bluuebunny/crossref_metadata_2025 huggingface dataset:
Dry Matter Production and Translocation in Maize Subjected to Drought during Grain Fill1
Authors: Jurgens S. K. , Johnson R. R. , Boyer J. S.
Published: July 2010

Because dry conditions most frequently occur during the second half of the growing season, the yield loss to be expected and the physiological mechanisms that cause the loss need to be understood in grain crops. In order to study this problem, the objective of this research was to withhold water from field‐grown maize (Zea mays L.) during the grain filling stage to determine the relative effects of drought on photosynthesis and translocation. Located in bordered field plots, plants were grown in large pots arranged in 75‐cm row widths at a density of 40,770 plants/ha. Drought imposed 10 days after pollination caused leaf water potentials to range between −15 and −19 bars during the day for the rest of the growing season. In control plants, daytime leaf water potential remained between −3 and −16 bars. Soon after drought was imposed, leaf area began to decline and grain yield was ultimately reduced to 42% of the control. The drought increased grain protein concentration but decreased oil concentration.

Analysis of dry matter accumulation showed that, as grain development progressed, the rate of grain fill began to exceed the rate of dry matter accumulation, indicating a net redistribution of stored assimilates. In the desiccated plants, the redistribution continued after the cessation of net plant dry matter production and occurred earlier and to a larger extent than in controls. A 14C translocation study confirmed that grain fill drew on stored photosynthate to a greater extent in desiccated plants than in controls. Because of this redistribution of photosynthate, grain yield was related to the total dry matter accumulated by the plants during the growing season. It should be emphasized that the experiment was designed to assure complete floral development and fertilization and, therefore, the sink size for photosynthate was the same in the desiccated and control plants.

To measure translocation during the drought, the second leaf above the ear was exposed to 14C 7 and 21 days after water was withheld. The amount of 14C translocated was inhibited by the dry conditions. On the first exposure date, desiccated plants retained a higher percentage of the 14C in the exposed leaf and translocated a lower percentage of the 14C to the grain than on the second exposure date. On the second exposure date, the proportion of 14C in the grain was not significantly different from that in the control plants. This continued translocation, despite a lack of plant dry matter accumulation, indicates that photosynthesis was more inhibited than translocation during the dry conditions. The differences in 14C translocation at different times suggest that interpretations of long term drought effects on translocation should be based on extended studies of dry matter or 14C movement rather than short term movement of 14C alone.
Foliar Application of P. II. Yield Responses of Corn and Soybeans Sprayed with Various Condensed Phosphates and P‐N Compounds in Greenhouse and Field Experiments1
Authors: Barel D. , Black C. A.
Published: July 2010

Greenhouse and field experiments were conducted with corn (Zea mays L.) and soybeans (Glycine max L. Merr.) to evaluate the growth response of foliar sprays with several condensed phosphates and P‐N compounds. The maximum concentration of P tolerated in solutions of tri‐ and tetrapolyphosphates applied as sprays in the greenhouse was 1.3% with corn and 1.1% with soybeans. The maximum concentration of P tolerated as orthophosphate was 0.5% with corn and 0.4% with soybeans. With soybeans, the yields of plants sprayed with various condensed P compounds significantly exceeded the yields of the unsprayed control, which would not be classed as P‐deficient on the basis of the P content of the leaves. Spraying the plants, however, increased the P concentration in the leaves. Phosphoryl triamide produced the highest yields of above‐ground dry matter of corn plants in an experiment in which several P‐N compounds and condensed phosphates were brushed on the leaves. Several different condensed phosphates were sprayed on corn and soybeans in a field experiment on a fine loamy, mixed, mesic typic haplaquoll (Webster silt loam). An increase in yield of corn that was statistically significant at the 5% level was obtained from spraying. The yields with tri‐ and tetrapolyphosphate were, respectively, 760 and 754 kg/ha above the control yield of 10,234 kg/ha. With soybeans, the increase in yield due to treatment was significant at the 18% level, and the increase was equivalent to 256 kg/ha above the control yield of 3747 kg/ha.
Yield and N Percentage of Spring Wheat as Affected by Phosphate Fertilizer Moisture Use, and Available Soil P and N1
Authors: Nutall W. F. , Zandstra H. G. , Bowren K. E.
Published: July 2010

Yield response of wheat (Triticum aestivum L.) to P fertilizer is quite variable on summerfallowed fields in western Canada. Because yield response to P fertilizer was only partially explained by NaHCO3‐soluble P (available soil P), experiments were conducted in northeastern Saskatchewan to evaluate N and moisture effects on yield response and protein percentage of wheat.

Over a 4‐year period, 18 N and P fertilizer trials with spring wheat were seeded on six soil types of the Black (Udic Haploboroll), Dark Gray (Mollic Cryoboralf), and Gray Wooded (Typic Cryoboralf) soil areas in northeastern Saskatchewan. Before seeding, soil samples were taken for N and P soil analyses and moisture determination. Maximum and minimum air temperatures and rainfall were recorded daily at each site in order to make estimates of soil moisture by a budget system (rainfall minus evapotranspiration) throughout the growing season.

Grain yields ranged from 1297 kg/ha (control) on a soil having a NaHCO3,‐soluble concentration of 8.4 µg P/g to 4,973 kg/ha where 11 kg N and 22 kg P/ha were applied on a soil testing 17.9 µg P/g. Wheat yield responses were negatively correlated with sodium NaHCO3‐soluble P, exchangeable ammonium‐N and positively correlated with nitrate‐N in soil at planting. Negative correlations occurred between wheat yield response and soil moisture deficit (rainfall minus evapotranspiration) at both heading to soft dough and from soft dough to ripe growth periods; wheat yield response was positively correlated with moisture deficit from jointing to heading (mean R2 = 77.6%). Yield response at the highest rate of 29 kg P/ha was not significantly affected by moisture deficit. Yields of the control had a significant quadratic relationship to NaHCO3‐soluble P (R2 = 64.3%).

Nitrogen percentage of the controls was increased by high nitrate‐N in soils. With but one exception, high moisture use and low moisture deficit at later growth stages were associated with lower N percentage of grain (mean R2 = 91.4%).

Most of the variability of wheat yield response to P fertilizer was accounted for by soil N, P, and moisture. Management practices that will increase the amount of N in the soil and reduce the amount of water available in the late stages of crop development will produce grain with the highest protein percentage on summerfallow fields in northeastern Saskatchewan.
Physiological and Morphological Characteristics of Large and Small Leaflet Alfalfa Genotypes1
Authors: Leavitt J. R. C. , Dobrenz A. K. , Stone Joe E.
Published: July 2010

A rapid test for identifying high‐yielding genotypes of all crop plants, including alfalfa (Medicago sativa L.), is needed. Because previous work indicated that alfalfa yield is closely associated with leaflet size, 15 alfalfa genotypes with large primary leaflets and 13 alfalfa genotypes with small primary leaflets were identified by visual selection in the field and compared for yield, leaflet size, specific leaf weight (SLW), and rate of carbon exchange in the spring of 1974. The large leaflet alfalfa genotypes had significantly higher yield, larger leaflets, and lower SLW than the small leaflet genotypes when the data were combined over the entire growing season. The large leaflet genotypes had significantly higher rates of total photosynthesis per plant, significantly lower rates of apparent photosynthesis per unit leaf area than the small leaflet genotypes, and equal rates of apparent photosynthesis per gram of leaves to those of the small leaflet genotypes.

Correlation coefficients were calculated between the various morphological and physiological parameters measured on all genotypes. The best selection criteria for yield was total leaf area per plant (r=0.92, significant at 1% level). Dry matter production was positively and significantly associated with total CO2 uptake per plant (r=0.63, 1% level) and leaflet area of primary leaflets (r= 0.47, 1% level). Although apparent photosynthesis showed a significant but negative (r=−0.26, 570 level) association with yield, its predictive value was low. Carbon exchange, apparent photosynthesis, dark respiration, post‐illumination‐burst, and photorespiration were significantly and positively associated with each other. Further research is needed to determine if vegetatively propagated swards of large leaflet alfalfa would outyield swards of small leafet afalfa.
Pima and Upland Cotton Response to Irrigation Management1
Authors: Kittock D. L.
Published: July 2010

American Pima cotton (Gossypium barbadense L.) traditionally is stressed more for moisture before irrigating than is Upland cotton (G. hirsutum L.). With improved cultivars of each species, many growers now irrigate both in a similar manner. The purpose of this research was to determine if current cultivars of the two species respond differently to irrigation. Upland and Pima cultivars were compared for 4 years under five irrigation regimes at Phoenix, Ariz. Water was metered into closed basins. Treatments consisted of watering every 7, 14, and 21 days for 4 years. Additional treatments for 2 years were watered every 28 days and watered every 7 days at 50% more water than the original 7‐day treatment. Highest yield of Pima cotton was from a treatment of one irrigation regime drier than Upland cotton in 3 of 4 years and the same regime for 1 year. Pima cotton lint yield was reduced more by excess water and less by water stress than was the yield of Upland cotton. Higher lint yields were obtained under less frequent irrigation (greater water stress) in years of low productivity. These data suggest that yield of Upland cotton may be increased by more frequent irrigation than is the current practice.
Estimating Nodule Activity of Sainfoin, Alfalfa, and Cicer Milkvetch Seedlings1
Authors: Major D. J. , Hanna M. R. , Smoliak S. , Grant R.
Published: July 2010

Legume cultivars with improved symbiotic dinitrogen‐fixing capabilities greatly benefit agriculture. Limited research on several forage legume species has suggested that breeding for improved dinitrogen fixation should be possible, but effective screening techniques are needed if significant breeding progress is to be made. This paper describes a study conducted on three forage legumes to determine the relationship of several plant characteristics to dinitrogen fixation, with a view to developing a nondestructive method of identifying plants with superior dinitrogen‐fixing ability.

Growth of 500 seedlings of sainfoin (Onobrychis viciaefolia Scop.), 425 of alfalfa (Medicago sativa L.), and 417 of cicer milkvetch (Astragalus cicer L.) was measured in a N‐free rooting medium. At harvest, seedlings were clipped above the cotyledonary node, nodules were removed and dry weights of shoot, root, and nodules were determined. The amount of acetylene reduced by nodules and the nitrogen content of shoots were determined on one‐fifth of the plants before harvest. Large variations were observed for all of the variables measured. For all three species, variation in nodule dry weight accounted for 60 to 71% of variation in shoot dry weight. Variation in nodule activity, as measured by the acetylene reduction assay, accounted for 18 to 45% of variation in shoot dry weight. These results suggested that shoot dry weight was a good estimator for nodule dry weight and nodule activity in a N‐free rooting medium.

The amount of acetylene reduced by alfalfa nodules was not as closely related to shoot dry weight as it was for sainfoin or cicer milkvetch. A poor relationship between shoot percent N and shoot growth in sainfoin and alfalfa suggested that all available N in the shoot was used for top growth by these species, whereas in ucer milkvetch, a portion of the N in the shoot was not used for growth.
Influence of N and P on the Yield and Chemical Composition of Quackgrass Growing on an Organic Soil1
Authors: Schoper R. P. , Malzer G. L. , Simkins C. A.
Published: July 2010

Infestation of pure grass swards by quackgrass (Agropyron repens L.) has been a problem in grass production on organic soils in northern Minnesota. To determine if these problem areas could be utilized and managed effectively for forage production of quackgrass, trials were established in 1974 to determine the influence of N and P fertilization. In 1975, N and P fertilizer treatments were reapplied to the same plots.

In this 2 year study, the effects of 9 N and 5 P treatments were studied on an existing stand of quackgrass on an organic soil in northern Minnesota. Nitrogen at 168 kg/ha significantly increased dry‐matter yields by 62% in the first year, and 66% in the second, with a maximum yield of 6.96 metric tons/ha. Splitting of N applications influenced seasonal forage production, but had no effect on total yield. The percent crude protein ranged from 15.8 to 27.9, and was significantly increased by the application of N. Phosphorus at 50 kg/ha increased dry matter yields by 37% in the first year, and 52% in the second, with a maximum yield of 7.30 metric tons/ha. The application of P fertilizer significantly increased the P concentration of the plant tissue with optimum yields being obtained with tissue P concentrations ranging from 0.24 to 0.41%.
Phosphite Injury to Corn1
Authors: Lucas R. E. , Warncke D. D. , Thorpe Virginia A.
Published: July 2010

A liquid fertilizer containing phosphite was toxic to over 1,000 ha of corn (Zea mays L.) in southern Michigan. The fertilizer contained 9% N, 8% P, and 7.5% K and was applied over the seed at planting time. Toxicity was also obtained when the foliage was sprayed with the same fertilizer. Laboratory tests using paper chromatography and greenhouse trials identified the P source as a phosphite (HPO3)−2. Plants showed white, variegated streaking of the leaves in mild cases and spindly, rolled, yellowish‐white leaves in severe toxicity.
Cultivation During Early Season and Irrigation Influences on Corn Production1
Authors: Sorensen V. M. , Hanks R. J. , Cartee R. L.
Published: July 2010

Early season cultivation was shown previously by Cartee and Hanks to influence production of dry bean (Phaseolus vulgaris L.). Preliminary results indicated similar effects on sweet corn (Zea mays L.). Consequently, studies were conducted for another year with sweet corn and later expanded with field corn (Zea mays L.) to include irrigation and variety variables. The “coleoptile” cultivation (seedbed hilling just prior to coleoptile emergence) produced a statistically significant 29 to 40% increase in fresh ear yield in the sweet corn, compared to the “Control” (no cultivation) for 1971 and 1972, respectively. “Coleoptile” cultivation increased yields of dry matter for field corn 6% over the control treatment which was significant at the 0.05 level, but did not affect grain yields. The “blind” cultivation treatment (seedbed hilling at planting time) produced no significant differences in dry matter or grain yields for the field corn. “Blind” cultivation was not used in the sweet corn trial. Ear yields of sweet corn on the “normal” treatment (seedbed hilling when plants are 20 to 25 cm high) were significantly greater than the “control” by 12 to 20% in 1971 and 1972; however, the yields of dry matter and grain of field corn were not significantly greater than the control.

An interaction of cultivation and irrigation on dry matter (but not grain) yields of field corn was indicated. Yields tended to be higher for the “coleoptile,” “blind,” and “normal” cultivation compared to the control, only where mild water stress occurred. The effect of cultivation was not evident for the extremely dry or extremely wet irrigation levels.

A very high positive correlation (r > 0.95) between evapotranspiration (ET) and yield was obtained during both years of the field corn trial. The relation of relative yields vs. ET was similar for all varieties. Thus, an early cultivation in irrigated sweet corn should result in substantial yield increases. In irrigated field corn, moderate dry matter but little grain yield increases should result from early cultivation. Yield increases due to cultivation appear to be more probable under moderate water stress.
Wet Season Aeration Problems Beneath Surface Mulches in Dryland Winter Wheat Production1
Authors: Rickman R. W. , Klepper B. L.
Published: July 2010

Denitrification was a suspected cause of localized poor growth in winter wheat (Triticum oestivum L.) fields in the northwest. Experimental objectives included monitoring soil aeration, soil nitrogen supply and plant growth in field soils with poor and normal plant growth to establish the probability of localized denitrification. Measured anaerobic conditions occurred above and in restricting layers of slowly draining soils supporting poor growth but not in adjacent, unlayered soils supporting good growth. The layered soils were Natrixerolls occuring in a Calcic Haploxeroll which is the major soil of the landscape in experimental area. Laboratory measurements of soil texture and soil and plant N combined with neutron meter field measurements of soil water, platinum microelectrode measurements of soil 02 diffusion rate, and plant dry matter accumulation explained growth and yield differences.

Surface mulch of burlap (simulating a heavy straw cover) increased water infiltration in both soils but by doing so, prolonged low 02 levels in slowly draining soils. Although both soils had been fertilized at the same rate and were no more than 3 m apart, plants growing on the slowly draining soil had lower N contents than those on the normal (well drained) soil. Beneath the mulch essentially all of the fertilizer N was lost on the slowly draining soil and yield was 35% lower than that on mulched normal soil. Without the mulch, the slowly draining soil reduced yield by 15%. Loss of N through denitrification was the most probable cause of reduced plant growth and yield. Localized application of N late in the spring or trial of nitrification inhibiting compounds were suggested as remedies to counteract the problem.
Photoassimilate Distribution in Spartina alterniflora Loisel. I. Vegetative and Floral Development1
Authors: Lytle R. W. , Hull R. J.
Published: July 2010

The halophytic grass Spartina alterniflora Loisel. is a major contributor to the productivity and stability of Atlantic tidal salt marshes. To better understand the reproductive resiliency of this grass, the seasonal energy transfer to vegetative and sexual reproduction was compared under marsh conditions. In most studies, the youngest fully expanded leaf blade of single culms was exposed to 14C02 at selected physiological ages during the 1972 through 1974 growing seasons. Photosynthate distribution was traced by gross radioautography and quantified by radioassay of plant parts. At all developmental stages, current photosynthate was translocated to basal tillers and to shoots originating from attached rhizomes. Even during the boot stage, basal organs including rhizomes, roots, and tillers received 6% of upper leaf photosynthate. The rhizome system became a major sink for assimilated carbon only late in the growing season. Spartina alterniflora partitioned more than 30%, of its current photosynthetic productivity to vegetative reproduction during most ontogenetic phases.
Path Coefficient Analysis of Correlation Between Stress and Barley Yield Components1
Authors: Campbell W. F. , Wagenet R. J. , Bamatraf A. M. , Turner D. L.
Published: July 2010

Water and fertility management practices are needed that will ensure economic crop production on irrigated lands in semi‐arid regions with extremes in drought and salinity. Barley, Hordeum vulgare L., was used as an indicator crop to evaluate the interactive effects of fertilizer (N and P), salinity, and irrigation management on crop yields. Greenhouse experiments with four replications were imposed on a nonsaline nongypsiferous Hunting silty clay loam soil (Aquic Ustifluvent). Nitrogen (0, 112, 224 or 448 kg N/ha) and P (0, 45 or 90 kg P/ha) were applied as urea and calcium superphosphate prior to planting. Six to eight seeds were planted in 576 pots and irrigated with tap water until the plants reached the two‐leaf stage, at which time they were thinned to two plants per pot. Salinity (ECW = 0.5, 1.5> 4.5, or 13.5 mmhos/cm) and water (irrigation interval of 2, 4, or 8 days) management treatments were then initiated. Data were collected on yield components and environmental factors.

Regression coefficients (r3) on interactions were low, indicating that a small proportion of the total yield variability was accounted for by the various variables. However, water quality and quantity and N fertilizer interactions exhibited significant (P < 0.01) effects on yield components. Moreover, a negative yield response was produced by decreasing irrigation frequency and increasing water salinity. According to the correlation coefficients, three yield components (main heads, tiller heads, and floret abortion) had comparable effects on yield. In contrast, the path coefficients analysis attributed yield differences to direct and indirect influences of various parameters. Where correlation analysis simply measured mutual association between the various parameters and variables, the path analysis measured the relative importance of each. Although results indicated reduction in yield parameters, if managed correctly, moderately saline water can be used to obtain reasonable (but not maximum) yields. Where maximum yield decisions have to be made, however, better quality land and water should be used for crop production.
Potassium Effect on Protein Formation and Amino Acid Turnover in Developing Wheat Grain1
Authors: Mengel K. , Secer M. , Koch K.
Published: July 2010

Earlier investigations have shown that the potassium ion (K+) promotes grain protein synthesis. It is not yet known whether this K+ effect is directly related to the requirement of K+ for formation of peptide bonds or is more indirectly related to the translocation of amino acids into developing grain. Wheat (Triticum aestivum L. “Kolibri”) was grown in solution culture to study the N transformations in developing grain of wheat. At two K levels (K1:0.3 and K2:2.0 me/liter) plants were treated with 15N labeled ammonium nitrate for 2 days (2 weeks after anthesis) and then grain samples were obtained from both K treatments periodically until full maturation. Initially, grain from the K2 treatment contained almost twice as much free amino acids as grain from the K1 treatment. This treatment difference gradually disappeared with grain development. The 15N label in the free amino acids declined faster in grain from the K2 treatment. Concomitant with this decline the 15N content of the grain proteins increased with the K2 treatment exceeding the K1 treatment.

Potassium increased the rate of amino acid translocation into the grain as well as the conversion of amino acids into grain proteins (albumin, globulin, prolamin, and glutelin). The accumulation of free amino acids hi the K2 treated grain suggests the influence of K was stronger on the translocation of amino acids into the grain than the conversion into proteins. The K concentration of the grain was not influenced greatly by K treatment, whereas, stalk and leaf levels showed remarkable differences. It is concluded that an indirect effect of K+ on grain protein formation results from amino acid translocation into the grain and not from the influence of K+ on peptide bond formation. The heaviest 15N label was found in glutamine, whereas glutamate showed the highest rate of N turnover.
Relationships Among Some Biological and Empirical Fertilizer Response Models and Use of the Power Family of Transformations to Identify an Appropriate Model
Authors: Mombiela F. A. , Nelson L. A.
Published: July 2010

A systematic procedure is often needed to select the best model for representing response to fertilizer input. Several traditional fertilizer response models are shown to belong to a series consisting of the Power Family of transformations of (A‐y) where y is the yield and A is the maximum yield. Transformations of both A‐y and x, the level of added nutrient, also belong to the series. Tukey’s method of plotting the data and trying different transformations of (A‐y) (and perhaps x) to linearize the data is recommended for finding a model which best approximates the relationship. There is a great deal of flexibility in the system so the best model may turn out to be one of the traditional fertilizer response models or it may be a less common member of the series of transformations of (A‐y) in the Power series. Of the traditional models the quadratic model represents the weakest transformation that will linearize the A‐y vs. x plot; Balmukand’s and Nelder’s inverse polynomial models are among the strongest. Mitscherlich’s model represents an intermediate transformation between the quadratic and Nelder’s model.
Yield and N Content of Soybean Seed as Influenced by Rhizobium japonicum Inoculants Possessing the Hydrogenase Characteristic1
Authors: Hanus F. Joe , Albrecht Steve L. , Zablotowicz Robert M. , Emerich David W. , Russell Sterling A. , Evans Harold J.
Published: July 2010

Rhizobium japonicum strains possessing the hydrogenase characteristic (Hup+) are capable of forming nodules that recycle the H2 produced during N2 fixation. Experiments were conducted to compare seed yield and N content of soybcan (Glycine max (L.) Merr.) inoculated with Hup+ and Hup‐ strains under field conditions. Hup+ wild‐type strains (USDA 143, USDA 6, USDA 122, USDA 110, USDA 136, and SR), H2 uptake negative (Hup−) wild‐type strains (USDA 117, USDA 135, USDA 120, and USDA 16) and Hup− mutants (SR2 and SR3, derived from Hup+ SR) were used as inoculants. Chehalis silt loam (mesic Cumulic Ultic Haploxeroll) and Ephrata loamy fine sand (mesic Xerollic Camborthid) relatively free of indigenous R. japonicum were used in the experiments. Bacteroid H2 uptake rates and H2 evolution from nodules from inoculated plots indicated no appreciable mixing among treatments. The inoculants applied to these relatively high N soils did not significantly affect seed yield, however, plants inoculated with the Hup+ strains appeared greener, matured later, and in all four experiments produced seed with significantly higher N percentage than plants inoculated with groups of Hup− strains. Average data from all four exepriments showed that Hup+ inoculants increased crude seed protein 8.9%. These results provide further evidence that R. japonicum inoculants for soybeans should possess the capacity to oxidize H2 produced as a by‐product of N2 fixation.
Prediction of Bermudagrass Composition and Digestibility with a Near‐Infrared Multiple Filter Spectrophotometer
Authors: Burdick Donald , Barton Franklin E. , Nelson Billy D.
Published: July 2010

Agronomists, plant breeders, and ruminant nutritionists have long sought a rapid, accurate technique for determining the chemical composition and nutritive value of forages. Recently, near‐infrared (NIR) spectroscopy has been proposed as a way to accomplish this. Although monochrometer‐type instruments have been used to predict forage quality, filter‐type instruments have not been used for this purpose. Compared to monochrometer‐type instruments which can scan the entire NIR region, filter instruments have higher relative optical energies and may be more useful for generating quantitative data for certain forage constituents. Filter instruments can scan selected portions of the NIR in about 20 sec instead of the 1 or 2 min required by monochrometers. The relative low cost of filter instruments also permits their use for routine analytical determinations.

This study was conducted to evaluate the applicability of a NIR multiple filter Spectrophotometer for determining, on a dry matter basis, crude protein, neutral detergent fiber, acid detergent fiber, lignin, and in vitro and in vivo dry matter digestibilities for three groups of field‐grown bermudagrass (Cynodon dactylon (L.) Pers.) cultivars processed as freeze‐dried forage, sun‐cured hay, and drum‐dehydrated pellets. We particularly wanted to determine if the same set of wavelengths could be used for all samples. Primary and secondary wavelengths for predicting each forage constituent were initially selected with a monochrometer type instrument. Corresponding wavelengths were then selected for the filter Spectrophotometer. Samples of known composition and digestibility were run and the resulting reflectance data used to derive a multiple regression equation from which the quality of the unknown samples was determined.

The filter spectrophotometer's six “tilting” filters covered selected regions of the NIR spectrum from 1.50 to 2.36 µm. The same filters and wavelengths could be used to predict the composition and digestibility of the freezedried forages and sun‐cured hays. However, new wavelengths had to be selected to determine crude protein in the drum‐dehydrated pellets. Standard errors obtained with the NIR filter instrument were 0.58 to 1.15 for crude protein, 1.39 to 2.77 for neutral detergent fiber, 1.07 to 2.46 for acid detergent fiber, 0.50 to 0.66 for lignin, 1.90 to 3.37 for in vitro dry matter disappearance, and 1.78 to 254 for in vivo digestible dry matter. Generally, these errors compare favorably with those obtained by conventional laboratory methods. Additional research will probably result in standard errors of prediction being lowered even more, which should result in this technique gaining wide acceptance for forage analysis.
Metribuzin Injury in Soybeans as Influenced by Application Timing and Cultivation1
Authors: Moshier L. J. , Russ O. G.
Published: July 2010

Kansas growers wish to improve broadleaf weed control in soybeans [Glycine max (L.) Merr.] grown in sandy soils with high pH or low organic matter content. Metribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazin‐5 (4H)‐one] applications would effectively control broadleaf weeds on such soils; however, crop injury risk would also be present. Thus, a field experiment was initiated to determne if a 3‐week interval between herbicide application and planting or cultivation after soybean emergence improved tolerance of soybeans grown on a soil with a high pH and low organic matter content. Metribuzin was applied at 0.6 or 1.1 kg/ha and incorporated prior to soybean planting in a Haynie very fine sandy loam (coarse‐silty, mixed, calcareous, mesic Typic Udifluvent) with pH of 7.9 and 0.7% organic matter content in 1978 and 1979. Visual injury of 4‐week‐old plants was less in 1978 but more in 1979 when metribuzin was applied 3 weeks before planting rather than immediately before planting. Injury in 7‐week‐old plants was not significantly affected by time of metribuzin applications in 1978 but was greater from applications immediately before planting compared to applications 3 weeks prior to planting in 1979. Injury differences were attributed to rainfall quantity and pattern. The meribuzin applications at 0.6 or 1.1 kg/ha 3 weeks prior to planting did not affect soybean yields either year even though the higher rate reduced plant stand and plant height. Yields were reduced only when metribuzin was applied at the higher rate immediately before planting. Cultivation at 3 and 7 weeks after soybean planting did not significantly affect soybean tolerance either year.
Phosphorus Uptake and Dry Weight of Stylo and White Clover as Affected by Chlorine1
Authors: Chrisholm Richard H. , Blair Graeme J.
Published: July 2010

Caribbean stylo (Stylosanthes hamata L. Taub, ‘Verano’) and white clover (Trifolium repens L., ‘Ladino’) commonly grow in soils of markedly different available P status. In addition, stylo generally grows on highly leached tropical soils that have low levels of Ca and Cl. Before comparisons can be made of P utilization in these species, it is necessary to characterize their nutrient requirements, including the P × Cl interaction in each species, as this affects P uptake and growth.

In this work, the effect of solution Cl level on P uptake by stylo and white clover was investigated in a controlled environment, solution culture study. Four P levels (1, 2, 4, 8 µM) and four Cl levels (10, 20, 30, 40 µM for stylo and 10, 30, 100, 200 µM for white clover) were used. Increases in the Fe, Cu, Mo, Ca, and S levels of a previously used nutrient solution were necessary, under the conditions of our work, to satisfy the requirements for growth of species in this study.

Maximum dry matter yield and P uptake were recorded in white clover tops and roots in the 8 µM P/100 µM Cl treatment and in stylo tops in the 8 µM P/30 µM Cl treatment. Maximum root yield in stylo was recorded in the 30 µM Cl treatment, with no significant response to P at this Cl level. Stylo root P uptake was at a maximum in the 8 µM P treatment.

The results demonstrate the necessity of adjusting the nutrient solution composition to match the requirements of the species under study before embarking on comparisons of differences in the uptake or utilization of a particular element.
Response of Soybeans in Different Maturity Groups to March Plantings in Southern USA1
Authors: Boote K. J.
Published: July 2010

Information is lacking on the performance of soybean [Glycine max (L.) Merr.] cultivars grown under lengthening rather than shortening days. Soybean cultivars in a range of maturity group (MG) were planted in March at Gainesville, Florida (29° 40' N) during 1976 through 1979. The soil type was Kendrick sand (loamy, siliceous, hyperthermic Arenic Paleudult) and Gainesville sand (hyperthermic, coated Typic Quartzipsamment). Cultivars were evaluated with two objectives in mind: I) to determine yield and reproductive performance of cultivars in a range of MGs under short but lenthening days, and 2) to identify high yielding cultivars which matured by late June so that a second warm‐season crop could be planted.

Cultivars in MG 000 to I were uniformly early flowering, early maturing, short, and low yielding, but those in MG II, III, and IV were each slightly slower in reproductive development, of later maturity, taller, and higher yielding. Although MG II, III, and IV cultivars flowered within 33 days after emergence, their postflowering development was slower which resulted in more vegetative growth, a longer seed filling period, and better seed yields. With March planting at this location, MG II, III, and IV cultivars normally matured by late June. ‘Williams’ (MG III) was one of the better cultivars, yielding 3,000, 3,200, 2,760, and 2,800 kg/ha in the four seasons. ‘Amsoy 71’ (MG II), ‘Calland’ (MG III), ‘Union’ (MG IV), and ‘Cutler 71’ (MG IV) produced acceptable yields; however, the latter three cultivars had poorer seed quality, matured later, and often retained green stems and a few green leaves at pod maturity.

Cultivars of MG V, VI, VII, and VIII flowered about 10 days later than MG 000 to IV and progressed slowly into pod development. Cultivars of MG V matured most of their pods by 1 August but retained many green leaves and exhibited very poor quality seed. Those in MG VI, VII, and VIII were so adversely affected by the long days of May, June, and July that they did not complete reproductive growth until September and October.

With selection of soybean cultivars of appropriate maturity, March planting with maturation by late June was Eeasible at this latitude, thus permitting double cropping of soybeans after soybeans.
Nitrogen Utilization by Tall Fescue from Sewage Sludge Compost Amended Soils1
Authors: Tester C. F. , Sikora L. J. , Taylor J. M. , Parr J. F.
Published: July 2010

The agronomic value of sewage sludge compost as an N source for tall fescue (Festuca arundinacea Schreb. ‘Kentucky 31’) was evaluated in a greenhouse pot study. An Evesboro loamy sand (mesic, coated Typic Quartzipsamments) and a Fauquier silt loam (fine, mixed, mesic Ultic Hapludalfs) soil were amended with four rates of sewage sludge compost (0 to 6% on a dry weight basis) equal to 0 to 135 metric tons/ha, a lime treatment, two rates of N (0 and 195 kg/ha), P (0 and 390 kg/ha), and N plus P in a factorial design. Kentucky 31 tall fescue was grown and harvested at 40, 76, 120, and 167 days. The clippings and one replicate of roots and crowns grown in the Evesboro soil were analyzed for total N.

Total N uptake by fescue grown in compost amended Evesboro soil was significantly greater than with Fauquier soil treated similarly. Fescue N content was linearly related to the compost amendment for both soils and was significantly increased by the addition of N and P singly or in combination. The largest fescue N increase was obtained by the addition of N and P. Nitrogen uptake was limited by the mineralization rate of compost organic N. Regression equations describing total N uptake and fescue N concentration as affected by compost amendment, fertilizer addition, and time, required, in most cases, a quadratic term for compost amendment to explain the variation in Fescue N.

During 167 days of growth the fescue utilized approximately 8% of the compost N and 80% of the fertilizer N. Based on the N content of fescue grown in Evesboro soil an equivalent fertilizer value of 166 kg N/ha was obtained for the 135 metric tons/ha compost amendment compared with the fertilizer treatments.
Regrowth, Nodulation, and Nitrogenase Activity of Strophostyles helvola with Rigorous Defoliation1
Authors: Lynd J. Q. , Odell V.
Published: July 2010

Indigenous legumes contribute toward increased N nutrition and enhanced grazing productivity of both native and improved pasture swards. However, quantitative assay of symbiotic dinitrogen fixation by pastured legumes is difficult. The objective of these studies was to determine defoliation effects on regrowth, nodulation, nitrogenase activity (C2H2 red.) and associated nodule enzymology of trailing field bean [Strophostyles helvola (L.) Ell.]. Plants were grown in a Psammentic Paleustalf (Eufaula) and inoculated with Rhizobium leguminosarum Frank, ATCC 10314. Characteristics of nondefoliated plants during 3 years of field experiments included near exponential growth with 10‐fold increase in dry weight from 1.49 to 17.45 g at 30 to 120 days after emergence (DAE). Number of stems tripled and stem length increased six‐fold. Average nodules per plant increased from 80.2 to 239.6. Nodule mass as fresh weight increased from 0.94 to 6.17 g, and mature nodules increased from 13% to 89%. Differences in regrowth after defoliation at 30‐day intervals was not significant averaging 4.21 g, CV 11 %. Nodules per plant after regrowth averaged 113 with fresh nodule wt. 2.06 g and 27 % were mature nodules. Nitrogenase (C2H2 red.) activity levels were highest at 90 DAE, 168.2 μmols. C2H4g−1h−1. Regrowing plants after defoliation averaged 156.3 μmol C2H4g−1h−1. Highest cytosol enzyme activity levels were for aspartic transaminase (AST) with 25.0 IU (nondefoliated) and 25.9 IU (defoliated) g−1 fresh nodule. Glutamine synthetase (GS) was 1.7 IU (nondefoliated) and 12.0 IU (defoliated). Multiple regression indicated significance for glutamate dehydrogenase (GDH) but not glutamine 2‐oxoglutarate aminotransferase (GOGAT) with interactions for the equation of best fit with P < 0.05 level as nitrogenase (C2H2 red.) = 13.3 nodule wt. + 0.5 nodule no. + 4.5 nodule maturity % + 58.6 GDH, R2 = 80.9 and CV 11%. More knowledge of indigenous pastured legumes, as S. helvola, could have practical significance for improvement of symbiotic N fixation and grazing production for the extensive pastured regions with severe soil and climate limitations.
Dry Matter and Leaf Area Relationships in Winter Barley1
Authors: Ramos J.M. , Garcia Del Moral L.F. , Recalde L.
Published: July 2010

An estimate of leaf area, which is required for most models of plant growth, is a time‐consuming and costly process, especially in large‐scale field experiments. The objective of this study was to obtain equations which could be used to determine quickly the leaf area of barley (Hordeum spp.) plants with the least margin of error. Six cultivars of winter barley were used, four, six‐rowed (Hordeum vulgare L.) and two, two‐rowed (Hordeum distichon L.) grown in Granada, Spain, (thermic, Calcixerollic Xerochrept soil) during 1979, 1980, and 1981. Leaf area was found to be strongly correlated with the leaf dry matter (r=0.957) during all of Feekes stages of growth. The aboveground dry matter was also found to be highly correlated with leaf area (r=0.969), but only until Feekes seventh stage (second node of stem formed, next‐to‐last leaf just visible). From this it is apparent that leaf dry matter in winter barley gives a good estimate of leaf area during all of its development, while the total dry matter can also be used until the seventh growth stage.
Forage Yield and Quality of Brassicasp. Established Using Preemergence Herbicides1
Authors: Griffin J. L. , Jung G. A. , Hartwig N. L.
Published: July 2010

abstract

Brassica sp. may serve as high energy forage crops at times when forage availability may be limited. Field studies were conducted in the Northeast to assess forage yield and quality of 'Sirius' turnips (Brassica rapa L.) and 'Perko' rape (B. napus L.) planted on a Hagerstown silt loam (fine, mixed, mesic Typic Hapludalf) soil in late May (1978) and late April (1979). Preemergence herbicides including metolachlor [2‐chloro‐N‐(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐ l‐methylethyl) acetamide], pendimethalin [Nl‐ethylpropyl)‐3,4 dimethyl‐2,6‐dinitrobenzeneamine], and nitrofen [2,4‐dichlorophenyl p‐nitrophenyl ether] were applied alone and in various combinations to determine effectiveness in reducing weed competition. Forage yields of turnips and rape 100 days after seeding were generally not affected by the herbicide treatments. However, associated weed yields in both turnips and rape were significantly reduced with all herbicide treatments applied. Pendimethalin applied at 2.2 kg ha−1was phytotoxic to both turnips and rape reducing yields 67 and 17%, respectively, as compared to the untreated control. Forage dry matter yields of turnips and rape with adequate weed control were as high as 5068 and 6711 kg ha−1, respectively. In 1978, turnip whole plant crude protein (CP) concentration was highest (227 g kg−1) where pendimethalin was applied at 2.2 kg ha−1. The 2nd year CP levels for turnip leaves were similar for all herbicide treatments, but root levels were highest where pendimethalin at 2.2 kg ha−1was used. The high rate of pendimethalin severely inhibited root development resulting in smaller roots with higher CP. Rape CP levels in 1978 were generally highest where herbicides were used, but in 1979, rape CP was not affected by herbicide application. Averaged across herbicide treatments, turnip (whole plant) and rape CP levels averaged 121 and 106 g kg−1, respectively. In vitro dry matter disappearance for turnips and rape were similar averaging 898 g kg−1and were not affected by herbicide application. Results indicate that appropriate preemergence herbicides will reduce early season weed competition and will enhance early production of turnips and rape. The high production potential and the high dry matter digestibility 100 days after seeding warrant consideration of turnips and rape for use as supplemental summer forage crops.
Dryland Rice Response to an Irrigation Gradient at Flowering Stage1
Authors: Cruz R. T. , O'Toole J. C.
Published: July 2010

Sensitivity of rice (Oryza sativaL.) to flowering stage water stress is well recognized. However, as with other cereals, there is lack of field research which quantifies plant and soil water status at the flowering stage in relation to water stress‐mediated reductions in crop yield. A rice cultivar was subjected to six levels of irrigation using a line‐source sprinkler system in the field on a silty clay loam, Typic Hapludoll soil during the dry season in which a stable rainless period is the climatic norm. Irrigation level 6 (wettest) was irrigated at the rate of 1.10 of pan evaporation while level 1 (driest) relied solely on pre‐line source water storage. Evapotranspiration during the 15‐day treatment period at flowering was linearly related to grain yield. The dominant yield component influencing grain yield was spikelet sterility.

At irrigation level 6 in which soil moisture was reduced to 95% of the total crop extractable water, midday leaf water potential was −0.9 MPa, and spikelet sterility was 20%. At level 1, soil moisture was 28.6% of the total crop extractable water, midday leaf water potential −2.5 MPa, and spikelet sterility 73%. The exsertion of the rice panicle was found to be sensitive to changes in leaf water potential. Up to 30% of water stress‐mediated spikelet sterility was associated with poor panicle exsertion. The degree of panicle exsertion during flowering stage water stress may be a useful visual criterion in the selection of breeding lines with high degree of reproductive stage drought resistance.
Salt Effects on Emergence and Seedling Mortality of Guayule1
Authors: Miyamoto S. , Piela K. , Davis J. , Fenn L. B.
Published: July 2010

Establishment of guayule (Parthenium argentatumGray) by direct seeding has been unreliable due to poor seedling emergence and subsequent mortality. Laboratory germination, greenhouse and small field plot tests were performed for evaluating possible salinity interactions. Guayule seeds (593, 11591, and bulk collection) germinated 60 to 85% in petri dishes containing high saline solutions (EC = 22 dSm−1). Yet, emergence from well‐watered sandy soils was reduced sharply with increasing salinity, e.g., less than 10% emergence at irrigation water salinity of 4.5 dSm−1in field plots irrigated twice a day. Seedling mortality was negligible when irrigated with distilled or low salt water, but increased with increasing salinity. Both emergence and seedling survival rates were highly correlated (r = −0.94) with the salinity of surface (0 to 1 cm depth) soil samples. Salts introduced through irrigation water accumulated mostly in the surface 0.5 cm of soils with concentrations ranging from 4 to 22 dSm−1in soil saturation extract. Salt concentrations at seeding depths (0.5 to 0.8 cm) were, however, low enough to allow seed germination. Low emergence and high seedling mortality observed here appeared to be related to hypocotyl and seedling damage by salts accumulated on soil surfaces. Such damage can occur in soils classified as nonsaline when irrigated with water having salinity as low as 1 dSm−1.