bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Plant and Row Spacing on Dryland Soybean Yield and Water‐Use Efficiency1
Authors: Alessi J , Power J. F. 
Published: July 2010

AbstractData on effects of plant and row spacing on yield of soybeans [Glycine max (L.) Merr.] have given conflicting results. Most such experiments were conducted under conditions of little or no water stress. The experiments reported here, conducted under more severe stress conditions, broaden the water‐availability spectrum covered. Each spring, 1976 through 1979, soybeans were seeded on Temvik silt loam (fine‐silty, mixed Typic Haploborolls) at Mandan, N.D., in row widths of 15, 45, and 90 cm, and at within‐row spacings of 11, 15, and 23 cm, which resulted in plant populations of 48,000 to 580,000 plants/ha.Soil water depletion by soybeans was generally confined to the upper 90‐cm soil depth. Average (4‐year) water use was 23.6 cm, and was not significantly affected by plant spacing. In 2 of the 4 years, total water use was greatest and average soybean yields were least Prom the 15‐cm row width. Within‐row spacing affected yields in only 1 of the 4 years.Water‐use efficiency was least for 15‐cm rows in 3 of the 4 years. These data suggest that planting in 15‐cm rows enhances water use prior to flowering. In extreme drought situations, this enhanced earlyseason water use leaves less water available for pod‐fill, and seed yields may be reduced accordingly. Under less severe water stress, however, plant and row spacing has no affect on soybean yield.
Production and Quality of Four Bermudagrasses as Influenced by Rainfall Patterns1
Authors: Griffin J. L. , Watson V. H. 
Published: July 2010

AbstractBermudagrass (Cynodon dactylon L. Pers.) is the major warmseason perennial forage crop used for beef production in the Southeast. Seedhead production is irregular and consequently cannot be used as an index of age or quality. Chronological age is, therefore, important in making management decisions. Since bermudagrass production and quality may vary with season and year, ‘Coastal’, ‘Alicia’, ‘Callie’, and common bermudagrass harvested at 2‐, 4‐, 6‐, and 8‐week intervals were evaluated over 2 years in northeast Mississippi on a Leeper fine sandy loam (fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) soil.During the 1975 growing season rainfall was generally adequate and total dry matter yields of Coastal, Alicia, and common bermudagrass harvested at the four intervals were similar. Forage yields of Callie, however, averaged 20% higher than the other grasses because of higher production during July and August. In 1976, rainfall was especially low during August (2.0 cm) and total yield of the hybrid bermudagrasses were similar averaging 72% higher than that of common. Lower total season yields of common were reflected in less regrowth during July and August. Averaged over the grasses, total forage yields harvested at 4‐, 6‐, and 8‐ week intervals were 2.6 metric tons/ha lower in 1976 than in 1975 and were related in general to higher early‐season (June to July) forage yields in 1975 and limited regrowth in August and September 1976.Crude protein (CP) was higher for Callie and common both years of the study. Neutral detergent fiber (NDF) and acid detergent fiber (ADF) varied little among grasses or harvest intervals. The increase in CP (3.4 units) and decrease in NDF (3.8 units) observed in 1976 appeared related to rainfall patterns, variation in regrowth potential among the grasses, and possible changes in the proportion of leafstem fractions. Averaged over years, Callie was higher in CP (11.9 vs. 10.3%) and digestible dry matter (55.3 vs. 53.0%), and lower in lignin (5.2 vs. 5.7%) than the other grasses.Results suggest that selection of hybrid bermudagrasses over common should be based mainly on their potential to produce significantly more dry matter when moisture is limiting.
Yield and Development of Winter Wheat at Elevated Temperatures1
Authors: Johnson R. C. , Kanemasu E. T. 
Published: July 2010

AbstractThe influence of temperature on wheat (Triticum aestivum L.) yield components is known to differ depending on plant growth stage. Our objective was to determine how increased temperatures at five growth stages influenced development, yield, and yield components of winter wheat. Field experiments were conducted on the semi‐dwarf cultivar Newton grown in Eudora silt loam (coarse‐silty, mixed, mesic Fluventic Hapludolls). Transparent plexiglass chambers occupying 1.1 m2 of crop surface were heated continuously an average of 3.4 and 6.4°C above ambient temperatures during double ridge, terminal spikelet, stem extension, anthesis, and milky ripe developmental stages. Because the rate of development depends primarily on temperature, the treatments were expressed as accumulated thermal units (TU = Σ max °C + min °C/2) above ambient TU during each growth stage; where TU is thermal units, and max °C and min °C are maximum and minimum daily temperatures, respectively. At harvest, plot yields were determined and yield components estimated. Compared with controls, kernel weights were significantly increased by temperature treatments of 48 TU at double ridge in 1978‐1979 (P ≤ 0.05) and 44 TU in 1979‐1980 (P ≤ 0.10). High temperature treatments at terminal spikelet in 1978‐1979 reduced kernels per head (P ≤ 0.5) from 19.1 to 15.4, at least partly by reducing grain‐bearing spikelets per head. An increase in kernel weight was associated with that reduction in kernels per head so final yield was not significantly reduced. An average reduction of 2.4 kernels per head by the 101 TU treatment at anthesis significantly reduced yield in 1979‐1980. At milky ripe, average kernel weights were generally reduced by high temperatures both years. Increasing temperatures at any of the five growth stages advanced plant development relative to control plants. Using data from both years, kernel weights correlated positively with days (r = 0.83) and accumulated TU (r = 0.84) during grain filling. Development appeared to increase exponentially when daily TU was above about 27. Advancing anthesis a few days, when subsequent temperatures are less likely to be high, may benefit kernels per head and/or average kernel weight.
Oxidation Status and Gas Composition of Wet Turfgrass Thatch and Soil1
Authors: Thompson D. C. , Smiley R. W. , Fowler M. Craven 
Published: July 2010

AbstractExcess thatch in turfgrasses is often associated with decreased plant vigor and increased disease susceptibility. Thatch is the primary rooting medium for many grasses, and is a substrate that possesses many prerequisites for anaerobiosis. The oxidation status and the gas composition in unsaturated thatch of mature Kentucky bluegrass (Poa pratensis L.) were measured to determine if anaerobiosis occurs under field and greenhouse conditions. Soils under the sods included a Hudson silty clay loam (fine, illitic, mesic Glossaquic Hapludolf), a Riverhead sandy loam (coarse−loamy, mixed, mesic Typic Dystrochrept), and an Arkport fine sandy loam (coarse−loamy, mixed, mesic Psammentic Hapludalf). Measurements of redox potentials (Eh) and concentrations of oxygen (O2), carbon dioxide (CO2) and ethylene (C2H4) were made. Conditions of poor oxidation, including low Eh and O2 and CO2 concentrations, and accumulations of C2H4, were measured in thatch on poorly drained soils in the field and in the greenhouse. Applications of lime and calcium arsenate amplified the extent of poor oxidation in thatch, whereas calcium nitrate improved the oxidation status. Thatch depth and a coring procedure did not influence thatch oxidation. The Eh varied diurnally and was lowest in wet thatches during warm, sunny days when thatch became warmer (by up to 7°C) than the air. Poorly oxidized conditions for periods over 7 h were measured in moist but unsaturated thatch in the field. The temperature of thatch appeared to be important in governing the oxidation status. Measurements of Eh were considered to provide rapid and useful insights into the gaseous composition of wet thatches. Our results imply that phytotoxic products of poorly oxidized environments may accumulate in wet thatch on warm sunny days. Such conditions may also be common in field−grown cores of mature turfgrass which are moved to the greenhouse for study. The relevance of these results to the occurrence of diseases such as Fusarium blight are discussed.
Corn Response to Sulfur Application in Coastal Plain Soils1
Authors: Reneau R. B. 
Published: July 2010

AbstractSulfur (S) fertilization is expected to increase corn (Zea mays L.) yields in coarse‐textured, well‐drained, and low organic matter Coastal Plain soils. This increase is expected because of the reduced quantities of S applied to agricultural lands in the form of by‐products from fertilizers applied to satisfy other nutrient requirements, increased removal of S from soil with increased crop yields, and increased emphasis on reducing atmospheric pollutants (thus decreasing S additions from atmospheric sources). This study was conducted to determine if corn yields could be increased by S additions to Coastal Plain soils and to determine if extractable soil S or tissue analyses could be employed to predict this response. Ten S fertilization experiments were conducted over a wide range of soils during 1978,1979, and 1980. Results showed that increased corn yields can be expected with S application on soils that are moderately well to well‐drained, low in organic matter, and belong to the fine loamy or coarser textured family of soils, and have acid monocalcium phosphate extractable soil SO4‐S concentrations ≤ 2.3 mg kg−1 in the surface horizon. When extractable soil S present in the Ap horizon was related to actual yield increases (∆y max) with a refitted Mitscherlich equation, a significant relationship was evident and 62% of the observed variability in relative yield could be explained. Fertilizer applications ranging from 18 to 28 kg S ha−1 were required to achieve 90% of maximum yield. The requirements appeared to be dependent on the method of application (broadcast preplant or split between broadcast and sidedress). When the relationship between total S and N:S ratio in the leaf below and opposite the ear leaf at silking and ∆y max was examined, 67 and 82% of the observed variation in ∆y max could be explained by a refitted Mitscherlich and a linear equation, respectively. From these equations it was estimated that the critical concentration for total S and N:S ratio would be 1.7 g kg−1 and 16, respectively. These data indicate that extractable soil S or tissue analyses could be used to identify fields that might be S deficient.
Turf Quality of Kentucky Bluegrass Cultivars and Energy Relations1
Authors: Mehall B. J. , Hull R. J. , Skogley C. R. 
Published: July 2010

AbstractFuture turfgrass improvement will depend upon recognizing those physiological properties responsible for stress tolerance and recovery from injury. Once recognized, these properties may be incorporated into the screening program of cultivar improvement efforts. Because energy capture and transport are basic to plant growth, we measured the variation in these processes between several Kentucky bluegrass (Poa pratensisL.) cultivars of varied origin and growth habit. In turn, CO2‐exchange rate (CER), clipping growth rate, and nutrient factors were evaluated for their correlation with turf quality. Field plots were on an Enfield silt loam (coarse‐silty over sandy skeletal, mixed, mesic, Typic Distrochrept). Carbon dioxide exchange rate was measured on plots of 15 cultivars during mid‐summer, 1978, and nine cultivars during late summer, 1980. On both dates, CER differed between cultivars and in 1978 were positively correlated with turf quality. Correlations between CER and clipping growth were significant but apparent photosynthesis was not related to leaf P and K content or nutrient efficiency ratios (mg dry wt. mg−1K or P). No significant differences in photosynthate partitioning to roots were noted between 10 cultivars in August or October 1978. This was based upon 14C recovered from roots 2 days following exposure of turf to 14CO2for 15 min. Nevertheless, the percentage of current photosynthate translocated to roots was positively correlated with the size of the root system and negatively correlated with clipping production. Kentucky bluegrass cultivars which partition more energy to roots appear more likely to produce quality turf. Of the cultivars tested, ‘Enmundi’ possessed the most favorable energy distribution pattern and produced a quality turf.
Optimum Crop Water Application as Affected by Uniformity of Water Infiltration1
Authors: Letey J. , Vaux H. J. , Feinerman E. 
Published: July 2010

AbstractEconomic analyses of irrigated agriculture stress that yield levels which maximize profits can be attained with less water than maximum yields. A premise of such analyses is that irrigated soils have perfectly uniform rates of infiltration. A general method for evaluating the effects of nonuniform infiltration rates on optimal levels of water application is developed. Empirical analyses of the implications of non‐uniform infiltration rates on optimal levels of applied water, yields, and profits are reported for corn (Zea maysL.) and cotton (Gossypium hirsutumL.). The results are critically influenced by the nature of the water yield relationships postulated for these crops. For corn, where excessive water applications apparently have no effect on yield, nonuniform conditions reduce yield and profit. These outcomes can be offset by increasing water applications and optimal levels of applied water increase as the degree of uniformity declines. For cotton, nonuniformity leads to decreases in yields and profits that cannot be offset by increased water applications. This is attributable to the apparent sensitivity of cotton yields to excessive applications of water. For both crops, increases in the price of water provide little incentive to improve the uniformity of infiltration. The results demonstrate that conventional economic analyses which ignore infiltration uniformities, underestimate optimal levels of applied water, often substantially.
Yield Reduction from Defoliation and Plant Cutoff of Determinate and Semideterminate Soybean1
Authors: Pickle C. S. , Caviness C. E. 
Published: July 2010

AbstractResearch has been conducted on the response of determinate and indeterminate soybean [Glycine max(L.) Merr.] to various plant‐damage treatments, but information is limited on the response of genotypes with a semideterminate growth habit. Our objective was to determine the yield response of a determinate cv., Forrest, and a semideterminate strain, R74‐334, to different levels of defoliation and plant cutoff at two growth stages. Treatments consisted of plants being cut off at half height, cut off at half height and defoliated below the cut, or completely defoliated. The treatments were applied to 25, 50, 75, or 100% of the plants at growth stages V5 and R3. These field experiments were conducted on a Captina silt loam (fine‐silty, mixed, mesic Typic Fragiudult) during two growing seasons. Mean yields of Forrest were significantly higher than those of R74‐334 during both years. Most of the treatments at V5 did not significantly decrease yield and in three treatments significantly increased yield. Yields generally were significantly reduced at R3 by treatments involving 50% or greater plant damage. The greatest reduction in yield occurred when 100% of the plants were cut off at half height and then completely defoliated. Yield of Forrest was reduced by 51% and that of R74‐334 by 44% with this treatment. The yield of both genotypes was reduced 33% by 100% defoliaton at stage R3. None of the first order interactions involving genotypes was statistically significant, which indicates that the two genotypes responded similarly to these plant‐damage treatments. Although there was some variability in the response of the genotypes to certain treatments, the data indicate that determinate and semideterminate soybean recover about the same from plant cutoff and/or defoliation. Therefore, the same loss values that have been developed for determinate soybean probably should be used for semideterminate types.
Distribution Pattern of Yield Components in ‘Braxton’ Soybeans1
Authors: Ramseur E. L. , Wallace S. U. , Quisenberry V. L. 
Published: July 2010

AbstractNodal and other distribution patterns of seed yield and yield components are useful in modeling soybean [Glycine max(L.) Merr.] growth, in analyzing the factors responsible for yield differences between experimental treatments, and in predicting yield. The purpose of this study was to determine the influence of irrigation and intrarow spacing on the distribution of yield and yield components in a determinate soybean cultivar. ‘Braxton’ soybeans were grown in 0.91 m rows on a Cecil sandy loam soil (clayey, kaolinitic, thermic Typic Hapludults) at intrarow spacings of 43, 61, 102, and 305 mm between plants and under three irrigation treatments: full‐season irrigation (FSI), irrigation beginning at bloom (BI), and no irrigation (NI). At maturity, samples were collected to determine pod number, seeds per pod, seed number, yield, and single seed weight for the main stem positions at each node and for the branches originating at each node. Branches contributed more pods, seeds, and yield than did main stems in all treatments, while seeds per pod and single seed weight were similar on stems and branches. Increases in intrarow spacing increased seed number and yield on branches and decreased pod number, seed number, and yield on the stems. Irrigation had little influence on the branch/stem ratios of yield components. Full‐season irrigation and BI had greater numbers of pods, numbers of seeds, yield, and seeds per pod on stems and branches and greater single seed weight on stems than did NI. With the exception of stem seeds per pod which was greater for BI, there were no differences between the two irrigated treatments. Seed number, pod number, and yield were maximized in the lower half of the nodes whereas seeds per pod and single seed weight were greatest in the upper nodes. The upper six nodes contributed the least to yield in all treatments. Increases in intrarow spacing increased the contribution of the lower nodes to yield whereas irrigation decreased the relative contribution of the lowest nodal division. We concluded that the large contribution of lower nodes to yield was due to the large proportion of yield borne on branches produced from lower nodes. Increases in spacing resulted in greater contribution to yield of these large branches and thus to a greater concentration of yield at lower nodes. Irrigation influenced distribution of yield through influences on distribution of all yield components.
Annual Bluegrass Seedhead Emergence as Predicted by Degree‐Day Accumulation1
Authors: Danneberger T. K. , Vargas J. M. 
Published: July 2010

AbstractSeedhead production of annual bluegrass (Poa annuaL.) during the spring reduces annual bluegrass root production and disrupts the aesthetic and playing qualities of the turf. A method of predicting when annual bluegrass seedheads visually emerge through maximum production would be a benefit to turf managers in that management practices such as vertical mowing and core cultivation could be suitably adjusted. A model to predict the number of seedheads from visual emergence through maximum production for a perennial annual bluegrass turf was developed from three field locations in Michigan. The proposed model is seedhead no. = −6249.4 + 41.099 (DD) − 0.08573 DD2+ 0.0000575 DD3where DD = degree‐day accumulation above 286 K beginning April (R2= 0.65).
Tall Fescue and Kentucky Bluegrass Response to Fertilizer and Lime Seed Coatings1
Authors: Hathcock A. L. , Dernoeden P. H. , Turner T. R. , McIntosh M. S. 
Published: July 2010

AbstractSlow establishment of turfgrasses from seed is frequently associated with inadequate or improper application of fertilizer and lime. Coating of these items on seed may enhance germination and seedling growth, and reduce time and energy involved in seedbed preparation, particularly when establishing turf on steep slopes or over large areas of land. The objectives of this greenhouse study were to determine the effects and potential benefits of coating ‘Kentucky‐31’ tall fescue (Festuca arundinacea Schreb.) and ‘Adelphi’ Kentucky bluegrass (Poa pratensis L.) seed with various rates and combinations of N, P, and K fertilizers and lime (L). Seedlings were grown in either a Sassafras sandy loam (fine‐loamy, siliceous, mesic Typic Hapludult) or an Evesboro sandy loam (mesic, coated Typic Quartzipsamment) soil. Seed of both species coated with treble superphosphate exhibited little or no germination. The harmful effect of treble superphosphate seed coatings was probably due to hydrogen ion toxicity to developing embryos. Dicalcium phosphate (P‐source), urea (N‐source), sulfate of potash (K‐source), dolomitic limestone, and seed coating adhesives (Methocel A‐15 and gum arabic) had no deleterious effects upon seed germination or seedling growth. Seed of both species coated with P (22 kg ha−1) alone or in combination with N (24 kg ha−1) generally exhibited significantly improved germination percentages when compared to other treatments. Seedlings from NP and NPKL treatments generally exhibited improved growth compared to seedlings grown without N and P combined. This study provides evidence that coating seed with L and fertilizer improves germination and seedling development in Kentucky bluegrass and tall fescue. Seed coatings therefore may provide an alternative to soil incorporation of lime and fertilizers in situations where proper seedbed preparation is not feasible.
Nitrogen Uptake Patterns of Potatoes with High‐Frequency Sprinkler‐Applied N Fertilizer1
Authors: Lauer D. A. 
Published: July 2010

AbstractIn order to understand utilization of N by Russet Burbank, a commonly grown indeterminate potato (Solanum tuberosum L.) cultivar, it is necessary to determine the partitioning of N in the plant. Fertilizer N efficiency is closely related to the latter. The objective of this research was to examine differences in N uptake patterns of Russet Burbank potatoes with N applied at excessive, adequate, and deficient levels in daily sprinkler irrigation. The N levels were selected on the basis of statistical significance of yield response to N fertilization. Experiments in 1980 and 1981 were done on a Quincy sand to loamy sand (mixed, mesic, Xeric Torripsamments) typical of coarse‐textured soils used for potato production in the Western United States. Daily mid‐season applications of a urea‐NH4NO3 solution were made for about 10 weeks through solid set sprinklers. Samples of vines and tubers were collected weekly and analyzed for total N. To show partitioning and time changes of vine and tuber N, regression curves were fitted to data for N uptake with time after emergence. Rate of N uptake functions were derived and used to determine N sink dominance by vines or tubers. At fertilizer rates greater than adequate for optimum tuber yield, the excess N showed up as increased N in vines and tubers with vines as the dominant N sink. At adequate and deficient N levels tubers were dominant N sinks, however, the deficient plants did not have a sufficient N supply for optimum yield. A desirable N uptake pattern is associated with the following: (i) A fertilizer N level that is adequate such that tuber yield and economic return on fertilizer investment are optimized which is about 340 kg N/ha for these experiments and (ii) The tubers express N uptake dominance (highest rate) from the start of rapid tuber development causing peak quantity of vine N uptake in the first one‐third to one‐half of the post‐emergent growth period.