, 40, 80, 120, 160 and 200 kg/ha) on determinate dry bean yields for 2 years.

Seed yields increased significantly in both years with increasing rates of N. Average yields were 2,150, 2,704, 3,048, 3,147, 3,366 and 3,779 kg/ha, respectively, for the six rates of N indicating that higher rates of N might have produced greater seed yields. Yield components (yield/plant, pods/plant, seed/size) also increased with increasing N. Percent crude protein and crude protein yield were closely related to the amount of N applied. Leaf area index, canopy height, canopy width, plant height, and pod length were significantly affected by the amount of N applied; however, addition of N had no appreciable effect on specific leaf area and leaf area ratio. Nitrogen increased dry matter production but had no effect on the distribution of dry matter. At 50 days from planting, dry matter was highest in leaflets (47.7%) followed by stems (28.9%) and was least in flowers (1.2%).
Resistance to Water Transport in Rice Plants1
Authors: Tomar V. S. , Ghildyal B. P.
Published: July 2010

Rice (Oryza sativa L.) is grown either in continuously flooded “lowland” soils or under rainfed conditions in “upland” soils. The objective of the study was to determine whether there are differences in resistance to water transport between plants grown in flooded and non‐flooded soils. This information may be useful in understanding the plant‐water relations under two cultural practices.

In a greenhouse, rice variety ‘IR‐8’ was grown under flooded and 0.33 bar soil suction for 45 to 50 days. The resistance to water transport in different plant parts and in the whole plant was measured by a transient flow method. The effect of an increased air saturation deficit from 15 mb to 45 mb on transpiration rate and on leaf water potential was studied in a controlled environment chamber.

The resistance to water transport in the non‐flooded plants was nearly twice as high as in the flooded plants. The non‐aerenchymatous roots of non‐flooded plants had about 17 times more resistance than aerenchymatous roots of flooded plants.

The gradient between leaf and soil water potential increased markedly when plants were exposed to high air saturation deficit; however, the transpiration rate remained almost constant.

These studies indicate the existence and development of large resistances to water transport in rice plants.
An Electro‐Optical Temperature Controller for Maintaining a Constant or Relative Temperature1
Authors: Brown J. M.
Published: July 2010

A simple, inexpensive temperature controller may be constructed utilizing thermistors in a Wheatstone bridge configuration. The unit may be used to maintain a constant temperature or to regulate the temperature of a plant enclosure to that of the naturally varying ambient temperature.
An Improved, Rapid, Field Method to Measure Photosynthesis with 14CO21
Authors: Naylor D. G. , Teare I. D.
Published: July 2010

Recognizing a need for a rapid, accurate, one‐man technique for comparing photosynthesis rates in fields, we developed one based on the application of a short pulse of air containing 14CO2 over an enclosed leaf (a modification of Shimshi technique) and subsequently determining CO2‐uptake by measuring radioactivity in the enclosed area. The system contains a solenoid on‐off, air‐flow switch driven by an electronic timer, which eliminates human error in judging exposure times, and a miniature photosynthesis chamber designed to ensure adequate ventilation. The 14CO2‐exposed leaf samples were digested in an organic solubilizer for scintillation counting. Exposure times of 15 to 20 sec produced optimum photosynthetic rates for wheat (Triticum aestivum L.), soybean (Glycine max (L.) Merr.), and sorghum (Sorghum bicolor (L.) Moench); however, optimum gas flow rates varied with crops. Soybean required a higher flow rate for optimum photosynthesis than wheat, sorghum, or corn (Zea mays). Photosynthetic rates measured by the 14CO2 technique compared well with rates we observed with infrared gas analysis. Sampling time is short and the system is portable and rugged. If consistent exposure time and flow rates are used, the technique can be valuable for comparing photosynthetic rates between genotypes or among various treatments in an experiment.
Row Spacing and Potential Productivity in Sugarcane1
Authors: Bull T. A.
Published: July 2010

Sugarcane (Saccharum spp. hybrid) has been reported to respond only slightly to reduced interrow spacing. However, commercial cultivars are released after 10 to 15 years selection at a single row spacing and would be expected to be suited to that particular spacing. To determine if sugarcane has the genetic potential to exhibit increased productivity at high stalk populations, the performance of unselected seedlings was compared with that of commercial cultivars at several planting densities (2.6 to 32 setts/m2) and interrow spacings (25 to 140 cm). Comparisons were made over a 2‐year period in small scale field trials and in pot culture.

Reduction of the interrow spacing from 140 to 50 cm significantly increased the yield of some cultivars in an irrigated field trial. The superiority of close row spacing treatments was maintained when the ratoons were grown under natural rainfall.

About 7% of an unselected seedling population planted at high density (32 setts/m2) in pot culture performed better than commercial cultivars planted at the same or lower (5 setts/m2) density. Clones which gave superior yields at high planting density were not significantly better than other seedling or commercial clones when grown at conventional planting density. Consequently, exploitation of increased productivity due to reduced interrow spacing should involve selection at the row spacing adopted.
Wheel Traffic on Regrowth and Production of Summer Annual Grasses1
Authors: Fribourg Henry A. , Overton Joseph R. , Mullins James A.
Published: July 2010

Wheel traffic is known to affect soil characteristics, seed germination and seedling emergence, and has been observed to damage stubble of plants harvested for greenchop. The objective of this study was to measure the gross effects of the passage of tractor and wagon wheels on the regrowth of ‘Sudax SX‐11’ sorghum [Sorghum bicolor (L.) Moench] and ‘Gahi‐1’ pearlmillet [Pennisetum americanum (L.) K. Schum]. Four experiments were conducted during the 1969–71 period at two locations on silt loam soils. Wheel traffic consisted of passing a front (152‐mm wide) and a rear (315 or 396‐mm wide) wheel of a medium‐sized tractor (1,745 or 2,190 kg) over the grass stubble after a greenchop harvest. One year, a 1360 kg wagon followed the tractor. Dry matter regrowth of both grasses was decreased by traffic. The reduction was sometimes 15 to 20%, often 30%, and occasionally 50%. The greatest reduction could be attributed to the first wheel passage, additional traffic having less effect than the first. These results indicate that reducing the number of wheel tracks across a field, either by the use of matched equipment or planned traffic patterns, could lead to greater efficiency of production of summer annual grasses for greenchop.
Growth of Sorghum and Soybeans in Picloram‐treated Soil1
Authors: Bovey R. W. , Miller F. R. , Baur J. R. , Meyer R. E.
Published: July 2010

Picloram (4‐amino‐3,5,6‐trichloropicolinic acid) residues in soil may occur as a result of weed control practices on cropland and injure subsequent crops. This study was conducted to determine how soil residues of picloram affected the growth and dry matter production of sorghum (Sorghum bicolor (L.) Moench) ‘Topland’ and soybeans (Glycine max (L.) Merr.) ‘Hill’ grown in soil at various time intervals after picloram had been applied.

The potassium salt of picloram was applied at 1.12 kg/ha and incorporated by disking into a Wilson clay loam soil 1½, 3, 6, 7, 12, 14, 16, 19, and 26 months before planting of sorghum and soybeans in the Spring of 1972 and 1973. Soil, sorghum, and soybeans were analyzed for picloram content at time of harvest. After maturing, crop plants were counted and harvested by clipping two rows, 4.1 m long at the soil level in each plot. Plants were weighed and oven‐dried for dry matter determination. Germination tests were conducted with harvested sorghum seed.

Sorghum was grown on picloram‐treated soils 12 months after application without reduction in plant numbers, dry matter production, flowering, or germination. No picloram was detected in sorghum seed (immature and mature) produced by plants seeded 6 or 12 months after application of herbicide to the soil. Because soybeans were sensitive to small amounts of picloram in the soil, they should not be grown in a picloram‐treated clay soil for at least 2 years after application. Earlier planting risks possible reduction in stand and dry‐matter production in situations similar to this study.
Winter Mulch Covers, Spring Vigor, and Subsequent Growth of Agrostis1
Authors: Evans G. E.
Published: July 2010

The potential use of mulches to reduce winter injury of turfgrasses (Agrostis spp.), and the associated adverse effect upon incidence of snow mold (Typhula sp.) raised the question of whether these materials in combination with recommended and elevated fungicide rates would have an effect upon vigor. Accordingly, a study of the effects of several mulches and fungicide levels upon spring vigor and subsequent growth of three bentgrasses was conducted in the field over a 6‐year period.

In 5 of 6 years Agrostis tenuis ‘Holfior’ produced highest clipping yields in nonmulched, nonchemically treated plots, Agrostis tenuis ‘Highland’ produced lowest clipping yields. Doubling the recommended rate of fungicide did not significantly increase clipping yield.

Straw mulch reduced clipping yield markedly for all cultivars regardless of fungicide level. Black plastic in combinations with recommended fungicide rates, resulted in only slight reduction of clipping yield. Clear and perforated clear plastics were the best mulches of those treated, although highest clipping yields occurred in years of low snow mold incidence. The “greenhouse” effect of these mulches is believed responsible for much of the observed yield differences.

In 5 of 6 years, Agrostis palustris ‘Penncross’ produced greatest clipping yields prior to July 10, after that highest yields were produced by Holfior.
Reaction of Maize Hybrids and Inbreds to Southern Corn Leaf Blight1
Authors: Hallauer Arnel R. , Martinson C. A.
Published: July 2010

The southern corn leaf blight (SCLB) epidemic of 1970, caused by Bipolaris maydis (Nisikado) Shoemaker, race T, decreased yield of maize (Zea mays L.) 15% nationwide. Use of Texas male‐sterile cytoplasm (T) in the production of hybrids was an important factor in the severity and spread of SCLB. Some information, however, indicated that some T‐cytoplasm lines showed more tolerance to SCLB infection than others in 1970. Our primary objective was to determine the effects of SCLB infection on inbred lines that had shown a differential reaction to SCLB in T cytoplasm. Inbred lines and hybrids produced among the inbred lines were evaluated.

Nine inbred lines and 144 reciprocal single crosses produced on normal (N) and T cytoplasm were artificially infected and compared in greenhouse seedling and field tests for reaction to SCLB. Data also were obtained in the field tests for yield and five other agronomic traits.

Correlations of the greenhouse tests with the field tests for SCLB infection were 0.56* (* significant at the 1% level) for the inbred lines and 0.65* for the single crosses. On the average, the inbred T‐cytoplasm lines averaged 8.4% less than those on N cytoplasm; B67TRfRf, however, was 55.3% lower yielding than its N counterpart. The effects of SCLB infection on yield for the T‐cytoplasm single crosses were greater than for the inbred lines. The 72 T‐cytoplasm single crosses averaged 19.9% less yield than the 72 N‐cytoplasm single crosses. Yield losses using hybrids produced on T cytoplasm ranged from 13.4% for B68 × Mol7 to 37.2% for B67 × W64A; B68 and Mol7 were classified as relatively resistant and B67 and W64A as being susceptible to SCLB in T cytoplasm. Our results show that inbred lines express different levels of reaction to SCLB infection in T cytoplasm.
Herbicidal Effects of Tebuthiuron and Glyphosate1
Authors: Baur J. R. , Bovey R. W.
Published: July 2010

These studies were conducted to gain a better understanding of the differences in activity of two new herbicides with three commonly used herbicides with regard to their effects on growth, phytotoxicity and germination. This information is necessary for the further evaluation of the new compounds. New herbicides N‐[5‐(1,1‐dimethylethyl)‐1,3,4‐thiadiazol‐2‐yl ]‐N,N′dimethylurea (tebuthiuron) and N‐(phosphonomethyl)glycine (glyphosate) were compared with 1,1′‐dimethyl‐4,4′‐bipyridinium ion (paraquat), alkanolamine formulation of 2,4‐dichlorophenoxyacetic acid (2,4‐D), and 7‐oxabicyclo[2.2.1.] heptane‐2,3 dicarboxylic acid (endothall). Growth and phytotoxic effects were evaluated on cowpea [Vigna unguiculata (L.) Walp.] and sorghum [Sorghum bicolor (L.) Moench] seedlings. Germination effects were studied on seed of sorghum, cowpea, and wheat (Triticum aestivum L.)

Greenhouse grown seedlings of cowpea (10 to 12‐days old) and sorghum (25 to 28‐days‐old) were treated by applying 100 μ1 aqueous solution of the test compounds to one unifoliolate leaf of cowpea or to the partially unfurled true leaf of sorghum. Rates ranged from 1.4 to 1,434 μg/plant depending on the herbicide. Evaluation of phytotoxic and growth responses was made 10 to 12‐days post‐treatment. In cowpea, the growth response was determined by measuring the length of the first internode. In sorghum, fresh weight served as a measure of the growth response. Cowpea phytotoxicity was determined on percent dead plants per six‐plant replicate. For sorghum, phytotoxicity was measured as percent desiccation/ plant. Absorption times were determined by washing treated seedlings at intervals for a 6‐hour period. All experiments were repeated six to eight times with each treatment being replicated six and 10 times, cowpea and sorghum respectively.

The order of decreasing effectiveness of the five herbicides for growth and herbicidal effectiveness for cowpea and sorghum was paraquat, glyphosate, tebuthiuron, 2,4‐D, and endothall. Endothall‐glyphosate mixtures were synergistic in inhibiting growth of cowpea. Endothalltebuthiuron mixtures were generally synergistic in killing and inhibiting growth of sorghum.

Absorption of growth‐inhibiting levels of all five herbicides occurred within the first 60 min. of exposure. Phytotoxic levels of tehuthiuron, paraquat, and endothall were absorbed within 5, 30, and 60 min, respectively. Glyphosate showed rapid action and resistance to removal by washing.

Glyphosate and tebuthiuron had little inhibitory effect on germination of sorghum, wheat, or cowpea. Paraquat severely inhibited germination of all three species; endothall and 2,4‐D inhibited only cowpea.
Weanling Meadow Vole and Dairy Cow Responses to Alfalfa Hay1
Authors: Shenk J. S. , Barnes R. F. , Donker J. D. , Marten G. C.
Published: July 2010

Weanling meadow voles (Microtus pennsylvanicus) have been suggested as a bioassay of the feeding value of forage. To test the relationship between vole and ruminant intake and performance, six alfalfa (Medicago sativa L.) forages were fed to dairy cows and weanling voles. The six forages represented early and late‐harvested hay in 3 consecutive years. The dairy cow rations consisted entirely of forage, vole diets contained 70% forage. Intake and production responses for both animal species were higher with feedings of early‐cut hay than of late‐cut hay. Multiple regression analyses showed that the neutral detergent fiber and protein concentration of the forages were important factors in the observed responses of each animal species. A linear equation was calculated that accounted for 91% of the variation in milk production from vole weight gain. The study supports the theory that weanling vole may provide useful information about the feeding value of forage for the ruminant animal.
Calculation of Rate of Nutrient Uptake by Growing Roots1
Authors: Khasawneh F. E.
Published: July 2010

Equations are presently available to calculate the rate of nutrient uptake by growing roots. They can be used to estimate an average rate of uptake by the entire root system, but they fail to give specific information on uptake by a unit segment of root or on the effects of aging and morphological changes of such a segment on its capacity for uptake. This paper gives a theoretical analysis of the process of nutrient uptake by a growing root system. The objective of this analysis is to derive equations that would give such specific information. A frequency distribution function is used to partition root systems into a continuum of age groups, each possessing a rate of uptake that is a function of the age of that group. Equations are derived that utilize time‐series measurements of root length and nutrient accumulation in the plant. These derivations are used to calculate parameters of nutrient uptake related to two properties of the root system: (i) the rate of nutrient uptake of a unit segment of root and the manner by which this rate changes with aging and (ii) the rate of nutrient flux into the entire root system as a function of time.