bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrate Fertilizer Timing, Irrigation, Protein, and Yellow Berry in Durum Wheat1
Authors: Robinson Frank E. , Cudney David W. , Lehman William F.
Published: July 2010

In the irrigated desert area of Imperial Valley, Calif., Cocorit 71 durum (Triticum durum Desf.) was developing sufficient yellow berry to be penalized in price received by growers. The objectives of the study were to define the relationship between nitrate fertilizer timing, protein, and yellow berry in grain and to recommend the N fertilization program leading to the highest yield of low yellow berry grain yield. The study was conducted on a well drained vertic torriorthent of the entisol order. Plots were fertilized with 0, 135, 202, 270, or 404 kg/ha of N as ammonium nitrate in three treatments: all preplant (P), half preplant, and half at tillering (PT); and one‐third each at the preplant, tillering, and boot stages (PTB). Grain protein content differed significantly between treatments. Yellow berry decreased by 16.4 to 18.5% for each percentage increase in crude protein in the grain. PTB gave significantly higher protein in the grain than the other treatments. Protein content had significant linear correlation with shatter, lodging, average grain size, and grain density. PTB at 270 kg N/ha was the lowest N application that gave a consistently high yield, with less than 25% yellow berry. The wetter of two irrigation treatments had significantly less lodging in 1976, and longer straw, higher yield, and lower grain density in 1977. Effects were similar to the above in comparison treatments of ‘Mexicali 75’ durum and ‘Yecora Rojo’ (Triticum aestivum L.), a hard red spring wheat. It was recommended that N fertilization be 90 kg/ha at preplant, again at tillering, and again at the boot stage.
N Deprivation in Maize During Grain‐Filling. I. Accumulation of Dry Matter, Nitrate‐N, and Sulfate‐S1
Authors: Friedrich J. W. , Schrader L. E. , Nordheim E. V.
Published: July 2010

Maize (Zea mays L.) has a noted propensity for accumulating large amounts of nitrate‐N (NO3‐N). However, the availability of such NO3‐N for assimilation during periods of restricted N supply has not been assessed. In addition, the availability of sulfate‐S (SO4‐S) affects the accumulation and assimilation of NO3‐N. Little is known about the effect of NO3‐N supply on SO4‐S accumulation. Such information is vital to efforts to improve the efficiency of nutrient utilization by crops. The objective of this greenhouse experiment was to determine the effect of N deprivation during grain‐filling on the accumulation of dry matter, NO3‐N, and SO4‐S. Maize plants were grown hydroponically in a modified Hoagland's solution. At silking the nutrient solution was replaced with fresh solution, with or without NO3‐N. Plants were harvested and separated into seven fractions at silking and 1, 2, 3, 5, and 7 weeks after silking. Plants that were supplied NO3‐N during grain‐filling contained almost twice (1.8×) as much N at physiological maturity (7 weeks after silking) as did N‐deprived plants. Ear dry weight was not affected by N deprivation. The concentration of NO3‐N in all fractions declined during grain‐filling; however, N deprivation enhanced this decline in the roots, lower stem, and upper stem. Lack of N did not affect NO3‐N concentration in the lower leaves, upper leaves, or ear. The concentration of SO4‐S in the roots nearly doubled between silking and physiological maturity when plants were deprived of NO3‐N, but did not change when N was supplied. The concentration of SO4‐S in all other parts was not markedly affected by N deprivation. Apparently, maize plants can compensate for a restricted N supply during grain‐filling by utilizing NO3‐N stored in the roots and stem.
Evaluation of Big Bluestem, Indiangrass, Sideoats Grama, and Switchgrass Pastures with Yearling Steers1
Authors: Krueger C. R. , Curtis D. C.
Published: July 2010

Ideal pasture systems must supply high yields of quality forage throughout the grazing season. When cool‐season grasses predominate, forage is often in short supply during the summer months. This study was designed to compare improved cultivars of perennial, warm‐season grasses that were grown for pasturage in July and August. Pure stands of ‘Pawnee’ big bluestem (Andropogon gerardi Vitman), ‘Holt’ indiangrass (Sorghastrum nutans (L.) Nash), ‘Pierre’ sideoats grama (Bouteloua curtipendula (Michx.) Torr.), and ‘Nebraska 28’ and ‘Summer’ switchgrass (Panicum virgatum L.) were grazed with yearling steers from 1973 to 1975 at the Pasture Research Center, Norbeck, South Dakota. Grazing was initiated about 9 July and continued for 42 days on big bluestem, 38 days on sideoats grama, 33 days on Nebraska 28 switchgrass, and 31 days on indiangrass and Summer switchgrass. Steer gains averaged 1.08 to 0.70 kg/day, and were highest on indiangrass, similar on Nebraska 28 and Summer switchgrass and sideoats grama, and lowest on big bluestem. Number of steerdays of grazing per hectare ranged from 199 on big bluestem to 111 on indiangrass. Beef gains per hectare ranged from 147 to 112 kg, and were highest and similar on Nebraska 28 and Summer switchgrass and big bluestem, and lowest on indiangrass and sideoats grama. The results of this experiment indicate that big bluestem and switchgrass pastures can be used successfully for beef production in July and August.
Methodology for Identifying Wide Adaptability in Crops1
Authors: Nor Khalid M. , Cady Foster B.
Published: July 2010

When several cultivars are grown over a range of environments, regression measures of stability or wide adaptability can be estimated. The most commonly used measures include Eberhart and Russell's and Finlay and Wilkinson's. These measures use the average yield of the cultivars at each site as an index of the site's productivity. Because of conceptual and statistical problems associated with using the site mean yields, emphasis is now on a principal component method, based on measurements of environmental variables at each site, for formulating an environmental index. We wished to retain the regression approach of the earlier developers. The objective of this paper, therefore, to develop multivariate regression methodology for providing an alternative environmental index not dependent on the cultivar responses. The index is based on physical measurements of the environments affecting crop yield. The resulting data analysis, based on a beta response model, is straightforward and easy to apply in the same general situations as previous stability and adaptability studies. The methodology is applied to a set of corn (Zeo mays L.) data from several New York environments. Adaptability rankings using the new methodology compare favorably with those based on site means (Spearman rank correlation of 0.69 with 16 degrees of freedom). With improved measurement techniques and understanding of site variable and yield relationships, the environmental index methodology can be an alternative regression measure of stability or wide adaptability.
Effect of N Fertilizer on Yield, Protein Content, and Symbiotic N Fixation in Fababeans
Authors: Richards J. E. , Soper R. J.
Published: July 2010

Fababeans (Vicia faba L. var. minor) are potentially an important source of crude protein in Western Canada. Thus the effect(s) of combined inorganic N on fababean growth performance are of considerable interest. This experiment was conducted to determine the effect(s) of fertilizer‐N on fababean shoot and root yields, protein contents, N uptake, N fertilizer uptake, and symbiotic N fixation. Nitrogen fertilizer as NH4NO3, was applied to fababeans grown in an Udic Haploborall soil in rates up to 900 mg N/pot (300 mg N/kg soil), as split applications of 75 mg N/pot (25 mg N/kg soil), and as single large mid‐season applications of 300 mg N/pot (100 mg N/kg soil. 15N‐labelled fertilizers were used to measure N fertilizer uptake, and were also used with a reference crop to measure symbiotic N fixation. The split application treatment received labelled‐15N in the manner described by Fried et al. (1975), enabling efficiency of N fertilizer uptake for each application time to be determined.

Fababeans, when nodulated with effective strains of Rhizobia, obtain their N from soil and symbiotic fixation. Results obtained from this experiment indicate that these two sources of N were able to fully satisfy fababeans' N demand throughout their entire growth cycle. Aerial yield was not affected by N fertilizer up to 600 mg N/pot (200 mg N/kg soil) applied at seeding, by 300 mg N/pot applied in four 75‐mg portions, nor by single midseason applications of 300 mg N/pot. Only the highest rate of N employed, 900 mg N/pot at seeding, significantly increased fababean yield, the increase being 13.2%. However, protein content and total N uptake into fababean shoots were unaffected by all N applications used.

Fababeans, nodulated with an effective Rhizobia strain were efficient symbiotic fixers. Fababeans receiving no N fertilizer fixed 708 mg N/plant, or 87.10%, of their total N content. Fababeans were capable of fixing substantial amounts of N after pod‐fill, amounting to at least 28% of the total seasonal symbiotically fixed N. A significant (r3 = 0.99) linear inverse relationship occurred between fertilizer‐N uptake and symbiotic N fixation. Increasing quantities of fertilizer uptake into fababean tissues decreased plant N derived from fiiation.

Fababeans were as adept as barley in extracting available soil and fertilizer‐N, and evidence indicates fababeans preferentially feed from soil and fertilizer N sources.
Potassium Fertilization Influences on Coastal Bermudagrass Rhizomes, Roots, and Stand1
Authors: Keisling T. C. , Rouquette F. M. , Matocha J. E.
Published: July 2010

Losses of yield and stand of ‘Coastal’ bermudagrass (Cynodon dactylon L. Pers.) due to inadequate K fertility have been observed numerous times. Stand deterioration has been attributed to “winter‐kill”, disease, and lack of “physiological hardening” of the plants. Since all the aerial parts of the bermudagrass plant die when temperatures are as low as ‐2 to ‐3 C, underground stems (rhizomes) are important for maintaining and generating growth in the spring. Studies were conducted to investigate the effects of K fertility practices on rhizome production and rhizome regrowth reserve as related to certain stand and tissue characteristics. Old P and K factorial rate studies on Darco (Grossarenic Paleudult; loamy, siliceous, thermic) and Cuthbert (Typic Hapludult; clayey, mixed, thermic) soils were used. Annual fertility rates used on prior experiments were 0, 112. and 224 kg/ha K, 0 to 136 kg/ha P, and 364 to 504 kg/ha N. The influence of residual P and K fertility on stand ratings, rhizome production, and Ca, Mg, and K content of the forage was measured. Stand ratings in the spring were found to be related to rhizome production. The first increment of 112 kg/ha of K increased rhizomes 800 kg/ha on the Darco soil. Rhizome production required higher rates of K on the Cuthbert soil which gave a response of 1,500 kg/ha of rhizomes to the highest K rate used. Lowering the K rate resulted in lower K in the tissue and an observable loss of vigor in the root system. Depending on the soil K reserve, production levels ,and previous fertility practices, Coastal bermudagrass hay meadows on which K fertility levels are inadequate may exhibit the characteristics described above.
Yield and N Content of Closely Clipped Bahiagrass as Affected by N Treatments1
Authors: Beaty E. R. , Tan K. H. , McCreery R. A. , Powell John D.
Published: July 2010

Pensacola bahiagrass (Paspalum notatum Flugge) is normally grown in pure stands and produces forage primarily on stolons growing along the soil surface. Harvesting by clipping has been at a height of 6 to 7 cm and N fertilization has traditionally been in split applications with the first in March or April. Advantages of split applications have not been established and clip ping at 6 to 7 cm may seriously underestimate forage production. More detailed information is needed to accurately establish total forage yields and seasonal forage production patterns under close clipping. A field clip ping investigation was conducted where bahiagrass sod receiving 0, 84, 168, and 336 kg/ha of N fertilizers in one of six time of application combinations was harvested monthly at a height of 0 to 3 mm.

The first year, dry forage production increased from 3,042 kg/ha with 0 N, to 6,398 kg/ha with 336 kg/ha of N. In the second year, forage production at the same N rates ranged from 3,812 to 12,151 kg/ha. Close clipping (0 to 3 mm stubble) resulted in different seasonality of forage production and N concentrations when compared to previous results where clipping was at heights of 6 to 7 cm. Increasing the N application rate increased root and stolon weights.

Forage production efficiency of applied N (kg dry matter produced/kg N applied) decreased from 54.6 for the first 84 kg/N/ha applied to 34.0 for the additional N from 84 to 168 kg/ha and further to 5.2 for N from 168 to 336 kg/ha N. With unfertilized bahiagrass, N should be applied by or before early March, but after the first year, time of N application makes no practical difference in yield. At low N rates, harvesting to a stubble height of 3 cm or less will significantly increase the amount of forage utilized , harvested, or reduce the amount of N applied.

It was concluded that close grazing or clipping of Pensacola bahiagrass wilt: a) increase digestibility by keeping the forage green; b) increase the effective yield of a pasture; and c) split applications of N may provide better forage distribution over a season without affecting yield.
Seed Protein and Nitrogen Effects Upon Seedling Vigor in Wheat1
Authors: Bulisani E. A. , Warner R. L.
Published: July 2010

Seedling vigor appears to be enhanced by seed protein, but the influence of exogenous N supply and timing upon this effect have not been clearly established. Growth chamber and field experiments were conducted to determine the effects of seed protein and N upon seedling vigor of ‘Nugaines’ and ‘Wanser’ winter wheat (Triticum aestivum L.). Seed were obtained from a N fertility experiment, sieved into seven size classes, and analyzed for protein. Seed protein content varied from approximately 8 to 16%. Within each seed lot the largest seed had approximately a 2.5% higher protein percentage than the smallest seed.

In growth chamber experiments seedling vigor was significantly increased by seed weight and percent protein. However, most of the variation was attributed to the amount of N in the seed and not to the percentage protein or seed weight per se. The addition of N significantly increased seedling dry weight and N content, and promoted a significant two‐fold increase in the shoot‐to‐root ratio. Differences in seedling vigor due to seed protein content were eliminated if adequate N was applied within the first 3 days of germination. Rate of emergence and grain yields in the field on a Palouse silt loam soil (fine‐silty, mixed, mesic Pachic Ultic Haploxerolls) were not affected by seed protein content. However, large seed significantly increased the seedling emergence rate index and grain yields. Nitrogen application had no effect upon emergence rate which may have been due to the availability of high levels of soil N.

Seed protein enhances seedling vigor (dry weight) if N is withheld for more than the first 3 days of germination, but apparently has no effect if adequate N is available during early stages of germination.
Manganese Deficiency and Toxicity Sensitivities of Soybean Cultivars
Authors: Ohki K. , Wilson D. O. , Anderson O. E.
Published: July 2010

Soybean [Glycine max (L.) Merr.] cultivars vary in plant growth response to Mn deficiency and toxicity. Cultivar selection for field studies to evaluate responses to Mn deficiency and toxicity is important. The objective of this study was to determine the differential sensitivity of cultivars to Mn deficiency and toxicity prior to regional field studies on the diagnosis and correction of Mn problems in the production of soybeans.

For evaluating relative ranking of cultivars sensitive to Mn deficiency, seven soybean cultivars were grown in solution culture at severe (5 µg Mn/liter) and mild (50 µg Mn/liter) deficiency levels and compared with controls, (1,000 µg Mn/liter). For toxicity evaluations, seven cultivars were grown at severe (20 mg Mn/liter) and mild (10 mg Mn/liter) toxicity levels with controls at 0.5 mg Mn/liter.

Cultivar sensitivity to Mn deficiency was partially dependent on the level of deficiency stress. ‘Davis’, ‘Lee 74’, ‘Bragg’, and ‘Pickett 71’ were the most sensitive under severe deficiency and Lee 74, Bragg and ‘Hutton’ were the most sensitive under mild deficiency. Davis, Lee 74, Pickett 71, Bragg, and ‘Ransom’ were the most sensitive to severe Mn toxicity at the severe Mn toxicity level. At mild toxicity, shoot weights as percent of control were similar for all cultivars. Visual symptom ratings and leaf blade Mn concentrations were significantly correlated with shoot dry weight as percent of control for Mn deficiency and toxicity stresses. The increased sensitivity to Mn toxicity by Lee 74 compared to that previously reported for the ‘Lee’ cultivar may be a result of genetic changes which occurred during the development of Lee 74.
Influence of Induced Lodging on Pod Distribution and Seed Yield in Soybeans1
Authors: Noor Ramli Bin Mohd , Caviness C. E.
Published: July 2010

Lodging occurs frequently in soybeans [Glycine max (L.) Merr.] and has been shown to reduce yields of indeterminate cultivars under most conditions: Information is limited on effects of lodging on determinate cultivars, types commonly grown in the southern U. S. Influence of lodging on pod distribution and seed yield was measured during a 2‐year study in the field on ‘Forrest’, a determinate cultivar and ‘R74‐334’, a semideterminate strain, at three stages of growth. Growth of the semideterminate strain in Arkansas resembled that of indeterminate cultivars grown in the Midwest. Plants were lodged at 0°, 45°, and 90° angles from the vertical at a vegetative stage (V8) and two reproductive stages (R2 and R4).

A significant yield reduction was obtained from induced lodging at full pod (R4) but none at the vegetative (V8) or full bloom (R2) stage of development. The determinate cultivar and semideterminate strain were affected similarly by the lodging treatments. Lodging resulted in an increase in percentage of pods on lateral branches at stages V8 and R2 but no change was noted at R4. Number of seeds per pod was not affected by plant lodging. Lodging affected the number of seeds per plant more than seed size. Decrease in seed yield, therefore, was primarily due to reduction in number of seeds produced on lodged plants.
Apparent Photosynthesis, Evapotranspiration, and Light Penetration in Two Contrasting Hard Red Winter Wheat Canopies1
Authors: Johnson R. C. , Witters R. E. , Ciha A. J.
Published: July 2010

Crop canopy structure is highly variable in time and space influencing canopy light interception, apparent photosynthesis (AP), and evapotranspiration (ET). Our objectives were to relate AP and ET to light interception, leaf area index (LAI), temperature, and yield in two row‐spacings of winter wheat (Triticum aestivum L.) in a field environment. ‘Wanser’ winter wheat was planted at 20 — (140 kg seeds ha−1) and 40 — cm (70 kg seeds ha−1) row spacings in Ritzville silt loam (Mesic Calciorthidic Haploxerolls). Two aluminum frame chambers covered with mylar and occupying 0.74 m2 of soil surface area were used with infrared gas analyzers to measure AP and ET in each row spacing from the respective differences between chamber intake and exhaust CO2 and H2O concentrations. On clear days from stem extension to the milky ripe developmental stage and when incoming short‐wave solar radiation (SR) was 700 War−2 (± 140 Wm−2), best fit quadratic polynomial regression curves of AP and ET were obtained for each row spacing. Interception of SR across rows in each spacing was measured after anthesis with tube solarimeters 2, 27, and 53 cm above the soil surface.

Values of LAI, AP, and ET were generally greater in the 20‐ than hi the 40‐cm spacing. After anthesis, LAI declined sharply in both spacings resulting in decreasing AP values; but ET was not greatly reduced. In contrast to days before anthesis, average air temperatures after anthesis were generally greater than average leaf temperatures. Sensible heat transferred from air to foliage was apparently an energy source promoting ET late in crop development. After anthesis, SR differed significantly between spacings at 2 cm, but not at 27 or 53 cm above the soil. Plant heights in both spacings were about equal averaging 70.3 cm. At 18 days after anthesis (watery ripe stage), the 20‐cm spacing had about 22% less SR 2 cm above the soil than the 40‐cm spacing. At that tune AP and LAI values were about equal between spacings so that the greater SR intercepted by 20‐cm spacing was apparently by tissue of low photosynthetic capability, such as dead or senescing leaves and tillers. Both spacings had statistically equal grain yields (2,102 kg ha−1 average); but the 20‐cm spacing had 67% more heads m−2, resulting hi more kernels nr*, than the 40‐cm spacing. The 40‐cm spacing had greater kernel weights and about 2.5 more kernels/head than the 20‐cm spacing. Increasing winter wheat yields by increasing post‐anthesis light interception appears unlikely unless sufficient water were available to maintain dense stands with high post‐anthesis LAI values.
Irrigation Scheduling and Plant Population Effects on Growth, Bloom Rates, Boll Abscission, and Yield of Cotton1
Authors: Guinn G. , Mauney J. R. , Fry K. E.
Published: July 2010

Techniques are needed for conserving water and shortening the cotton (Gossypium hirsutum L.) fruiting season in irrigated areas. We conducted field tests at Phoenix, Arizona during the summers of 1978 and 1979 to determine the influence of delaying the first irrigation on subsequent growth, fruiting, and yield of cotton grown in an Avondale clay loam (fine‐loamy, hyperthermic, Typic Torrifluvents). In 1978, the first post‐plant irrigation was applied when the first flower bud (square) became visible (E) or 14 days later (L). Two levels of irrigation during the remainder of the season, normal (N) or 0.6 normal (D), were used as subplots. Delaying the first irrigation slowed growth, square production, and leaf area development, and slightly decreased the number of bolls set by any given date. Despite these apparent adverse effects the LN treatment produced heavier bolls, fewer damaged bolls, and the highest yield. Although LN received 13 cm less water than EN, it produced an average of 606 kg more seed cotton per ha. Water deficit during the remainder of the season (D) greatly decreased growth and yield. In 1979, the first post‐plant irrigation was applied at the time of first visible square (E), 7 days later (M), or 16 days later (L). Two plant populations, 94,000 (Hi) and 52,000 (Lo) plants per ha were also variables. The final irrigation was applied 13 August to shorten the season. Despite a 16‐day delay in the first irrigation, one less irrigation, and a short‐season (early termination), L produced about the same yield as E. The low population produced slightly fewer blooms, but retained more and produced slightly higher yields than the high population. Treatment MLo produced the highest yield, and LLo gave the greatest water‐use efficiency. Delaying the first irrigation conserved water and gave satisfactory yields despite early termination in 1979.

Although water deficit during the bloom stage hastened cutout, delaying the first irrigation had little effect on earliness. Likewise, low plant population caused no appreciable delay in setting the crop.
Morphological Development of Rice Seedlings in Water at Controlled Oxygen Levels1
Authors: Turner Fred T. , Chen Cy‐Chain , McCauley Garry N.
Published: July 2010

Germination and seedling establishment of rice (Oryza sativa L.) is usually less than optimum in water saturated and flooded soils apparently because of a deficiency of available oxygen (O2). However, the effect of low O2 level on rice germination and seedling development is not well defined. To evaluate the effect of varying O2 level on rice seedling development and to identify rice cultivars which may be more tolerant to the low O2 concentrations associated with water saturated rice soils, seeds of four rice cultivars were incubated in water containing six O2 concentrations. Gas flow meters and regulators allowed mixing of air and N2 gas to obtain O2 levels of 21, 10.5, 5.3, 2.0, 1.0, and 0% (99.995% N2 gas) which were bubbled through special water filled containers placed in a growth chamber providing 400 microeinstein m−2 sec−1 light intensity, 12‐hour day, and 27 C constant temperature.

Oxygen concentration had little effect on coleoptile emergence from rice seed but low O2 levels enhanced coleoptile elongation. Maximum coleoptile length (20 mm) occurred at 0% O2, making it appear that rice germinated at very low O2 levels. However, it was apparent that root and shoot (leaf) growth were inhibited at 0% O2, providing evidence that low O2 levels can restrict rice stand establishment.

The critical O2 level for maximum shoot elongation appeared to be about 5%. The critical O2 level for root elongation was less evident. Roots of ‘Labelle’ and “Bellemont’ seedlings reached maximum length at O2 levels as low as 5% whereas roots of ‘Calrose 76’ and ‘M 101’ seedlings continued to increase in length as the O2 level was maintained at 10.5 and even 21%. Differences in cultivar tolerance to low O2 levels were observed among the 10 cultivars evaluated. Also, rice cultivars exhibited tolerance to low O2 levels in terms of one parameter (root, shoot, or coleoptile length) without showing tolerance in terms of the other two parameters.
Descriptive Comparison of Senescent and Nonsenescent Sorghum Genotypes1
Authors: Duncan R. R. , Bockholt A. J. , Miller F. R.
Published: July 2010

Under normal field conditions, leaves of many typical sorghum [Sorghum bicolor (L.) Moench] lines such as BT×378, RT×7000, RT×2536, and SC 214(IS 1598C) senesce after grain maturity. In the field, several upper leaves of three partially converted lines [SC0056 (IS 12568), SC0599 (Rio), and SC0170 (IS12661)] from the sorghum conversion program remained green and apparently vigorous after grain maturity. This phenomenon of green leaf retention after the grain reached physiological maturity was termed “nonsenescence”. The purpose of this study was to compare standard (senescent) and nonsenescent lines to determine characteristics which describe differences between the two genotypes and to define desirable qualities of the nonsenescent lines.

Senescent and nonsenescent lines were evaluated in the field for three growing seasons, 1974 to 1976, at College Station, Texas. The soil type was Ships clay (Udertic Haplustoll) intergrading toward a Norwood clay loam (Typic Udifluvent). Several plant characteristics (growth parameters, yield and yield components, basal tiller production, stem diameter, percent basal stem sugar concentration, and total leaf blade chlorophyll content) were measured to characterize genotypic differences. Experimental design was a randomized complete block with four replications. Growth data were recorded during the reproductive stage of development. The nonsenescent genotype required 2 days longer to reach 50% anthesis, averaged 3 to 4 cm shorter height, produced two to three more basal tillers per plant, had larger stem diameters, maintained higher basal stem sugar concentrations, and produced higher leaf blade chlorophyll contents than did the senescent genotype. Data involving leaves (green leaf number and weight, senesced leaf number and weight, leaf area index, leaf area duration, and leaf area ratio) favored the nonsenescent genotype. The grain‐leaf ratio of the senescent genotype exceeddthat of the nonsenescent genotype 30 days after anthesis because of a consistent reduction in leaf area due to senescence. Except for test weight (which was higher in the nonsenescent genotype), yield and yield components were generally inconsistent between genotypes.

Parameters which could reasonably be measured in a breeding program to select for nonsenescent genotypes might include stem diameter and stem sugar concentration, tiller counts of a ratoon crop, and number of green leaves retained after grain maturity. Leaf area and chlorophyll measurements after the grain has reached physiological maturity might provide more conclusive Information on nonsenescence capability, but would probably not be feasible in a breeding program.
Selected Determinate Soybean Cultivar Yield Responses to Row Spacings and Planting Dates1
Authors: Boquet D. J. , Koonce K. L. , Walker D. M.
Published: July 2010

Previous studies to determine row spacing (RS)‐planting date (PD) effects on yield of determinate soybeans [Glycine max (L.) Merr.] in the southern USA have been conducted north of 33° Lat, and have produced conflicting results. Current data on the effects of these planting variables are not available for a large portion of the Gulf Coast area that now supports a large and rapidly expanding soybean industry. The objectives OP this experiment were to study: 1) the effects of selected RS and PD on yield of selected cultivars of determinate soybeans; 2) the interaction of RS with PD; and 3) the interaction of cultivars with RS and PD.

Five cultivars, ‘Forrest,’ ‘Davis,’ ‘Lee 74,’ ‘Centennial,’ and ‘Bragg’ were planted in RS of 25, 50, and 100‐cm on 6 PD between 15 April and 1 July in 1976, 1977, 1978, and 1979. The field plots were located on a Mhoon silty clay soil (Typic Fluvaquent). Averaged over years, the five cultivars evaluated produced significantly higher yields when grown in 25 and 50‐cm RS compared with the 100‐cm RS. The interaction between cultivar and RS was significant due to variability among cultivars in the yield increase when RS was reduced; 3 q/ha with Davis and Bragg, 4 q/ha with Lee 74, and 6 q/ha with Forrest and Centennial. The size of yield increases resulting from reduced row spacing was relatively consistent across PD. Because lower yields were recorded at all three RS at nonoptimum PD the yield increases, when expressed as a percentage of the yields obtained in 100‐cm rows, were larger at the nonoptimum dates, however. Optimum PD was not affected by RS but differed among cultivars. Forrest and Lee 74 had highest yields when planted on 15 May while the other three cultivars had similar yields at PD from 1 May to 1 June. Results indicated that significantly higher yields are possible with current determinate cultivars when both RS and PD are selected for individual cultivars.
Response of Sunflower to Uniformity of Plant Spacing1
Authors: Robinson R. G. , Ford J. H. , Lueschen W. E. , Rabas D. L. , Warnes D. D. , Wiersma J. V.
Published: July 2010

Plant spacing in the row is variable in most sunflower (Helianthus annuus L.) fields. The amount of yield loss from moderately uneven stands of sunflower should be known before undertaking expensive techniques to increase uniformity of plant distribution. The objective of this research was to measure the effects of uniformity of plant distribution on sunflower seed yield, plant growth, and seed quality. Four plant distributions of oilseed and nonoilseed cultivars in rows 76 cm apart and in a population of 49,000 plants/ha were established at five locations in Minnesota in 1979 and 1980. Soils were Typic Haplaquolls, Aerie Calciaquolls, and Aerie Haplaquepts. Plant distributions were: single plants 27 cm apart; paired plants 53 cm apart; five plants each 13 cm apart, 80‐cm space; seven plants each 9 cm apart, 80‐cm space, single plant, 80 cm space. Uniformly spaced, single plants lodged least and produced heads of lowest moisture percentage at harvest and seed of highest yield and oil percentage. Yield reductions from uneven plant distributions ranged from none to 31% and averaged 10%. Greater lodging was the most consistent detriment of nonuniform plant spacing. The magnitude of differences in seed quality among the plant distributions was small and consequently of relatively little economic importance.
Response of Sugarcane to Silicate Source and Rate. I. Growth and Yield1
Authors: Elawad S. H. , Gascho G. J. , Street J. J.
Published: July 2010

Sugarcane (a complex trispecies hybrid of Saccharum) is one of few crops which are highly responsive to applications of silicate materials. Variety ‘C.P. 63‐588’ was grown on a Pahokee muck soil (euic, hyperthermic Lithic Medisaprist) to evaluate effects of silicate sources and rates on growth of cane and sugar yield. Data were collected from the initial planting and a subsequent ratoon crop. Silicate materials were applied to 79.2 m2 field plots at the rates of 0, 5, 10, 15, and 20 metric tons/ha of TVA slag, Florida slag, and Portland cement. A factorial experiment was established in a randomized complete block design with five replications. The silicate materials were broadcast by hand and then thoroughly mixed with the soil by a disc harrow. Growth was measured as plant height, stem diameter, and number of millable stalks. Yield was determined as metric tons of cane and sugar per ha. Application of silicate materials increased plant height, stem diameter, number of millable stalks, and cane and sugar yields in both plant and ratoon crops. Addition of 15 metric tons/ha of silicate materials increased cane and sugar yields by 68 and 79% in the plant crop, and by 125 and 129% in the ratoon crop, respectively. Although there was no significant difference among the silicate materials in the plant crop, Florida slag increased growth and yield more than the other two materials in the ratoon crop. The vital role of Si in sugarcane growth was evident by increased plant size and increased tillering.
Yield and Yield Components of Four Spring Barley Cultivars Under Three Tillage Systems1
Authors: Ciha A. J.
Published: July 2010

Soil erosion is a serious problem in the Palouse Region of the Pacific Northwest. A field study was conducted under three environmental conditions [Palouse silt foam (fine‐silty, mixed, mesic, Pachic Ultic Hapoxerolls) during 1980 and Athena silt loam (fine‐silty, mixed, mesic, Pachic Haploxerolls) during 1979 and 1980] to determine the effects of three tillage systems on grain yield and yield components of four commercial spring barley (Hordeum vulgare L.) cultivars, ‘Steptoe’, ‘Advance’, ‘Vanguard’, and ‘Kimberly’. The experiments were conducted using conventional tillage (fall plow and spring disk), conservation tillage (fall chisel and spring disk), and no‐tillage (standing stubble) systems.

Grain yields were not significantly influenced by tillage; however, yields under no‐tillage were consistently greater than yields from conventional tillage. Test weight, 100‐kernel weight, and percent plump kernels were significantly increased with no‐tillage when compared to conventional tillage, but no‐tillage barley had significantly fewer heads/m2 and reduced plant height than conventional tillage. Tillage practice had no significant effect on seeds per head. Environment significantly influenced all yield and yield components. Significant tillage ✕ environment interactions for test weight, height, and 100‐kernel weight did exist. While significant differences in yield and yield components existed among the cultivars examined, no cultivar ✕ tillage interactions were present for any of the parameters examined in this experiment. Results suggest that spring barley cultivars developed and selected under conventional tillage systems are equally adapted to no‐tillage systems. Since grain yields were not significantly affected by tillage system under the conditions of this experiment, the use of no‐tillage systems for spring barley production should be adapted whenever possible to reduce soil erosion.
Double Cropping Cotton and Wheat1
Authors: Smith C. Wayne , Varvil J. J.
Published: July 2010

Several “fast fruiting” or “early” genotypes of cotton (Gossypium hirsutum L.), have been developed over the past several years to reduce losses associated with adverse autumn weather, allow later planting to escape early season disease problems, reduce insect and weed pests associated problems, and to reduce the inputs required to make and protect an acceptable yield. These earlier maturing types may provide the opportunity of year‐round land use by double cropping with a winter grain.

Four genotypes, ‘Deltapine 16’, ‘Rex 713’, ‘Coker 304’, and Arkugo 4, were included to represent a range of genetic maturity. These entries were compared when monocropped or double cropped after wheat (Triticum aestivum L.) in a prepared seedbed or planted directly into the wheat stubble. The experimental design was a split plot of a randomized complete block. The test site was Memphis silt loam (a fine‐silty, mixed, thermic Typic Haplustalfs). All other production practices were normal for the locale with no irrigation.

Results indicated that seedcotton yields of double cropped cotton, as compared to monocropped, would be reduced by 35 to 50% with an early maturing genotype and 50 to 65% with full season, Delta cultivars. These results would discourage double cropping with wheat in the northern areas of the U.S. cotton belt. However, lint yields of double cropped Arkugo 4, the fastest fruiting type studied, were such that further development of early season types should be encouraged.

No detrimental effects of double cropping on quality of fiber or percent lint were noted in 1976 or 1978.
Influence of Subsurface Irrigation and Organic Additions on Top and Root Growth of Field Corn1
Authors: Mitchell W. H. , Sparks D. L.
Published: July 2010

Numerous attempts have been made to increase root proliferation by modifying soil profiles possessing undesirable chemical and physical properties.

Field and laboratory studies were conducted over a 5‐year period on an Evesboro loamy sand (mesic, coated Typic Quartzipsamments) soil from Delaware to determine the effect of organic additions and type of irrigation on corn (Zea mays L.) grain yield, root distribution, and on selected soil properties. The study also sought to determine if organic additions would increase the effectiveness of subsurface irrigation. Organic additions, made only in the 1st year of the study, consisted of 10 ✕ 40 cm chisel (C) openings at 76 cm intervals which were filled with solid waste (SW) and/or poultry manure (PM) at 65 metric tons/ha. No attempt was made to superimpose corn rows directly above the chisel openings. Irrigation types were subsurface (SSI), and trickle irrigation (TI). Grain yields were significantly higher in C + SSI than in C + TI treatments. Chiseling + SSI increased the average 5‐year corn yield 4,300 kg/ha over C alone which demonstrated the pronounced effect that SSI had on yield. Organic additions had no signifciant effect on grain yields, although yields for the C + SW treatment were numerically higher than for the C + PM treatment each year of the study, and the former averaged 1,150 kg/ha higher over the 5‐year period. The C + SW treatments also produced higher yields than the control (NC). Chiseling, without incorporation of organic materials (C) was no more effective than leaving the soil undisturbed (NC). Organic additions enhanced root growth more than yield of corn. The subsoil was essentially devoid of roots without chiseling or organic additions. The highest CEC and organic matter levels at the end of the 5‐year study were found in the organic addition trench adjacent to the SSI lines. Corn roots proliferated in this region and in most cases enveloped the irrigation lines. Lateral as well as vertical movement of Ca, K, Mg, and P occurred with the lowest concentrations occurring in the plow layer. Movement of plant nutrients laterally from the organic addition trench into the surrounding subsoil probably contributed to root extension and could be significant in terms of nutrient utilization.
Urease Activity in a Kentucky Bluegrass Turf1
Authors: Torello W. A. , Wehner D. J.
Published: July 2010

The components of a turfgrass ecosystem, including plants, an intervening layer of thatch and the underlying soil, influence the fate of topically applied urea fertilizer. The loss of urea N by ammonia volatilization may be governed by the rate of urea hydrolysis. The main objective of this study was to determine the extent of urease activity associated with turfgrass plant tissue, thatch, and the underlying soil. This information may help elucidate the mechanism of ammonia loss following urea application. Because a turfgrass stand frequently possesses an extensive thatch layer that may serve as the primary plant growth medium, additional objectives included. i) determining the effects of air drying and seasonal variation on the activity of urease in thatch; ii) determining the variability in thatch urease activity by analyzing multiple field samples; and iii) determining the variation of urease activity within a thatch profile. Turfgrass clippings, thatch, and underlying Flanagan silt loam soil (Aquic Argiudoll) samples were taken from a field‐grown Kentucky bluegrass (Poa pratensis L.) turf in either September 1980 or March 1981. On a dry weight basis, urease activity was 18 to 30 times higher from turfgrass clippings and thatch than from soil. Air drying thatch increased urease activity by 20% over moist samples while air drying soil samples had no apparent effect. Greenhouse incubation of winterdormant thatch samples increased urease activity 40 %, presumably in response to the duration of increased temperature. Thatch urease activity varied between sampling sites but still remained extremely high compared to soil activity. Within each thatch sample (1 × 1 × 2 cm), urease activity was highest in the upper 1.0 cm of the profile. It was concluded that thatch urease activity was variable in nature depending upon seasonal conditions which contrasts sharply with extremely stable soil urease activities. These findings suggest that, because of the high level of urease in thatch, ammonia volatilization will occur from most urea‐treated turfgrass stands, regardless of the type of underlying soil unless the urea is thoroughly washed into the soil.
Herbicide and Planting Date Influence Establishment of Sod‐Seeded Alfalfa1
Authors: Martin N. P. , Sheaffer C. C. , Wyse D. L. , Schriever D. A.
Published: July 2010

Yield and quality of perennial grass pastures can be improved through sod‐seeding of alfalfa (Medicago sativa L.). Herbicides have been widely used for grass suppression in sod‐seeding; however, the influence of the time of application on herbicide effectiveness requires study. Our objective was to determine the effects of planting dates and rates and types of herbicides on alfalfa establishment and yield when interseeded into perennial grass sod. A field study was conducted for 2 years on a Typic Halaquol, fine loamy, over sand, mixed, mesic soil. Alfalfa was sod‐seeded into a mixed smooth bromegrass (Bromus inermis Leyss.), Kentucky bluegrass (Poa pratensis L.), and quackgrass (Agropyron repens L.) sod on 21 April, 10 May, 19 May, and 2 June in 1978; and 19 April, 4 May, 21 May, and 2 June in 1979. On each planting date, paraquat (1,1′‐dimethyl‐4,4′‐bipyridinium ion) and glyphosate [N‐(phosphonomethyl) glycine] were each broadcast sprayed at 0.6, 0.8, and 1.1 kg ha−1. Dalapon [2,2‐dichloropropionic acid] was broadcast sprayed at 3.4, 5.6, and 9.0 kg ha−1. Greatest seeding year legume yields were obtained with the medium or high dalapon rates for the April seeding dates or with the medium or high glyphosate rates for the late May seeding date. The lowest average legume yields across all herbicides occurred for the June seeding date each year. Dalapon was the most effective herbicide across all rates for suppressing grass and increasing alfalfa yields for the April planting dates each year when grass regrowth was limited. For the early May planting date, dalapon treatments had the lowest grass yields. Alfalfa yields for dalapon and glyphosate treatments were not consistently different. For the late May planting date, glyphosate provided the greatest grass suppression and alfalfa yields. Herbicides and herbicide rates can be selected for grass suppression and legume establishment based on extent of grass vegetative development. Under low rainfall conditions, grass suppression may not insure successful legume establishment.
Agronomic, Chemical, and Smoke Characteristics of Flue‐cured Tobacco Lines with Different Levels of Total Alkaloids1
Authors: Chaplin James F. , Burk L. G.
Published: July 2010

abstract

Total alkaloids (predominately nicotine) are important constitutents in flue‐cured tobacco (Nicotiana tabacum L.). Due to varying nicotine levels in cigarettes, it is of interest to see what effect varying alkaloid levels in tobacco have on certain agronomic and chemical characteristics of the cured leaf. Experiments were conducted at two locations to develop lines of flue‐cured tobacco with different levels of total alkaloids and to evaluate these lines for agronomic, chemical, and smoke characteristics. Three flue‐cured cultivars with different total alkaloid levels were chosen as recurrent parents. The parents and alkaloid levels were: 'Coker 139' (1.88%), 'NC 95' (3.28%), and 'SC 58' (4.51%). Each cultivar was crossed with a low alkaloid line (0.20%). After the initial cross, backcrosses were made in each F2population between a low alkaloid plant and its respective recurrent parent. BC5F7generation plants with different levels of total alkaloids were selected and advanced to the BC5F7to obtain stable lines. Also dihaploids were developed from BC5F7plants and lines with different levels of total alkaloids were selected. Both the BC5F7and dihaploid populations were evaluated. Based on these tests the line with the highest yield and grade index at each alkaloid level was further evaluated for total alkaloids, reducing sugars, yield, grade index, days to flower, plant height, and number of leaves per plant. Lines with the following levels of total alkaloids were evaluated: NC 95 family ‐ 0.34, 1.08, 2.05, 3.11, and 3.55%; SC 58 family ‐ 0.38, 1.59, 1.90, 2.82, 4.18, and 4.82%; and the Coker 139 family ‐ 0.20, 0.93,1.66,1.84, and 2.17%. The 1.08% line in the NC 95 and 1.59% line in the SC 58 families were dihaploids. None of the lines converted appreciable amounts of nicotine to nornicotine. Therefore, the total alkaloid levels reflected predominantly nicotine. In most families the high alkaloid lines gave the highest grade index. Days to flower, plant height, and number of leaves per plant were not associated with total alkaloid levels in cured leaf. Cigarette smoke from the different tobacco lines was evaluated by two smoke panels. The results from Panel A indicated that it was difficult to associate any of the taste parameters with levels of total alkaloids in the leaf. The results from Panel B indicated that an increase in total alkaloids in the leaf was accompanied by an increase in flavor of the smoke.
Reaction of a Resistant and a Susceptible Corn Hybrid to Various Southwestern Corn Borer Infestation Levels1
Authors: William W. Paul , Davis Frank M.
Published: July 2010

Infestation of corn (Zea maysL.) by the southwestern corn borer [Diatraea grandiosella(Dyar)] can result in substantial losses. Corn genotypes with resistance to leaf feeding damage by the southwestern corn borer have been developed; however, no data on the effectiveness of this resistance in preventing yield and plant height reductions have been reported. To compare the effects of varying infestation levels on a leaf‐feeding‐resistant and a leaf‐feeding‐susceptible corn hybrid, plants in the 10 to 12 leaf stage of growth were infested with 0 to 40 southwestern corn borer larvae per plant in a field study grown on a Leeper silty clay loam (fine, montmorillonitic, nonacid, thermic, Vertic Haplaquepts) in 1982 and 1983. Plants were evaluated for leaf feeding damage, height, and grain yield. Infestation of the susceptible hybrid with 0 to 40 larvae per plant resulted in a linear decline in plant height and yield as infestation level increased. Infestation with 40 larvae per plant reduced yield 39%. Conversely, neither plant height nor yield of the resistant hybrid was significantly reduced at any infestation level. The level of resistance found in the resistant hybrid was, therefore, adequate to prevent losses.