bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dryland Evaporative Flux in a Subhumid Climate: II. Plant Influences1
Authors: Ritchie Joe T. , Burnett Earl 
Published: July 2010

AbstractSeasonal variation in three plant factors and in evaporation rates were determined for dryland cotton and grain sorghum in central Texas. Plant factors measured were fractional ground cover, dry matter production, and leaf area index (LAI). When an adequate supply of soil water was available in the rhizosphere, plant factors influenced evaporation rates during most of the first half of the groiwng season until a “threshold” canopy LAI was obtained. A threshold canopy LAI is defined as the minumum LAI necessary to obtain 90% of potential evaporation (Eo) from row crops when the soil evaporation (Es) is small. The threshold LAI was approximately 2.7 for both crops studied. After the threshold canopy LAI was obtained, evaporation was practically independent of plant factors and equal to Eo, as estimated from daily net radiation, until soil water movement to plant roots began to limit evaporation.Es strongly influenced the actual evaporation rates obtained when plant canopy LAIs were below 2.7, To evaluate the influence of plant factors on the resulting plant evaporation (Ep) independent of Es, it was necessary to attempt a rational separation of Es, and Ep. Es was assumed to be equal to the net radiation equivalent of evaporation below the plant canopy when the soil surface was wet. After the soil surface dried sufficiently to limit water movement to the surface, Es was estimated from the measured soil water content near the surface. Ep was estimated using the measured evaporation and Es. The ratio Ep/Eo was found to be related to the LAI according to the equationEp/Eo = −0.21 + 0.70 LAI1/2, 0.1 ≤ LAI ≤ 2.7This nonlinear relation indicates that Ep is larger per unit of leaf area for smaller plants than for larger plants with LAIs approaching 2.7. Sensible heat originating over partially dry surface soil between plant rows was a significant source of the total energy contributing to EpThe physiological stage of growth did not greatly influence the amount of energy used in evaporation as grain sorghum plants approached maturity when an adequate supply of soil water was available.The results imply a possibility for improving water‐use efficiency of dryland crops by using higher plant populations and closer row spacings to decrease Es if the soil water supply and seasonal rainfall is adequate to produce an economic yield.
Spectral Properties of Soybean Leaves1
Authors: Gupta Ram K. , Woolley Joseph T. 
Published: July 2010

AbstractLight transmission and reflection by leaves are dependent on leaf pigmentation, morphology, and internal structure, all of which may be different in different ages and varieties of soybean leaves. These differences were measured and characterized in the hope that they would prove to be useful in varietal identification by remote sensing techniques.The reflectance and transmittance of three varieties of soybean leaves were measured over a wavelength range from 500 to 2500 nm using a ratio recording spectroreflectometer. Spectral characteristics of soybean leaves as affected by leaf age were determined. Reflection and absorption of light incident on the upper surfaces (faces) were compared with that of the lower surfaces (backs) of the same leaves. The spectral characteristics of three varieties of soybeans did not differ very much except in the visible region of the spectrum studied. Relatively young leaves reflected more than did old leaves of the same variety in the visible. This was associated with the chlorophyll development. The upper surface reflected less than did the lower surface of the same leaves in the visible region. Such differences were explained on the basis of internal leaf structure and composition.Although the spectral properties of the three soybean varieties have been established, it was not possible to make varietal identification on the basis of the spectral qualities.
Late Spring Applications of Nitrogen for Efficient Utilization and Enhanced Production of Grain and Grain Protein of Wheat1
Authors: Hucklesby D. P. , Brown C. M. , Howell S. E. , Hageman R. H. 
Published: July 2010

AbstractApplications of 56 and 112 kg N ha‐1 (as KNO3) on April 2 and 23 and May 9 and 224 kg N ha‐1 on April 23 to Arthur and Blueboy (soft red winter) and Parker (hard red winter) wheats increased yield of grain, grain protein and grain protein percentage without exception. The average increases for all treatments and varieties for grain yield, grain protein and percentage grain protein were 21, 63 and 36% over the respective control values. Based only on amino acid composition, quality of the grains was unaffected by the nitrogen treatments. Depletion of soil nitrogen estimated by removal of grain alone for all varieties occurred not only in the control plots but in plots receiving 56 and 112 kg N ha‐1. Only the 224 kg N ha‐1 treatment plots gave an estimated net gain in soil nitrogen.The favorable results obtained for grain and grain protein production, the increasing availability of lodgeresistant wheats, and the concern over nitrate pollution of ground water and streams, all indicate that the practice of split applications of nitrogen made late in the spring to wheat has merit.
Quantitative Effects of Nitrogen Fertilizer on the Development and Downward Movement of Soil Acidity in Relation to Level of Fertilization and Crop Removal in a Continuous Corn Cropping System1
Authors: Pierre W. H. , Webb J. R. , Shrader W. D. 
Published: July 2010

AbstractThe effect of NH4NO3 in a continuous corn cropping system on the depth distribution and amount of soil acidity produced was studied on four medium‐acid, prairie‐derived soils. To avoid the confounding effect of soluble salts, pH determinations were made after preliminary leaching of the soils and also by the 0.01 M CaC12 method. The amounts of acidity were measured by determining the quantities of CaCO3 required to bring the N‐treated plots to the pH of the No‐N plots.With amounts of N ranging from 1,525 to 2,626 kg N/ha no pH changes were found below the 15‐25‐cm layer. However, after a total of 5,600 kg N/ha had been used within 5 years pH changes were found at a depth of 30 to 45 cm.The total amount of acidity developed averaged 35% of the theoretical (3.57 kg CaCO3 per kilogram N) in the three experiments that received N ranging from a total of 1,525 to 2,626 kg N/ha over 13 to 15 years. In the experiment where 1,120 kg N/ha were used annually, the acidity developed was 60% of theoretical. This larger amount of acidity developed per unit of N with excessive N applications is explained by the lower percentage of fertilizer N recovered by the crop and the higher percentage remaining in the soil or leached as nitrates.With all additions of N, the development of much less than the theoretical amount of acidity is explained in part by the low excess base compared with N in the corn grain and cobs harvested. It is also, evidently, due to relatively large losses of N from the soil without an equivalent loss of bases, and it seems likely that such losses are due largely to denitrification.
Response of Corn to Small Amounts of Fertilizer Placed with the Seed: I. Greenhouse Studies1
Authors: Miller M. H. , Bates T. E. , Singh D. , Baweja A. S. 
Published: July 2010

AbstractThe effects of a complete NPK fertilizer banded with the seed of corn (Zea mays L.) were compared with those of larger amounts banded 3.8 cm to the side and below the seed. With the side band there was little uptake of applied P at the fourth week after seeding, and differences in growth favoured fertilizer with the seed up to the seventh week. Distance from the seed and toxicity of the higher fertilizer concentrations in the side band are suggested as reasons for the difference.Potassium banded with the seed added to the response obtained with N and P in one out of three trials. A small percentage of K is believed desirable in fertilizer applied with the seed, except on high‐K soils.When fertilizer was sprayed on the seed only, the response was small compared to that with the same concentration sprayed in a band across the seed and soil. Considering the small amount of fertilizer on the seed, the response was large, however, and leads to speculation on the effect of coating seed with fertilize.When a 6‐10.5‐5 fertilizer was banded with the seed at rates above 56 kg/ha in 91‐cm rows, there was an appreciable delay in emergence. The main advantage from fertilizer with the seed is the early growth response. High rates which delay emergence would therefore cancel the advantages which have been demonstrated.
Response of Corn to Small Amounts of Fertilizer Placed with the Seed: II. Summary of 22 Field Trials1
Authors: Bates T. E. 
Published: July 2010

AbstractFertilizer was banded with the seed of corn (Zea mays L.) at rates supplying 3.1, 5.4, and 2.5 g N, P, and per K meter of row, respectively, in 22 field trials. Fertilizer with the seed delayed and reduced emergence in several trials. On the average, it increased the dry weight of 36‐day‐old plants 36%, decreased the time to silking by 1.2 days, decreased the ear moisture at harvest 1.2% and increased grain yield 2.9%. A significant yield decrease due to fertilizer with the seed was observed in two trials. Fertilizer with the seed reduced ear node height and, in two trials, plant height. The effect on lodging was variable.
Feeding Corn or Molasses to Cattle on Orchardgrass Pasture1
Authors: Hart Richard H. , Bond James , Carlson G. E. , Rumsey T. R. 
Published: July 2010

AbstractCattle grazing an orchardgrass (Dactylis glomerata L.) pasture were self‐fed corn plus fat, molasses plus urea, or no supplement, at three stocking rates within each supplement treatment. Forage availability, supplement consumption, and the interaction between them accounted for 87% of the variability in ADG. Gain/ha increased linearly with stocking rate, until stocking rate became too high to permit grazing all season. Molasses increased ADG and gain/ha, and corn increased these still more. Supplements increased slaughter and carcass grades, overall meat desirability, and all components of desirability except color. Supplement will increase return to land, labor, and management, unless beef prices are unusually low and supplement prices are unusually high; feeding corn will usually be more profitable than feeding molasses.
Influence of Growth Stage and Stubble Height on Herbage Yields and Persistence of Smooth Bromegrass and Timothy1
Authors: Knievel Daniel P. , Jacques Aino V. A. , Smith Dale 
Published: July 2010

AbstractAlthough it is generally accepted that time of cutting and height of cutting are important in yield and persistance of forage grasses, studies of their interaction have produced variable results. Differences in environmental conditions (e.g., temperature and moisture) among field investigations could be responsible for this variability. Smooth bromegrass and timothy were harvested at three growth stages and two cutting heights in the field. Timothy was grown at warm and cool temperatures in the growth chamber and harvested at five growth stages and two cutting heights.Highest seasonal herbage yields and stand persistence of smooth bromegrass (Bromus inermis Leyss.) and timothy (Phleum pratense L.) in the field were obtained when the first crop was cut at early anthesis. Stand persistence was not affected by stubble height when both grasses were cut at early anthesis. Seasonal herbage yields were higher with a 4‐cm than with a 10‐cm stubble height. Bromegrass was more productive and persistent than timothy over the entire experimental period. Very few weeds occurred in the bromegrass during 1967 and 1968, and in the timothy during 1967. In 1968, timothy stands cut at early anthesis contained only 1 to 2% of weeds, but there were 6 to 15% in treatments cut at the tillering or inflorescence emergence stages.Highest herbage growth rate (HGR) and tillering rate of timothy in the growth chamber occurred with cutting at an early leafy stage or at early anthesis at both cool (18 C day/10 C night) and warm (32 C day/24 C night) temperatures. Lowest HGR occurred with cutting at midstem elongation and inflorescence emergence. Warm temperatures significantly reduced HGR and tillering rates at all growth stages and stubble heights. Cutting at a 4‐cm compared with a 12‐cm stubble height significantly lowered HGR at almost all growth stages at warm temperatures, but only at the tillering stage at cool temperatures. These results indicate that the yield and stand persistance response of cool‐season grasses to growth stage at cutting and height of cutting is partially dependent on temperature before and after cutting.
Effects of Soil Temperature Regimes on Growth Characteristics, Nutrition, and Grain Yield of IR22 Rice1
Authors: Bhattacharyya A. K. , De Datta S. K. 
Published: July 2010

AbstractThe effects of soil and water temepratures of 15, 25 and 35 C on the growth, nutrition, and grain yield of rice (Oryza sativa L.) were studied at three stages of growth in the greenhouse. The dwarf variety IR22 was used as the test plant. Plants grown at greenhouse temperature were used as the control.Low temperatures at the early vegetative stage retarded the growth of shoots and roots. Compared with the control, higher soil temperatures accelerated the growth and development of the plants. A temperature of 15 C delayed panicle initiation by 17 days and extended the time required for complete heading. Crop maturity was proportionately delayed. Soil temperatures during the early vegetative growth stage had little effect on the concentration of N, P, K and Si in plant tissues. Grain yields were unaffected by the temperature treatments at this stage.The plants were highly sensitive to cool soil and water temperatures during panicle development. Low soil temperature caused the death of lower leaves and chlorosis of the upper leaves, and both vegetative growth and dry matter production were retarded. Heading was also delayed at the low temperature and it took longer for all the panicles to emerge. Furthermore, fewer spikelets were formed and injury to some of them was observed. Dry matter production was highest at 25 and 35 C during panicle development. Grain yields were significantly decreased by a soil temperature at 15 C during this period.Plant growth and grain yields were least affected by low soil and water temperatures during the period from heading to crop maturity.
Age Effects of Cotton Leaves on Light Reflectance, Transmittance, and Absorptance and on Water Content and Thickness1
Authors: Gausman H. W. , Allen W. A. , Escobar D. E. , Rodriguez R. R. , Cardenas R. 
Published: July 2010

AbstractCotton plants (Gossypium hirsutum L.) were grown in the growth chamber, greenhouse, and field to study effects of leaf maturation on spectral properties, water content, and thickness of single leaves.In the 500‐ to 750‐nm region and at 1,650 and 2,200 nm, leaf age had a variable effect on reflectance. Over the 750‐ to 1,350‐nm wavelength interval (WLI), leaf reflectance was a maximum at node 8, and gradually decreased from node 8 to node 13.At the 1000‐nm wavelength, greenhouse‐ and field‐grown leaves had reflectances of approximately 51.0% compared with 46.0% for growth chamber‐grown leaves. For all environments middle‐aged leaves had highest reflectances.Field‐ and growth chamber‐grown leaves of all nodes except 3 from the apex had higher absorptance at the 550‐nm wavelength than greenhouse‐grown leaves. Middle‐aged leaves from all three environments had maximum absorptance.Greenhouse‐grown leaves had approximately two to four times higher absorptance at the 1000‐nm wavelength than field‐ and growth chamber‐grown leaves. For greenhouse leaves, absorptance was least at node 8. Leaf age had little influence on absorptance of field‐ and growth chamber‐grown leaves.Growth chamber‐grown leaves had the highest and fieldgrown leaves the lowest water content. In the growth chamber and field, leaf water content increased with leaf age.Leaf thickness generally increased with leaf maturation in all three environments, but growth chamber‐grown leaves were thinnest.Because growth chamber‐grown plants developed shadetype leaves, measurements on these leaves differed markdly from measurements made on leaves of field‐ and greenhouse‐grown plants. Thus growth chamber results should not be extrapolated to field conditions, unless it is known that the environmental conditions in the growth chamber closely simulate field conditions.
Advection and Evapotranspiration of Wide‐Row Sorghum in the Central Great Plains1
Authors: Hanks R. J. , Allen L. H. , Gardner H. R. 
Published: July 2010

AbstractThis study was conducted to evaluate the importance of advection as a source of energy for evapotranspiration from grain sorghum planted in 1‐m rows with both irrigated and dryland conditions. Detailed measurements of temperature, water vapor content, and wind speed were made within and above the canopy at various times and positions within the field during August 1967. Evapotranspiration was also measured by soil moisture sampling. Three types of advection were observed. Withincanopy advection resulted from the large amount of exposed dry soil between rows, which caused soil temperature between the rows to be as much as 20 C higher than plant temeprature. About 64% of the energy used to heat up the soil was used for transpiration in the irrigated plot, whereas only about 21% of the energy was used for transpiration in the dryland plot. Border advection, manifested by horizontal temperature and water vapor gradients, occurred over most of the plot irrigated but was most evident from 0 to 40 m from the upwind edge. This type of advection yielded sufficient energy to account for about 30% of the energy used for evapotranspiration from the irrigated plot. Large scale advection, manifested by temperature inversions, was found to occur during the night and probably yielded very little energy used for evapotranspiartion.
Influence of Fertility Ratios on Winter Hardiness of Bermudagrass1
Authors: Gilbert W. B. , Davis D. L. 
Published: July 2010

AbstractThe influence of different ratios of nitrogen, phosphorus, and potassium on cold tolerance of two golf‐green bermudagrass (Cynodon spp.) cultivars was investigated. Samples from field‐produced turf were depleted of soil nutrients before the fertility ratios were applied, then cold‐hardened in a growth chamber prior to being subjected to a standard freezing test. Significant differences occurred among several ratios in the amount of regrowth obtained in the greenhouse following freezing. Differences among treatments became greater with the decrease in tmperature. Ratios in which the levels of nitrogen and potassium were approximately equal and about 4 to 5 times greater than phosphorus gave the greater quantities of regrowth. Inferior treatments were those with higher amounts of nitrogen in relation to the other two nutrients. Of those tested, it was found that a ratio of 4‐1‐6 was superior in producing cold tolerance. These results indicate that a balanced fertility program with emphasis on adequate potassium in late summer would improve the cold resistance of the two bermudagrasses.
Effect of Gypsum and Drought Stress on Maize (Zea mays L). II. Consumptive Use of Water1
Authors: Downey Lloyd A. 
Published: July 2010

AbstractThe effect of three defined periods of drought stress on the consumptive use of water by field grown maize (Zea mays L.) was measured using a complete water balance approach. Water status within the crop was defined by noon measurements of relative turgidity (RT). The treatments were set out in a randomised block design with a further comparison between the untreated (sodic) soil and the same soil treated with gypsum at 22.4 m tons ha−1.The components of the water balance — soil stored moisture, rain, and applied irrigation — were measured directly, and deep drainage was calculated from chloride redistribution. The no‐stress treatment (RT at noon maintained > 90%) used 59 cm in evapotranspiration during the growing period. Drought stress (RT at noon < 90%) for a period of 20 days during male meiosis (early stress) reduced this total evapotranspiration to 44 cm, while drought stress during grain filling (late stress) reduced it to 51 cm. The application of gypsum had no significant effect on water use nor on water entry at irrigation.Application efficiency (total evapotranspiration/total applied water) was 86%, 79%, and 85% on the no‐stress, early‐stress, and late‐stress treatments respectively. The balance (15 to 20%) of applied water was lost as deep drainage, indicating that results on more permeable soils would be inaccurate if this component were ignored.Maximum water use of 0.9 cm day−1 (or 0.8 of class “A” pan) occurred during anthesis. This period was delayed 10 days by early stress. Water use efficiency was highest for the early stress‐87 kg dry grain/cm water/ha and lowest for the late stress‐26kg.
Light Intensity and Sunfleck‐size Distributions in Plant Canopies1
Authors: Norman J. M. , Miller E. E. , Tanner C. B. 
Published: July 2010

AbstractA theory predicting the gap‐size distribution of a canopy of horizontal, azimuthally symmetric, randomly located, flat leaves of any shape is compared to measurements in sumac (Rhus typhina L.), sunflower (Helianthus annuus L.), and an artificial canopy. Light intensity distributions of the solar beam component on a horizontal surface below these canopies are predicted by combining the gap‐size distribution theory with penumbral effects of the finite solar disc. These predictions of the beamcomponent distribution are then combined with average diffuse penetration theory and a new scattering theory to produce a final light intensity distribution for comparison with measurements from a miniature light sensor in visible and near‐infrared wavelength bands. The agreement is good and indicates that sizable penumbra effects occur in canopies only 2 m in height.
Factors Affecting the Development of Flue‐Cured Tobacco Grown in Artificial Environments. III. Morphological Behavior of Leaves in Simulated Temperature, Light‐Duration, and Nutrition Progressions During Growth1
Authors: Raper C. D. 
Published: July 2010

AbstractThe growth environment of a plant determines the ultimate expression of many characteristics of development. Among other environmental variables, a plant growing in the field encounters seasonal progressions of temperature, daylength, and nutrient supply. To determine if these natural, seasonal progressions are essential for reproducing “normal” field growth of flue‐cured tobacco (Nicotiana tabacurn L. ‘Coker 319’) in controlled‐enviromnent facilities, simplified simulations of temperature, light‐duration, and nitrogen and potassium nutrition were established in controlled‐enviromnent rooms. Regression‐descriptors plots of regression equations with leaf‐stalk position as the independent variable) of size, shape, and specific weight of mature leaves from plants grown under combinations of these simulated progressions and constant temperature, light‐duration, and nutrition regimes were evaluated relative to characteristic regression‐descriptors derived from field grown plants.A seasonal progression of temperature and progressive reductions of nitrogen and potassimn supply are critically involved in determining the physical attributes of leaves characteristic of “normal”, field‐grown tobacco. Combined with a continuous daily light‐duration of 9 hours, the simulated progressions of temperature and nutrition most nearly facsimilated a “normal” leaf‐size ordering and resulted in the least disruption of “normal” variations of leaf shape and specific leaf weight due to stalk position.