Browsing by Author "Starling, Thomas M."
Now showing 1 - 8 of 8
Results Per Page
Sort Options
- Barley for Silage in VirginiaStarling, Thomas M.; Polan, Carl E.; Murley, W. Ray (Virginia Cooperative Extension Service, 1968-07)
- A comparison of determinate and indeterminate soybean lines for double cropping in VirginiaPyle, Marjorie Elizabeth (Virginia Polytechnic Institute and State University, 1982)Forty lines, 20 determinate and 20 indeterminate, from four soybean (Glycine max L. Merrill) crosses were evaluated under full-season and double cropping conditions to compare the performance of the two plant types under both cropping systems. The parents and selected lines were in the range of Maturity Groups IV and V. In 1980, the lines were planted 1 July in a replicated test at Warsaw, VA while in 1981 these lines were planted in three replicated tests on 11 June and 8 July at Warsaw and on 12 June at Orange, VA. Both June plantings were considered full-season. Standard cultivars in 1980 included 'Essex', 'Williams', and 'Crawford'. 'Bay' and 'Will' were added in 1981. Yields were similar in 1980 for both plant types with the determinates yielding 10.1 q/ha and the indeterminates yielding 9.9 q/ha. In 1981, the yields were similar for both types at Orange with the determinates and indeterminates yielding 26.4 and 26.5 respectively. The types were significantly different in the 11 June planting at Warsaw, with yields of 28. 6 and 28. 0 q/ha for the determinate and indeterminate lines, respectively. The opposite was observed for the 8 July planting in which the indeterminates yielded 21.2 q/ha and the determinates yielded 20.8 q/ha. A comparison of the two determinate and indeterminate lines with the highest yields in both 1981 Warsaw plantings showed that indeterminates were more adaptable to double cropping, though high yielding lines of both types were present. The high yielding indeterminates of the 8 July planting had a tendency to be taller and more erect than the determinates, an attribute desirable for double cropping. Lines that were highest yielding in the 11 June planting were ranked lower in the 8 July planting and vice versa. Spearman' s rank correlation for yield in the two Warsaw plantings had a coefficient of 0. 23, indicating a high degree of specific adaptation to the two environments. Selection of better adapted lines for double cropping appears feasible. The indeterminate trait appears to make some contributions to this adaptation.
- Diallel analysis of rind puncture and grain yield and their interactions with plant densities for twelve elite inbred lines of maize, Zea mays LPerry, Christopher O. (Virginia Polytechnic Institute and State University, 1983)To better understand the genetics of stalk quality in elite Corn Belt germplasm, combining ability estimates for stalk quality as measured by rind puncture were obtained for twelve inbred lines of maize representing elite Corn Belt germplasm. Secondly, an attempt was made to assess the practical utility of the rind penetrometer as a tool to measure stalk quality in an applied maize breeding program. The twelve inbred lines of maize were crossed in a diallel manner to produce the 66 F₁ single cross hybrids. Hybrids were hand planted in single-row plots with three replications at Holland, Virginia on 10 April and 15 and 16 April, 1981 and 1982, respectively. Plots were comprised of four split-plots corresponding to planting densities of 39,536, 49,420, 59,304 and 69,188 plants per hectare. Rind puncture data were collected from five competitive plants in each density for each hybrid at midsi lk and two to three weeks later. Data were also collected on percent erect plants, stalk pinch values, and grain yield. Analyses of variance were performed on the means for each hybrid-density combination for all traits. Model I, Method 4 of Griffing (1956) was followed to obtain estimates of GCA and SCA effects. Highly significant differences were detected among hybrids and densities for rind puncture and grain yield in both years. Significant differences were also detected among hybrids for percent erect plants and stalk pinch value, although no significant difference among densities was evident. No significant difference was detected between dates of measurement for rind puncture. nents were highly significant for all GCA and SCA compotraits. Hybrid by density interaction was significant for grain yield and percent erect plants but not for rind puncture or stalk pinch. Hybrid by date interaction for rind puncture was highly significant in 1982 only. Considerable additive genetic variation associated with GCA was detected for rind strength as measured by rind puncture in elite Corn Belt germplasm. The rind penetrometer appears to be a useful tool to aid the breeder in identifying genotypes with superior rind strength, which in turn is a component of total stalk strength.
- A diallel study of flowering and of ear components of yield in Corn Belt maize and their interactions with population densityMcClane, John Michael (Virginia Polytechnic Institute and State University, 1985)A diallel study of American Corn Belt maize (Zea mays L.) was conducted at Holland, Virginia in 1981 and 1982. All possible crosses of twelve inbred parents (A619, A632, B73, H60, H93, H96, Mo17, Oh7B, Pa91, Val7, Va.79:419, Va85) were planted in three replications with population density treatments of 39,536, 49,420, 59,304, and 69,188 pl/ha in strips across hybrid treatments. Analyses of variance and combining ability analyses were performed on traits measuring the timing of anthesis (pollen shed) and silk emergence, on ear components of yield, and on components of kernel size. Density effects were highly significant for all traits, except for that of pollen shed duration, in the analyses combined over years. Hybrid-by-year interactions were highly significant for all traits. Correlations between GCA effects of grain yield and GCA effects of silking delay (anthesis-to-silking interval), kernels per row on the ear, ear kernel number, and kernel depth[(ear diameter - cob diameter)/2] were -0.79, 0.64, 0.66, and 0.80 in 1981, and 0.24, 0.81, 0.71, and 0.26 in 1982, respectively. Moisture stress sufficient to cause wilting occurred before and during silking in 1981. Apparently, short silking delay was associated with high moisture stress tolerance for grain yield in 1981 and was associated with long ear shoot length in 1982. Deep kernel depth apparently was associated with drought stress tolerance for yield as well. The heritabilities of ear traits were higher the earlier they became established in the sequence of development. Heritabilities of silking delay and most ear components of yield were increased by increasing planting density. However, the correlations among flowering and ear traits largely were unaffected by density, perhaps because densities were not high enough to make barrenness a substantial factor in grain yield. The most important traits related to yield were silking delay, kernels per row, kernel depth, and kernel row number. GCA to SCA variance component ratios were increased by combining data over years and by the more optimum season for yield.
- Inheritance of reactions to gray leaf spot and maize dwarf mosaic virus in maize and their associations with physiological traitsDonahue, Patrick J. (Virginia Polytechnic Institute and State University, 1989)Gray leaf spot, caused by Cercospora zeae-maydis, can be a yield-limiting factor in maize where continuous minimum tillage practices are followed. Commercial corn hybrids were evaluated for response to gray leaf spot for seven years at two Virginia locations (Shenandoah and Wythe Counties) and one year at a third location in Virginia (Montgomery County). Yield losses, when comparing resistant to susceptible classes, were approximately 2,000 kg ha⁻¹ at Wythe County in 1982, 750 kg ha⁻¹ at Shenandoah County in 1984, and 2,150 kg ha⁻¹ at Montgomery County in 1988. The inheritance of reaction to gray leaf spot was studied using a 14 inbred diallel in Montgomery and Wythe Counties, Virginia in 1987 and 1988 planted in randomized complete block designs. Resistance was found to be highly heritable and controlled by additive gene action. Inbreds producing high yielding, resistant, and agronomically superior hybrids were identified (B68, NC250, Pa875, Va14, Va17, and Va85); and several hybrids between these lines had high levels of resistance, high yield, and good general agronomic characters (B68 x KB1250, KB1250 x Pa875, and NC250 x Pa875). Currently available inbreds could be used to produce hybrids with higher levels of resistance than hybrids currently available to growers, and these could serve as a basis for gray leaf spot breeding programs. Lesion size measurements were not correlated with disease scores. Late-season photosynthesis rates were associated positively with resistance. The hybrids of some inbreds were found to produce high levels of pigment (believed to be anthocyanins) around the gray leaf spot lesions. These did not limit the size of the individual lesion later in the season. Some pigment(s)-producing genotypes were found to be resistant when the pigment character was expressed. This type of resistance must prevent or inhibit infection of the leaf but not later colonization, once established. Maize dwarf mosaic virus (MDMV) also limits maize production in some areas where johnsongrass (Sorghum halepense L.) is a problem. Resistance to MDMV was found to be mainly additive and highly heritable. However, a strong specific combining ability component was found, indicating that the background of the material receiving resistance genes may have a strong effect on the expression of resistance. Inbreds capable of producing high-yielding, resistant, and agronomically acceptable hybrids are available (B68, NC250, A632, Pa875, Va17, and Va85); and several hybrids between these lines have high levels of resistance, high yield, and good general agronomic characters (B68 x KB1250, KB1250 x Pa875, and NC250 x Pa875).
- Inheritance of resistance to Rhynchosporium secalis (Oud.) J.J. Davis in BarleyChi, Kuo-Ruey (Virginia Tech, 1961-05-26)Thirty-two resistant varieties of winter type barley from the United States Department of Agriculture's World Collection were chosen for a study of the inheritance of scald resistance. They were crossed with Wong (0.1. 6728), a highly susceptible variety and with Hudson (0.I. 8067), a highly resistant variety. The crosses with Wong were made for the purpose of determining the number of pairs of genes for resistance in each of the resistant varieties. The crosses with Hudson were made for the purpose of determining whether any of the resistant varieties has genes for scald resistance at loci other than in Hudson. The F2 seedling populations from these crosses were studied in the greenhouse at Blacksburg in the early spring of 1960 and the winter of 1961.
- Location of genes conditiioning resistance of barley to leaf rust (Puccinia hordei Otth)Larkins, James Russell (Virginia Polytechnic Institute and State University, 1982)Conventional linkage and primary trisomic analyses were undertaken to locate genes conditioning resistance of barley (Hordeum vulgare L.) to Puccinia hordei Otth. The linkage relationships of resistance genes Pa in Speciale (C.I. 7536) and Pa₇ in Cebada Capa (C.I. 6193) with genes known to reside on chromosomes 2 and 3 were studied in crosses involving Speciale and three chromosome 2 markers (e, gs₅, and lr), and in crosses involving Cebada Capa and four chromosome 3 markers (gs₂, uz, als, and yst₂). The location of the resistance gene Pa₃ in Estate was studied by primary trisomic analysis. Inheritance of leaf rust resistance was determined by seedling reaction to culture 57-19, race UN4 of Puccinia hordei. The inheritance and linkage relationships of marker genes and rust resistance were analyzed from F₂ and F₃ coupling data. A recombination value of 41.0 ± 2.2% was found between Pa and gs₅, a marker for chromosome 2L. No evidence was obtained linking Pa with genes e or lr, but population sizes were too small to detect reliably loose linkages in these populations. A loose association was observed between Pa₇ and yst₂ a marker for chromosome 3S; however, the data were not sufficiently homogeneous to permit estimation of a recombination value. The data from crosses involving Pa₇ and uz were not consistent but one population exhibited a trend which suggested these genes might be linked. No evidence of linkage was observed in crosses between Pa₇ and the genes gs₂ and als, although population sizes were limited. The assignment of Pa₇ to chromosome 3 was confirmed by primary trisomic analyses. By the same method, the Pa₃ gene in Estate was shown to be independent of chromosome 3. High temperatures during leaf rust inoculation and incubation periods resulted in poor expression of infection type in crosses involving Estate and Triplo 4, 5, and 6. Despite this the data from these crosses indicated that Pa₃ is not likely inherited through chromosomes 4 through 6. Accrued data suggest that Pa₃ may be located on chromosome 1.
- Wastewater application to soils: hydraulic and nitrogen considerationsSimon, John J. (Virginia Polytechnic Institute and State University, 1986)Land application of domestic and industrial wastewaters provides an effective means of recycling water and its components into the ecosystem. Successful treatment by soil requires that wastewater is applied in quantities that both maintain infiltrative capacity of the soil and do not exceed the capacity of the soil-plant system to assimilate biological and chemical contaminants. Application of N-rich wastewaters requires that consideration be given to both the ability of the soil to transmit the hydraulic load and remove sufficient N to maintain groundwater quality standards. A textile wastewater containing high concentrations of organic N was spray-irrigated to tall fescue (Festuca arunindinacea) to determine optimum N application levels. Nitrogen balances were determined at each N level and and the potential for predicting the leaching component of the excess N applied was investigated. Historically on-site wastewater disposal systems (OSWDS) for treating septic tank effluent (STE) have been designed on a hydraulic loading basis with N pollution potential essentially ignored. Many soils have been deemed unsuitable for application of STE because of textural, water table, or landscape restrictions. The relations between soil properties, hydraulic performance of OSWDS, and N distribution around OSWDS are evaluated. Wastewater from a nylon processing plant was applied to 'Ky 31' tall fescue at total Kjeldahl nitrogen (TKN) levels of approximately 250, 430, and 1900 kg ha⁻¹ during 1982 and 1983. Fescue yield and N removal was comparable to agricultural yields at similar N application levels. Nitrogen balances indicate that plant uptake efficiency decreased with increasing organic N levels above the 250 kg ha⁻¹ level and that maximum uptake occurred at the 450 kg ha⁻¹ level. Most of the N not recovered in plant tissue mineralized rapidly to the nitrate NO₃⁻ form and leaching was noted during the winter and spring. This data is evaluated with quasi-transient analytical solution of the convection-dispersion equation. The movement of the solute center of mass is predicted on the basis of assumptions of piston flow as well as alternative assumptions of mixing via plate layer theory. Prediction of the location of the center of solute mass (α) provides a moving lagrangian coordinate solution around which dispersion of solute is calculated. The assumptions made about the sequence of evaporation and infiltration events significantly influence the prediction of α and hence the agreement between predicted and measured solute distribution. Both approaches give results which are within experimental error and provide a rational basis for predicting leaching losses and carry-over NO₃⁻ available to future crops. Prototype OSWDS with low pressure distribution installed in three clayey limestone-derived soils were dosed with STE at flux densities ranging from 0.4 to 3.6 cm d⁻¹ on a trench bottom area basis. Ponding was noted in OSWDS at all sites dosed at the 3.6 cm d⁻¹ flux due to both underlying hydraulic restrictions and resultant anaerobic conditions. It is concluded that clayey B horizons low in swelling clays but moderately well structured can be dosed at flux densities up to 2 cm d⁻¹ if low pressure distribution of STE is used. Nitrification was found to be quite limited in soils where effluent was ponded above a restrictive layer but occurred readily within 30 cm below trenches which were freely drained or had matric potentials of at least 40 cm of water. Ratios of NO₃⁻ to Cl⁻ indicate that only limited denitrification can be expected and that substantial NO₃⁻ does leach from below OSWDS in the direction of water flow.