bluuebunny/crossref_metadata_2025 huggingface dataset:
Hybrid and Nitrogen Influence on Pearl Millet Production in Nebraska: Yield, Growth, and Nitrogen Uptake, and Nitrogen Use Efficiency
Authors: Maman Nouri , Mason Stephen C. , Galusha Tom , Clegg Max D.
Published: July 2010

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a staple grain crop in the arid and semiarid regions of Africa and India, and a new grain crop in the USA. A 2‐year field experiment was conducted near Mead, NE, in 1995 and 1996 on a Sharpsburg silty clay loam (fine, smectitic, mesic Typic Argiudoll) soil with approximately 29 g kg−1 organic matter, 35 kg ha−1 NO3–N, and pH of 6.0. The objective was to determine the influence of hybrid and N on grain yield, dry matter accumulation and partitioning, and growth rates throughout the growing season. Nitrogen concentrations, uptake, and use efficiency were also determined. Treatments were a factorial combination of the pearl millet dwarf hybrids (59022A × 89‐0083, 1011A × 086R, and 1361M × 6Rm) and N levels (0 and 78 kg ha−1) in a randomized complete block design. Two plants per plot were sampled at 2‐wk intervals and partitioned into plant parts, dried, weighed, and analyzed for N concentration. Applied N increased grain yield by 0.4 to 0.5 Mg ha−1, but had only a small effect on dry matter accumulation and partitioning. Hybrid differences were small for grain yield. Pearl millet dry matter accumulation increased cubically in both years, with maximum crop growth rates among hybrids ranging from 0.48 to 0.57 g m−2 per growing degree day (GDD) in 1995 and ranging from 1.9 to 3.1 g m−2 GDD−1 maximum in 1996. The relative growth rate among hybrids declined from 0.012 to 0.020 g−1 m−2 GDD−1 in both years to near zero at physiological maturity. Nitrogen concentrations were higher during the vegetative stages and decreased with plant age. Applied N decreased N use efficiency for aboveground biomass (NUE1) by 18 to 25 g DM g−1 N, and N use efficiency for grain (NUE2) by 7 to 12 g grain g−1 N. Environmental variability due to years had a greater effect on yield, growth, and N levels than hybrid and applied N.
Soybean PI 416937 Root System Contributes to Biomass Accumulation in Reciprocal Grafts
Authors: Pantalone Vincent R. , Rebetzke Gregory J. , Burton Joseph W. , Carter Thomas E. , Israel Daniel W.
Published: July 2010

Soybean [Glycine max (L.) Merr.] plant introduction PI 416937 (PI4) has an extensive fibrous‐like root system that contributes to enhanced drought and Al tolerance. The root system of PI4 appears to be more highly nodulated than standard southern U.S. cultivars, and thus has potential for enhanced N2 fixation. Genetic transfer of PI4 root system to soybean cultivars may lead to increased seed N at harvest through increased biomass or seed protein concentration. This hypothesis has not been tested. The objective of this study was to determine the influence of PI4 root system on plant productivity and protein accumulation in soybean seedling reciprocal grafts grown to maturity in the field. In three experiments, grafts were initiated 5 d after greenhouse planting by transversely severing the hypocotyl 2 cm below the apical meristem and transferring wedge‐cut scions to severed root stock. Plants were then transplanted and grown in the field. PI 416937 maintained its superior root fibrosity in graft combination with other genotype scions. In Exp. 2, at the end of the season, plants of non‐PI4 scions grafted to PI4 root stock averaged significantly higher in root fibrosity score (8.2) than the mean of their self‐grafts (6.0); however, when PI4 scions were grafted to root stock from other genotypes, the root fibrosity score decreased significantly (6.6) compared with PI4 self graft (8.4). Thus, grafting revealed that the root system itself, rather than the scion of PI4, regulates expression of the fibrous‐like rooting trait. Seed protein concentration did not increase significantly for genotype scions grafted to PI4 root stock. In Exp. 3, ‘Lee 74’ or N85‐492 grafted to PI4 root stock had significantly higher seed dry weight (161.1 g plant−1 for Lee 74 grafted to PI4 vs. 96.4 g plant−1 for the self‐graft; 129.5 g plant−1 for N85‐492 grafted to PI4 vs. 79.4 g plant−1 for the self‐graft). The fibrous‐like root system of PI4 enhances seed biomass when grafted to some non‐PI4 genotypes. The genetic transfer of the PI4 rooting trait to elite germplasm through applied breeding may lead to the development of more productive soybean lines.
Fungal Endophyte Effects on Production of Legumes in Association with Tall Fescue
Authors: Hoveland Carl S. , Bouton Joseph H. , Durham Robert G.
Published: July 2010

The fungal endophyte, Neotyphodium coenophialum (Morgan‐Jones & W. Gams) Glenn, Bacon & Hanlin (syn. Acremonium coenophialum Morgan‐Jones & W. Gams) is generally considered to enhance the competitive ability of tall fescue (Festuca arundinacea Schreb.) with legumes, but substantiating field data are limited. Our objectives were to determine if endophyte infection of tall fescue affects stand density and forage production of (i) red clover (Trifolium pratense L.), ladino clover (T. repens L.), and alfalfa (Medicago sativa L.) harvested at 3‐wk intervals and (ii) alfalfa at low and high seeding rates harvested at 3‐wk and 9‐wk intervals. The first study compared alfalfa, red clover, and ladino clover in association with ‘Jesup’ E+ (endophyte‐infected) and E− (endophyte‐free) tall fescue, harvested at 3‐wk intervals for 3 yr. The second study had alfalfa broadcast planted at 11.2 and 22.4 kg ha−1 with E+ and E− tall fescue planted broadcast at 11.2 and 22.4 kg ha−1 or in rows at 22.4 kg ha−1. This was harvested at 3‐wk intervals for 3 yr, then at 5‐wk intervals for 1 yr. In the first study, clovers and alfalfa cut at 3‐wk intervals for 3 yr had similar (P > 0.05) legume yields when grown with both E+ and E− tall fescue. In the second study harvested at 3‐wk intervals, E+ tall fescue adversely affected (P < 0.05) the associated alfalfa the second year, and by the third year the yield of alfalfa planted at 22.4 kg ha−1 in mixture with E+ tall fescue was only 71% of alfalfa with E− tall fescue (P < 0.05). Similar differences occurred the next year when cut at 5‐wk intervals. Stands of alfalfa or tall fescue after 4 yr were not affected (P > 0.05) by endophyte. The results suggest that endophyte infection of tall fescue increases competition with legumes, but it may be modified by seeding rates or grass sod density.
Wheat Management in Warm Environments: Effect of Organic and Inorganic Fertilizers, Irrigation Frequency, and Mulching
Authors: Badaruddin Mohamad , Reynolds Matthew P. , Ageeb Osman A.A.
Published: July 2010

Wheat (Triticum aestivum L.) yields are reduced by heat stress in many countries worldwide. The main objective of this study was to determine whether modifications to currently recommended crop management practices could improve wheat yield at hot‐environment sites in three countries. Field trials were conducted between 1991 and 1993 in Sudan and Bangladesh by their respective national agricultural research systems (NARS) and in Mexico by the International Maize and Wheat Improvement Center (CIMMYT). Crop establishment and other plant characteristics were measured to help understand the basis of improved performance and to identify potential diagnostic traits. Management factors included (i) irrigation, (ii) inorganic fertilizer (NPK), (iii) organic fertilizer in the form of farmyard manure (FYM), (iv) straw mulch, (v) genotype, and (vi) sowing date. Control treatments represented recommended practices and gave yields of 3.6 t ha−1, averaged across all environments. Considering main effects, FYM (10 t ha−1) gave the highest yield response (14%) and approximately equivalent levels of NPK gave the lowest (5.5%), suggesting that organic fertilizer provided growth factors in addition to nutrient content. Mulch and extra irrigation increased yield in Sudan and Mexico, which are hot environments with low relative humidity, but not in hot, humid Bangladesh. In Mexico, extra inputs were more beneficial under hotter, spring‐sown conditions than for winter sowings, with responses of 17 and 8% to extra NPK, 17 and 14% to FYM, and 11 and 6% to mulch, respectively. Comparison of heat‐tolerant (Glennson 81) and heat‐sensitive (Pavon 76) genotypes showed that the heat‐tolerant genotype was generally more responsive to additional inputs. Improved performance in response to inputs was generally associated with better stand establishment, and with significant increases in plant height, grain per unit area, and aboveground biomass; in Mexico, there was also an association with higher canopy temperature depression and light interception. The possibilities of realizing the benefits of applied organic matter and mulch treatments through residue retention and reduced tillage are briefly discussed.
Nitrogen Stress Effects on Growth and Nitrogen Accumulation by Field‐Grown Tomato
Authors: Scholberg Johannes , McNeal Brian L. , Boote Kenneth J. , Jones James W. , Locascio Sal J. , Olson Stephen M.
Published: July 2010

There are few growth studies evaluating within‐season effects of N on vegetative growth and N accumulation of tomato (Lycopersicon esculentum Mill.). Growth analysis of field‐grown tomato for a number of Florida locations and management systems is presented here. Severe N stress resulted in fewer and smaller, but thicker, leaves. With increasing N, average leaf area index (LAI) increased from ≈0.75 to ≈3, but radiation use efficiency (RUE) typically increased less then 30%. Lower RUE under N‐limited conditions reflected a decrease in N concentration of the most recently matured leaves from 40 mg g−1 to as little as 15 mg g−1. Over the life of well‐fertilized crops, leaf N concentrations dropped from 55 to 65 mg g−1 during initial growth to 20 to 35 mg g−1 at final harvest. Corresponding N concentrations for fruit and for stems were 30 to 35 mg g−1 and 15 to 25 mg g−1. Severe N stress affected leaf and stem N concentrations most drastically, whereas N in fruits was less variable. With lower N supply (N < 180 kg ha−1) under careful management, nitrogen use efficiency (NUE) for field‐grown tomato was ≈0.4 Mg fresh fruit (kg N)−1 and average crop N accumulation increased from 37 to 210 kg N ha−1 as N fertilization increased from 0 to 333 kg N ha−1. As a fraction of the fertilizer N applied N fertilizer recovery ranged from 0.36 to 0.74 and 0.61 to 0.96 for drip‐irrigated and subirrigated crops, respectively.
Using a Nitrate Specific Ion Electrode to Determine Stalk Nitrate–Nitrogen Concentration
Authors: Wilhelm Wallace W. , Arnold S. L. , Schepers James S.
Published: July 2010

The end‐of‐season stalk NO3test has been used to determine N sufficiency in corn (Zea maysL.). Nitrate concentration is commonly determined with flow‐injection analysis (FIA), which is accurate but uses hazardous chemicals and is time‐consuming. Use of a simpler method of NO3determination, such as the NO3specific ion electrode (SIE), may save time and costs, and reduce hazards. The objective of this study was to compare estimates of stalk NO3concentration by FIA and NO3SIE. For FIA, NO3was extracted with 2MKCl, and the extract was filtered before analysis. For SIE, NO3was extracted with 0.04M(NH4)2SO4, and the extract was analyzed without filtration. The slope of the linear regression between concentrations estimated by SIE and FIA did not differ from 1.0. Use of the NO3SIE, compared with FIA, reduces costs, sample processing, and use of hazardous chemicals.
Binary Legume–Grass Mixtures Improve Forage Yield, Quality, and Seasonal Distribution
Authors: Sleugh Byron , Moore Kenneth J. , George J. Ronald , Brummer Edward C.
Published: July 2010

Yield and forage quality of kura clover (Trifolium ambiguum Bieb.) and intermediate wheatgrass [Thinopyrum intermedium (Host.) Barkw. & D.R. Dewey] mixtures compared with commonly grown forages such as alfalfa (Medicago sativa L.) and smooth bromegrass (Bromus inermis Leyss.) have not been fully explored. Our objective was to evaluate the effects of alfalfa, birdsfoot trefoil (Lotus corniculatus L.), and kura clover grown in binary mixtures with orchardgrass (Dactylis glomerata L.), smooth bromegrass, and intermediate wheatgrass on seasonal distribution of forage yield and quality. Plots of each species in monoculture and binary legume–grass mixtures were established in a randomized complete block design in 1994 near Boone, IA. Yield was measured monthly during the 1995 and 1996 seasons. In vitro dry matter digestibility (IVDMD), neutral‐detergent fiber (NDF), and crude protein (CP) concentrations were determined for each monoculture or mixture. Total yield was highest for monoculture alfalfa, alfalfa–intermediate wheatgrass, and alfalfa–smooth bromegrass with 13400, 12700, and 12600 kg ha−1 respectively in 1995, and 7500, 6800, and 6700 kg ha−1 respectively, in 1996. Kura clover had the lowest NDF (357 g kg−1) and highest IVDMD (740 g kg−1) concentrations compared with other forages. Yield, CP, and IVDMD concentrations of monoculture grasses were lower than those of the legume–grass mixtures or of the monoculture legumes. Legumes improved the seasonal distribution of yield and forage quality by beig more productive at later harvests. Yield of alfalfa–intermediate wheatgrass was equal to or better than other alfalfa–grass mixtures and could make a valuable legume–grass alternative.
Productivity of Kentucky Bluegrass Pasture Grazed at Three Heights and Two Intensities
Authors: Bryan William B. , Prigge Edward C. , Lasat Mircea , Pasha Talat , Flaherty Daniel J. , Lozier John
Published: July 2010

Sward height before grazing and amount of forage harvested affect production, composition, and utilization of rotationally stocked pasture. In this 3‐yr field study, yearling steers (Bos taurus L.) grazed 400‐m2 plots of Kentucky bluegrass (Poa pratensis L.)–white clover (Trifolium repens L.) pastures every time sward height reached either 11.8 cm (short), 13.7 cm (medium), or 15.3 cm (tall). Plots were grazed with enough steers to remove either 50 or 60% (grazing intensity) of the herbage mass in 4 h. The experimental design was a 3 × 2 (height treatment × grazing intensity) factorial with four replications. Sward heights before and after grazing periods were measured. Herbage mass, apparent growth rate, herbage removed, rejected area, and percent utilization were calculated. Average herbage mass before grazing ranged from 1855 to 2350 kg dry matter (DM) ha−1. Average herbage mass after grazing varied from 855 to 1060 kg DM ha−1. Apparent herbage growth rate (54 kg DM ha−1 d−1) and herbage removed (7520 kg ha−1) were highest on the short height treatment with low grazing intensity (50% removal). Assuming a sigmoidal growth curve, maximum apparent growth rate occurred at 10.5‐cm sward height. More than twice as much herbage was removed in the wettest year compared with the driest. In the dry year, height and intensity of grazing had little effect on herbage production. Thus, the benefits farmers can expect from more intensive grazing management will be more evident in a year of good growth.
Enhancing No‐Tillage Systems for Corn with Starter Fertilizers, Row Cleaners, and Nitrogen Placement Methods
Authors: Vetsch Jeffrey A. , Randall Gyles W.
Published: July 2010

No‐till production of corn (Zea mays L.) often gives slower early plant growth, lower yields, and reduced profitability in the northern Corn Belt. The objective of this field experiment was to determine if N source/placement method and row cleaner and starter fertilizer use on high‐phosphorus testing soils would enhance no‐till production of continuous corn (CC) and corn after soybean [Glycine max (L.) Merr.] (CSb). Experiments were conducted for each cropping system on a tile‐drained Nicollet–Webster clay loam complex (fine‐loamy, mixed, superactive, mesic Aquic Hapludoll and fine loamy, mixed, superactive, mesic Typic Endoaquoll, respectively) from 1996 to 1998. A 23 factorial design included combinations of with or without row cleaners, 0.0 or 93.5 L ha−1 (0 or 10 gal acre−1) of 10–15–0 starter fertilizer, and N sources anhydrous ammonia (AA) or spoke‐injected urea‐ammonium nitrate (UAN). A preplant broadcast application of UAN plus N‐(n‐butyl)thiophosphoric triamide (NBPT) also was compared with spoke‐injected UAN. Averaged across 3 yr, surface residue coverage during the growing season remained >60% for CC and >40% for CSb for all treatments, but was about 8% lower with knife application of AA compared with spoke‐injecting UAN. Grain yields were not affected by N source. Yield response to starter fertilizer depended on N source and row cleaners. Continuous corn responded to starter fertilizer (0.5 Mg ha−1 or 7 bu acre−1) when AA was used, but not when UAN was used. Yields of CSb were increased 0.5 Mg ha−1 (8 bu acre−1) by starter fertilizer when row cleaners were not used, but by only 0.2 Mg ha−1 (3 bu acre−1) when row cleaners were used. Injecting UAN increased CC and CSb yields 0.7 Mg ha−1 (10 bu acre−1) and 0.4 Mg ha−1 (6 bu acre−1), respectively, compared with preplant broadcasting of UAN plus NBPT. The data suggest that no‐till corn yields on fine‐textured, high P testing soils can be enhanced most consistently by using starter fertilizer and by injecting N below the soil surface.
Wheat Response to Differences in Water and Nutritional Status between Zeoponic and Hydroponic Growth Systems
Authors: Steinberg Susan L. , Ming Douglas W. , Henderson Keith E. , Carrier Chris , Gruener John E. , Barta Dan J. , Henninger Don L.
Published: July 2010

Hydroponic culture has traditionally been used for controlled environment life support systems (CELSS) because the optimal environment for roots supports high growth rates. Recent developments in zeoponic substrate and microporous tube irrigation (ZPT) also offer high control of the root environment. This study compared the effect of differences in water and nutrient status of ZPT or hydroponic culture on growth and yield of wheat (Triticum aestivum L. cv. USU‐Apogee). In a side‐by‐side test in a controlled environment, wheat was grown in ZPT and recirculating hydroponics to maturity. Water use by plants grown in both culture systems peaked at 15 to 20 L m−2 d−1 up to Day 40, after which it declined more rapidly for plants grown in ZPT culture due to earlier senescence of leaves. No consistent differences in water status were noted between plants grown in the two culture systems. Although yield was similar, harvest index was 28% lower for plants grown in ZPT than in hydroponic culture. Sterile green tillers made up 12 and 0% of the biomass of plants grown in ZPT and hydroponic culture, respectively. Differences in biomass partitioning were attributed primarily to NH4–N nutrition of plants grown in ZPT compared with NO3–N in hydroponic nutrient solution. It is probable that NH4–N‐induced Ca deficiency produced excess tillering and lower harvest index for plants grown in ZPT culture. These results suggest that further refinements in zeoponic substrate would make ZPT culture a viable alternative for achieving high productivity in a CELSS.
Effects of Salinity on Grain Yield and Yield Components of Rice at Different Seeding Densities
Authors: Zeng Linghe , Shannon Michael C.
Published: July 2010

One possible management option for growers in dealing with decreases in rice (Oryza sativa L.) production caused by salinity is to compensate yield reduction by increasing seeding density. Our objectives were to investigate the effects of salinity and seeding density on grain yield and yield components, and analyze the relationships of the yield components to final grain yields at different seeding densities under salinity. Plants were grown in the greenhouse in sand irrigated with nutrient solutions. The treatments included seeding densities of 400, 600, and 720 seeds m−2 and salt levels of 1.0, 3.9, and 6.5 dS m−1. Salinity effects were highly significant on grain yield, plant stand, seed weight per plant, seed weight per panicle, and spikelets per panicle, but not significant on panicle density, kernel weight, and shoot weight per plant at seeding densities tested. Grain yield was not significantly increased with an increase of seeding density. Plant stand and panicle density were significantly increased, while seed weight per plant, fertility, and harvest index were significantly decreased with increases of seeding densities. The density‐dependent seed weight per plant under salinity was explained by the competition within and among plants at high‐density populations affected by salinity. Seed weight per panicle accounted for 62% of total variation and contributed more than panicle density to the grain yield under salinity. It was concluded that yield loss under moderate salinities may not be compensated for by increasing seeding density above normal density levels.
Comparison of Three Statistical Models Describing Potato Yield Response to Nitrogen Fertilizer
Authors: Bélanger Gilles , Walsh John R. , Richards John E. , Milburn Paul H. , Ziadi Noura
Published: July 2010

Estimation of optimum fertilizer rates is of interest because of growing economic and environmental concerns. Optimum fertilizer rates can be determined by fitting statistical models to yield data collected from N fertilizer experiments. We evaluated quadratic, exponential, and square root models describing the yield response of potato (Solanum tuberosum L.) to six rates of N fertilization (0–250 kg N ha−1) with and without supplemental irrigation at four on‐farm sites in each of three years (1995 to 1997) in New Brunswick, Canada. Economic optimum N rates (Nop) varied among sites and models. The proportion of variability (R2) explained by the three models was similar. The quadratic model, however, calculated a greater Nop value (175 kg N ha−1) averaged over all sites than those calculated by the square root (123 kg N ha−1) and exponential (80 kg N ha−1) models. Regression residues of the quadratic model were closer to a normal distribution than those of the other two models, indicating a less systematic bias. Economic losses were greatest when the quadratic model was the most appropriate model, but the data were fitted to the exponential (loss of $204–240 ha−1; all values in Canadian dollars) or square root model (loss of $58–201 ha−1). We conclude that the quadratic model is the most appropriate for describing the potato yield response to N fertilizer and predicting Nop for areas with a ratio of the cost of N fertilizer to the price of potatoes similar to that in Atlantic Canada.
Cover Crop Effects on Nitrogen Availability to Corn following Wheat
Authors: Vyn Tony J. , Faber John G. , Janovicek Ken J. , Beauchamp Eric G.
Published: July 2010

Maximizing the environmental and economic benefits of cover crops partially depends on an accurate estimate of the N fertilizer requirement of subsequent crops. Four trials involving cover crop, tillage, and N rate variables were conducted from 1992 to 1995 in southcentral Ontario on well‐drained Typic Hapludalf soils. Rye (Secale cerealeL.), oilseed radish [Raphanus sativus(L.) var. oleiferus Metzg (Stokes)], oat (Avena sativaL.), and red clover (Trifolium pratenseL.) cover crops were established after winter wheat (Triticum aestivumL.) to evaluate their effects on soil NO3–N levels as well as subsequent corn (Zea maysL.) grain yield response at fertilizer rates of 0 and 150 kg N ha−1. Corn response to cover crops was compared in autumn plow and no‐till tillage systems. Within no‐till, autumn vs. spring chemical kill for red clover and rye was also evaluated. Although red clover biomass N yields were usually at least double those with other cover crops, all cover crops were equally effective at lowering residual soil NO3–N concentrations following wheat harvest. Presidedress NO3–N concentrations after autumn‐killed or plowed red clover were at least 24% higher than after any other cover crop. Grain corn yield responses indicated that red clover substantially enhanced N availability to corn in both autumn plow and no‐till systems, but that oilseed radish, oat, and rye cover crops did not enhance N availability to succeeding corn, compared with the no‐cover treatment, in either tillage system. Furthermore, the presidedress NO3–N test reliably estimated N fertilizer requirements of corn following all cover crop systems except spring‐killed red clover.
Spatial Distribution of Extractable Phosphorus, Potassium, and Magnesium as Influenced by Fertilizer and Tall Fescue Endophyte Status
Authors: Schomberg Harry H. , Stuedemann John A. , Franzluebbers Alan J. , Wilkinson Stanley R.
Published: July 2010

Animals influence nutrient cycling within grazed systems, and the effect may be greater with tall fescue (Festuca arundinacea Schreb.) because of endophyte‐produced alkaloids that cause fescue toxicosis and alter animal behavior. Twelve grazed tall fescue pastures, established in a Cecil sandy loam (fine, kaolinitic, thermic Typic Kanhapludult) soil near Watkinsville, GA were used to measure fertility (134–15–56 and 336–37–139 kg N–P–K ha−1 yr−1) and endophyte (low, 0 to 29% and high, 65 to 94%) effects on P and K distribution. Soil samples were collected in winter 1997 at distances of 1, 10, 30, 50, and 80 m from permanently located shade and water sources at eight depth increments down to 1.5 m. Nutrient accumulation was greatest 1 m from shade and water sources where P, K, and Mg concentrations were 1.7 to 8, 2.5 to 15, and 1.1 to 1.5 times greater than average concentrations at the remaining distances, depending on depth and fertility level. Accumulation of P, K, and Mg in the area 10 to 80 m from shade and water was limited. When summed for the 0‐ to 300‐mm depth and estimated on a per hectare basis, extractable P was 64% greater in high than in low endophyte‐infected tall fescue pastures at 1 m from shade and water sources (703 vs. 428 kg ha−1, LSD = 93) and averaged 252 kg ha−1 for remaining distances. Endophyte levels did not affect K distribution and only affected Mg distribution under the low‐fertility treatment. Endophyte effects accrued over a long time period, which would indicate that altering grazing and pasture management (movement of animals, fertilizer and lime applications, and location of shade and water sources) to reduce these effects would be needed only occasionally to reduce potential environmental risks.
Tillage, Cover Cropping, and Poultry Litter Effects on Cotton: I. Germination and Seedling Growth
Authors: Nyakatawa Ermson Z. , Reddy K.Chandra
Published: July 2010

Inadequate and less vigorous crop stand is a constraint to adoption of conservation tillage in cotton (Gossypium hirsutumL.) production. We evaluated the effects of tillage (conventional till, mulch‐till, no‐till), cropping system (cotton–winter fallow, cotton–winter rye,Secale cerealeL.), and N source and rate (ammonium nitrate and poultry litter; 0, 100, and 200 kg N ha−1) on cotton seedling emergence on a Decatur silt loam soil (Typic Paleudults) in northern Alabama, from 1996 to 1998. Cotton seedling counts under no‐till were 40 to 150% greater than those under conventional till at 1 and 2 d during seedling emergence. Cotton–winter rye cropping system had 14 to 50% greater seedling counts than cotton–winter fallow cropping during the first 4 d of emergence in 1998. Poultry litter source of N gave 17 to 50% greater cotton seedling counts than ammonium nitrate during the first 4 d of emergence in 1998. In all these cases, the differences progressively narrowed down by the 4th day of seedling emergence. Cotton seedling counts were significantly correlated to cotton growth parameters and lint yield, especially in the drier year (1998). These results were attributed to soil moisture conservation during seedling emergence. Our results show that conservation tillage improved cotton germination, emergence, dry matter, and lint yield. Therefore, no‐till with winter rye cover cropping and poultry litter can be used for achieving early cotton seedling emergence and growth in the U.S. cotton belt where dryland cotton production systems are on the increase and safe disposal of poultry litter is becoming an environmental problem.
Effects of Tillage, Crop Rotation, and Nitrogen Fertilization on Wheat under Rainfed Mediterranean Conditions
Authors: López‐Bellido Luis , López‐Bellido Rafael J. , Castillo Juan E. , López‐Bellido Francisco J.
Published: July 2010

The combined long‐term effects of tillage method, crop rotation, and N fertilizer rates on grain yield have not been studied in rainfed systems under Mediterranean climates. As part of a long‐term experiment started in 1986, a field study was conducted between 1994 and 1998 to determine the effects of tillage (TILL), crop rotation (ROT), and N fertilization on wheat (Triticum aestivum L.) growth and yield in a rainfed Mediterranean region. Tillage treatments included no tillage (NT) and conventional tillage (CT). Crop rotations were wheat–sunflower (Helianthus annuus L.) (WS), wheat–chickpea (Cicer arietinum L.) (WCP), wheat–faba bean (Vicia faba L.) (WFB), wheat–fallow (WF), and continuous wheat (CW). Nitrogen fertilizer rates were 0, 50, 100, and 150 kg N ha−1 on a Vertisol (Typic Haploxerert). A split–split plot design with four replications was used. Heavy rainfall during this research negatively impacted vegetative growth and grain yield of the wheat due to waterlogging. Wheat yield in the wet years was lower under NT than under CT. Yield decreased in the following crop rotation sequence: WFB ≫ WF > WS > WCP ≫ CW. Wheat responded to N fertilizer at rates up to 100 kg N ha−1 in the wet years but exhibited no response in the dry years. Yield under CT was higher at all N rate applied to wheat. The effect of N fertilizer on yield was more marked for the rotations with no legumes. The incorporation of the results for the 4‐yr period to those of the long‐term experiment provides more consistent information on the characterization and performance of the various systems.
Rice Yield and Nitrogen Utilization Efficiency under Alternative Straw Management Practices
Authors: Eagle Alison J. , Bird Jeffrey A. , Horwath William R. , Linquist Bruce A. , Brouder Sylvie M. , Hill James E. , van Kessel Chris
Published: July 2010

Nitrogen fertility is an important component of rice (Oryza sativa L.) cultivation systems, especially where air and soil quality issues have prompted a search for alternatives to rice straw burning. This study examined the effects of different rice straw management practices and winter flooding on yield, N uptake, and N use efficiency. The experiment, established on two sites in California, was initiated in 1993 on a Sodic Endoaquert near Maxwell and in 1994 on a Xeric Duraquert near Biggs. Main plot treatments were winter flooding and no winter flooding, and four straw management practices—straw burned, incorporated, rolled, and baled/removed—were subplot treatments. Zero N fertilizer microplots were established yearly in each plot. At currently recommended N fertilization levels, where other nutrients were sufficient, grain yield was unaffected by alternative straw management or winter flooding. However, in the third year after experiment initiation, the grain yield in zero N fertilizer plots was greater where straw was retained, i.e., incorporated and rolled. In Years 3 through 5 at Maxwell, straw retention increased N uptake by rice by an average of 19 kg N ha−1 where no N fertilizer was applied and by 12 kg N ha−1 at recommended rate of N fertilizer application. Winter flooding further increased crop N uptake when straw was retained. The additional available soil N from straw led to increased N uptake without corresponding increased grain yield, which decreased N use efficiency and necessitates the re‐evaluation of N fertilizer application rates.
Long‐Term Cropping Effects on Maize
Authors: Cárcova Jorgelina , Maddonni Gustavo A. , Ghersa Claudio M.
Published: July 2010

Long‐term cropping in the Rolling Pampa of Argentina may reduce available soil water for maize (Zea maysL.) production. Grain yield, however, has not decreased possibly because of genetic improvement. Our objectives were to: (i) evaluate root and shoot growth and its relation to crop evapotranspiration (ETa), (ii) analyze interactions among hybrids and length of the cropping period on grain yield and its components, and (iii) establish functional relations between grain yield components and their determinant processes. Three hybrids with contrasting production stability coefficients and representing different eras of maize breeding were grown at three farms in 1994 to 1996 in fields with short (S) and long (L) cropping periods on silty clay loam soils (fine, illitic, thermic Typic Argiudolls). Silking took place 5 to 6 d later in L than in S and a significant (P< 0.05) reduction (21–36%) of ETawas observed in L vs. S around this stage. Lower root abundance (reduction of 60%) and canopy size (reduction of 6–13%) in L have probably contributed to less ETa. In addition, the ontogenic delay exposed crops grown in L to more stressful meteorological conditions around silking. Kernel number (KN), closely related to grain yield (r2> 0.65), was significantly associated with daily ETaaround silking. The modern hybrid established a greater KN mm−1d of ETa(853 kernels m−2mm−1d) compared with the older ones (386 kernels m−2mm−1d). This characteristic may mask the deleterious effects of long‐term cropping on maize grain yield.
Nitrogen Placement, Row Spacing, and Furrow Irrigation Water Positioning Effects on Corn Yield
Authors: Lehrsch Gary A. , Sojka R. E. , Westermann D. T.
Published: July 2010

Furrow irrigation often leaches NO3–N. We hypothesized that banding and sidedressing N fertilizer on a nonirrigated side of a corn (Zea mays L.) row would maintain yield and decrease NO3–N leaching. In a 2‐yr field study in southern Idaho on a Portneuf silt loam (coarse silty, mixed, superactive, mesic Durinodic Xeric Haplocalcid), we evaluated the effects of (i) N placement (broadcast vs. banded), (ii) row spacing (0.76 m vs. a modified 0.56 m), and (iii) irrigation water positioning (applying water to the same side or alternating sides of a row with successive irrigations) on field corn yield and N uptake. We irrigated every second furrow nine times in 1988 and seven times in 1989. Compared with broadcasting, banding maintained grain yield in 1988 and increased it by 11% in 1989. Where N was banded in 0.56‐m rows in 1989, silage yield when only the nonfertilized furrow was irrigated was 22.9 Mg ha−1, which was 22% greater than when alternating furrows were irrigated. Compared with 0.56‐m rows, the 0.76‐m rows had no effect on 2‐yr average grain yield but tended to increase 2‐yr average silage N. Banding N on one side of a row, rather than broadcasting, and applying water all season to the furrow on the other side of the row maintained or increased grain yield, increased silage yield by up to 26%, and increased N uptake in silage by up to 21%, particularly from N‐depleted profiles. Applying water to the same furrow, rather than alternating furrows, did not reduce yield or N uptake.
Yield, Yield Distribution, and Nutritive Value of Intensively Managed Warm‐Season Annual Grasses
Authors: Fontaneli Renato S. , Sollenberger Lynn E. , Staples Charles R.
Published: July 2010

The annual grasses pearl millet [Pennisetum glaucum (L.) R. Br.] and sorghum‐sudangrass [Sorghum bicolor (L.) Moench] are alternatives to warm‐season perennials in forage systems for lactating dairy cows (Bos taurus) in the southern USA. Large fluctuations in forage production during a short growing season, however, make their management difficult. During 2 yr, seeding date and cultivar effects on dry matter (DM) yield, yield distribution, and nutritive value of these grasses were measured, and treatments were replicated four times. There were four seeding dates in 1996 starting on 10 May and six in 1997 starting on 20 March. Seeding dates were 3 wk apart. Three millet (‘GK 600’, ‘Millex 32’, and ‘Tifleaf 2’) and two sorghum (‘Hygrazer’ and ‘SX 15’) cultivars were tested. Soils were a loamy, siliceous, thermic Grossarenic Paleaquult and a hyperthermic Grossarenic Paleudult. Total DM yield, averaged across cultivars, decreased from 7.4 to 5.6 Mg ha−1 from the first to the fourth seeding date in 1996 and from 7.4 to 4.4 Mg ha−1 from the first to the sixth seeding date in 1997. Leaf percentage generally was above 70% and often greatest for Tifleaf 2. Seasonal distribution of DM was affected by planting date but not by cultivar. In conclusion, choice of species or cultivar had less impact on the responses measured than did planting date. Seeding at two dates approximately 3 to 6 wk apart is a good strategy for improving yield distribution of these cultivars and providing high nutritive value forage for nearly 5 mo.
Water Deficit–Induced Senescence and Its Relationship to the Remobilization of Pre‐Stored Carbon in Wheat during Grain Filling
Authors: Yang Jianchang , Zhang Jianhua , Wang Zhiqing , Zhu Qingsen , Liu Lijun
Published: July 2010

Remobilization and transfer of the pre‐stored food in vegetative tissues to the grains in monocarpic plants require the initiation of whole plant senescence. However, mechanisms by which plant senescence promotes remobilization of assimilates are rather obscure. This study examined the relationship between the senescence induced by water deficits and C remobilization during grain fill. Two semi‐winter wheat cultivars (Triticum aestivum L.),Yangmai 158 and Yangmai 931, were treated with two levels of nitrogen (normal [NN] or high [HN]) and three levels of soil moisture (well‐watered, moderate water deficit, and severe water deficit). Results showed that water deficits enhanced the senescence by accelerating loss of leaf nitrogen and chlorophyll and increasing lipid peroxidation. At maturity, 75 to 92% of pre‐anthesis 14C stored in the straw was reallocated to grains in water‐deficit treatments, 50 to 80% higher than the amount in well‐watered treatments, indicating that water deficits promoted remobilization. The peak values of abscisic acid (ABA) in both leaves and grains under water‐deficit treatments were 63 to 144% higher than those under well‐watered treatments. The elevated ABA level correlated with the degree of earlier leaf senescence, the 14C partitioning into grains, and the carbon remobilization. The activites of both acid invertase (INV) and sucrose synthase (SS) in grains were also enhanced by water deficits at the midstage of grain fill. Our results suggest that the senescence and remobilization promoted by water deficits during grain fill are coupled processes in wheat, and elevated ABA concentration may play a regulative role.
Increasing Water Use and Water Use Efficiency in Dryland Wheat
Authors: Angus J. F. , van Herwaarden A. F.
Published: July 2010

Water use efficiency (WUE), the ratio of grain yield to crop water use, provides a simple means of assessing whether yield is limited by water supply or other factors. Based on this assessment, yields of commercial dryland wheat (Triticum aestivum L.) crops in southeastern Australia are usually not limited by water. Transpiration efficiency (TE), the ratio of yield to transpiration, is relatively stable for well‐managed crops, but the amount of water used is strongly affected by crop management. In a review of 13 comparisons of water use and wheat yield, providing optimum N fertilizer or suppressing cryptic root diseases with break crops increased water use by 23 mm and yields by 378 kg ha−1, equivalent to 10% of the control yields. The additional soil water was extracted to levels of water potential as low as ‐5 MPa. A possible means of increasing yield potential of dryland crops is to manage transpiration so that relatively more water is used during the vegetative phase when vapor pressure deficit (VPD) is low, and hence TE is high. However, based on budgets of soil water and soluble carbohydrates stored in the vegetative organs and available for retranslocation, this option provides lower TE than conserving soil water for transpiration until grain filling when assimilates are directed to grain. Increasing the proportion of water transpired during the vegetative phase with N fertilizer can lead to particularly inefficient water use because increasing N status generally reduces the soluble carbohydrate reserves available for retranslocation to grain.
Interseeding Cover Crops into Soybean and Subsequent Corn Yields
Authors: Hively W. Dean , Cox William J.
Published: July 2010

Organic producers in the northeastern USA have difficulty establishing cover crops after soybean [Glycine Max(L.) Merr.] harvest. We interseeded species into soybean on an organic farm without livestock to identify cover crops that do not interfere with soybean harvest, provide significant ground cover, and increase subsequent corn (Zea maysL.) yields. Foenugreek (Trigonella foenum‐graceumL.), rye (Secale cerealeL.), wheat (Triticum aestivumL.), strawberry clover (Trifolium fragiferumL.), and Austrian winter pea (Dolichos lignosusL.) did not meet establishment and height requirements at the time of harvest. White clover (Trifolium repensL.), red clover (Trifolium pratenseL.), barrel medic (Medicago lupulinaL.), alfalfa (Medicago sativaL.), annual ryegrass (Lolium multiflorumL.), and creeping red fescue (Festuca rubraL.) met these requirements and generally provided >30% ground cover. Interseeded grasses provided the most biomass (0.5–1.1 Mg ha−1) at spring plowdown. Interseeded legumes did not establish well in 1996–1997 and produced only 0.1 to 0.2 Mg ha−1biomass in 1997. Corn yielded more following Dutch white clover (7.2 Mg ha−1) and medium red clover (6.7 Mg ha−1) than following no cover (5.7 Mg ha−1) in 1996 but yielded the same in 1997 (5.7, 6.3, and 6.2 Mg ha−1, respectively). Corn yielded less following annual ryegrass (5.3 Mg ha−1) and creeping red fescue (5.1 Mg ha−1) than following no cover in 1997. More research is needed to identify conditions that would reduce the risk of poor establishment of interseeded legumes or reduced corn yields following interseeded grasses.
Planting Date and Foliar Fungicide Effects on Yield Components and Grain Traits of Winter Wheat
Authors: Kelley Kenneth W.
Published: July 2010

In the eastern Great Plains, winter wheat (Triticum aestivum L.) typically is planted from late September through November. However, grain yield and grain quality often are reduced by variable weather conditions in the spring and foliar disease infections. Field studies were conducted in southeastern Kansas from 1990 through 1995 on a Parsons silt loam soil (fine, mixed, thermic, Mollic Albaqualf) to evaluate effects of planting date, with and without a foliar fungicide (propiconazole: (1‐{[2‐(2,4‐dichloro‐phenly)‐4‐propyl‐1,3‐dioxolan‐2‐yl] methyl}‐1H‐1,2,4‐triazole), on grain yield, yield components, and grain quality (test weight and protein) of hard and soft red winter wheats with different maturities and disease resistances. In 2 of 6 yr, grain yields of all cultivars planted in late September were reduced significantly by barley yellow dwarf virus (BYDV) infection. Intermediate planting dates in mid‐ to late October resulted in the best grain yield and quality in most years. Grain yields and test weights of November‐planted wheats were more variable and depended on specific environmental conditions. Grain yield and test weight responses to foliar fungicide depended on severity of specific foliar diseases, cultivar disease resistance, and environmental conditions, but significant yield increase occurred 77% of the time. Planting date had no significant effect on foliar fungicide effectiveness. Foliar fungicide had no effect on grain protein, head density, or kernels per head. Results indicate that a foliar fungicide application could be beneficial in protecting grain yield and test weight potential of both hard and soft winter wheat cultivars when conditions are favorable for foliar disease epidemics in the eastern Great Plains wheat‐growing region.
Combining Results from Augmented Designs over Sites
Authors: Federer Walter T. , Reynolds Matthew , Crossa Jose
Published: July 2010

The class of augmented designs contains two kinds of treatments, standard or check and new or augmented. The latter are usually considered to be random effects while the check treatments are considered as fixed effects. New treatments are usually not replicated and the checks are replicated as points of reference. An augmented experiment design is a screening design. It is obtained by selectinganyexperiment design for the check treatments and then enlarging the blocks or increasing the number of rows and/or columns to accommodate the new treatments. The new treatments are randomly distributed among the blocks or among the rows and columns. An augmented design has many advantages over systematic check arrangements and is useful for shortening the selection cycle over standard methods. Statistical procedures are available for recovering inter‐block or inter‐row‐column and inter‐variety information at each site. Procedures are presented herein for combining the results from single experiments over sites. Inter‐site information may be recovered for random site effects. The method recommended for combining results is invariant to experiment design changes, variance heterogeneity, changes in checks from site to site, and different response models for each site. An experiment involving 120 new wheat genotypes and checks was conducted at three sites. It is used to illustrate the statistical procedure for combining results over sites. The new wheat genotypes exhibited a relatively large genotype × site interaction, indicating their site and environmental specificity.
Effect of Soybean Plant Populations in a Soybean and Maize Rotation
Authors: Ennin Stella A. , Clegg Max D.
Published: July 2010

Plant population of soybean [Glycine max (L.) Merr.] may influence the residual N contribution to a cropping system and yield benefits to following cereals. Field studies were conducted from 1994 to 1996 on a N‐depleted Sharpsburg silty clay loam soil at Mead, NE to: (i) determine soybean yield at different plant populations; (ii) investigate residual N, chlorophyll–N–yield relations, and yield benefits from these different soybean populations to a following maize (Zea mays L.) crop; (iii) and compare N credits from soybean assessed with fallow and cereal plots as references. Eight soybean populations from14 000 to 544 000 plants ha−1 in narrow 50‐cm rows, a fallow plot, and a maize plot were followed by maize in a rotation study. Soybean yield was highest at populations of ≥129 000 plants ha−1. Maize grain yields were highest following fallow and soybean populations <20 000 plants ha−1, intermediate following higher soybean populations, and least in continuous maize. This is most likely due to N uptake as indicated by chlorophyll and N accumulation of maize. Nitrogen credits to maize were 16 to 46 kg N ha−1 when calculated as Nitrogen Fertilizer Replacement Values (NFRVs). This is probably overestimating the potential N contribution from soybean because N credits from soybean populations assessed with fallow instead of maize as references were negative. A net positive N balance due to soybean reached a maximum of 17 kg N ha−1, but soil N was depleted at populations <20 000 plants ha−1. We conclude that yield increases of maize in rotation with soybean may be due to N from reduced N immobilization, N added to the soil from N2 fixation, and possibly from non‐N rotation effects such as water use efficiency.