bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cotton and Corn Root Development in Two Field Soils of Different Strength Characteristics1
Authors: Grimes D. W. , Miller R. J. , Wiley P. L. 
Published: July 2010

AbstractMany agriculturally important soils in the San Joaquin Valley, being compact and of high strength, may pose special problems in water management. The higher than normal frequency of irrigation often required to meet evapotranspiration demand suggests that plant root development has been limited. This study was conducted to determine the influence of high penetrometer soil strength, found naturally occurring in the field, on the root development of cotton (Gossypium hirsutum L.) and corn (Zea mays L.). Additional objectives were to determine if root distribution could be influenced by planting geometry and density, and to relate soil water depletion to observed root density (cm of root/cm3 of soil).Cotton and corn plots, having a variable row width and plant density, were established on each of two field soils that differed considerably in strength as measured with a recording soil penetrometer. Root densities of the two crops were related to the independent variables penetrometer strength (measured in situ), and soil depth in a regression model that accounted for 75% of the observed variation. A high‐density plant population of cotton caused higher root densities in the 30 to 122 cm‐depth zone in a low‐strength soil than that with normal plantings. A linear relation between water depletion and root density indicated average water uptake values for fully transpiring corn and cotton to be respectively 2.33 × 10−a and 7.86 × 10−3 cm8/cm/day.Field measured soil strength was effective for diagnosing or predicting mechanical root growth restrictions of well drained soils.
Effect of Dew on Leaf Water Potentials and Crop Resistances in a Paspalum Pasture1
Authors: Kerr J. P. , Beardsell M. F. 
Published: July 2010

AbstractOpportunities for comparing the water status of crops when the presence or absence of dew is the main environmental variable are rare. This paper reports the results of such a comparison made on successive days on a Paspalum dilatatum (Poir) pasture. Leaf water potentials (Ψ1) were measured with a pressure chamber, and the energy balance method was used to determine evapotranspiration. Crop resistances (rc) were calculated from the micrometeorological data.The presence of dew halved the early morning crop resistances (1.7 compared to 0.9 sec cm−1). The paspalum pasture did not appear to exercise stomatal control over evapotranspiration until most of the dew had evaporated. At ca 1000 hours rc was 1.6 sec cm−1 on both days.Leaf water potentials measured before sunrise were −1.3 bars and at noon were ca −13.0 bars on both days, but the pattern of change in Ψ1 between these times varied. In the absence of dew Ψ1 decreased rapidly to reach −12.0 bars at 0900 hours; whereas with dew present, relatively high Ψ1 were maintained until most of the dew had evaporated.Dew, which is a significant feature of many agricultural regions, may thus have an important effect on the water balance of pastures and crops and thereby enhance production.
Dry Matter Accumulation in Maize in Response to Defoliation1
Authors: Egharevba P. N. , Horrocks R. D. , Zuber M. S. 
Published: July 2010

AbstractPrior investigations have reported the effect of leaf removal at various stages of development on yield of corn (Zea mays L.), but none have studied the pattern of grain dry matter accumulation. Therefore, this study was conducted to evaluate the effect of leaf loss on dry matter accumulation patterns of corn grain and grain yields. Defoliation was begun 10 days after 50% silking and continued at 10‐day intervals for the next 40 days. Leaf removal treatments consisted of removing 1) no leaves (control), 2) all leaves below the ear, 3) all leaves above the ear, and 4) all leaves. Dry matter accumulation was monitored by sampling ears at 5‐day intervals from 50% silking to black layer formation.Regardless of severity, defoliation within 30 days after silking significantly reduced total accumulated dry matter. Complete defoliation was more detrimental (6.4 to 82% yield loss) than partial defoliation (1.5 to 32.7% yield loss). These losses varied with time (after 50% silking) of treatment application. The effect of removing all leaves above the ear was not significantly different from that obtained by removing all leaves below the ear.Yield component affected most by leaf loss, for the overall treatment period, was kernel weight (12.7 to 53% decrease). However, number of kernels was greatly reduced (62.3%) when all leaves were removed 10 days after silking. Complete leaf removal thereafter and partial leaf removal affected number of kernels considerably less (approximate decline, 20%).This study showed that severe leaf loss at the onset of silking and until at least 10 days after 50% silking decreased grain yields because of fewer kernels. However, yield decreases associated with less severe leaf loss or loss 20 days or more after 50% silking were largely related to a decline in kernel weight. In addition to providing a better understanding of patterns of dry matter accumulation, these data may be useful to individuals required to estimate grain yield after a significant loss, to natural causes, in plant leaf area.
Corn Growth as Affected By Ammonium vs. Nitrate Absorbed From Soil1
Authors: Dibb D. W. , Welch L. F. 
Published: July 2010

AbstractThe effect of NH4 on corn (Zea mays L.) growth in a soil medium is of interest because of the possibility of significantly decreasing leaching and denitrification losses of applied N by preserving N in the NH4 form. The objective of this investigation was to determine growth and nutrient content of corn plants when the principal form of N was either NH4 or NO3.Corn, grown in the greenhouse in a soil medium, was allowed to absorb N as either NH4 or NO3. A chemical nitrification inhibitor and different sources of added N were used to manipulate the form of N available for absorption. The maximum amount of N absorbed as NO3 was estimated as the difference between the NO3 content of fallow and cropped pots at harvest. Plants grown with NH4 and a nitrification inhibitor were estimated to have absorbed at least 95% of their N as NH4. Other plants absorbed N almost solely as NO3. The effect of NH4 versus NO3 absorption on stover yield, percent N, Ca, Mg, K, and P in the plant was determined.Yield of corn plants was not negatively affected by form of N absorbed when the meq ratio of applied N:K was 2:1. Visual tissue damage and decreased yield were symptomatic of NH4 nutrition where the meq applied N:K ratio was 3.3, 4.0, 4.4, 6.6, and 8.0. Nutrient content of the plants reflected strong cation:cation and cation:anion interactions among N form absorbed and Ca, Mg, K, and P. Soil pH appeared to be affected less by form of N absorbed by the corn plants than by nitrification of applied NH4.
Equipment for Seeding Experimental Plots of Small Grains, Grasses, and Legumes1
Authors: Barker R. E. , Bond J. J. , Zachmeier L. G. 
Published: July 2010

AbstractMany specialized experimental plot planters have been developed but they are usually expensive and have limited use. This note describes seeding equipment for experimental plots developed by modifying conventional farm implements. The equipment provides the benefits of uniform soil compaction, single cone seeder with distribution to multiple rows, and enclosed cab for seeding during inclement weather. The equipment is adaptable for seeding isolation seed production blocks, large plots for agronomic studies, or variety trials of small grains, grasses, and legumes.
Soil Temperature, Air Temperature, and Defoliation Effects on Growth and Nonstructural Carbohydrates of Kentucky Bluegrass1
Authors: Youngner V. B. , Nudge F. J. 
Published: July 2010

AbstractKentucky bluegrass (Poa pratensis L., is used for turf in many areas where soil and air temperatures are high for long periods. Using controlled temperature water baths and growth chambers, Kentucky bluegrass ‘Merion’ plants were grown at various soil and air temperatures and at three clipping heights to determine the interaction effects of temperature and defoliation on growth. Defoliation reduced dry weight of tops, number of innovations, root length and percent of nonstructural carbohydrates at all soil and air temperatures. Although a soil temperature of 18 C produced the most root and top growth in unclipped plants, this superiority was completely negated by defoliation.A soil temperature of 27 C resulted in reduced root growth compared to that at 18 C. Defoliation intensified the unfavorable effect of the high soil temperature.Nonstructural carbohydrate levels were lowest at the soil temperature (18 C), that produced the highest vegetative growth in unclipped plants. Differences in nonstructural carbohydrates among the soil temperature treatments were greatly reduced by defoliation.In the growth chambers where soil and air temperatures were in equilibrium results were in general consistant with those where soil temperatures were regulated separately by means of the water baths. Highest number of innovations was obtained at 10 C regardless of defoliation treatment. Highest dry matter production of tops was obtained at 21 C on unclipped plants while all plants became dormant at 32 C and made no measurable growth.
Tall Fescue Turf as Affected by Mowing Height
Authors: Burns Robert E. 
Published: July 2010

AbstractTall fescue (Festuca arundinacea Schreb.) is a common turf and pasture grass in much of the United States. In an effort to determine the optimum cutting height for both uses, plots in a good stand of established tall fescue were mowed at 1.3, 2.5, 4, and 5 cm, when they reached a height 50% greater than the mowed height. The influence of cutting height on seasonal and total yield, appearance, density, and ground cover was determined. One‐half at each plot was overseeded with fescue immediately prior to the test and also in the fall of the first year. In the first year, total yield was higher when mowed at the two lower cutting heights. There was no difference in yields the second year and overseeding had little effect on yield. Both cover and plant density were usually greater at the two intermediate cutting heights and in the overseeded plots when compared with non‐overseeded plots. At the end of 4 years there was no difference in turf cover due to mowing height. This research indicates that with adequate fertilizer tall fescue can do well when maintained at low heights.
Precision Soil Sampler1
Authors: Walker Milton E. , Stansell J. R. , Shannon J. E. 
Published: July 2010

AbstractA precision soil sampler has been developed that allows a soil core 15.2 cm long to be taken which can be divided into subsamples 2.54 cm or smaller. Speed, accuracy and accessibility are some advantages of this type of sampler over other soil‐tubes.
Nitrogen Fixation by Intact Annual Rangeland Species in Soil1
Authors: Vaughn Charles E. , Jones Milton B. 
Published: July 2010

AbstractThe acetylene reduction technique is widely used as an assay of N2 fixation, but its application to intact N2‐fixing systems in soil has been limited. The purpose of this research was to develop methods suitable for short‐duration assays of entire nitrogenase systems and to utilize these methods in studies of N2 fixation by annual rangeland species growing intact in potted soil.Experiments conducted with nodules excised from subclover plants (Trifolium subterraneum L.) indicated large diurnal variation in acetylene reduction rates; the greatest activity being observed between 1200 and 1600 hours and the minimum at 0400 hours. All standard assays of intact cultures were conducted between 1200 and 1600 hours to standardize light conditions. The pots were sealed, cultures exposed to an air‐acetylene atmosphere, and ethylene production was measured. Ethylene production rates of intact subclover plants were linear over a 75‐min period if the gases were mixed during an incubation by pumping a syringe inserted through a rubber serum stopper fitted in the bottom of the pot.Successive biweekly assays of 30 or 60 min duration were conducted on seven species of annual clovers during complete growth cycles. All species exhibited major exponential phases in ethylene production activity which coincided with flowering and seed development. There was a significant linear relationship between ethylene production and both herbage dry matter production and N content. An average of 3.2 moles of ethylene was produced per mole of total plant N contained in four subclover cultures. Ethylene production during a 4‐month period by soil organisms in the rhizosphere of an annual grass, soft chess (Bromus mollis L.), was significantly and inversely related to the amount of fertilizer N applied. Ethylene production was significantly higher in the grass rhizosphere than in comparable fallow soils, except where 160 mg N (100 ppm) was applied to the grass cultures.The results indicate that these short‐duration, nondestructive assays are of value in making quantitative estimates of N2 fixation. They are particularly useful for repeated samplings of cultures in situ during entire growing seasons.
High‐frequency Trickle Irrigation and Row Spacing Effects on Yield and Quality of Potatoes1
Authors: Phene C. J. , Sanders D. C. 
Published: July 2010

AbstractSoil water is a major limiting factor in the production and quality of potatoes (Solanum tuberosum L.). The objectives of this research were to determine the effects of trickle irrigation under controlled soil matric potential and two row spacings on the yield, quality, and nutrient contents of potatoes. Potatoes, trickle irrigated with nutrient solution and grown on 100‐cm row spacing (CSI) on sandy loam (Typic Palendult) soil, yielded 76% more marketable potatoes than those trickle irrigated under a plastic mulch and grown on twin row spacing (TRI) and 206% more than 100‐cm spaced, nonirrigated potatoes (CSNI). Water deficit, calculated by subtracting rainfall from 80% of pan evaporation, was 14.0 cm. Soil matric potentials 15 cm from the soil surface were not different for the CSI and TRI treatments irrigated, respectively, with amounts of water equivalent to 60 and 43% of the water deficit. The N and Mg contents of tubers were increased by irrigation. Leaf petiole nitrate N of CSI and TRI potatoes was consistently greater than 16,000 ppm, a critical level for Russett Burbank potato production in Idaho, but fell significantly below that level for the CSNI potatoes after an extended drought.
Effect of Ammonium to Nitrate Ratio on Growth and Anthocyanin Development of Perennial Ryegrass Cultivars1
Authors: Nittler L. W. , Kenny T. J. 
Published: July 2010

AbstractImproved methods of determining cultivar purity of perennial ryegrass, Lolium perenne L., seed lots, are needed. We conducted studies to find characteristics in which cultivars might differ. Seedlings were grown in sand and were supplied with solutions in which 0, 25, 50, 75, or 100% of the N was NH4 and the remainder was NO3. Growth and anthocyanin development were affected by ratio of ammonium to nitrate. Cultivars differed in both characteristics. Growth, as determined by tiller height, was greatest when plants were grown with 25% of the N as NH4. Anthocyanin development, as determined by percentage of the tiller height showing red color, was greatest when plants were grown with a solution in which 100% of the N was NH4. Cultivar differences in tiller height were greatest when plants were grown with 25% of the N as NH4. Cultivar differences in anthocyanin development were greatest when plants were grown with 75% of the N as NH4. With this solution, cultivars differed in percentage of plants in which red color extended the entire length of the tillers. Both anthocyanin development and tiller height were useful in determining cultivar purity of seed lots.
Effect of Variations in the Shoot:Root Ratio upon the Chemical Composition and Growth of Soybeans1
Authors: Sanders J. L. , Brown D. A. 
Published: July 2010

AbstractPublished data suggest that the soybean root system may be a limiting factor in maximizing soybean yields. The present study measured the effect of the root:shoot ratio upon the growth and yield of soybeans. Research in growth chamber and field evaluated the effect of varying the shoot:root ratio upon nutrient uptake and growth of ‘Lee 68’ soybeans [Glycine max (L.) Merr.]. Grafting prepared seedling plants with varying shoot:root ratios of 1:1, 1:2, 1:3, 2:1, and 3:1. The grafted plants performed vigorously in both the growth chamber and field. Grafted plants were analyzed for N, P, K, Ca, Mg, Na, Fe, Mn, Zn, and Cu. Increasing the number of shoots gave increases in the total nutrient uptake but the magnitude was not as great as it was from increasing the number of roots. When the number of shoots was increased, the leaf area, number of leaves/plant, seed yield, and number of seeds/plant were increased. However, increasing the number of shoots did not increase the growth characteristics and seed yield as dramatically as increasing the number of roots. Even though the physical shoot:root ratio was varied by grafting, the shoot:root ratio based on the dry weight of plant material remained constant at approximately 10:1.
Effect of P, Ca, and Mg Concentrations in Solution Culture on Growth and Uptake of These Ions by Rice1
Authors: Fageria N. K. 
Published: July 2010

AbstractNutrient requirements during various phases of plant growth are affected by many factors. Greater knowledge of this subject is warranted by the intensification of agriculture. The present study was undertaken to determine the effect of varying concentrations of P, Ca, and Mg on the growth and uptake patterns of these ions by rice (Oryza sativa L.). Rice plants were grown in culture solution of these ions. Minimum concentrations required for maximum growth were 25 μM P, 250μM Ca, and 33 μM Mg respectively. At higher P concentrations a linear absorption isotherm was obtained with respect to P content in the plant tissue. The critical concentration of P in the tops of 100‐day old plants was 0.4%. To support maximum growth, Ca content varied from 242 to 2,373 μg‐atoms/five plants for 25 to 125 days of growth. Maximum growth was characterized by a relative absorption (IM) rate ranging from 14 to 320 μg‐atoms of Ca/g dry weight of roots/day during the period of cultivation. To support maximum growth, plants must absorb 13.7, 7.7, 4.3, 4.0, and 2.4 μg of magnesium per g fresh weight of roots/hour at 25, 50, 75, 100, and 125 days of growth respectively. With the advancement of age, P and Ca content in plants and their utilization quotients were increased but relative growth rate and rate of Ca and Mg absorption decreased.
Anatomical Response of Potato Stems and Roots to Soil Moisture and Rates of Fertilizer1
Authors: Singh Gurbachan , Struchtemeyer R. A. 
Published: July 2010

AbstractThis study was conducted to determine the effect of three moisture regimes and three rates of fertilizer on the anatomy of stems and roots of the ‘Katahdin’ cultivar of potato, Solanum tuberosum. A Caribou loam (coarse loamy, mixed frigid Dystric Eutrochrept) was used in a greenhouse experiment. The soil was placed in pots. Fertilizer at rates of 0, 168, and 336 kg N/ha, in a 10‐15‐15 mixture, was used. Soil moisture stresses equivalent to 3C, 50, and 70% depletions of available moisture were allowed to develop. The data showed that the area of the xylem in the stems decreased as soil moisture stress increased. The highest rate of fertilizer reduced the area of the xylem, but increased the diameter of the individual vessels. In the roots the area of xylem and phloem decreased while the area of cortex increased with an increase of soil moisture stress in the 75‐day experiment. The area of xylem tended to increase while the cortical tissue tended to decrease with increases in the rate of fertilization.
Growth of Subterranean Clover in a Range Soil as Affected by Microclimate and Phosphorus Availability. II. Laboratory and Phytotron Studies1
Authors: Osman A. , Raguse C. A. , Sumner D. C. 
Published: July 2010

AbstractGrowth of subterranean clover (Trifolium subterraneum L) seedlings on a soil known to be P‐deficient was studied under controlled‐environment conditions representative of the winter growth period in California's Mediterranean climate annual rangeland.Ambient air temperature was 20C maximum (4 hours) and 4.4C minimum (12 hours), employing natural photoperiods and light intensities from November to March. Phosphorus treatments were approximately 0, 22, 45, 90, and 180 kg/ha. A P adsorption isotherm was determined for the Sobrante and Las Posas soils used.Inoculated seeds of ‘Woogenellup’ subterranean clover were seeded into pots containing 3.6 kg of soil. Plants were sampled at the 1.5, 3.0, and 4.5 stages of trifoliolate leaf development for plant weight and P content determinations.The pots were reseeded with the same cultivar at 30 seeds/dm2 and grown to the five‐leaf stage. Shoots and roots were removed separately and used to determine nodule numbers, shoot and root weights, and P and nitrogen tissue content.The P adsorption isotherm predicted a fixation capacity of ca 80 and 120 kg/ha at equilibrium solution values of 0.1 and 0.2 ppm P respectively.Plant weights were significantly affected by P rates only at the 3.0 and 4.5 leaf stages. Total P per plant was a more consistent indicator of P availability than was percent P. Shoot:root ratios, nodules per plant, and percent crude protein in shoot and root increased with P availability.Fertilizer application rates that provide a minimum soil‐solution level of 0.2 ppm P are indicated for optimal subterranean clover growth during Mediterranean climate winter conditions.
Yield Loss of Corn Due to Corn Stunt Disease Complex1
Authors: Scott Gene E. , Rosenkranz Eugene E. , Nelson Loyd R. 
Published: July 2010

AbstractThe seriousness of a disease is reflected in the amount of yield reduction caused by the disease under field conditions. We wished to obtain data on the amount of yield loss of corn (Zea mays L.) caused by the corn stunt disease complex which includes the maize chlorotic dwarf virus (also referred to as Ohio corn stunt agent) and the Mississippi corn stunt agent, believed to be a mycoplasma; and to determine if time of initial disease symptoms influences the amount of yield reduction. Corn hybrids were subjected to natural infection under field conditions during 5 years. Plants showing disease symptoms were tagged and yields from these plants were compared with plants not showing disease symptoms. Yields from diseased plants were less than 50% of those from healthy plants in each of the 5 years. The number of ears and kernels per plant was reduced more than was the weight of kernels on the diseased plants. Plants showing disease symptoms early in the season were more severely affected than plants that developed symptoms later. From our data, we concluded the following: diseased plants showing symptoms as early as 52 days after planting would produce no grain; plants showing first symptoms as late as 107 days after planting would produce normal yield; between the two extremes the yields on diseased plants would be reduced by 1.82% of that on healthy plants for each day the first symptoms appeared earlier than 107 days after planting.