bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water Transfer through Cotton Plants Connecting Soil Regions of Differing Water Potential
Authors: Baker J. M. , van Bavel C. H. M. 
Published: July 2010

AbstractSeveral studies have shown that water can move through plant root systems from wet to dry soil during periods of low evaporative demand. It has been suggested that such movement could be important in alternate furrow or drip irrigation systems, where water is applied in a discrete or nonuniform manner. This study was undertaken to examine this question, using a physical experiment and computer simulation. A growth chamber experiment was conducted with three rows of cotton (Gossypium hirsutum L.) plants. The outer row plants were grown over vertical barriers such that half of their root systems shared a volume of soil with the center row plants, while the other half was hydraulically isolated in separate soil compartments. The center compartment was allowed to dry, while the outer compartments were watered daily. Soil moisture was measured throughout all compartments twice daily by gamma densitometry. When the potential gradient between center and outer compartments reached 1.0 MPa, the gamma readings showed overnight movement of water from wet to dry soil that could only have taken place through the root systems of the outer row plants. The overnight transfer of water, while significant, was not sufficient to fully supply the daytime transpiration demand of the unirrigated center row plants. It was also less than that predicted by computer simulation, unless the latter reflected the inability of the xylem water potential of cotton plants to equilibrate with soil water potential during periods of low evaporative demand. Regardless, the results suggest that water transfer by root systems should not be excluded in simulations of water movement in the soil‐plant‐atmosphere system.
Nitrogen Fertilization of No‐Till Winter Wheat and Rye. I. Yield and Agronomic Responses
Authors: Fowler D. B. , Brydon J. , Baker R. J. 
Published: July 2010

AbstractWinter wheat (Triticum aestivum L.) and rye (Secale cereale L.) can be grown successfully in most parts of western Canada if sown directly into standing stubble. However, soil N is usually limiting under this production system. Consequently, 40 field trials were conducted over a range of soil types and environmental conditions to determine yield and other agronomic responses of no‐till winter wheat and rye to N fertilizer applied in the spring. Each trial consisted of three to 12 replications with N rates of 0 to 303 kg ha−1. Nitrogen fertilizer had little effect on days to heading, days to maturity, test weight, and seed weight. Increased N resulted in height increases of up to 25 cm in wheat and 8 cm in rye in some trials, and decreases of up to 9 cm in both wheat and rye in other trials. Winter rye demonstrated a greater N use efficiency and yield potential than winter wheat. The relationships between grain yield (Y) and total available N were best described by modified inverse polynomials, Y = (1 − N/903) uN/(N + u/65.8) for wheat, and Y = (1 − N/800) uN/(N + u/88.5) for rye, where u represents the upper limit of yield when N is not limiting. These curves accounted for 99.3 and 98.7% of the observed variation in grain yield of wheat and rye, respectively. Maximum yields were related to moisture status during the growing season and were achieved at different rates of N fertilization.
Analysis of Trace Elements in Forages by Near Infrared Reflectance Spectroscopy
Authors: Clark D. H. , Cary E. E. , Mayland H. F. 
Published: July 2010

AbstractUse of near infrared reflectance spectroscopy (NIRS) for elemental analysis has been limited to a few elements including Ca, P, K, and Mg. However, other elements are of interest in the agricultural industry. Therefore, NIRS spectra were collected on forage samples consisting of tall fescue (Festucu arundinacea Schreb.), crested wheatgrass (Agropyron cristatum and A. desertorum), and alfalfa (Medicago sativa L.). Elemental concentrations of Ba, Li, Mo, Ni, Pb, V, AI, S, and Si were determined by ICP (Inductively Coupled Argon Plasma) analysis while selenium (Se) was determined by fluorometry. The elemental analyses were regressed against NIRS apparent absorption from 1100 to 2500 nm at 2‐nm increments. Coefficients of variation [CV = (standard error of performance / the mean from the chemical procedure) ✕ 100] ranged from a high of 211% for Li in crested wheatgrass to 11% for S in alfalfa. Determination of Ba, Li, Mo, Ni, Pb, and V exhibited enough inconsistency in CVs among the three forages to preclude their determination with NIRS. Aluminum and S appear to be present in an organic form that NIRS is able to detect (CV = 22 and 15, 21 and 12, and 28 and 11%, for tall fescue, crested wheatgrass, and alfalfa, respectively). Silica exhibited slightly more variation than S or AI, with alfalfa having the highest CV (49%). Selenium was only determined on a tall fescue population with a CV = 27%. Using the statistical values as parameters indicative of NIRS utility, it appears that A1 and S are the only elements in this group of minerals that can be determined with NIRS for these forage types.
Carbon Dioxide Exchange During Mist Propagation of Jojoba Cuttings
Authors: Feldman William R. , Palzkill David A. , Dobrenz Albert K. , Hogan LeMoyne 
Published: July 2010

AbstractCarbon dioxide exchange parameters of jojoba (Simmondsia chinensis (Link) Schneider) tip cuttings were studied to determine whether significant photosynthesis occurs prior to rooting, whether fertilization during the rooting process affects carbon dioxide exchange, and whether a non‐destructive method for monitoring progress of root development could be developed. Cuttings were collected from field‐grown plants and placed under intermittent mist in a double‐poly greenhouse. Osmocote (19‐2.6‐l0), a controlled release fertilizer, was incorporated at 0, 1.5, 3.0 and 5.9 kg m−3 into a 1:1 perlite:vermiculite medium at time of inserting cuttings. Photosynthesis and respiration of the cuttings were monitored periodically from the time of insertion until they had rooted and been potted‐up. Gas exchange was monitored at 28°C and at a light level of 700 µmol m−2 s−1. Root respiration was determined using a chamber designed to isolate the base of the cutting together with the medium and any developing roots from the leaves and stem. Significant differences in C02 flux and root growth (dry wt) were found over the 11 wk of the study. Photosynthetic rates during the first wk under mist were moderate (ca. 3 µmol C02 m−2 s−1), declined steadily from the beginning of the study until rooting, and then increased significantly. This suggests that treatments such as shading, which increase plant cutting survival prior to rooting, but which also reduce photosynthesis, could likely be used prior to root formation without negative effects on rooting. Dark respiration declined steadily from the beginning of the study until rooting and increased slightly thereafter. Root respiration paralleled photosynthesis. Photosynthesis at lining out was significantly correlated with root dry weight, root respiration, and leaf succulence. Root dry weight and root respiration were significantly correlated, implying that monitoring of root respiration could be used as a non‐destructive method of monitoring root growth. During the 11 wk of the study, no consistent differences among the fertilizer treatment groups were found in either C02 flux or in root growth (dry wt).
Nitrogen Partitioning in Cowpea as Influenced by Rhizobial Strain and Mineral Nitrogen
Authors: Luyindula N. , Weaver R. W. 
Published: July 2010

AbstractPartitioning of nitrogen into the pods of legumes is an important yield determinant. The ability of cowpea [Vigna unguiculata (L.) Walp.] ‘Bush Purple Hull’ to partition N from dinitrogen fixation and assimilated nitrate into pods was measured with the aid of 15N. Cowpea was inoculated with four strains of Bradyrhizobium species and grown in a glasshouse to maturity. Two nitrate treatments were included; one provided an initial dose of starter N (40 mg plant−1) and the other provided split applications of N throughout the growth period (total of 240 mg plant−1). With starter N only, the results indicated that the strain of rhizobia did not influence partitioning of biologically fixed dinitrogen or nitrate N into pods. However when inoculated with either of two strains, cowpea partitioned approximately 63% of the total assimilated nitrate from the continuous N treatment into the pods, whereas another strain partitioned approximately 52% into pods. Of the total N from dinitrogen fixation, 53 and 58% was partitioned into the pods for the starter N and continuous N treatments respectively. The strains of rhizobia were similar in the quantity of nodule tissue formed on the roots, but the quantity of N contained in the nodule tissue varied from 40 to 20 mg N plant−1 for the starter N treatment. It appears that strains of rhizobia should be considered when undertaking experiments involving N partitioning.
Early Season Development of Floral Buds in Cotton
Authors: Ungar E. D. , Kletter E. , Genizi A. 
Published: July 2010

AbstractImproving irrigation and pest control strategies in upland cotton (Gossypium hirsutum L.) requires a better understanding of the factors influencing the formation and retention of fruiting bodies. The objective of this study was to investigate the effect of irrigation regime, boll load, and fruiting position upon floral bud dynamics. Field experiments were conducted during 3 yr on a Gan Shmuel vertisol (clayey, montmorillonitic, calcareous, thermic Typic Chromoxerert). Treatments comprised four irrigation patterns, and one zero‐load (continuous flower removal) treatment. Dates of shedding, attainment of 1 cm size, and flowering were recorded by fruiting position for all buds on sympodia formed during the first 75 to 100 d after emergence. Of a total of 7972 buds observed, 51, 33 and 16% flowered, shed <1 cm size, and shed>l cm size, respectively. Shedding of buds <1 cm size was more sensitive to treatment than shedding of buds >1 cm size. The probability of bud formation at L2 and L3 was strongly affected by sympodium number (Ln represents the nth fruiting position on a sympodium). Flowering declined from 74% at L1 to 16% at L4. The zero‐load treatment achieved the highest flowering percentage (66%) and number of fruiting positions per sympodium. The lowest flowering percentage (42%) resulted from severe, and relatively late, water stress. Strong positive associations between the shedding of contemporary buds at different relative positions on the plant indicate that an important component of shedding is the response to common stress stimuli. Weaker negative associations between the fate of noncontemporary buds can be explained by the negative feedback of boll load on bud retention.
Birdsfoot Trefoil Management. II. Yield, Quality, and Stand Evaluation
Authors: Alison M. W. , Hoveland C. S. 
Published: July 2010

AbstractManagement recommendations for birdsfoot trefoil (Lotus corniculatus L.) are based mainly on research conducted in the northern USA. The relevance of this work to more southern‐adapted birdsfoot trefoil cultivars needs to be examined. These studies were conducted to determine the effect of stubble height and harvest interval on herbage yield and quality of northern‐ and southern‐selected birdsfoot trefoil cultivars when grown in the southern USA. Two field experiments were established on a Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludult) soil near Athens, GA. ‘Fergus’ and GA 1 birdsfoot trefoil entries were harvested every 21, 28, and 42 d to stubble heights of 5 and 10 cm. The birdsfoot trefoil entries ‘AU Dewey’, ‘Dawn’, Fergus, Ga 1, and ‘Norcen’ were harvested to 3, 5, and 10 cm every 21 d. Entries AU Dewey, GA 1, and Fergus were most productive, but herbage yields of all entries increased with length of time between harvests. Harvesting every 21 d at a 3‐cm stubble height generally reduced yields. After 2 yr, stands of AU Dewey, GA 1, Dawn, and Norcen were reduced 59, 45, 24, and 15%, respectively, while Fergus was unaffected. The AU Dewey and GA 1 entries should be allowed either a higher stubble or regrowth periods longer than 21 d because of erect growth habit. In vitro dry matter digestibility of all entries remained high (> 700 g kg−1) throughout the season and was not affected by harvest treatment. Results of these studies indicate that birdsfoot trefoil cultivars respond differently to harvest management.
Water‐Deficit Effects on Alfalfa at Various Growth Stages
Authors: Halim R. A. , Buxton D. R. , Hattendorf M. J. , Carlson R. E. 
Published: July 2010

AbstractStudies of water‐deficit effects on forage quality of alfalfa (Medicago sativa L.) have generally considered water stress throughout plant growth. This experiment was conducted to compare, with an unstressed control, the effects of short‐term soil‐water deficits occurring at three growth stages. Plants were grown in 100‐L containers set into the ground and protected with an automatic rain‐out shelter. Control treatments were watered weekly or twice weekly to raise the soil‐water level to field capacity. Watering was excluded during the third or fourth week of regrowth for plants that were stressed at vegetative and bud stages, respectively. For plants stressed at the flower stage, watering was excluded during the sixth or seventh week. Plants were harvested at five weekly intervals beginning 21 d after an initial defoliation. Stress at the bud or flower stages reduced leaf‐to‐stem ratio (LSR) by 25 and 38% of control, respectively. Stress at the vegetative stage did not affect LSR. As a result of lower LSR, in vitro digestible dry matter (IVDDM) in plants stressed at the bud or flower stages was 4% less than that of the control. The IVDDM of herbage in plants stressed at the vegetative stage was not different from the control. Crude protein (CP) concentration in stems increased by up to 8% of the control when plants were stressed at the vegetative or bud stages. Concentration of CP in leaves of stressed plants was 5 to 11% less than that of the control. Herbage CP concentration was up to 12% less than that of the control with stress at the bud or flower stages. Cell wall (CW) concentration in stems and total herbage was generally lower in plants stressed at the vegetative and bud stages. After rewatering, forage quality recovered in plants stressed at the bud stage. Most of the decline in forage quality due to stress at the bud or flower stages was caused by reduction in LSR and deterioration of leaf quality.
Phenological Stage and Herbage Quality Relationships in Temperate Grasses and Legumes
Authors: Sanderson Matt A. , Wedin W. F. 
Published: July 2010

AbstractPhenological indexes that account for variation in chemicál composition of herbage would be valuable to farmers and researchers. Hence, the objective of this study was to relate neutral detergent fiber (NDF) and in vitro digestible dry‐matter (IVDDM) concentrations in herbage and plant parts of alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), timothy (Phleum pratense L.), and smooth bromegrass (Bromus inermis Leyss.) to phenological development of each species. Four replicate plots of each species were harvested at four 2‐wk intervals during the spring of 2 yr. Alfalfa was separated into leaves (including flowers) and stems; red clover into leaflets (including flowers), petioles, and stems; and bromegrass and timothy into leaf blades and stems (including sheaths). Herbage from two plots of each species was scored for phenological stage according to a species‐specific index and a mean stage number (mean stage by weight, MSW) was calculated. For each plant part, NDF and IVDDM concentrations were regressed on MSW across years. Alfalfa leaves remained constant in NDF (206 g kg−1 dry matter, DM) and IVDDM (783 g kg−1 DM) with increasing MSW; however, MSW accounted for 97% of the variation in NDF and IVDDM concentrations of alfalfa stems and herbage. Herbage concentrations of NDF and IVDDM were more closely related to MSW than were concentrations of NDF and IVDDM in leaflets, stems, or petioles of red clover, and leaf blades and stems of bromegrass and timothy. Only in alfalfa did MSW adequately account for variation in NDF and IVDDM of herbage and plant parts. Phenological models for the other species adequately accounted for variation in some, but not all, plant parts.
Alfalfa Persistence and Yield with Irrigation
Authors: Rice J. S. , Quinsenberry V. L. , Nolan T. A. 
Published: July 2010

AbstractThree field experiments were conducted to investigate the effects of irrigation on alfalfa (Medicago sativa L.) forage yield, distribution of yield, and stand persistence. Two of the studies were conducted near Clemson, SC on a Cecil sandy loam (clayey, kaolinitic, thermic, Typic Hapludults) with the third conducted at Blackville, SC on a Facevilie loamy sand (clayey, kaolinitic, thermic, Typic Paleudults). All irrigation was initiated when average soil‐water pressure reached ‐20 kPa at the 20‐ and 40‐cm depths as measured by tensiometers. The average forage yield response to irrigation across the studies in the Clemson (Piedmont) experiments was 2.6 Mg ha−1. The response varied from year to year and no irrigation ✕ cultivar interaction was detected. Stands deteriorated more rapidly with irrigation and seasonal distribution of forage production was only slightly improved. The average response to irrigation in the Blackville experiment (Coastal Plains) was also 2.6 Mg ha−1; however, the response in the second year was negative and the study was terminated because irrigated stands were depleted. An interaction with cultivar was detected in the second year as a result of negative irrigation responses for seven cultivars and a positive response for one cultivar. The positive response reflected the fact that only one cultivar had more than a 70% stand in August of the second season. Diseases did not appear to be severe enough to explain the losses. We conclude that irrigation of alfalfa in the Southeast is a marginal practice.
Ethephon and Nitrogen Use in Winter Wheat
Authors: Van Sanford D. A. , Grove J. H. , Grabau L. J. , MacKown C. T. 
Published: July 2010

AbstractThe plant growth regulator ethephon ([2‐chloroethyl] phosphoric acid) has often been used to reduce height and lodging of intensively managed soft red winter (SRW) wheat [Triticum aestivum (L.) em. Thell]. The effect of ethephon on traits that determine grain yield has not been widely studied. This study was conducted to determine whether ethephon alters N use and other yield‐related traits in SRW wheat. Nine SRW cultivars were evaluated for 2 yr near Lexington, KY on a Maury silt loam (fine, mixed, mesic Typic Paleudalf). Lodging was negligible in both years. Total plant N at anthesis was significantly increased in plots treated with ethephon at Feekes growth stage (GS) 6 (12%) or GS 9 (15%). Similarly, dry matter (DM) at anthesis was increased 9 and 11% when ethephon was applied at GS 6 and 9, respectively. However, neither total N nor DM at maturity was significantly altered by ethephon application. Remobilization of vegetative N was increased 13% in ethephontreated plots. Ethephon applied at either GS increased the relative importance of N uptake efficiency vs. N partitioning efficiency in determining cultivar variation in N use efficiency. Application of ethephon did not alter grain yield, harvest index, or N harvest index. Ethephon had little or no influence on rate and duration of kernel growth, and slightly decreased kernel size (4%) when applied at GS 6. We conclude that ethephon has a minimal effect on the yield‐determining traits evaluated in this study. However, the pronounced effect of ethephon on the nature of cultivar differences in N use efficiency warrants further study.
Dry Matter and Nutrient Accumulation and Partitioning by Proso Millet
Authors: Rodriguez J. B. , Westfall D. G. , Peterson G. A. 
Published: July 2010

AbstractInformation on dry matter accumulation and nutrient uptake pattern for proso millet (Panicum miliaceum L.) is very limited. Therefore, a project was initiated to measure dry matter accumulation and N, P, K, Ca, Mg, S, Fe, Mn, Zn, and Cu uptakes in whole plants, stalks, leaves and heads of proso millet during the growing season. The two cultivars, Cope and Dawn, were field grown on an Aridic Argiustoll that had optimum nutrient and water availability. Plant samples were collected at weekly intervals starting 30 d after planting, and continuing throughout the growing season. Nutrient concentrations, dry matter accumulation, and mineral uptakes were very similar for both varieties. Whole plant concentrations of most nutrients decreased from emergence to maturity, except for Ca, Mg, and Mn which increase with time. From anthesis to maturity, dry matter accumulated rapidly at a rate of 0.5 Mg/ha/d, tripling during this period. Heads at maturity accounted for 55% of the total plant dry matter, which is higher than for wheat (Triticum aestivum L.) or grain sorghum (Sorghum bicolor L.). Proso millet accumulated N and P during heading like grain sorghum, which is more efficient than corn (Zea mays L.). Dry matter accumulation and nutrient uptake patterns are illustrated during the life cycle of this plant.
Indirect Estimation of Botanical Composition of Alfalfa‐Smooth Bromegrass Mixtures
Authors: Moore K. J. , Roberts C. A. , Fritz J. O. 
Published: July 2010

AbstractBotanical composition of grass‐legume mixtures greatly influences the productivity and quality of the sward and is therefore an important variable in many agronomic studies. Four indirect methods of estimating the botanical composition of mixed swards of alfalfa (Medicago sativa L.) and smooth bromegrass (Bromus inermis Leyss.) were evaluated to determine their relative efficacy. The methods were the constituent differential method using either neutral detergent fiber (NDF) concentration or crude protein (CP) concentration as variables, a modified constituent differential method where NDF and CP concentrations were used simultaneously as variables, and near infrared reflectance spectroscopy (NIRS). Mean deviations of predicted alfalfa percentages from known values were lowest for NIRS at all stages of maturity and averaged 1.5 percentage units. Of the constituent differential procedures, NDF was the most reliable variable for predicting alfalfa percentage over all maturities with deviations averaging 2.9 percentage units. Based upon the results of this study, NIRS would be the preferred method for estimating botanical composition of grass‐legume mixtures; however, in cases where NIRS is unavailable or inappropriate, the constituent differential method using NDF as a single variable would be an acceptable alternative.