bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Whole‐plant Indicator of Soybean Physiological Maturity1
Authors: Gbikpi Pascal J. , Crookson R. Kent 
Published: July 2010

Loss of green color from the pod has been suggested as an indication of physiological maturity for individual soybean [Glycine max (L.) Merrill] seeds. In this study, we evaluated the usefulness of green pod color loss as an indicator of the physiological maturity of an entire soybean plant. We also studied the relationship of this visual change to other stages of whole‐plant soybean development and maturity already in use or described in the literature. The study was conducted in 1978 and 1979 at St. Paul, Minn. on a well‐drained Waukegan silt loam (sandy‐skeletal, mixed mesic Typic Hapludolls). The 1st year, cvs. ‘McCall’ (Group 00) and ‘Hodgson 78’ (Group I) were used. In 1979, ‘Altona’ (Group 00) and ‘Steele’ (Group I) were added. Seed dry weight was measured at 1‐week intervals for 8 weeks which spanned the maturation phase. The calculated date of physiological maturity was then related to a variety of visual plant changes.Loss of green pod color was found to be the most reliable indicator of physiological maturity across years, cultivars, and maturity groups. Stage R7 according to Fehr and Caviness (occurs when one normal pod on the main stem has reached its mature color) was next most reliable, but occurred before physiological maturity and interacted with years. The ‘all pods brown’ stage occurred midway between physiological maturity and harvest maturity (harvest maturity = average seed moisture at 13%). On the average, early maturing seeds reached physiological maturity 11 days before late maturing seeds. Seed moisture content averaged 44% when the entire plant was physiologically mature. Color of petioles and stems, and color or senescence of leaves were not reliable indicators of physiological maturity.
Associations Among Pod Dimensions and Seed Weight in Soybeans1
Authors: Frank S. J. , Fehr W. R. 
Published: July 2010

Selection for seed weight among soybean [Glycine max (L.) Merr.] genotypes can be accomplished by indirect selection for width of mature pods. Our study was designed to evaluate additional variables that could influence the effectiveness of indirect selection for seed weight. The objectives were to determine the influence of number of seeds per pod on pod length, width, and thickness; to determine if measurements on full‐size green pods were as effective for selection as measurements on mature pods; and to determine which pod dimensions would be most effective for indirect selection. Data were obtained on F4 plants and their progeny from six populations in three Iowa environments.Number of seeds per pod had a significant effect on pod length, but was of no practical importance on pod width or thickness. Selection for pod length or width based on measurements of full‐size green pods was as effective as selection based on mature pod dimensions. Selection for pod length or width was more effective than for pod thickness. Use of pod length or width alone was as effective for selection as evaluation for pod area or volume. Pod width was considered the most efficient character to use for indirect selection because it can be measured without regard to number of seeds per pod and is faster to measure than pod length.
Selection for Agronomic Characters in Hill and Row Plots of Soybeans1
Authors: Garland M. L. , Fehr W. R. 
Published: July 2010

The objectives of the study were to compare the effectiveness of selection for yield, maturity, height, lodging, and phenotypic score among soybean [Glycine max (L.) Merr.] lines in hill and row plots and in random and nonrandom complete‐block designs. Progeny from 50 random S3 plants of Maturity Group II were grown in two‐row, unbordered plots with 69 cm between rows within the plot and 102 cm between plots and in single, unbordered hill plots spaced 102 ✕ 102 cm. A randomized complete block design was used for the row plots, and both randomized and nonrandomized complete‐block designs were used for the hill plots.There was no difference in the effectiveness of selection for yield between random and nonrandom hills. The hill and row plots were equally effective in selecting the top two lines. Actual genetic gain was 2.5 q/ha for random hills, 2.8 q/ha for nonrandom hills, and 3.0 q/ha for row plots with a 10% selection intensity. Considering possible differences in the selection differential and number of years per cycle between hill and row plots, the predicted genetic gain per year was 0.6 q/ha for random hills compared with 0.4 q/ha for rows.Selection for maturity, height, lodging, and phenotypic score was similar in effectiveness for the three plot arrangements. Genotypic correlations of line performance between random and nonrandom hills had coefficients of 0.99 to 1.02 for the four characters. The genotypic correlations between hills and rows ranged from 0.89 to 0.99. Hill plots were as effective as rows for phenotypic selection of agronomically desirable genotypes.Evaluation of yield, maturity, height, lodging, or phenotypic score can be done effectively in single, unbordered hill plots. The primary advantages of hills are the reduction in number of years required for cultivar development or recurrent selection by eliminating the need for a generation of seed increase and the larger number of lines that can be tested. Nonrandom hill plots may be useful in cases where randomization prevents efficient discarding of inferior lines before harvest.
Fruit Temperature, Growth Rates, and Yield of Peanuts1
Authors: Dreyer J. , Duncan W. G. , McCloud D. E. 
Published: July 2010

This experiment was conducted to test our hypothesis that the number of fruits established per plant should be inversely proportional to the growth rates of the individual fruits. Peanuts (Arachis hypogaea L.) were chosen as the test plant because their peculiar growth habit enabled us to vary fruit growth rates in a field experiment by cooling or warming the small soil volume occupied by the growing fruits with minimal effects on foliage and root temperatures.As predicted by the hypothesis, slower growth rates per fruit obtained by cooling the soil of the fruiting zone 4 C below the average ambient soil temperature of 27 C caused more fruits to be established. Warming the soil of the fruiting zone 3, 7, and 10 C above the ambient soil temperature had much less effect on fruit growth rates and consequently only the highest temperature caused a significant reduction in the number of fruits established. When harvest was delayed, as necessary to allow slower growing fruits to mature, average fruit weights were nearly the same for all except the warmest soil treatment. Thus the lower soil temperature resulted in a higher fruit yield because more fruits developed to nearly the same average weight but a longer filling period was required. The highest temperature produced the lowest yield because fewer and somewhat smaller fruits were produced.
Selecting for Grain Protein and Yield in Sorghum Random‐Mating Populations1
Authors: Ross W. M. , Kofoid K. D. , Maranville J. W. , Voigt R. L. 
Published: July 2010

Grain protein and grain yield relationships were studied in six sorghum [Sorghum bicolor (L.) Moench] populations tracing to the same base but developed with different objectives. Two cycles of selection for high and low grain protein in NP7BR were evaluated in Nebraska with 200 S1 progenies each that arose from intermating mass‐selected fertile plants. Means, variance components, heritabilities, genetic and environmental correlations, and expected correlated responses were determined. The same information was collected on 150 S1 progenies each from the related populations, NP7BR and NP9BR, selected for grain yield in Nebraska and for drought tolerance in Arizona, respectively.Change from the first selection cycle to the second selection cycle was significant by mass selection for both high and low grain protein percentage in NP7BR. The 0.4% gains in either direction were about one‐half of those predicted, and protein and grain yield had strong negative genetic correlations (− 0.42 to − 0.65). Populations selected for grain yield produced more protein per ha (protein yield) than did populations selected for protein. In all populations, the expected correlated response of protein or of yield was negative when the other trait was selected. Protein percentage showed little correlated response with selection for protein yield except in NP7BR. Selection for protein yield would be expected to result in yield advances equal to selection for yield per se without drastic decreases in grain protein, but high environmental correlations between grain yield and protein yield would exist.
Release od Soluble Protein and Nitrogen in Alfalfa. III. Influence of Shading1
Authors: Walgenbach R. P. , Marten G. C. 
Published: July 2010

Changes in leaf anatomy, morphology, and chemical composition due to different amounts of solar radiation could affect the apparent bloat potential of alfalfa (Medicago sativa L.) mediated via release of soluble protein into rumen fluid in the presence of ample available carbohydrates. Our objectives were to determine whether shading during growth would influence production characteristics as well as concentration of several N fractions and total nonstructural carbohydrates (TNC) released from alfalfa.Alfalfa was shaded with saran shades [0 (control), 47, and 73% shade] from 12 May to 1 June [Period (P)l], 30 June to 7 July (P2), and 9 to 16 August 1978 (P3). Total nitrogen (TN), total soluble N (TSN), soluble nonprotein N (SNPN), soluble protein N (SPN), total nonstructural carbohydrates (TNC) were determined.The 73% shade reduced yields 42% for P1, 30% for P2, and 24% for P3, while the 47% shade reduced yields 29% for P1, 22% for P2, and 10% for P3 compared to the respective control yields. In P1 (20 days of shade), concentration of SNPN in herbage was 10.1 mg/g dry wt for control, 10.5 mg for 47% shade, and 11.5 mg for 73% shade, while that of SPN was 14.8 mg for control, 13.8 mg for 47% shade, and 12.6 mg for 73% shade.In P2 (7 days of shade), concentrations of TN, TSN, and SNPN in herbage increased as shade increased. Shade did not significantly influence the herbage concentrations of SPN in P2. In P3 (7 days of shade), shade did not significantly affect herbage concentrations of any of the N fractions. Shade of 73% reduced the TNC concentrations in herbage 16% for P1, 44% for P2, and 19% for P3, while shade of 47% recuded TNC 8% for P1, 28% for P2, and 10% for P3, compared to that in control herbage.Reduced apparent bloat potential of alfalfa, as estimated by SPN release, occurred only in plants grown under low solar radiation for a continuous 20‐day period. However, both short and long periods of decreased solar radiation caused decreased TNC concentrations in herbage. Because an abundant supply of TNCis essential for the microbial activity that leads to gas production in the rumen, even relatively short periods of shade could be considered as potentially bloat suppressing. We conclude that the usual incidence of cloudy weather is not likely to be a major mediator of bloat incidence in ruminants that graze alfalfa, although periods of high solar radiation maybe considered bloat‐promoting rather than bloatsuppressing.
Response to Selection for Resistance to Four Diseases in Two Corn Populations1
Authors: Miles J. W. , Dudley J. W. , White D. G. , Lambert R. J. 
Published: July 2010

Index selection designed to maximize gain in resistance to a single disease and selection for resistance based on disease score, per se, were evaluated. Responses to index and per se half‐sib family selection for resistance to northern corn leaf blight (caused by Helminthosporium turcicum Pass.), Diplodia stalk rot [caused by Diplodia maydis (Berk.) Sacc.] and anthracnose leaf blight and stalk rot [caused by Colletotrichum graminicola (Ces.) Wils.] in two corn (Zea mays L.) populations (RSL and RSSSC) were measured by comparing the performance of selected bulks with base populations in artificially inoculated evaluation trials in 2 years.Modified ear‐to‐row index selection was effective in increasing resistance to northern corn leaf blight in both populations, and to Diplodia stalk rot and to anthracnose stalk rot in one population each. Half‐sib selection on disease score per se in one population (with recombination of remnant seed) was effective in increasing resistance to northern corn leaf blight, anthracnose leaf blight and anthracnose stalk rot. No consistent correlated response in grain yield (measured in uninoculated evaluation trials) to selection for disease resistance was found.Observed response to selection agreed well with predicted response based on variance and covariance estimates obtained from previous half‐sib evaluation experiments. Selection on indexes constructed from data on several traits and designed to maximize gain in disease resistance was no more effective than selection on disease score per se.
Diurnal Leaf Elongation of Contrasting Tall Fescue Genotypes1
Authors: Volenec J. J. , Nelson C. J. 
Published: July 2010

Leaf elongation rate (LER) of tall rescue (Festuca arundinacea Schreb.) leaves is associated with tillering rate and forage yield. We performed two experiments. Objectives of Exp. I were to determine if differences in LER among genotypes were due to differential growth during the photoperiod and dark period, and of Exp. II to determine the relationship between leaf water potential and LER. Plants were grown in a controlled environment chamber with a 14‐hour photoperiod and a constant temperature of 21 or 23 C measured at the leaf intercalary meristem. Potentiometers were used to measure leaf elongation of genotypes selected for high yield per tiller (HYT, rapid LER) and low yield per tiller (LYT, slow LER). In Exp. II, stomatal diffusive resistance, leaf water potential, and LER of these genotypes were measured.Mean LER for the HYT genotype (0.9 mm hour‐1) throughout two 48‐hour periods was greater than that for the LYT genotype (0.6 mm hour‐1). Mean LER of both genotypes was significantly higher during the dark periods than during the photoperiods, averaging respectively 1.1 and 0.7 mm hour‐1 for the HYT genotype, and 0.7 and 0.5 mm hour‐1 for the LYT genotype. The 67% increase in LER during the dark period over that during the photoperiod for the HYT genotype was significantly greater than the 33% increase for the LYT genotype. Brief, but substantial increases and decreases in LER coincided with the time the lights went off and on. This response was associated closely with times of increases and decreases in stomatal diffusive resistance, and subsequent changes in leaf water potential. Leaf water potential was higher for the HYT than for the LYT genotype and was associated with LER of both genotypes. In Exp. I, LER averaged 1.3 and 0.8 mm hour‐1 for the HYT and LYT genotypes, respectively, during a 41‐hour dark period. These rates were similar to those maintained during the normal 10‐hour dark periods, and we concluded that daily photosynthate production was not needed to maintain high LER in the dark. Thus, the difference in LER between genotypes was due, in part, to a genotype by leaf water potential interaction which allowed the HYT genotype to more effectively utilize the dark period.
Visual Indicators of Physiological Maturity of Hard Red Spring Wheat1
Authors: Hanft J. M. , Wych R. D. 
Published: July 2010

Field experiments were conducted in 1979 and 1980 to identify visual indicators that coincide with physiological maturity (PM) and 95% maximum kernel dry weight (95% MKW) in hard red spring wheat (Triticum aestivum L.). Dates of PM and 95% MKW were calculated from polynomial regression equations fitted to dry weight accumulation data from eight genotypes differing in several agronomic traits. In 1980, kernels were divided into three groups according to their position on the spike (bottom, middle, and top) to determine the order in which kernels achieve their maximum dry weight.The mean number of days from anthesis to 95% MKW and PM ranged from 22.3 to 33.7 and 27.9 to 40.1, respectively, depending upon planting date and genotype. Kernels matured, in order, from the top of the spike down. The time of 95% MKW preceded PM by about 7 days. Of the 13 visual characteristics observed during the grain‐filling period, first appearance of the pigment strand in the crease most closely coincided with the calculated date of PM. Complete loss of green color from the glumes also occurred close to PM. Complete loss of green color from the flag leaf most consistently coincided with the time of 95% MKW. An abrupt drop in kernel moisture content also occurred at 95% MKW. Complete loss of green color from the flag leaf could, therefore, be used as an indicator of the commencement of rapid kernel dry‐down and the final stage of grain filling which ends when the pigment strand is first visible and the glumes have lost all green color. Kernel moisture percentage at PM and 95% MKW was too variable to be considered a reliable indicator of either PM or 95% MKW.
Theory for Transfer of Alleles1
Authors: Dudley J. W. 
Published: July 2010

The objectives of this paper are to provide a theoretical framework for developing methods for incorporation of favorable alleles governing quantitative traits from exotic germplasm into adapted populations and to present computer simulation results evaluating the theory. Theoretical considerations suggest that the results apply to either improvement of an inbred line by adding favorable alleles from another line or to addition of favorable alleles from an exotic source to an adapted synthetic.The results suggest that 1) if one parent has more loci containing favorable alleles than the other, at least one generation of backcrossing to the recipient population prior to initiation of selection will enhance the probability of recovering a population which outperforms the better parent or a llne better than the best llne which could be isolated from the better parent, 2) selection starting in the appropriate generation will usually be necessary to either improve the population mean to the desired level or to increase to a reasonable level the probability of obtaining a superior inbred line, and 3) the more diverse the parents, the more useful one or more generations of backcrossing becomes.
Assessment of Acetylene Reduction by Sainfoin and Alfalfa over Three Growing Seasons1
Authors: Krall J.M. , Delaney R.H. 
Published: July 2010

Sainfoin (Onobrychis viciifolia Scop.) has many positive characteristics as a forage legume, but frequently exhibits poor stand persistence. Insufficient nitrogen (N2) fixation has been suspected contributing to the stand persistence problem in sainfoin. Nitrogen fixation (acetylene reduction) rates of sainfoin have been reported for seedling plants, however, there is no information on fixation rates for established stands.A root box technique which allowed for the measurement of acetylene reduction on intact perennial plants for several growing seasons was used. Acetylene reduction of sainfoln and alfalfa (Medicago sativa L.) grown in soils collected from six existing sainfoin fields was measured at various stages of plant growth over three growing seasons. Sainfoin acetylene reduction rates were 36 to 75 % greater than alfalfa with the difference increasing with plant age.Percent non‐structural carbohydrates (NSC) were 10 % higher alfalfa taproots compared to sainfoin after the third growing season. Total NSC of sainfoin and alfalfa taproots was 1.8 and 6.9 g, respectively. Visual observation indicated that root and crown diseases resulted in significant mortality of sainfoin.Results indicated that acetylene reduction of sainfoin was superior to alfalfa while a consistent trend favoring a particular soil was not found. Carbohydrate storage and disease susceptibility may contribute more to the stand persistence problem of sainfoin than poor N2 fixation.
Effects of Recurrent Phenotypic Selection for High and Low Photosynthesis on Agronomic Traits in Two Maize Populations1
Authors: Crosbie T. M. , Pearce R. B. 
Published: July 2010

Selection for high or low photosynthetic rate in plant populations may influence important agronomic traits. We studied the effects on agronomic traits of five cycles of recurrent phenotypic selection (RPS) for high CO2‐exchange rate (CER) in two maize (Zea mays L.) populations and three cycles of selection for low CER in one population.Estimates of the weighted‐average change in allelic frequency (Δpα) showed significant reductions in plant and ear heights and significant increases for percentages of plants not root and stalk lodged after five cycles of RPS for high CER in BSULl(RPH). Estimates of Δpα after RPS for high CER in BSUL2(RPH) were significant only for percentage dropped ears, which increased slightly across five cycles of selection. Estimates of Δpα for RPS for low CER in BSUL2(RPL) indicated that days to 50% pollen shed had increased significantly across cycles. Changes in grain yield were not significant for any population, but Δpα for low CER selection in BSUL2(RPL) was significantly greater than Δpα for high CER selection in either BSULl(RPH) or BSUL2(RPH). Estimates of Δpα for grain yield of both BSULl(RPH) or BSUL2(RPH) were negative, but not statistically significant at the 5% probability level.
Three Cycles of Simple Recurrent Selection for Early Heading in Winter Wheat1
Authors: Avey D. P. , Ohm H. W. , Patterson F. L. , Nyquist W. E. 
Published: July 2010

A recurrent selection program in winter wheat (Triticum aestivum L. em Thell) was initiated by intermating 12 two, three, and fourway hybrids involving 16 cultlvars and lines to determine gain from selection for early heading, to develop genotypes which are earlier heading than currently available types, and to demonstrate the feasibility of recurrent selection in wheat improvement. The hybrid population produced by intermating these 12 hybrids was the nonselected base population. Three cycles of selection and intermating of S0 plants were carried out in the greenhouse. Hybrid plants from each of the three cycles, S1 plants or the selfed progeny from S0 plants selected to intermate in each cycle, plants of the base population, and the 16 parents were planted in the field at two locations in fall of 1979.The largest gain from selection was realized in the first selection cycle. Additional progress was made in the following two cycles, but at slower rates. Mean days to heading after 30 April for the base population were 14.2 and 23.4 at Sullivan and Lafayette, Indiana, respectively. Mean days to heading for hybrid populations from cycles 1, 2, and 3 at the 10% selection level were, respectively, 12.0, 11.7, and 11.2 at Sullivan; and 22.2, 21.6, and 21.6 at Lafayette.Realized heritability estimates from cycle 1 were 0.92 and 0.49 for the selected S0 populations, and 0.31 and 0.36 for the selfed progenies at Sullivan and Lafayette, respectively. The heritabilitles of cycles 2 and 3 were lower, 0.24 to 0.32, and were similar for the S0 and S1 generations. These data suggest that in the first cycle, selection acted largely on major genes which showed some nonadditive gene action, while selection in cycles 2 and 3 acted on minor genes governed by additive and/or additive × additive effects.Recurrent selection for early heading in winter wheat was effective in shifting the population means in the desired direction.