bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Increasing Foliage and Soil Reflectivity on the Solar Radiation Balance of Wide‐row Grain Sorghum1
Authors: Fuchs M. , Stanhill G. , Moreshet S. 
Published: July 2010

AbstractExcessive radiant heat load limits the growh of plants in dryland farming during the rainless summer. The use of reflectants to control the radiation balance in field conditions is examined here.Modifications of the solar radiation balance in a wide‐row sorghum [Sorghum bicolor (L.) Moench ‘726’] crop grown on a dark brown grumusol (Chromoxererts) were obtained by spraying a white kaolin suspension on 1,000 m2 field plots. Treatments consisted of separate applications of the kaolin on the foliage and on the soil surface, and combined applications on both the foliage and the soil.Radiation transfer equations were used to quantify the effect of the various treatments on the solar radiation absorption of the foliage, and of the soil. These equations account for the presence of direct and diffuse components in the downward solar flux and make specific reference to a simplified definition of the radiation scattering properties of the foliage and the soil. Measurements of the diurnal variation of the solar radiation reflection above each experimental plot and fisheye determinations of the foliage distribution validated the simplifying assumptions used in deriving the transfer equations. With some additional assumptions the equations are extended to predict absorption by the foliage and the soil from daily totals of the global radiation.The reflectivity of the foliage increased by 24% immediately after spraying kaolin on the canopy. A 17% increase persisted 5 weeks later. The corresponding seasonal net solar absorption was reduced by 6%. The soil treatment doubled the solar reflectivity of the soil, causing an 18% decrease of the solar absorption by the soil. The increased reflected solar flux from the soil surface was partly intercepted by the foliage, and produced a 9% increase of absorption by the foliage. The application of kaolin to both the foliage and the soil resulted in very little change in the absorption by the canopy, the whitening of the foliage being offset by the addition of the radiation reflected by the soil, but was most effective in increasing the solar reflection from the field. Larger reductions of the canopy solar radiation balance can be expected by improving the dispersion of the kaolin coating on the entire foliage.
Biological Significance of Reed Canarygrass Alkaloids and Associated Palatability Variation to Grazing Sheep and Cattle1
Authors: Marten G. C. , Jordan R. M. , Hovin A. W. 
Published: July 2010

AbstractTotal basic alkaloid concentration of reed canarygrass (Phalaris arundinacea L.) is negatively correlated with palatability (selection when a choice is offered) of the grass to ruminant animals. The significance of these alkaloids to ruminants not offered a choice of pasture forage remained unknown. Our objectives were to determine whether alkaloid concentration and alkaloid type differences among reed canarygrass genotypes affect animal performance, grass intake, and health of grazing sheep and cattle.Replicated pastures representing two primary alkaloid types (gramine vs. tryptamine‐carboline) and two alkaloid concentrations were primarily established from eight clones of reed canarygrass. During 1973 and 1974, these pastures were grazed by lambs and during 1975, by steers.Total alkaloid concentration of the grass was highly negatively associated with average daily gains by lambs and steers (r= —0.91, —0.90, and —0.91 for 1973, 1974, and 1975, respectively). Alkaloid concentration was highly negatively correlated with an estimate of voluntary intake (r = −0.85) by lambs not offered a choice of reed canarygrass genotypes, but alkaloid concentration was not usually overtly associated with voluntary intake by steers. Animals had more diarrhea when grazing high‐alkaloid plants and when grazing tryptamine‐carboline‐containing compared to gramine‐containing plants. This physiological upset may have been a major contributor to reduced animal gains.Breeding or managing reed canarygrass cultivars for lower alkaloid concentration per se, and breeding for tryptamine‐carboline‐free (gramine‐containing) cultivars, should provide pasture that has improved animal performance potential. “Phalaris staggers” or “sudden death” were not incited in sheep or cattle grazing exclusively reed canarygrass that had very high indole alkaloid concentrations. This indicated that these disorders, thought to be caused by indole alkaloids in animals grazing Phalaris species, are very likely not caused by indole alkaloids alone.We have conclusively demonstrated that palatability differences and their associated alkaloid concentration differences among reed canarygrass genotypes have a substantial biological significance for grazing lambs and steers.
Yields and Nutrient Accumulation by Determinate Soybeans, as Affected by Applied Nutrients1
Authors: Terman G. L. 
Published: July 2010

AbstractMost published results with southern determinate soybeans [Glycine max (L.) Merr.] are concerned with only a single fertilizer treatment and/or one or two sampling dates. Consequently, field experiments were conducted to determine effects of applied N and K on dry matter yields, nutrient concentrations, and nutrient uptake at several sampling dates and on final grain yields. Rates of 0, 86, and 172 kg of applied K/ha and 0 and 70 kg of N were compared in a field experiment on Sango sil (Ochrepic Fragiudult) in 1973 and K rates of 0, 75, and 150 kg/ha in 1974.Marked responses to applied K were obtained. Maximum dry matter yields and nutrient uptake occurred during the early pod filling stage of growth. Dry matter yields then declined as a result of greater loss of leaf and petiole drop than of increase in grain filling. Concentrations of K in leaves, topgrowth, and grain increased with amount of applied K, but top trifoliate leaf blade concentrations were lower than some published recommended levels for high yields. Marked reciprocal relationships occurred among concentrations of K and Ca or Mg in top trifoliate leaves and topgrowth.Several combinations of N, P, K, and S foliar‐ and soil‐applied during pod filling were also compared in a 1976 pot experiment on Sango sil. Grain yields and concentrations of each applied nutrient were increased in leaves and grain. Pod numbers were highly correlated with grain yields.
Changes in Chemical Composition of Kentucky Bluegrass and Tall Fescue Herbages Following N Fertilization1
Authors: Hojjati S. M. , Templeton W. C. , Taylor T. H. 
Published: July 2010

AbstractMost research on N fertilization of grasslands has dealt with yield responses, with much less attention to feed quality. These field studies were undertaken to determine the effects of four rates of N and harvest time on levels of crude protein (CP), P, Ca, K, and Mg in spring and early‐summer aftermaths of Kentucky bluegrass (Poa protensis L.) and tall fescue (Festuca arundinacea Schreb.) grown on Typic Paleudults soil.NH4NO3 was applied to supply 50, 100, 150, and 200 kg N/ha. The fertilizer treatments were replicated in time (9 April, 30 April, and 21 May), as well as space, to introduce different environmental conditions and plant development stages. Herbage samples were collected weekly during three 6‐week periods following fertilization.CP in both grasses increased with larger applications of N, reaching peak values of 32.8 and 32.5% in bluegrass and tall fescue, respectively, in the first growth period, 2 weeks after fertilization. Minimum values of 11.8 and 9.7% occurred in 6‐week growths of bluegrass and fescue, respectively, with 50 kg N/ha.Effects of N on P concentrations were inconsistent. Concentrations of Ca and K in both grasses rose with increasing N, as did Mg in the first two growth periods. In the second half of period 3, high N decreased Mg concentrations. The latter effect and the fact that high levels of N reduce Mg availability to animals indicate an increased likelihood of tetany, especially with bluegrass, when large amounts of N are applied in spring.Elemental concentrations of Ca, P, and K in both grasses appeared adequate to meet ruminant requirements, irrespective of N application. With the possible exception of K, none of the four elements appeared to be limiting for plant growth. Bluegrass herbage, especially in growth period 3, often contained less than 2.0% K.Ca/P ratios increased with higher applications of N in periods 2 and 3, but not in 1. Effects of N on K/(Ca+Mg) ratios were inconsistent, but values only once reached the critical level of 2.2.
Root Growth and Nutrient Uptake Characteristics of Some Cowpea Varieties1
Authors: Adepetu J. A. , Akapa L. K. 
Published: July 2010

AbstractEfficient utilization of fertilizer P and K by a crop depends, to a large extent, on the amount of roots that contact the fertilizer nutrient, as well as the capacity of the root to absorb the contacted nutrient. In order to find a Nigerian cowpea that utilizes soil and applied nutrients best, five cowpea cultivars commonly cultivated in Nigeria were grown in fertile and N, P, and K deficient soils in the greenhouse. Specific objectives were to determine differences in root growth (length) and nutrient uptake efficiencies of roots (μg/m) among the five cultivars.To determine the effect of age on the ability of a cowpea plant to utilize soil nutrients, cowpea cultivar ‘H113–4’ was grown for 30 days in solution culture and changes in root length and nutrient uptake rates (μg/m‐day) as functions of plant age were evaluated. When grown in fertile soil, ‘Ife‐brown’, H113–4, and Westbred cultivars had significantly greater root lengths (17.5, 17.2, and 16.7 m respectively) than ‘1534’ (14.3 m.); while ‘Crimson's’ root length (15.4 m) was intermediate. In the N‐P‐K‐ deficient soil, however, Crimson had the most extensive root system (19 m). Apparently, H113–4 had the greatest total uptake of P, K, and Ca (9.9 mg), K uptake efficiency (360 μg K/m root length), and shoot:root ratio (W/W). Also, the P and Ca uptake efficiencies of this cultivar (160 and 75 μg/m respectively), and the dry matter yield (0.94 g) were among the highest. The total length of roots of Hl13–4 was a linear function of plant age (R2 = 0.94) up to 30 days of age. Phosphorus and K uptake rates in solution culture decreased tremendously from 34 μgP/m‐day and 380 μgK/m‐day, at 5 days old, to 8 μgP/m‐day and 95 μgK/m‐day at 30 days, respectively. Deficiency of K in the solution culture markedly reduced P uptake by the root. It is concluded that H1 13ߝ4 variety has superior potential over other cowpea varieties studied for efficient utilization of applied P and K; and that the nutrient absorption capacity of young cowpea roots decreases rapidly with age.
Effects of Intercropping on Soybean N2‐Fixation and Plant Composition on Associated Sorghum and Soybeans1
Authors: Wahua T. A. T. , Miller D. A. 
Published: July 2010

AbstractSorghum (Sorghum bicolor (L.) Moench) and soybean (Glycine max (L.) Merrill) are being intercropped in the tropics so that crops more effectively utilize water; there is better weed control, and soil fertility is improved. A field experiment was conducted to determine the effects of sorghum‐soybean intercropping on soybean N2‐fixation and plant composition of both crops. The soil was a Flanagan series, a fine, montmorillonitic, mesic Aquic‐Argiudoll. Soybeans were intercropped with tall and semi‐ dwarf sorghum cultivars at 16 population densities from 1.38 to 33. plants/m2. Soybean N2‐fixation was estimated by acetylene reduction. Various plant parts were analyzed for present N.Nitrogen‐fixation by soybeans grown with tall sorghum was reduced 99% due to reduction in number of nodules per plant (77%), weight per nodule (50%), and specific nodule activity, SNA, (96%). Soybean dry matter and seed percent oil were also reduced by 87 and 8%, respectively. Soybean percent seed protein and leaf N were unaffected by intercropping.Soybeans grown with semi‐dwarf sorghum fixed 2.64 times more N than plants in monoculture but produced 40% less dry matter and 3% less oil in seed. Percent seed protein and leaf and stem N of soybeans were unaffected by intercropping. The increase in N2‐fixation was probably due to increases in number of nodules per plant (62%) and SNA (364%). Possible involvement of allelopathy, NO3‐ absorption, delayed senescence, and inter‐ specific mechanical support was considered.Protein yield of intercropped tall and semi‐dwarf sorghum was reduced by 15 and 71%, respectively. Only in the dwarf cultivar did intercropping increase percent seed protein by 15%. Sorghum grain oil was unaffected by intercropping.
Influence of Fertilizer and Residue Management on Grass Seed Production1
Authors: Canode C. L. , Law A. G. 
Published: July 2010

AbstractPostharvest residue burning, a standard practice in grass seed production in the Pacific Northwest, may be restricted because of concerns for air quality. This research compares the effects of burning with those of mechanical residue removal on red fescue (Festuca rubra L.), smooth bromegrass (Bromus inermis Leyss.), and crested wheatgrass [Agropyron desertorum (Fisch. ex Link.) Schult.].The experiments were conducted on a silt loam soil (Pachi Ultic Haploxerolls) as a split‐plot within each grass species. Main plots were three levels of 18‐10‐10‐7 fertilizer applied to supply N at 90, 112. and 135 kg/ha, with an associated increase in P, K, and S. Main plots were split for open burning and two levels of mechanical residue removal. Two crops of red fescue and four seed crops of smooth bromegrass and crested wheatgrass were evaluated.Average seed yields (kg/ha) for burning compared with mechanical straw removal were 636 vs. 495 for red rescue, 1,122 vs. 848 for smooth bromegrass, and 872 vs. 790 for crested wheatgrass. Straw and stubble removal, compared with straw removal alone, increased seed yield of red rescue and smooth bromegrass, but decreased seed yield of crested wheatgrass.Interactions of fertilizer rates and residue management were not significant. Increasing the fertilizer rate did not compensate for the reduction in seed yield associated with mechanical removal of residue. Seed yields of smooth bromegrass and crested wheatgrass were increased by high fertilizer rates as the age of stand increased.The increase in seed production resulting from burning residue apparently was associated with control of downy bromegrass (Bromus tectorum L.) and increased vigor of autumn regrowth. Diseases and insects were of little consequence and probably had little influence on seed yield in these experiments.
Effects of pH, P, and Al on the Growth and Chemical Composition of Crownvetch1
Authors: Vickers J. C. , Zak J. M. 
Published: July 2010

AbstractMassachusetts roadsides often consist of acid, infertile soil which is subject to erosion when without adequate cover. Crownvetch (Coronilla varia L.) is a legume which has been introduced for the purpose of rapid, attractive, and inexpensive stabilization of such sites. The response of crownvetch to soil acidity and correction of this condition have not been closely examined. This investigation consisted of combining three pH, two phosphorus and three aluminum rates in soil and water culture studies. The objective was to study the effects of the soil treatments on factors of soil acidity, as well as the chemical composition and growth of crownvetch. By studying the relationships among these factors it was hoped to better characterize the acid tolerance and cultural requirements of this species. In both media, mean dry weights increased as pH was increased from 4.2 to 5.4. Yields did not increase further at pH 6.3. Reduced P availability and excess exchangeable soil Mn, which resulted from the high lime level, appear to be involved in restricted plant growth at a soil pH of 6.3. Root Al content was negatively correlated with top weights; however, neither pH nor Al treatments were related to root length in soil and water culture. A mean exchangeable Al level of 4.5 ppm (at the highest Al rate) in soil and 5.0 ppm A (and above) in water culture appreciably diminished the growth rate of crownvetch. The high Al additions in these studies became more of a problem to plant growth at low pH and P conditions. It was found that the soil P application resulted in a lower incidence of symptoms of leaf black spot and enhanced root penetration. Liming this soil to pH 5.4, and applying 75 ppm P (168 kg/ha) significantly benefited the growth crownvetch. Optimum soil Al and Mn levels combined with enhanced Ca and P availability are thought to be major reasons for these benefits.
Use of a Bleach Test to Screen Single‐head Sorghum Selections for the Presence of a Testa Layer1
Authors: Kofoid K. D. , Maranville J. W. , Ross W. M. 
Published: July 2010

AbstractThe development of random mating populations of sorghum [Sorghum bicolor (L.) Moench] has resulted in an increase in the frequency of material with a testa layer. Since the testa layer has been associated with tannin, genotypes with a testa need to be identified in these populations with ease and certainity. Hence, a procedure using KOH and bleach (6% NaOCI by weight) to determine the presence of a testa layer in sorghum was modified for use on single‐head selections and was evaluated for its usefulness as a screening technique.Three concentrations of KOH:bleach (1:6, 1:5, and 1:4 w/v) at each of three water bath temperatures (50, 60, and 70 C) for three time periods (10, 15, and 20 min) were. tested to determine the optimum conditions for maximum color development of the kernels. Significant main effects were found for genotypes, time, and temperature. Partitioning of the genotype sum of squares into single degree of freedom comparisons showed significant differences between genotypes with and without a testa. Pericarp pigmentation also was found to significantly affect the rating in both the testa and nontesta material. However, this effect was not judged to be detrimental to the determination of presence or absence of a testa layer. Significant differences were found between waxy and yellow endosperm material, but this was probably due to pericarp pigmentation. Significant 2, 3, and 4‐way interactions indicated that no single combination of treatments was optimum for all entries. However, immersing kernels in a concentration of 1:5 (w/v) KOH:bleach at a water bath temperature of 60 C for 15 min resulted in a maximum rating for genotypes with a testa. Use of this procedure allows for the screening of a large number of selections for the presence of a testa layer with relative ease and reliability.
Fungicides in Kentucky Bluegrass Turf: Effects on Thatch and pH1
Authors: Smiley R. W. , Craven M. M. 
Published: July 2010

AbstractManagement of thatch and pH are important aspects of turfgrass culture. The use of disease‐preventive fungicides is a standard practice on highly‐maintained turfgrasses, and fungicides may be toxic to many thatch‐decomposing microorganisms. However, little information exists concerning the effects of long‐term fungicide programs on thatch accumulation. The influence of 14 fungicides, one nematicide, and of five mixed fungicide programs, applied over a 3‐year period, on thatch decomposition and the resultant pH of underlying soil was investigated on a blended Kentucky bluegrass (Poa pratensis L.) sod. The physical depth of noncompressed thatch was measured after samples were removed from plots with a Noer Soil Profile Sampler. Cores of 2.54 cm diam were used to determine pH characteristics of the soil profile. Thatch depths among fungicide treatments ranged from 2.8 to 22.0 mm, and the pH (saturated paste in 10 mM CaCl2) of the surface 3 cm ranged from 5.6 to 6.5. Thatch depth and pH of the surface 3 cm of thatch plus soil were inversely related (r = −0.797; significant at p = 0.001), although differences in pH among treatments were associated with the mineral soil fraction and not with the thatch. Fungicide‐induced reductions in pH occurred to depths exceeding 20 cm. Acidification of soil was apparently not the result of organic acids leaching from decomposing thatch, but was correlated (r = −0.564; significant at p = 0.01) with the contributions of sulfur (up to 491 g S/are/year) from the fungicides. Oxidation of sulfur from decomposing fungicides reduced the soil pH which, in turn, reduced the activity of microorganisms responsible for degradation of thatch. Thatch accumulation was not considered to be due to inhibitory effects of fungicides toward earthworms.
N Deprivation in Maize During Grain‐Filling. II. Remobilization of 15N and 35S and the Relationship between N and S Accumulation1
Authors: Friedrich J. W. , Schrader L. E. 
Published: July 2010

AbstractThe role of N and S remobilization in ear development of maize (Zea mays L.) has not been adequately assessed. The objective of this greenhouse experiment was to determine the effect of N deprivation during grain‐filling on N and S remobilization and the relationship between N and S accumulation. Maize plants were grown in nutrient solution containing 15N‐nitrate and 35S‐sulfate. After silking, the plants were placed in unlabelled solutions, with or without nitrate‐N. The amount of labelled and unlabelled N and S in several plant fractions was determined at silking and 1, 2, 3, 5, and 7 weeks after silking. The remobilization of labelled N and S was not markedly affected by N deprivation. Unlabelled N (when supplied) and unlabelled S accumulated in all plant fractions, but did not affect the concentration of N or S in the ear. Nitrogen deprivation resulted in only a 19% decrease in ear N content. Labelled N constituted 100% of the total ear N in plants deprived of N as compared to 84% for control plants. Labelled S comprised 73% of the total ear S in N‐derived plants as compared to 56% in plants supplied with N. The ratio of reduced N to reduced S (NR/SR) in the ear was lower in N‐deprived plants. The NR/SR, ratio in the leaves was not affected by N deprivation, and declined during grain‐filling. Apparently, the remobilization of N and S contributes more to ear development than does the absorption of N and S after silking.
Harvest Index of Soybeans as Affected by Planting Date and Maturity Rating1
Authors: Johnson D. R. , Major D. J. 
Published: July 2010

AbstractSelection for high harvest index has been used by plant breeders to improve the seed yield of several crop plants, but in soybean [Glycine max (L.) Merrill] errors in the estimate of harvest index may occur because of interactions with maturity or seeding date and because harvest index measured at maturity does not include leaf and petiole dry weights. The objective of this study was to examine harvest indices of 10 soybean genotypes representing a wide range of maturity and seeded on several dates and to compare estimates of harvest index calculated from biological yield measurements with and without leaf and petiole dry weights.Vegetative yield at the time of leaf senescence and seed yield at maturity were measured in 10 cultivars of soybean (two from each of maturity groups I–V) planted in a silt loam soil (fine, montmorillonitic, mesic Udollic Ochraqualfs) at five dates from late April through early July. Biological yield was defined as total above ground plant yield and harvest index was calculated as the ratio of seed yield to biological yield. A positive relationship was detected between biological and seed yield, presumably because of a strong photoperiod response. As biological yield increased, seed yield increased proportionally and harvest index stayed the same. Premature killing by frost decreased the harvest index. Variability for harvest index among cultivars within the same maturity group was indicated, but this was influenced by planting date and maturity group. It was concluded that selection for increased harvest index in soybean would have to be done within cultivars representing a narrow range of maturity and planted at the same time.