bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth Characteristics of Oriental Tobacco as Affected by Cultivar and Type1
Authors: Lolas P. C. , Galopoulos A. , Sficas A. G.
Published: July 2010

Oriental tobacco (Nicotiana tabacum L.) grown in Greece is classified commercially into three types: a) Aromatic, b) Neutral, and c) Taste. Although growth characteristics of flue‐cured and burley tobacco have been extensively studied, very little work has been done on oriental tobacco. Two cultivars of each of the three oriental types were grown in field plots replicated three times for 3 years. Data obtained at 0, 20, 30, 40, 60, 85, and 105 days after transplanting were: dry weights of roots, stalks, leaves, and inflorescences; plant heights; number of harvestable leaves; relative growth rate; and absolute growth rate. The types and cultivars differed significantly in their growth rates, and patterns after 60 days from transplanting. Generally, cultivars within the same type were not significantly different. All of the measured growth characteristics followed the sigmoid growth curve with the period of rapid growth being from 30 to 60 days after transplanting. Aromatic cultivars were fast growing, early maturing, and low in total dry matter. Taste cultivars, on the other hand, were slow growing, late maturing, and high in total dry matter. Neutral cultivars were intermediate. In all three types, leaves comprised about 40%, stems 25%, roots 18%, and inflorescences 17% of the total plant dry matter. It is concluded that the critical growth period for oriental tobacco cultivars and types is, as for flue‐cured and burley, 30 to 60 days after tansplanting.
Honey Bees as Pollinators for Hybrid Cotton Seed Production on the Texas High Plains1
Authors: Vaissière Bernard E. , Moffett Joseph O. , Loper Gerald M.
Published: July 2010

The production of hybrid cotton (Gossypium hirsutum L.) seed on a large scale requires the use of an economical and reliable agent for pollen transfer. In 1980, five commercial fields of cytoplasmicgenetic male‐sterile (A‐line) and male‐fertile maintainer (B‐line) cotton were grown on a thermic Torrertic Paleustolls soil on the Texas High Plains. To test the ability of the honey bee [Apis mellifera L. (Hymenoptera: Apidae)] for pollinating A‐line cotton, colonies were placed along the sides of three fields. In the two fields (14 ha; 15.5 colonies/ha, and 24 ha; 13.2 colonies/ha) where honey bee colonies were distributed along at least three sides of a field, the seed cotton yield of the A‐line was not significantly different from that of the B‐line, so that, when grown under a similar environment and with adequate pollen transfer, the A‐ and B‐lines produced equal yields of seed cotton. In the 24‐ha field, uniform pollination was achieved. In a third field (15.2 ha; 7.5 colonies/ha) where hives were located along only one edge, however, the A‐line seed cotton yield was 30% less than that of the B‐line and pollination was not uniform. In two other fields (4.0 and 1.4 ha, respectively) where no honey bees were provided, the A‐line yielded 79% less seed cotton than the B‐line in one case and 91% less in the other. Results demonstrated that pollen was transferred by honey bees, and the transfer efficiency depended upon the number and distribution of the colonies. On the other hand, pollination was highly variable and less than adequate when only native pollinators were present.
Pneumatic Applicator for Uniform Distribution of Dry Fertilizer on Small Plots1
Authors: Varvel G. E. , Severson R. K.
Published: July 2010

Uniform distribution of dry fertilizer materials on small plot areas has been a problem for many years because most of the equipment has been developed for field application. Recent developments of pneumatic herbicide and fertilizer application equipment have been made which allow uniform distribution of these materials over various size areas. These developments made components available which were used to construct a small‐plot applicator to broadcast or inject dry fertilizer. This applicator accurately and consistently metered and distributed three fertilizer materials which varied in particle size. The use of air to distribute the fertilizer also permits various applicator widths with the same machine.
Nitrogen Nutrition and Yield of Seedling Alfalfa as Affected by Ammonium Nitrate Fertilization1
Authors: Eardly B. D. , Hannaway David B. , Bottomley P. J.
Published: July 2010

Nitrogen fertilization of seedling legumes is a controversial management practice intended to provide an N source to the plant prior to the development of N2‐fixation activity. Field experiments were conducted in 3 consecutive years (1980,1981, and 1982) to evaluate the effect of ammonium nitrate (NH4NO3) at establishment on nodulation, acetylene reduction (AR), percentage herbage N, and dry matter yield of 10‐week‐old seedling alfalfa (Medicago sativa L. cv. Apollo). The soil at the field site was a Woodburn silt loam, a member of the fine‐silty, mixed, mesic Aquultic Argixeroll. The soil contained 8 to 12 mg kg−1 of available soil N. Six rates of NH4NO3‐N were applied preplant in 1980 and nine rates were applied preplant in 1981 and 1982 (0‐224 kg N ha−1) in a randomized complete block design. Data from the 1980 experiment suggested that the native population of Rhizobium meliloti Dang. was ineffective in N2 fixation. This was confirmed by effectiveness tests of native strains of R. meliloti in 1981. In 1982 an inoculation variable was added in a factorial treatment combination to examine the effects of NH4NO3 fertilization on the N nutrition and yield of both effectively and ineffectively nodulated alfalfa. Results from the three field experiments indicated that only plants which were ineffectively nodulated exhibited substantial increases in herbage yield and Kjeldahl N concentration in response to the “NH4NO3 applications. All rates of NH4NO3 fertilization decreased nodulation in a curvilinear response. For example, application of 45 kg N ha−1 reduced both nodulation and AR by 45% at 10 weeks (early bloom) regardless of rhizobial effectiveness. Nitrogen fertilization also increased weed competition in 1981 and herbage nitrate levels in 1982.
Wheat Performance Using No‐Tillage with Controlled Wheel Traffic on a Clay Soil1
Authors: Gerik Thomas J. , Morrison John E.
Published: July 2010

Wheat (Triticum aestivum L.) is frequently grown in rotation with summer annual crops. These crops are usually grown in widely spaced rows that can easily adapt to controlled‐traffic management, but high soil strengths prevent crop establishment into controlled‐traffic lanes, eliminating one or more rows of wheat. Wheat can compensate (within limits) for lost cropping area, but the effect of no‐tillage culture with controlled traffic is not known. We conducted this study to compare two tillage systems, conventional and no‐tillage with controlled traffic, on grain yield and yield components of wheat. It was conducted over a 3‐year period on an Austin silty clay (fine‐silty, carbonatic, thermic Entic Haplustolls). The no‐tillage treatment confined all wheel‐induced compaction to controlled traffic zones at 2‐m intervals. Crop residues were destroyed completely by repeated tillage and wheel traffic occurred randomly under the conventional tillage treatment. Hard red winter wheat (cv. Sturdy) was grown in rotation with row crops that were subjected to the same tillage and wheel traffic practices. Rows were spaced 20 cm apart in each tillage system, but two rows were deleted in the traffic zones of the no‐tillage treatment, resulting in 20% less cropped area. Plants on rows adjacent to the controlled‐traffic zones compensated for the absence of wheat within the traffic zones during years of adequate precipitation (1981 and 1983) by producing more tillers and grain than plants in rows within the no‐tillage treatment and those grown under conventional tillage. Drought in 1982 significantly lowered tillering and grain yields under no‐tillage. The study established that wheat can be grown using no‐tillage with controlled traffic. Wheat should be grown with no‐tillage controlled‐traffic technology where drought is minimized or as a component of a total management system where yield increases from alternative crops and/or lower production costs are primary issues.
Stomatal Closure Behavior Induced by Row Spacing and Evaporative Demand in Irrigated Peanuts1
Authors: Stone J. F. , Erickson P. I. , Abdul‐Jabbar A. S.
Published: July 2010

Peculiar stomatal action has been suggested as one causal factor for observed differences in water use between peanuts (Arachis hypogaea L.) grown in narrow and wide rows. This study was designed to characterize stomatal action in narrow‐ and wide‐row plantings on a Udic Argiustoll soil. Measurements of stomatal diffusive resistance (Rs) and leaf‐water potential (Ψw) were made daily at half hour intervals on irrigated peanuts grown in narrow‐row (NR) and wide‐row (WR) spacings during periods of flowering to pod development in 1979,1981, and 1982. Measurement days were classified as low, moderate, and high evaporative demand days according to respective daily meteorological conditions. In both NR and WR treatments the relationship between Rs and Ψw was generally linear. On certain days, however, NR‐Rs increased to much higher values earlier in the afternoon at a given Ψw than WR‐Rs. The effect was most pronounced on high evaporative demand days and was never noted on low evaporative demand days. Data for 3 years reveal the NR stomatal closure effect was real and repeatable.
Agronomic and Economic Response of Three Tropical Legumes to Lime and Phosphorus in an Acid Infertile Spodosol1
Authors: Snyder G. H. , Kretschmer A. E. , Alvarez J.
Published: July 2010

Numerous potential benefits have been cited for the inclusion of tropical legumes in pastures, but few commercial successes have been realized. Information is needed on even the most basic aspects of tropical legume culture. The study herein was designed to determine rates of lime and P for maximum yield of three tropical legumes, and to estimate the rates resulting in maximum economic return under field conditions. An acid infertile Spodosol was amended with lime up to 4000 kg ha−1 and P up to 80 kg ha−1. Equations relating herbage yield during the first 2 years of growth to rates of lime and P were developed. All three legumes (Aeschynomene americana L., Macroptilium atropurpureum Urb., and Desmodium heterocarpon DC.) responded positively to both lime and P. Maximum yield of Desmodium was obtained at lime and P rates of 2740 and 75 kg ha−1, respectively. Maximum calculated herbage yields of Aeschynomene and Macroptilium were obtained at lime and P rates somewhat in excess of maximum treatment levels. An economic analysis that considered hay as the produced product revealed that maximum economic returns occurred at lime and P rates only slightly lower than those for maximum yield. Considering protein as the product, for all three legumes lime and P rates of approximately 3000 and 75 kg ha−1 produced maximum yield and maximum economic return.
Biomass and Sugar Yield Response of Sweet Sorghum to Lime and Fertilizer1
Authors: Soileau John M. , Bradford B. N.
Published: July 2010

Soil fertility requirements for sweet sorghum [Sorghum bicolor (L.) Moench] as an alcohol fuel crop have not been well defined. The primary objective of this study was to determine the biomass and sugar (% Brix ✕ extracted juice) yield response of sweet sorghum to N‐P‐K and lime. The study was conducted for 2 years on a Wynnville silt loam (fine‐loamy, siliceous, thermic Glossic Fragiudult) soil in the Cumberland Plateau region of northern Alabama. Experimental design was a split‐plot with 0 or 8 Mg ha−1 dolomitic limestone and combinations of 0, 45, 90, or 180 kg ha−1 N, 30 or 90 kg ha−1 P, and 40 or 120 kg ha−1 K. Liming significantly increased yields of fresh and dry biomass, grain, and juice sugar extracted from stalks. The lime also greatly reduced exchangeable soil Mn and Al and increased Mg and decreased Mn concentrations of the biomass. Due to the dominant effect of lime and other interactions, biomass and juice sugar yields were not consistently related to applied N, P, or K. In nonlimed soil, biomass and sugar yields decreased with high N in the presence of low P‐K, but not with high P or K. This suggests an acidity ✕ P and/or K interaction related to toxicity of soil Mn and/or Al. In the limed soil the maximum dry biomass and sugar yields occurred with 180‐90‐120 (1981) or 90‐90‐120 (1982) kg ha−1 N‐P‐K, however yields from some treatments with lower levels of N, P, or K were often not significantly different at the 0.05 level. Inherent soil acidity and related Mg deficiency must be corrected to obtain maximum response of sweet sorghum to fertilization in Wynnville and associated soils of the Cumberland Plateau region.
Temperature Effects on Germination of Birdsfoot Trefoil and Seombadi1
Authors: Hur S. N. , Nelson C. J.
Published: July 2010

Forages are often planted in soils that are not at the optimum temperature for germination. Therefore, it is important to know the temperature range of germination and the temperature effect on germination rate. Our objective was to evaluate the time course of seed germination of ‘MO‐20’ birdsfoot trefoil (Lotus corniculatusL.) and seombadi (Dystaenia takesimanaKitagawa), a member of the Umbelliferae family, using germination chambers at constant temperatures of 3,6,9,12,15,20,25, and 30 °C. Final germination of both species was highest at 20 °C. Time to radicle emergence of birdsfoot trefoil decreased as temperature increased. Seombadi seeds germinated only between 12 and 25 “C with little temperature influence on time to radicle emergence. Birdsfoot trefoil showed a linear relationship between germination temperature and the reciprocal of time to reach 50% of final germination, but there was no relationship for seombadi, suggesting factors other than temperature were controlling the response. Base temperature for germination of birdsfoot trefoil was calculated to be 4.7 °C. Germination rate of birdsfoot trefoil showed a marked increase between 9 and 12 °C, suggesting an Arrhenius response, Le., an abrupt change in effect of temperature.
Rhizobium japonicumNodular Occupancy, Nitrogen Accumulation, and Yield for Determinate Soybean Under Conservation and Conventional Tillage1
Authors: Hunt P. G. , Matheny T. A. , Wollum A. G.
Published: July 2010

Nitrogen fixation and accumulation are important facets of soybean (Glycine maxL.) production. Three determinate soybean cultivars were grown on a Norfolk loamy sand (Typic Paleudult) with either conservation or conventional tillage. Plots were split for inoculation with strain 3I1b 110 of Rhizobium japonicum. Dinitrogen fixation was estimated by the difference between total shoot N for nodulating and nonnodulating ‘Lee’ isolines, and net N returned to the soil was estimated by the difference in dinitrogen‐fixed N and seed N. Drought was significant the first year; only 19.5 cm of rain fell during the podfill period. Rainfall and soil water were adequate the second year. Tillage, cultivar, and inoculation did not consistently affect the percentage of nodules formed by particular rhizobial strains, individually, but specific treatment combinations significantly affected nodular occupancy by certain strains. Inoculated ‘Coker 338’ had the highest shoot total N accumulation in both years; however, the difference between years overshadowed tillage, cultivar, or inoculation effects. For the 2‐y period, percentages of N supplied by N2fixation were estimated to be 58 to 67% and 49 to 65% under conservation and conventional tillage, respectively. Yields generally did not differ significantly for tillage or inoculation; however, Coker 338 soybean was lowest in seed yield even though it had the highest total N accumulation in the shoots. Estimates of net N returned to the soil varied more between years than between tillage treatments; values ranged from 14 to 40 kg ha−1in 1980 and 57 to 123 kg ha−1in 1981.
Cut‐Off, Break‐Over, and Defoliation Effects on a Determinate Soybean Cultivar1
Authors: Malone S. R. , Caviness C. E.
Published: July 2010

Extensive research has been conducted on the response of indeterminate soybeans [Glycine max(L.) Merr.] to different types of plant damage, but information on the effect on determinate growth types is limited. This research compared the responses of a determinate soybean cultivar to different intensities of cut‐off, break‐over, and defoliation at five stages of plant growth. The experiments were conducted on a Captina silt loam (fine silty, mixed, Typic Fragiudnlt) during 1981 and 1982 at Fayetteville, AR. Plants were cut off at the point that removed half fresh weight and defoliated below the cut, broken over at the point that divided the aboveground fresh weight in half and defoliated below the break, or completely defoliated. Treatments were applied to 33,66, or 100% of the plants at growth stages V10, R2, R3, R4, and R5. Yields generally were not reduced when 33% of the plants were treated. The cut‐off treatments generally caused greater yield reduction than break‐over or defoliation; defoliation generally caused a greater yield reduction than breakover when 66 or 100% of the plants were damaged. Yield reductions were greater when treatments were imposed at progressively later growth stages. Cut‐off and defoliation influenced seed weight and date of maturity more than break‐over, especially when all plants were treated. Seed weight was reduced when yield reductions were severe, but the loss in seed weight did not account for all the yield loss. Maturity was delayed up to 2 weeks by treatments at R2, R3, and R4, and hastened by treatments at R5.
Yield and Quality of Tobacco Grown with Supplementary Irrigation1
Authors: Orphanos P. I. , Metochis Chr.
Published: July 2010

Presently in Cyprus, tobacco (Nicotiana tabacumL.) is grown under supplementary irrigation with water high in CI. The present study sought to investigate the irrigation/yield relationship and the attendant concentration of CI and other constituents in the leaves. In three experiments in which one to six irrigations were tested, maximum evapotranspiration (ET) determined by the soil water balance method was reached 40 to 50 days after planting, and equaled evaporation from a screened Class A pan. The ET started declining just before the first leaf harvest, even though soil water was adequate. However, since soil water became limiting soon afterwards, the course of potential ET could not be followed. From the second leaf harvest until the end of the season, ET was very low (< 1 mm/day). Fresh yield increased from 12 Mg/ha with 60 mm irrigation to 28 Mg/ha with 360 mm irrigation, the highest amount tested. In contrast, dry matter yield only increased from 2.3 to 4.2 Mg/ha, respectively. Moreover, midrib material increased from 20% with 60 mm irrigation to 30% of the total leaf dry matter with 300 mm irrigation. Concentration of CI for the whole leaf increased from about 2% with 60 mm irrigation to 3% with 300 mm irrigation (disregarding the last sampling). Concentration of K decreased from 4 to 2% between the first and the third harvest and in one experiment it tended to increase with irrigation. Leaf P increased from about 0.1 with 60 mm irrigation to 0.2% with 180 mm irrigation. The burn rate of laminae, determined in one experiment, increased with irrigation, even though CI also increased.
Effect of Duration and Type of Natural Weed Infestations on Soybean Yield1
Authors: Jackson Lucinda A. , Kapusta George , Schutte Mason Dolores J.
Published: July 2010

The time of weed removal from a crop may be as important as the extent of removal. A 4‐yr field study was conducted at two locations each year to define the extent of soybean [Glycine max(L.) Merr.] yield and population reduction occurring from the presence of natural weed populations. Soil types were Typic Ochraqualfs and Typic Albaqualfs. ‘Williams 79’ soybeans were planted at approximately 30 seeds m− 1of row using 76‐cm spacing between rows. Grass, broadleaf, or grass plus broadleaf weeds were allowed to interfere 0, 1, 2, 3, or 4 weeks, or all season (control), prior to their removal. Weed populations in the control plots ranged from 16 to 148 plants m−2in 1981 and increased to 104 to 1172 plants m−2in 1984. Allowing grass, broadleaf, or grass plus broadleaf weeds to interfere with soybeans for up to 4 weeks did not reduce soybean yields under ample soil moisture conditions. However, under drought conditions or extremely high weed infestations, yield losses with 4 weeks of interference were observed. No differences were found between the competitive effects of grasses or broadleaves on soybean yield with 4 weeks or less of interference. Significant yield reduction occurred every year at both locations when grass plus broadleaf weeds interfered all season. Yield reductions from all‐season grass‐only or broadleaf‐only weed interference occurred most years, but were dependent on location, weed density, and environmental conditions. Soybean populations were reduced where weeds were most dense and were associated with yield decreases.
Effect of Water Deficit at Different Growth Phases of Peanut. I. Yield Responses1
Authors: Rao R. C. Nageswara , Singh Sardar , Sivakumar M. V. K. , Srivastava K. L. , Williams J. H.
Published: July 2010

The response of a peanut (Arachis hypogaeaL.) cultivar Robut 33‐1 to drought stress imposed at different growth stages was studied during the post‐rainy seasons of 1980–1981 and 1981–1982 on a medium deep Alfisol at ICRISAT Center, India. Irrigation amount was varied to three levels for each of the following phases: (i) emergence to maturity, (ii) emergence to the start of peg initiation, (iii) from the start of flowering to the start of seed growth, and (iv) from the start of seed growth to maturity. The amount of water applied (stress intensities) during these phases was varied using line‐source irrigation, but the crops otherwise were irrigated uniformly at regular intervals. The greatest reduction in kernel yield occurred when stress was imposed during the seed‐filling phase. Decreased irrigation during the early phase increased the pod yield relative to the fully irrigated control treatment by 19% during the 1980–1981 and by 13% during the 1981–1982 growing seasons. Lowest pod yields resulted from severe stress from emergence to maturity. The evapotranspiration‐yield relationships showed a strong interaction with timing of drought.
Aluminum Toxicity Effects on Growth and Nutrient Composition in Wheat1
Authors: Ohki K.
Published: July 2010

Aluminum toxicity is frequently the limiting factor to crop production in acid soils. The diagnosis of Al toxicity for a specific wheat (Triticum aestivumL.) cultivar could be simplified by tissue analysis. Greenhouse studies were undertaken to determine the critical Al toxicity level for the cultivar ‘Stacy’ and tissue nutrients affected by Al status. Wheat plants were grown in 10 levels of Al (0, 1.9, 3.7, 9.3, 18.5, 37.1, 74.1, 148, 222, and 297 µMAl) in nutrient solution for 28 days. Aluminum toxicity reduced top dry weight, root dry weight, plant height, tiller numbers, and top/root dry weight ratio. Aluminum concentrations in the blade and stem tissues were low (maximum of 0.3 mmol kg−1in Blade 1, the most recently developed leaf with a developed ligule) and were linearly related to Al in nutrient solution. Aluminum is not readily accumulated in Stacy wheat. The critical Al toxicity levels, defined as the Al concentration in the tissue associated with a 10% decrease from maximum top dry weight due to toxicity, were 0.12 mmol kg−1in Blade 1 and 0.08 mmol kg−1in the whole plant. Knowing these tissue values, one may be able to detect Al toxicity from similar uncontaminated tissue from the Stacy cultivar sampled in the field. Using washed Blade 1 would be preferable to using the whole plant because soil contamination would be minimized. Aluminum toxicity decreased all elemental concentrations in Blade 1 and whole plants. With the exception of P and K in Blade 1, the decreases in elemental concentrations were related by either a linear or quadratic regression.
Screening for Low Fertility Tolerance among Peanut Cultivars1
Authors: Branch W. D. , Gascho G. J.
Published: July 2010

Because of expansion of additional hectareage onto marginal soil types and the economical need to reduce production inputs, differential genetic responses to lower fertility practices need to be sought within crop species. During 1981 through 1983, tests were conducted to evaluate 24 peanut (Arachis hypogaeaL.) cultivars under low soil fertility. The Tifton loamy sand (fine‐loamy, siliceous, thermic Plinthic Paleudult) location selected for the experiment is a typical soil for peanut production in this area; however, this particular site had a 3‐yr mean pH of 5.3 with 10, 25, 69, and 19 mg kg−1P, K, Ca, and Mg, respectively (Mehlich I). Significant differences were found among the cultivars for yield and grade under these specific environmental conditions. ‘Early Runner’, ‘Florunner’, ‘Tifrun’, ‘Southeastern Runner 56‐15’, and ‘Tifspan’ were considered the most tolerant to low soil fertility based on total sound mature kernel yield. No meaningful relationship was found between yield and any singular soil or tissue nutrient concentration.
Planting Date Effects on Seedling Development of Perennial Warm‐Season Forage Grasses. I. Field Emergence1
Authors: Hsu F. H. , Nelson C. J.
Published: July 2010

Slow establishment of perennial warm‐season forage grasses is a problem in their utilization to improve animal production in summer when cool‐season grasses are less productive. A field experiment was conducted to determine temperature effects on field emergence, estimate base temperature required for emergence in the field, and provide insight toward optimum planting dates for warm‐season perennial forage grasses. Big bluestem (BB) (Andropogon gerardiiVitman), Causasian bluestem (CB) [Bothriochloa caucasica(Trin.) C. E. Hubb.], indiangrass (IG) [Sorghartrum nutans(L.) Nash], switchgrass (SG) (Panicum virgatumL.), and an annual species, crabgrass (CG) [Digitaria sanguinalis(L.) Scop.] were compared in a split‐plot field experiment with five replications. Unchilled seeds of each species were planted at approximately 2‐week intervals in a Mexico silt loam soil (fine, montmorillonitic, mesic Udollic Ochraqualf) near Columbia, MO from early April to late June in 1982 and 1983. Emerging seedlings were recorded frequently. The logistic function was used to fit the emergence data. No emergence data were obtained for CG since natural emergence also occurred. Maximum emergence percentage was obtained following planting on 30 Apr. and 2 June 1982, and 6 and 16 May 1983. Indiangrass had the highest emergence percentages of pure live seed with 38 and 51% in 1982 and 1983, respectively, followed by SG, BB, and CB. Survival percentage of emerged seedlings averaged about 90%, but was reduced to near 70% on late plantings when soil dried out rapidly. Entries with high emergence percentages also had their highest emergence rates (ER) at Et50(time to reach 50% of final emergence). Corrected ER index and ER50(reciprocal of Et50) were closely correlated (r= 0.99, P<0.01). Both are good indices for evaluating speed of emergence. However, ER50is based on actual measurements and has more agronomic significance and biological meaning. Base temperatures required for emergence in 1982 were estimated as 9.4, 9.9, 10.8, and 11.4 °C for IG, BB, SG, and CB, respectively. For 1983 temperatures were 10.0, 10.8, 10.4, and 9.5 °C, respectively. The data suggest optimum planting dates for these species between late April and mid‐May to maximize emergence percentage and reduce risks of high temperature and soil moisture stress.
Cassava‐Cowpea and Cassava‐Peanut Intercropping. I. Yield and Land Use Efficiency]1
Authors: Mason S. C. , Leihner D. E. , Vorst J. J.
Published: July 2010

Cassava (Manihot esculenta Crantz) is commonly intercropped with cowpea [Vigna unguiculata(L.) Walp] or peanut (Arachis hypogaeaL.) in the tropics. Little is known about how intercropping these species influences efficiency of land use and yields. Cassava, cowpea, and peanut were grown as sole crops and as intercrops on a Typic Dystropept soil at Santander de Quilichao, Colombia in 1981 and 1982. The objective of this study was to determine land use efficiency, yield, and yield components for cassava, cowpea, and peanut grown in intercropping and sole cropping systems. Cassava yields were reduced 2.3 to 4.7 Mg ha−1when intercropped with cowpea or peanut, except in 1982 when intercropped with cowpea. Cassava yield reductions due to intercropping were associated with the production of 1.5 to 3.9 fewer storage roots per plant than were produced by sole cropped cassava. When intercropped with cassava, cowpea seed yields were reduced from 3195 to 2170 kg ha−1in 1981, and from 2227 to 1328 kg ha−1in 1982. Averaged across years, peanut seed yield was reduced from 2099 to 1293 kg ha−1. Cowpea and peanut yield reductions due to intercropping were associated with the production of approximately 3.5 fewer pods per plant. Even though yields of component crops were reduced by intercropping, the cassava‐cowpea and cassava‐peanut intercropping systems resulted in 15 to 35% greater land use efficiency for the 11‐month growing season than resulted from the sole cropping systems. This is of importance in developing countries where available per capita arable land is low.
Plant Population Density Effects on Seed Yield of Birdsfoot Trefoil1
Authors: McGraw R. L. , Beuselinck P. R. , Ingram K. T.
Published: July 2010

Little is known about the effects of plant population density (PPD) on birdsfoot trefoil (Lotus corniculatusL.) seed production. Our objective was to ascertain the effects of a wide range of PPDs on seed yield and yield components of birdsfoot trefoil. ‘Norcen’ and ‘Viking’ birdsfoot trefoil were transplanted into the field at Roseau and St. Paul, MN in 1981 and 1982, respectively. An experimental design was used which provided 19 PPDs from 1.6 to 61 plants/m2. The Roseau soil was a Glyndon silt loam (coarse‐silty, frigid Aeric Calciaquoll) and the Rosemount soil was a Waukegan silt loam (Typic Hapludoll). Plants were sampled individually when the majority of their pods were brown. Forage yield, seed yield, seed yield components, and harvest index were measured on each plant. Seed yield/m2and forage yield/m2had asymptotic diminishing‐returns relationships to PPD. Forage yield/m2increased about 200% as PPD increased from 1.6 to 61 plants/m2. The PPD at which forage yield/m2reached 90% of its total change was 26.5 plants/m2. Seed yield/m2increased about 75% as PPD increased from 1.6 to 61 plants/m2. The PPD at which seed yield/m2reached 90% of its total change was 19.0 plants/m2. Seed yields were adjusted in response to increasing PPD by reductions in all yield components. Umbels per plant was most responsive to PPD, pods per umbel and seeds per pod had intermediate sensitivity to PPD, and seed mass showed the least change in response to PPD. Harvest index decreased as PPD increased, indicating that seed yield/m2increases were smaller than forage yield/m2increases as PPD increased. Plant population densities required for optimum seed production are less than those required for optimum forage production; thus, lower seeding rates may be used in establishing seed production fields.
In situ Nitrate Assimilation in Winter Wheat: Peduncle Injection with Nitrogen‐15‐Nitrate at Anthesis1
Authors: MacKown C. T. , Van Sanford D. A.
Published: July 2010

Nitrogen accumulation and assimilation following anthesis in winter wheat (Triticum aestivumL.) depends on the level of soil nitrate and the availability of carbon substrates to support plant transport and assimilation functions. Spike and peduncle nitrate assimilation was investigated by injecting at anthesis 100 µmol 15N‐nitrate (99 atom % 15N) into the hollow peduncles of field‐grown (Typic Paleudalf soil) winter wheat (‘Doublecrop’). Dry weight changes in vegetative and reproductive culm parts and N assimilation and partitioning were followed at 5‐day intervals until maturity, 40 days after anthesis (DAA). Between 10 and 25 DAA, accumulation of spike dry matter and N increased to 56 mg day−1and 79 µmol day−1. Over 80% of the injected 15N‐nitrate was absorbed through the peduncle cavity walls within 5 DAA. Differential utilization of endogenous nitrate and injected 15N‐nitrate or dilution of the injected 15N‐nitrate by soil derived nitrate was observed. Peduncle nitrate atom % 15N decreased from 90.6 (0 DAA) to 54.4 (10 DAA). Within 5 DAA, 50% of the recovered excess 15N was partitioned to the spike. In contrast, 20 DAA elapsed before 50% of the total spike N accumulated after anthesis was acquired. Only a small portion of the total excess 15N in the culm was recovered in the flag leaf (3%) and culm below the peduncle (2%). Collectively, these results indicate that the rapidly absorbed 15N‐nitrate was not incorporated uniformly with peduncle N, but the absorbed 15N was readily transported to the spike. Although the relative contribution of nonleaf components to assimilate soil‐derived nitrate absorbed after anthesis is not indicated, it is clear that the spike and peduncle have a considerable in situ capacity to assimilate nitrate immediately following anthesis.
Water Use Efficiency in Soybean Pubescence Density Isolines— A Calculation Procedure for Estimating Daily Values'1
Authors: Clawson K. L. , Specht J. E. , Blad B. L. , Garay A. F.
Published: July 2010

Daily trends of water use efficiency (WUE) throughout a growing season are seldom, if ever, reported. In this paper a method for calculating daily WUE from growth analysis data coupled with weekly estimates of water use from soil moisture measurements are made for near‐isogenic dense and normal pubescent lines of 'Harosoy' and 'Clark' soybean [Glycine mar (L.) Merr.]. Data were collected during a 2‐yr field study at Mead, NE. The soil at this site is classified as a Typic Argiudoll. Evapotranspiration rates (ET) were lower in both dense pubescent isolines compared with the normal isolines, but differences were significant only for the Harosoy cultivar. Peak ET rates in 1980 were 4.7, 4.3, 5.8, and 4.8 mm day−1for the Clark normal, Clark dense, Harosoy normal, and Harosoy dense isolines, respectively. The highest WUE per unit ground area (WUEgand per unit leaf area (WUEg) was observed in the dense pubescent Harosoy isoline. This was the result of a higher crop growth rate and a lower ET in this isoline. Average mid‐season WUEgand WUEgvalues were, respectively, 1.4 and 0.25 g dry matter (kg H2O)−1day−1greater for the dense Harosoy isoline than for the normal isoline. No effect of pubescent density on WUE in the Clark isoline was observed. The interaction of dense pubescence as indicated by results of our study illustrate the need to establish the effect of the dense pubescent gene in cultivars into which it is introduced.
Alternative Establishment Methods for Wheat Following Soybean1
Authors: Griffin James L. , Taylor Richard W.
Published: July 2010

A majority of wheat (Triticum aestivumL.) planted following soybean [Glycine max (L.) Merr.] in Louisiana is planted using conventional seedbed preparation. Delayed harvest of soybean due to late maturity or adverse weather may eliminate the option of planting a winter wheat crop. Field studies were conducted in southwest Louisiana on a Crowley silt loam (fine, montmorillonitic, thermic Typic Albaqualf) soil from 1980 to 1984 to compare various seeding methods for wheat following soybean. Planting methods included: (i) conventional seeding, (ii) overseeding at 50% soybean leaf defoliation (early overseeding), (iii) overseeding presoybean harvest, (iv) overseeding post‐soybean harvest, and (v) no‐till seeding in soybean residue. Wheat overseeded early was planted 16, 27, and 23 days prior to the other treatments in 1980, 1981, and 1983, respectively. Averaged over years, percent ground cover at approximately 100 days after early planting and at maturity was highest where wheat was overseeded early and lowest where it was seeded conventionally. Early season plant height averaged over years for wheat overseeded early was 21% greater than wheat overseeded preharvest, postharvest, and no‐till, and 47% greater than wheat seeded conventionally. Plant height at maturity was similar for all seeding methods. Yield obtained from wheat overseeded early was 14% higher than yields of the other treatments. Wheat yield was similar where wheat was seeded conventionally and no‐till. Differences in yield among the treatments were not reflected in wheat spike density or 500‐seed weight. Overseeding wheat in standing soybean and no‐till planting in soybean residue are viable alternative planting methods compared with conventional seedbed preparation. The earlier planting would allow wheat to establish more rapidly in the fall. Both overseeding and no‐till planting would be advantageous in a wet fall or where potential soil erosion would prohibit seedbed preparation.
Liming Rate and Method in Relation to Forage Establishment—Crop and Soil Chemical Responses1
Authors: Koch D. W. , Estes G. O.
Published: July 2010

Many fields, because of slope and rockiness, are not suited to conventional seeding. However, the no‐tillage methods of establishing perennial forages preclude the incorporation of lime. The objective of this experiment was to evaluate the response of perennial forages seeded without tillage to surface‐applied lime. A long‐term study was conducted on a Penichuk fine sandy loam (loamy‐skeletal, mixed, mesic Dystric Eutrochrept) in which alfalfa (Medicago sativa L.)‐orchardgrass (Dactylis glomerata L.) and birdsfoot trefoil (Lotus corniculatus L.)–timothy (Phleum pratense L.) mixtures were seeded conventionally and without tillage. Nine months prior to seeding, lime was broadcast at 0, 4.5, and 9.0 Mg ha−1, incorporated for conventional seedings, and left on the surface for no‐till seedings. Soil pH prior to initiating the study was 5.6. In comparison with incorporated lime and conventional establishment, surface liming and establishment without tillage resulted in less vigorous forage seedlings and slower establishment. There was no difference in seedling density with liming or seeding method. Yields of legumes and total forage the seeding year were greater with incorporated than with unincorporated lime. In succeeding years, however, annual yields and 6‐yr total yields from 4.5 Mg ha−1 lime rates were not significantly different due to liming method. Over the long term, there was a yield advantage to incorporation of lime at the 9.0 Mg ha−1 rate. Rates of 9.0 compared with 4.5 Mg ha−1 of surface liming did not speed pH adjustment with depth, and after 6 yr pH had increased to a depth of only 10 cm. Birdsfoot trefoil–timothy was more productive than alfalfa‐orchardgrass without lime, but less responsive to lime. The highest rate (9.0 Mg ha−1) of incorporated lime increased alfalfa‐orchardgrass yields the year of establishment, but similar rates of surface‐applied lime did not produce a yield response until the fourth year.
Defoliation Effects on Forage Dry Matter Production of a Perennial Ryegrass–Subclover Pasture1
Authors: Motazedian Iraj , Sharrow Steven H.
Published: July 2010

While many authors have reported the effects of either varying defoliation intensity or of varying defoliation interval on pasture dry‐matter production, both intensity and frequency of defoliation have rarely been simultaneously applied over a range of values in such a way that their interaction can be evaluated. The objective of this study was to quantify the response of pasture dry‐matter yield to simultaneous changes in defoliation intensity and frequency over a range of values. Effects of defoliation treatments on dry matter production were evaluated on a perennial ryegrass (Lolium perenne L.)–subclover (Trifolium subterraneum L.) hill land pasture growing on a Ultic Haploxeroll soil near Corvallis, OR. A combination of four defoliation intervals (clipped every 7, 21, 35, or 49 days) and three stubble heights (70, 55, and 40 mm of stubble remaining after defoliation) were applied during the 1980, 1981, and 1982 growing seasons, respectively. Total annual dry matter production in all 3 yr increased as defoliation interval increased from 7 to 49 days between defoliation events. Effect of stubble height on dry matter yield was apparently influenced by forage plant type and sward species composition. When the pasture was dominated by erect‐growing ryegrass in 1980, more dry matter was produced when 70 mm of stubble remained after defoliation; but when the more prostrate subclover dominated the sward in 1982, it yielded more with 40 mm of stubble. The results of this experiment suggest that short‐duration grazing systems, which provide long periods of nonuse for pasture regrowth, should result in more dry matter production than does continuous grazing.
Turfgrass Thatch Components and Decomposition Rates in Long‐Term Fungicide Plots1
Authors: Smiley R. W. , Fowler M. Craven
Published: July 2010

Thatch management procedures are an important component of high‐intensity turfgrass management programs. Some fungicides used for controlling turfgrass diseases are known to increase the accumulation of thatch, but the thatching tendency in response to applications of most fungicides is unknown. Three new fungicides and three previously studied fungicides were applied to Poa pratensis L. turfgrass seven times annually for 6 yr. The soil was a silty clay loam (Glossaquic Hapludolf). At another location, three applications each year were used in a similar study on a sandy loam (Typic Dystroshrept). Measurements were made of thatch depths, soil and thatch pH, physical composition of thatch (roots + leaf remnants, crowns, rhizomes, and mineral soil), selected microbial populations, and the decomposition rates for cellulose and thatch implanted into the turf (buried litter bag technique). Seven applications of benomyl or iprodione per year caused thatch to become deeper (p = 0.05) than in the untreated turf; however, three applications per year did not. Increased thatch accumulation did not occur with cycloheximide, metalaxyl, propiconazol, or triadimefon. None of the fungicides significantly reduced the decomposition rate of buried thatch, or altered the thatch pH or microbial composition. Iprodione and benomyl increased the overall amounts of recognizable tissue in the thatch matrix. Results of this study support the hypothesis that fungicides influencing thatch accumulation are likely to do so by increasing the rate of tissue production without changing the rate of tissue decomposition.
Growth Regulator Effects on the Composition of Seed of Five Peanut Cultivars1
Authors: Mozingo R. W. , Steele J. L. , Young C. T.
Published: July 2010

Since composition of the seed of peanut (Arachis hypogaea L.) is an important quality factor, the effect of the plant growth regulator, succinic acid 2,2 dimethylhydrazide (SADH, sold under the trade name Kylar), on seed composition needed investigation. Field tests were grown in Martin County, NC, on a Norfolk loamy fine sand (fine‐loamy, siliceous, thermic Typic Paleudult) and in Suffolk, VA, on an Eunola loamy fine sand (fine‐loamy, siliceous, thermic Aquic Hapludult) in 1981 and 1982. Peanut seed from treated and untreated plots of the cultivars ‘Florigiant’, ‘NC 6’, ‘NC 7’, ‘VA 81B’, and ‘NC 8C’ at each location were evaluated for fatty acid distribution, iodine value (IV), oleic/linoleic (O/L) ratio, percentage of extra large kernels (ELK), and arginine maturity index (AMI). Application of SADH in 1981 reduced the linoleic acid percentage and IV and increased the oleic acid percentage and O/L ratio. In 1982, SADH application led to significantly lower linoleic acid percentage and IV in all cultivars except VA 81B, and significantly increased the O/L ratio for Florigiant, NC 7, and NC 8C. Similar O/L changes were not significant for NC 6 and VA 81B. NC 7 had the greatest number of significant changes in composition percentages with decreases in palmitic, linoleic, arachidic, eicosenoic, behenic, and lignoceric acids, and an increase in oleic acid in seed of plants treated with SADH. The AMI values were lower for all cultivars and ELK percentage was higher for Florigiant and NC 6, indicating more mature seed, with SADH treatment. Thus, from the results of this 2‐yr study, the application of SADH to reduce foliage growth also affected the ELK, AMI, and fatty acid distribution of seed from several peanut cultivars.
Yield and Fiber Quality of Cotton Following Applicatioin of 2‐Chloroethyl Phosphonic Acid1
Authors: Smith C. Wayne , Cothren J. T. , Varvil J. J.
Published: July 2010

The indeterminate growth habit of cotton (Gossypium hirsutum L.) forces producers to harvest more than once or to postpone harvest for several weeks. Ethephon (2‐chloroethyl phosphonic acid) causes immature bolls to open, resulting in a greater percent of the crop harvested at first harvest or in once‐over harvest. The objectives of this study were to determine the effects of ethephon on seedcotton yields and fiber quality relative to the physiological stage of maturity at treatment with ethephon. ‘Stoneville 213’ and ‘CAMD‐E’ were planted on three dates in 1980 and Stoneville 213 on four dates in 1981 in Calloway silt loam, a Glossaquic Fragiudalf. Ethephon was applied at 1.12 kg ai. ha−1 and compared with no ethephon treatment in 1980 when plants ranged from 19 to 62% opened bolls. Stoneville 213 ranged from 12 to 72% opened when treated in 1981. The statistical design was a split‐block, split‐plot of a randomized complete block with four replications. Ethephon significantly reduced seed cotton yield when applied to cotton with 48 to 62% opened bolls in 1980 but not when applied to cotton averaging 22% opened. In 1981, no consistent effects of ethephon on seed cotton yields were detected. Over years, ethephon applied to cotton with 12 to 25% opened bolls did not reduce seed cotton yields relative to application to cotton with 48 to 72% opened bolls. No consistent detrimental effects on fiber quality were detected for fiber from first harvest or from once over harvest.
Normal‐12 and Brown Midrib‐12 Sorghum. I. Variations in Tissue Digestibility1
Authors: Akin D. E. , Hanna W. W. , Rigsby L. L.
Published: July 2010

Reduced lignin contents in brown midrib (bmr) mutants of sorghum (Sorghum bicolor L. Moench.) are reported to improve the digestibility of this forage. The objective of this study was to evaluate microscopically leaf blades of normal‐(N) 12 and bmr‐12 sorghum for variations in anatomy, histological reactions of tissues for lignin, and specific tissue digestion to elucidate the contribution of the bmr‐ 12 mutation to improved forage quality. No differences in anatomy or histology of lignified tissues was observed between N‐12 and bmr‐ 12 plants. Midribs of N and bmr plants, examined by scanning electron microscopy after a 48 to 72 h incubation with rumen fluid were partially degraded, with a tendency for parenchyma in bmr leaf blades to be more degraded than that in N leaf blades. Other tissues, i.e., epidermis and xylem, were not degraded in either plant type. In the non‐midrib portion of blades, the parenchyma bundle sheaths and adaxial sclerenchyma areas were degraded to a greater extent in bmr plants by mixed rumen microorganisms and by a pure culture of the cell wall‐degrading rumen bacterium Ruminococcus flavefaciens FD‐1. Epidermis and mesophyll at times more rapidly degraded in bmr plants. In leaf sheaths, no marked differences in digestion between N and bmr plants were found with parenchyma totally degraded in both plant types. Xylem and other tissues normally highly resistant to microbial degradation were not degraded in plant parts of either N or bmr types. The bmr‐12 mutation did not result in changes in leaf blade anatomy or histological reactions for lignin and did not result in susceptibility to microbial degradation of the most resistant tissues. The bmr‐12 mutation did allow an improved microbial degradation of marginally digestible tissue, i.e., those tissues usually only poorly degraded.