bluuebunny/crossref_metadata_2025_split huggingface dataset:
Components of Soybean Seed Yield as Influenced by Canopy Level and Interplant Competition1
Authors: Weil R. R. , Ohlrogge A. J. 
Published: July 2010

AbstractRecent work with genetic manipulation of the shape of the canopy and investigations of the source‐sink relationships in soybeans [Glycine max (L.) Merr.] have emphasized the need for more information on hew various canopy levels and yield components contribute to the whole plant seed yield. A study was conducted to determine the vertical distribution of seed yields within the canopies of eight highly productive commercial soybean fields. Also, by thinning the stands to one plant/m2 at the beginning of the pod‐filling period, the effect of decreased interplant competition on weight/seed was studied independently from other seed‐yield components. Plants thus thinned yielded 12.5% more per node with 11.5% higher seed weights than the normal density plants.The plant canopies were divided into five horizontal strata or canopy levels: canopy level 1 being the lowest 20% of the nodes, and so on. For the normal density plants, canopy levels 1, 2, 3, 4, and 5 contributed 19.51, 27.51, 26.51, 17.47, and 8.76% of the whole plant seed‐yields, respectively. The thinning treatment had its greatest effect at the top of the canopy, with progressively diminishing effects toward the bottom. Thus, in the uppermost canopy level the weight/seed was 23.9% greater on the thinned than on the unthinned plants, while weight/seed in the lowest canopy level was unchanged. This interaction between canopy level and plant density during the pod‐filling period may have been due to an alteration in the pattern of translocation and an inability of the lowest leaves to respond to increased light intensity.
Interaction Between Leaf Elongation, Photosynthesis, and Carbohydrate Levels of Water‐stressed Corn Seedlings1
Authors: Barlow E. W. R. , Boersma L. 
Published: July 2010

AbstractYoung rapidly expanding leaves of a corn (Zea mays L.) plant are major photosynthate sinks. Recent evidence indicates that expansion of these young leaves may be severely restricted for a considerable time during the diurnal light period by low leaf water potential and/or low soil temperature. To better understand effects on photosynthesis of prolonged diurnal reduction in leaf expansion, net photosynthetic rate of lower mature leaves, which act as a major source of photosynthate for young expanding leaves, was monitored under environmental conditions shown to restrict the expansion of the young leaves.When leaf elongation was restricted by lowering root temperature from 27.5 C to 15.0 C, net photosynthetic rate of the source leaf was reduced 47% and soluble carbohydrate content of the sink leaf increased 45% at the end of a 7‐hour treatment period. Only about one‐third of this reduction in net photosynthesis was due to the concurrent decrease in leaf water potential. When leaf elongation was restricted by cooling the shoot apical meristem region from 27.5 C to 6.0 C, net photosynthetic rate of the source leaf decreased 24% and its soluble carbohydrate content increased 23% while the soluble carbohydrate content of the sink leaf increased 40% at the end of a 7‐hour treatment. These experiments support the hypothesis that environmental factors which limit leaf elongation may indirectly decrease photosynthetic potential of source leaves within the time limits of the diurnal stress cycle.
Mulch, Nitrogen, and Irrigation Effects on Growth, Yield, and Nutrient Uptake of Forage Corn1
Authors: Khera K. L. , Khera Romesh , Prihar S. S. , Sandhu B. S. , Sandhu K. S. 
Published: July 2010

AbstractNitrogen, irrigation, and soil‐temperature regime are major factors influencing crop growth. Hot season crops in tropical areas are reported to benefit fom soil temperature reductions caused by straw mulching. But how the mulch would affect the nitrogen and irrigation requirements of the crop is not known. We studied the independent and combined effects of two rates of straw mulch, viz., 0 and 6 metric tons/ha; three rates of nitrogen, viz., 50, 100, and 150 kg N/ha; and three levels of irrigation, viz., 7.5 cm irrigations based on irrgation water (IW)/pan‐evaporation (PAN‐E) ratios of 0.6, 0.9, and 1.2 on forage corn (Zea mays L.) in a 2‐year field experiment.Green and dry forage yields and uptake of N and P significantly increased with mulching and with each successive increment of nitrogen. As the IW/PE ratio increased from 0.6 to 0.9 the green and dry forage yields and nutrient uptake increased significantly, but declined with further increase in irrigation. As a 2‐year average, mulching increased the dry forage yield by 11.8 quintals/ ha or 26% and showed a significant interaction with nitrogen rates. Fifty kg and 100 kg N/ha with mulch yielded as much as 100 kg and 150 kg N/ha without mulch, respectively.It is indicated that straw mulching in forage corn during hot and dry season increases yield and nutrient uptake and helps economize nitrogen.
Cotton Population Dynamics: Influence of the Within‐the‐Row Spacing and Emergence Time1
Authors: Wanjura D. F. , Bilbro J. D. 
Published: July 2010

AbstractDynamic and stochastic properties of cotton (Gossypium hirsutum L.) plant populations increase the difficulty of production management. The influence of four within‐the‐row plant spacings on beds spaced at 102 cm (5, 20, and 40 cm, and random 7.5 to 10 cm) and three times of emergence (5, 7, and 9 days in 1973; 6, 8, and 10 days in 1974) on means and coefficient(s) of variability (CV) of plant height, number of main stem nodes, squares, and bolls were measured over time using the cultivar ‘Tamcot 788’. The CV values for each plant component varied with stage of development. The range of CV values was 16 to 31% for plant height, 14 to 23% for number of main stem nodes, 30 to 187% for number of squares, and 36 to 270% for number of bolls. Emergence time exerted a significant influence on the CV values of all plant characters throughout the 1973 season and during the first 80 days in 1974. Plant spacing significantly affected CV values of squares and bolls at first square and peak bloom in 1973. In 1974 plant height was affected beginning at 86 days after emergence; number of main stem nodes, after 100 days; and number of bolls, after 93 days.Mean plant height and number of main stem nodes was greatest for early emerging plants. The highest number of bolls at maturity was produced on the earliest emerging plants in 1973. The 5‐cm plant spacing reduced the number of main stem nodes at maturity without affecting plant height in 1973. However, after midseason in 1974, plants spaced 5 cm were shorter and had fewer nodes than plants spaced 20 and 40 cm.Plants experienced greater moisture stress in 1974 than in 1973. The CV values for plant height and main stem node number during 1974 for plants spaced at 5 cm increased as the season progressed, but did not change for plants spaced at 20 and 40 cm. CV values for main stem node number and plant height showed no seasonal trend in 1973.Plant spacing and emergence time influenced the means and variabilities of plant components. The level of variability is different for each plant character and changes over time. An estimate of the true mean of a plant component over the season at the same confidence level would require adjustment of the sample size according to the variability changes.
Response of Oats to Water Deficit. II. Growth and Yield Characteristics1
Authors: Sandhu B. S. , Horton M. L. 
Published: July 2010

AbstractLittle information is available on the response of spring oats (Avena sativa L.) to periodic water deficits experienced at different growth stages. Knowledge concerning the manner in which oats responds to water stress is needed to aid in water management of the crop. The primary objective of this study was to determine the effect of a 9 to 11‐day water stress period imposed under a field environment upon the growth and yield components of spring oats (cultivar ‘Jaycee’). The crop was grown on pachic udic haploborolls soil (Lismore silty clay loam) in large pots buried in the field under a natural environment. The water stress periods were timed to occur during the boot stage and the anthesis through early grain formation stage (separately and in combination). Water stress at either stage decreased plant height and the number of florets per panicle. Plants stressed at anthesis through early grain formation had significantly more floret sterility and a fewer number of heads at maturity. Water deficits at all stages caused a marked decline in the yield of straw, tops without panicles, panicles, kernels, and dehulled kernels. Stress at the booting and the anthesis through grain filling depressed kernel yield 20% and 58%, respectively, whereas the combined stress reduced kernel yield 67%. Plants growing under soil water stress conditions appeared to root to a greater depth. On rewatering, the stressed plants, particularly those stressed in the boot stage, showed accelerated growth and profuse tillering. The results indicate that oats are more sensitive to soil water deficits which occur during the anthesis through early grain formation stage than during the boot stage. Therefore, cultural practices and water management should be so implemented to avoid soil water stress during the anthesis through early stage of grain formation.
Autumn‐Accumulated Tall Fescue and Orchardgrass. II. Effects of Leaf Death on Fiber Components and Quality Parameters1
Authors: Archer K. A. , Decker A. M. 
Published: July 2010

AbstractThe practice of accumulating late summer and fall forage growth for winter pastures is growing. As temperatures drop in the fall, and as growth rates decline, the percentage of dead leaf material increases. The effects of reduced growth rates, and increased leaf senescence, has a pronounced effect on the quality of accumulated forage. The objective of this research was to determine the relationship between dead leaf content and whole plant digestibility of autumn‐saved forage.Field experiments were conducted during 1970–71 on a Beltsville silt loam soil (Typic Fragiudults) to determine the influence of N application and soil temperature on leaf deaths, fiber components, and quality parameters of autumn‐saved ‘Ky‐31’ tall fescue (Festuca arundinacea Schreb.) and ‘Potomac’ orchardgrass (Dactylis glomerata L.).Nitrogen was applied at either 0, 50 (1970 only), or 100 kg N/ha in late September. In 1971, soil temperatures were maintained at ambient and aproximately 12, 20, and 27 C during the autumn using specially designed field equipment. Forage samples were collected from randomly‐selected, previously unharvested areas. These were separated into green and dead leaf fractions and analyzed for fiber components and quality parameters.Neither forage species, N application, nor soil temperature greatly affected neutral detergent fiber, acid detergent fiber, lignin, or silica contents of autumn‐saved forages. However, there were trends for high fiber and lignin contents in plants grown on high soil temperature plots and for increased fiber content with time during autumn and early winter. Green leaves had lower levels of neutral and acid detergent fiber, lignin, and silica than dead leaves.During autumn and early winter, the proportion of dead leaves in the pastures increased from approximately 20 to 46% in both years; IVDMD of the green leaf fraction decreased slightly during this period from 89 to 85%. In the dead leaf component, IVDMD remained at approximately 67% in 1970 but increased from 60 to 75% in 1971. Relationships were developed for both years which showed that IVDMD of the pastures decreased by 3.38% (r = −0.8477, P 0.001) and 1.0% (r= −0.3147, P 0.05), respectively, for each increase of 10% in dead leaf content.The data indicate that caution should be exercised when using dead leaf percentages alone to predict forage quality of fall‐saved pasture; instability in the IVDMD of the dead leaves appears to be a major factor.
Influence of Temperature on Tall Fescue Forage Quality and Culm Base Carbohydrates1
Authors: Smith A. E. 
Published: July 2010

AbstractInformation concerning the influence of temperature on fescue (Festuca arundinacea Schreb.) forage production and quality is limited. Most of the reported research has been accomplished in swards and in controlled environment chambers for short time periods or for extended time periods with infrequent clipping. This study was designed to determine the long‐term influence of two controlled temperature regimes on: a) fescue forage production and quality and b) culm base carbohydrate concentration while being frequently harvested. Plants grown in the cool environment (20/10 C day/night temperature) produced 20% more herbage with a 7% higher average in vitro dry matter digestibility than plants maintained in the warm environment (30/20 C). Crude protein and foliage moisture percentage were not influenced by these temperatures. Foliage tissue from plants grown in the cool temperature contained twice as much sucrose and 88% more fructosans than plants grown in the warm environment. Culm base material from plants grown in the cool environment contained 37% higher total water soluble carbohydrates than the plants from the warm environment. This difference was primarily due to differences in the longer chain fructosans indicating that storage carbohydrate production occurs under temperatures favorable to increased forage production.
Control of Weeds in Narrow‐Row Soybeans1
Authors: Burnside O. C. , Moomaw R. S. 
Published: July 2010

AbstractImproved weed control systems in the absence of row cultivation were researched in order to take advantage of higher yields of soybeans [Glycine max (L.) Merr.] grown in narrow rows. Weed control systems, utilizing 13 pre‐emergence and two postemergence herbicides or herbicide combinations and the rotary hoe, were devised for the production of narrow‐row soybeans at two locations in eastern Nebraska during 1972–74. Experiments were conducted on a Sharpsburg silty clay loam (Typic Argiudoll) at Lincoln and on a Judson clay loam (Cumulic Hapludoll) at Concord, Neb. Research was undertaken to reduce labor, energy, and production costs while attempting to achieve better weed control, earlier ground cover, and higher soybean yields. Selective control of grass weeds in soybeans was more readily accomplished than the control of such large‐seeded broadleaf weeds as Pennsylvania smartweed (Polygonum pensylvanicum L.), sunflower (Helianthus annuus L.), and valvetleaf (Abutilon theophrasti Medic.). Reduced application rates of grass herbicides were used successfully in narrow‐row soybeans. Weeds were controlled in soybeans, with a number of herbicide treatments, with only minor early crop injury and no stand reduction. Average weed yields from all herbicide treatments were markedly lower than those on weedy check plots, but were not significantly different from the hand‐weeded plots. All herbicide treatments except one produced average soybean yields that were equivalent to those on the hand‐weeded plots. Available weed control systems can eliminate the need for cultivation in narrow‐row soybean production. Such systems of weed control should increase soybean yields, reduce production costs, require less labor and fuel, and improve ground cover needed to protect our soil from wind and water erosion.
Effect of P, K, and Lime on Growth, Composition, and 32P Absorption by Merion Kentucky Bluegrass1
Authors: Watschke T. L. , Waddington D. V. , Wehner D. J. , Forth C. L. 
Published: July 2010

AbstractInformation is needed concerning the effects of different soil fertility levels on the activity of turfgrass roots in that part of the soil profile sampled for routine soil tests. In Pennsylvania, a sampling depth of 5 to 7.5 cm is suggested for established turf. A study was conducted on ‘Merion’ Kentucky bluegrass (Poa pratensis L.) to determine relationships among lime, phosphorus, and potassium applications; soil test results; foliar growth and elemental analysis; and root activity as determined by 32P uptake from three soil depths. In the field, soil pH values were 5.8 and 7.0, P ranged from 13 to 137 ppm, and K ranged from 0.14 to 0.43 meq./100g. Liming increased the Ca content in clippings from 0.35 to 0.42%. Phosphorus treatments increased P from 0.32 to 0.44%, and K was increased from 2.00 to 2.45% by K fertilization. Clipping yield was increased by P treatments. Sod plugs from the field were used in the greenhouse to determine root activity. Agar discs containing 32P were placed at a depth of 1.3, 3.8, or 6.4 cm, and clippings were assayed for 32P after 20 and 33 days. Shallow placement of 32P resulted in more absorption. A soil P × depth interaction was found for 32p absorption. A significant positive correlation between soil P and 32P absorption was obtained for the 1.3 cm depth, whereas a nonsignificant correlation was found for the 6.4 cm placement. Results indicated that P enhanced rooting, and the magnitude of absorption from the 1.3‐cm depth exemplified the need for P near the soil surface for optimum turf establishment.
Assessment of Four Techniques for Estimating Yield on Dryland Pastures1
Authors: Michalk D. L. , Herbert P. K. 
Published: July 2010

AbstractInformation is limited on the suitability of short‐cut methods of yield assessment in low density pastures in marginal environments. Since this information would be of value to researchers working in such environments, four short‐cut, double sampling techniques were compared with hand clipping to assess their usefulness in estimating yield in large‐scale experiments located on low density, lucerne‐based (Medicago sativa L.) pastures. The methods included the measurement of pasture height (Method 1); percentage ground cover (Method 2); and a combination of Methods 1 and 2 assessed either by calculating the product (HG) of the direct measurement of the parameters (Method 3); and by utilizing a plywood board dropped on the pasture the height measurement of which effectively integrates pasture height and cover into a single expression (Method 4). Percentage ground cover was not correlated with yield and was considered unsuitable for predicting yield in this type of pasture. Significant correlations were apparent between yield and the parameters of height, and a combination of height and cover. Sampling variation is discussed in relation to the use of these techniques. All techniques (excluding percentage ground cover) possessed sufficient sensitivity to distinguish yield differences in grazed lucerne pasture. The board technique, the most sensitive, required 53% less time than the others in data collection than clipping.
Non‐Destructive Leaf Area Estimation in Sunflower1
Authors: Schneiter A. A. 
Published: July 2010

AbstractAn accurate, easy rapid, non‐destructive method for leaf area determination in sunflower (Helianthus annuus L.) is needed. This study was designed to determine the feasibility of using different leaf parameters, or their combinations, to estimate leaf area. The study was conducted in the field with both oilseed and non‐oilseed sunflower which had been sown on Fargo clay (Vertic Haplaquolls). Plant material for leaf area determination was harvested and/or measured when 50% of the disc flowers had completed flowering. Comparisons between calculated and measured leaf area indicate the regression formula LA = {[(L−W)×.6683]−2.45}, which incorporates both leaf length and width is applicable for non‐destructive leaf area estimation of sunflowers. The formula can be utilized in sunflower grown under diverse environmental conditions.
Wheat Canopy Temperature: Relation to Plant Water Potential1
Authors: Ehrler W. L. , Idso S. B. , Jackson R. D. , Reginato R. J. 
Published: July 2010

AbstractDrought‐induced stomatal closure causes a rise in canopy temperature that can be detected remotely by infrared thermometers. Remote sensing of such a rise could lead to large scale irrigation scheduling and improvements in yield forecasts, provided that the increase in canopy temperature is a reliable indicator of plant water stress. Plant water stress can be measured reliably and simply by determining the plant water potential (Ψplant). This experiment was undertaken to demonstrate that crop canopy temperature responds specifically to changes in Ψplant and therefore can be used for long term crop monitoring by remote sensing techniques.The temperature difference between plant canopy and air (ΔT) was related to Ψplant, as shown by simultaneous, daily measurements of these parameters at 12 sites on six plots under different irrigation treatments. These data were obtained on clear days at predawn (just before sunrise) and 1400 hours. At predawn, Ψplant ranged from −2.0 bars in recently irrigated soil, in which the volumetric water content (θv) = 0.28, to −16 bars at the wilting point (θv = 0.15). At 1400 hours, Ψplant ranged from −15 bars when θv was 0.28 to −30 bars at the wilting point.At 1400 hours, ΔT was −3.8 C at full plant hydration (Ψplant = −15 bars). Increasing drought decreased Ψplant progressively and increased ΔT accordingly: when Ψplant decreased to −19 bars, ΔT was zero; when Ψplant was −48 bars, ΔT increased to 4.8 C. In demonstrating the relationship between ΔT and Ψplant these results support the validity of the temperature difference method for sensing plant response to drought.
Straw Mulch Effects on Soil Temperatures and Sorghum Germination and Growth1
Authors: Unger Paul W. 
Published: July 2010

AbstractThe possibility that lower than normal temperatures in residue‐covered soils may affect crops has caused concern regarding the use of conservation tillage systems in some regions. To evaluate this possibility in the Southern Great Plains, soil temperatures were measured at a 10‐ cnl depth in field plots on which 0 (check), 1, 2, 4, m 12 metric tons/ha of wheat (Triticum aestivum L.) straw were applied on the surface. The soil was Pullman clay loam, a fine, mixed, thermic Torrertic Paleustoll (order Mollisol). Objectives were to determine the effects of mulch‐induced temperatures on grain sorghum [Sorghum bicolor (L.) Moench] planting dates, germination, emergence, and growth, and to obtain information concerning effects of mulch rates on soil temperatures at various seasons and under specified climatic conditions. Increasing mulch rates delayed the time that soil reached favorable temperatures for sorghum germination and growth. However, temperatures were near optimum before normal planting dates and, therefore, mulches did not affect sorghum germination and only slightly delated emergence. Since temperatures with high mulch rates rarely, if ever, reached the optimum for sorghum growth, plants on these plots grew slower early in the season than those on plots with low mulch rates. Later in the season, when soil water limited growth, plants on high mulch late plots grew more than on other plots because of higher water contents. Increased mulch rates decreased average soil temperature means, maximums, minimums, and standard deviations during all seasons of fallow front wheat harvest to sorghum planting. However, when temperature of bare soil approached or fell below 0 C, the temperature effect was reversed. The change in temperature for each metric tons/ha of mulch as compared with bare soil was greatest for the 1‐metric ton/ha rate and generally decreased as mulch rates increased.