bluuebunny/crossref_metadata_2025_split huggingface dataset:
Variation, Heritability, and Relationship to Yield of Physiological Characters in Peas1
Authors: Hobbs S.L.A. , Mahon J.D. 
Published: July 2010

Seven quantitative physiological characters [photosynthetic CO2 exchange rate (CER), specific leaf weight, N2(C2H2) fixation, root respiration, respiratory cost of N2(C2H2,) fixation, growth duration, and relative growth rate] were examined in 25 pea( Pisum sativum L.) genotypes. To assess the possible use of these traits as criteria for selection in plant breeding, studies were carried out in three field environments, and four yield characters (total plant dry weight, seed dry weight, harvest index, and seed N) were determined.Despite the significant environmental effects on all characters except seed N, overall genotype means differed significantly for all but the cost of N2 fixation and relative growth rate. These last two characters were affected by large genotype ✕ environment interactions which may have obscured the significant within‐environment genotypic differences. Genetic coefficients of variation for the physiological characters varied from 2 to 13% and estimates of broad sense heritability were high except for cost of N2(C2H2) fixation and relative growth rate. Significant correlations were found between yield characters and physiological characters [total weight and growth duration; total weight and cost of N2(C2H2) fixation (negative); seed N and N2 fixation (negative); harvest index and specific leaf weight; harvest index and CER]; and among physiological characters (N2 fixation and root respiration; CER and relative growth rate).For areas with short growing seasons, rapid growth for a limited period with more assimilate being placed into seeds (high harvest index) may be desirable. The combination of such characters might produce maximum potential yield in the short time available. Because CER appears to be correlated with these traits and is highly heritable, selection on the basis of this non‐destructive character might be profitable in breeding such conditions.
Measurement of and Correlations among Selected Seed Quality Factors for 36 Texas Race Stocks of Cotton1
Authors: Shaver Ted N. , Dilday Robert H. 
Published: July 2010

Five seed quality factors (gossypol, oil, protein, and kernel percentages, and seed index) were measured for 36 Texas race stocks of cotton (Gossypium hirsutum L.) and three controls. Linear correlation coefficients were then calculated for all possible combinations of the five traits taken two at a time to determine whether those traits were related in this material.Texas race stocks were detected with significantly higher gossypol, oil, or protein percentages than the controls, but not with higher kernel percentages or seed indexes. Positive relationships were demonstrated between kernel and oil percentage (r = 0.71), kernel and protein percentage (r = 0.62), kernel percentage and seed index (r = 0.62), and protein percentage and seed index (r = 0.48). A negative relationship existed between seed index and gossypol percentage (r = −0.47). Gossypol level among the stocks was not related to the percentages of oil, protein, or kernel in the seed. In these stocks, increasing gossypol percentage for host plant resistance should not cause a reduction in quantity of oil or protein in the seed.
Effects of Okra‐Leaf, Frego‐Bract, and Smooth‐Leaf Mutants on Pink Bollworm Damage and Agronomic Properties of Cotton1
Authors: Wilson F. D. , George B. W. 
Published: July 2010

Eight isolines of cotton, Gossypium hirsutum L., which carried all possible combinations of Okra leaf (L°2), frego bract (fg), and Smooth leaf (Sm2) vs. their normal‐leaf and normal‐bract equivalents in the La 71‐7 (a Stoneville) background, were grown in replicated experiments for 3 years in Arizona in insecticide‐free environments. Percentage of seed damage caused by pink bollworm (PBW), Pectinophora gossypiella (Saunders), and 11 agronomic properties were studied.Mean seed damage in the Okra‐leaf isolines was 82% of that in the corresponding normal‐leaf lines, a significant reduction. The Okra‐leaf isolines were comparable to the normal‐leaf types in agronomic properties. Their only negative effect was an 8% lower lint yield (which was significant). Okra leaf interacted with frego bract only for boll size and with Smooth leaf only for seed index. Okra leaf interacted with years for seed damage because the Okra‐leaf isolines had 76% as much damage as the normal‐leaf stocks in 1979, but 85% as much in 1978 and 88% as much in 1980. Seed damage in the frego‐bract isolines was not significantly different from that in its normal‐bract counterparts. Frego bract interacted significantly with Smooth leaf for lint percent and with years for seed damage, total lint yield, bolls/plant, boll size, lint percent, and plant height. When closely examined, the interaction for seed damage suggested that frego bract afforded a slight advantage during the years when seed damage was relatively high. However, deficiencies in numerous agronomic properties (including a 24% lint yield reduction) and the five year ✕ agronomic property interactions offset any advantages in reduced seed damage afforded by frego bracts. Smooth‐leaf isolines unexpectedly displayed more seed damage than the hirsute‐leaf lines. Smooth‐leaf isollnes were also inferior to the hirsute‐leaf types in all agronomic properties except seed index and displayed significant interactions between years and percent lint yield at second and third harvest, total lint yield, bolls/plant, and date of first flower. For PBW resistance and agronomic performance, Okra leaf appears to have value, frego bract does not, and Smooth leaf must be reevaluated.
Plant Density Effects on Combining Abilities of Early Maize Synthetics1
Authors: Cross H.Z. , Hammond J.J. 
Published: July 2010

Five early maize (Zea mays L.) synthetics were evaluated for general combining ability (GCA), specific combining ability (SCA), average heterosis, and reciprocal effects to estimate the optimum plant density for combining ability analysis in early improved synthetics, and the importance of reciprocal differences in early maize synthetics. Yield and agronomic data were obtained for the five parental synthetics and 20 synthetic crosses grown at 45,500, and 57,000, and 67,500 plants/ha in each of four environments.The absence of GCA interactions with plant densities indicated that a single density within the range of those tested should adequately evaluate these synthetics. Significant reciprocal effects for ear moisture at harvest, kernel depth, and kernel rows/ear indicated that cytoplasmic effects were important in these synthetics. Reciprocal differences of more than 3% for ear moisture at harvest between synthetic crosses indicated careful choice of the female parent could be a means of reducing crop drying costs and facilitating earlier harvest.The absence of detectable SCA effects for these synthetics indicated inter‐population improvement methods would not be advantageous within this group of synthetics.Average heterosis for grain yield in this study was 10.7%. This heterosis can be attributed to increased kernel size and kernel number which is consistent with the idea that heterosis may be produced by an increased effective filling period duration (EFPD).
Interrelationships of Morphological and Economic Characters of Sunflower1
Authors: Beard Benjamin H. , Geng Shu 
Published: July 2010

Two phenotypically dissimilar open pollinated sunflower (Helianthus annuus L.) cultivars, ‘Peredovik’ and ‘Tchernianka’, and two hybrids, ‘Romsun 52’ and ‘Seedtec 304’ (produced by genetic and cytoplasmic male sterile systems, respectively), were sown at different dates and seeding rates for two years. The four cultivars were planted as a 4 × 4 latin square. Within each of the four replications, dates of sowing were randomly assigned to strips across the four cultivars. Within each cultivar‐sowing date combination, plant spacings were randomly assigned as 6‐row subplots. Data were collected from ten plants per plot for a number of morphological characters and from the plants in the two center rows for yield and oil characters.Principal component and path coefficient analyses indicate that even though these cultivars are phenotypically and genetically different, the response to date of planting, and the biological systems controlling the interrelationships between morphological, yield, and oil characters are similar. This may explain why some sunflower cultivars are superior at a wide range of locations, and at the same time are sensitive to environmental changes such as planting dates. The results also suggest that yield improvement through better management should apply to many types of cultivars in a wide range of environments.
Effects of Diurnal Variation in Temperature on the Carbon Balances of White Clover Plants1
Authors: McCree K. J. , Amthor M. E. 
Published: July 2010

In principle, the respiratory loss associated with the synthesis of plant biomass from a given amount of available photosynthate should be independent of temperature, while the maintenance loss rate should increase geometrically with increasing temperature. When the whole plant carbon balance is considered, the daily carbon gain with a diurnal cycle of temperature should therefore be smaller than with a constant temperature of the same mean, which is the opposite of that commonly assumed.The carbon balances of dense stands of white clover (Trifolium repens L. ‘Regal’) were determined from integrated CO2 exchange rates (CER). The carbon balances with a diurnal cycle of temperature (30 C day/20 C night, 30 C day/10 C night) were shown to be predictable from the balances at constant temperatures of 30 C, 20 C, and 10 C. With a 30 C day, the daily carbon gain (growth rate)increased as night temperature decreased. The gain with a 30/10 C diurnal cycle was less than that with a constant 20 C. These results agree with the above principles.The daily substrate input of carbon from photosynthesis, calculated as the integral of the CER in the light minus the CER in the dark during the daytime, was the same with the 30/10 C diurnal cycle as with a constant 20 C. The CER in the light (the so‐called “net photosynthetic rate”) was much smaller with the diurnal cycle, while the daytime CER in the dark was much more negative. This was attributed to accelerated use of substrate that could not be used during the cool night.Hourly changes in the CER and in the levels of the various pools of substrate were simulated using a dynamic carbon balance model after Thornley. Parameters of the model were varied until the simulated pattern of the CER matched the observed pattern at a constant 30 C, then the rate of use of substrate and the rate of degradation of biomass were reduced by a factor of 2 for each 10 C drop in temperature, day or night.There was good agreement between simulated and observed CER for all combinations of temperature tested. Minor differences were attributed to deviations from the assumed steady state of substrate production and use, and to accelerated senescence of leaves at 30 C. An additional limitation is that developmental effects were excluded. Nevertheless, it is clear that the daily carbon balance with a diurnal cycle can be expected to differ only slightly from the balance with a constant temperature having the same mean value.
Variability for Morphological and Physiological Traits Associated with Barrenness and Grain Yield in the Maize Population, Iowa Upright Leaf Synthetic #11
Authors: Smith C. S. , Mock J. J. , Crosbie T. M. 
Published: July 2010

Barrenness, the failure of a plant to produce a normal ear, is a major limitation to efficient conversion of light energy into grain in maize (Zea mays L.) grown at high plant densities. Our research was conducted to determine magnitudes of genetic variability and heritabilities for various traits of the maize population Iowa Upright Leaf Synthetic #1 (BSUL1) and to determine which traits were associated with barrenness and grain yield at high plant densities.We grew 144 S1 lines from BSUL1 for 2 years at one location and at two plant densities. Results indicated that BSUL1 contained large amounts of genetic variability for the 14 traits studied at 42,300 and 96,800 plants/ha. Significant heritabilities ranged from 0.31 for grain/leaf area at the high density to 0.91 for tassel branch number (low density). Phenotypic and genotypic correlations indicated that silking traits, pullen‐shed‐to‐silking interval, and grain/plant were highly correlated with grain yield and barrenness at both densities. Canopy orientation traits generally showed weak associations with grain yield and barrenness. Correlations and genotype × year interactions suggested that selection at a low density (42,300 plants/ha) in one location for traits correlated with barrenness should improve BSUL1 for tolerance to high plant densities.
Evaluation of Alfalfa Synthetic Varieties: Prediction of Yield in Advanced Generations and Average Clone Effects1
Authors: Rowe D.E. , Gurgis R.Y. 
Published: July 2010

First, second, and third generations of nine synthetic varieties derived from combinations of two to nine clones selected from the alfalfa (Medicago sativa L.) variety ‘Cherokee’ were harvested in field plots for three seasons to evaluate the effectiveness of a prediction formula for yields and to estimate genetic factors affecting yield. The Syn 1 yields were predicted as the average of all possible Fls. Yields of F1s were previously determined in a nine clone diallel. The Syn 2 yields were predicted as a function of the Syn 1 predictions adjusted by subtracting the average S1 yields of the clones in the synthetic variety.Observed yields were compared to predicted yields using product moment correlation analyses. The predictions of Syn 1 yields were inaccurate while those of Syn 2 were very good. For Syn 2 the overall means of the predicted and observed yields were the same with a highly significant correlation (r = 0.86).A genetic model was developed to determine average effects of the individual clones in synthetic varieties, the linear generation effect, the quadratic generation effect, and the interaction of the linear generation effect and the clone effects on the yields of the synthetics. All effects except the quadratic generation effect and the interaction term were statistically significant. The average effects of the individual clones suggested that two of the nine clones were much inferior to the others and may have been misclassified in the initial selection of clones. The advantages of this modeling approach are outlined.
Use of Transpiration Decline Curves to Identify Drought‐Tolerant Cotton Germplasm1
Authors: Quisenberry J. E. , Roark Bruce , McMichael B. L. 
Published: July 2010

Traditional plant breeding approaches have not been very effective in the development of higher yielding cotton (Gossypium hirsutum L.) cultivars for growth under water‐deficient field conditions. The purpose of this research was to evaluate the ability of a laboratory technique to identify cotton genotypes with higher growth rates under water stress conditions in the field. The technique consisted of detaching cotton leaves from the plant at sunset and hydrating those leaves overnight. The following day, the leaves were placed under a light‐bank in the laboratory and weighed every 2 min as they dried. From that data, transpiration decline curves were plotted. The curves exhibited stomatal and cuticular transpiration phases. The point where those two linear phases intersected was termed “mean stomatal closure” (MSC), and both time and relative water content (RWC) at that point were estimated. Sixteen entries were evaluated for transpiration decline curve components and growth rates in irrigated and dryland field plots in 1978 at Big Spring, Tex. In 1980, 12 different entries were evaluated for the same traits under dryland conditions at the same location.In 1978, entry differences occurred for all transpiration decline curve components in the irrigated test and for all components, except stomatal transpiration rates, in the dryland test. The interaction between entries and water levels was significant for all components. In 1980, only RWC at MSC and cuticular transpiration rates were different among entries. Growth rates among entries could not be separated statistically within any experiment. However, large negative correlation coefficients were measured between mean RWC at MSC and mean growth rates in the dryland tests in both 1978 and 1980. This relationship indicated that growth rates tended to be higher when the stomates remained open to a lower RWC before closure. The relationship was not significant in the 1978 irrigated test. Transpiration decline curves appear to be useful in screening cotton genotypes for differences in growth rates under conditions of water stress.
Cultivar ✕ Environment Interactions in Sugarbeet Yield Trials1
Authors: Campbell L. G. , Kern J. J. 
Published: July 2010

Sugarbeet (Beta vulgaris L.) yield and quality data from 5 locations and 4 years were used to determine the presence and magnitude of cultivar ✕ environment interactions in a major sugarbeet producing area, the Red River Valley of North Dakota and Minnesota. The cultivar ✕ location interaction for root yield indicated that cultivars tended to rank consistently different in the 4 years of testing at individual locations. Cultivar ✕ location, cultivar ✕ year, and cultivar ✕ location ✕ year variance components for sucrose, sodium, and potassium concentration were relatively small, compared to the cultivar variance component, indicating consistency in the relative expression of these characters. Years had a greater effect than locations on relative concentration of sucrose, sodium, potassium, and amino‐nitrogen, whereas cultivar ✕ year and cultivar ✕ location interactions were more nearly equal for yield. Second order interactions were significant for all traits except potassium concentration.Regression of cultivar mean yield on environmental mean yield and the contribution of individual cultivars to the cultivar ✕ environment variance component indicated that cultivars differed in their genetic potential to respond to a favorable environment. Regression coefficients for individual cultivars ranged from 0.85 for ‘ACH‐14 ’ to 1.11 for ‘Beta 1443 ’, with cultivar yields being 45.3 and 53.5 metric tons/ha, respectively. Three years of testing at five locations appeared to be adequate for characterizing cultivars for yield, sucrose concentration, and recoverable sucrose/ha.
Environmental Relationships with Forage Quality of Warm‐Season Perennial Grasses1
Authors: Pitman W. D. , Holt E. C. 
Published: July 2010

Seasonal patterns of digestibility of warm‐season perennial grasses in the southwestern U. S. A. generally show peaks in early spring and low values in mid‐summer. This research was conducted to determine if the patterns of digestibility of kleingrass (Panicum coloratum L.), green sprangletop [Leptochloa dubia (H.B.K.) Nees], and plains bristlegrass (Setaria macrostachya H.B.K.) were related to temperature, rainfall, relative humidity, and daylength under field conditions. Two selections of kleingrass (‘Kleingrass 75’ and Kleingrass 75‐25), and one each of green sprangletop and plains bristlegrass were harvested at 2, 4, and 8‐week frequencies during 1978 and 1979. Samples were separated into leaf and stem fractions with in vitro digestible organic matter (IVDOM) determined each fraction. From analyses with all four grasses combined, leaf and stem IVDOM was negatively correlated with temperature (r‐values from −0.353 to −0.419, all significant at 0.001 level) and daylength (r‐values as great as −0.378 with all significant at least at the 0.01 level). In general, leaf and stem IVDOM was positively correlated with measures of moisture conditions (r‐values up to 0.523 and 0.445 for rainfall and relative humidity, respectively).The environmental factors monitored were used in multiple regression models of leaf IVDOM, stem IVDOM, and percent leaf. Statistically significant models were obtained in most cases with R2 values up to 0.96. However, in a few cases less than 20% of the variation in IVDOM was accounted for by models maximizing R2 (with R2 values as low as 0.12). Distinct r elationships are apparent from these analyses; although, R2 values, partial regression coefficients, and individual environmental factors contributing significantly to the models were too variable for these models of leaf and stem IVDOM and percent leaf to be of general use. Overall trends in digestibility can be anticipated from knowledge of environmental factors, but forage digestibility cannot be accurately predicted from macroenvironmental factors.
Hybrid Vigor and Combining Ability in a High‐Low Yielding, Eight‐Parent Diallel Cross of Soft Red Winter Wheat1
Authors: Bitzer M. J. , Patterson F. L. , Nyquist W. E. 
Published: July 2010

A high‐low, eight‐parent diallel cross of soft red winter wheats (Triticum aestivum L. em. Thell.) was grown in hills to study hybrid vigor and combining ability for three components of grain yield and grain yield, using moderately diverse parents which varied in yielding ability. Diversity was based on plant type and parentages of the eight cultivars and lines. All were adapted for production in Indiana. Four parents were low in yield and four were high. This design provided 6 hybrids from low × low crosses, 16 from low × high, and 6 from high × high.Hybrids with grain yields which were significantly above that of the higher parent occurred infrequently, but such hybrids did occur in each crossing group. Heterosis above the midparental value was about 30% for low × low crosses, 25% for low × high crosses, and 19% for high × high crosses. Hybrid vigor for yield in low × high crosses was not significantly different from that in like by like crossing groups.The preponderance of the variability for yield components and grain yield was attributed to general combining ability. Successful hybrid wheats will most often come from high × high crosses because of the preponderance of general combining ability effects in wheat.
Water Relations, Forage Production, and Photosynthesis in Tall Fescue Divergently Selected for Carbon Isotope Discrimination
Authors: Johnson R. C. , Yangyang Li 
Published: July 2010

ABSTRACTCarbon isotope discrimination (Δ) has been correlated with the ratio of dry matter production to transpiration (water‐use efficiency, WUE) in C3 plants and is potentially useful for breeding crops with improved WUE. Therefore, an assessment of the selection response of Δ and its relationship to plant water status and forage production is needed. Divergent selection for high Δ (low WUE expected) and low Δ (high WUE expected) was completed for two cycles from a ‘Kentucky 31’ tall fescue base (Festuca arundinacea Schreb.) population (Co ). Water relations, forage production, and Δ were evaluated in Co and the selected populations in irrigated and dryland field environments in 1995 and 1996. Average realized heritability for Δ was 0.49, suggesting that Δ could be successfully manipulated in a breeding program. In 1995, leaf pressure potential (turgor) was higher in the populations selected for low Δ, but in 1996, no differences in water relations measurements were observed. High‐Δ populations always had lower forage production than observed in Co, but the low‐Δ populations never produced more than the Co population. In greenhouse‐grown plants, high‐Δ populations had higher internal substomatal [CO2] than Co, linking Δ with mechanisms that cause lower WUE. However, the internal [CO2] of the low‐Δ populations and Co did not differ, suggesting that selection for low Δ may not have increased WUE as expected. The results show that Δ is a heritable trait in tall fescue, but an absence of increased production in populations selected for low Δ may limit its utility in tall fescue breeding programs.