bluuebunny/crossref_metadata_2025 huggingface dataset:
Parent‐Offspring Popping Expansion Correlations in Progeny of Dent Corn ✕ Popcorn and Flint Corn ✕ Popcorn Crosses1
Authors: Robbins W. A. , Ashman R. B.
Published: July 2010

Experiments were conducted to determine the potential for use of dent ✕ popcorn (Zea mays L.) and flint ✕ popcorn crosses as breeding material for popcorn improvement. Two popcorn inbreds were crossed to both a dent and a flint inbred and several F1 plants from each cross were selfed. F2 plants from each of the four crosses were grown in 1979, self‐pollinated, and crossed to a single‐cross popcorn tester. The ears from the F2 plants were evaluated for popping expansion. The F3 and test‐cross families were grown in 1980 and evaluated for popping expansion. The popping expansion differences among the F3 families from all four crosses were highly significant. Linear correlations between the F2 and the F3, and the F2 and the test‐cross popping expansions were determined, and all correlation coefficients were highly significant. In the correlations of the F2 with the F3 the two flint ✕ popcorn crosses had coefficients of +0.84** (significant at the 0.01 level of probability) and +0.81**, which were the highest obtained, and the two dent ✕ popcorn crosses had coefficients at +0.63* and +0.76*. These high correlations, and the significant differences among F3 families, show that selection for popping expansion in F2 ears would be effective in population improvement. F3 families from the dent and flint corn crosses to one popcorn inbred had similar popping expansion means and ranges, indicating that popping expansion could be as easily recovered from crosses to dent corn as from crosses to flint corn.
Thermal Environment During Endosperm Cell Division and Grain Filling in Maize: Effects on Kernel Growth and Development in Vitro1
Authors: Jones R. J. , Quattar S. , Crookston R. K.
Published: July 2010

Relative effects of temperature during endosperm cell division (lag phase) and the effective grain‐fill period (EGFP) thephysiology of kernel development and final kernel mass in maize (Zea mays L.) were studied in vitro. Kernels were cultured at 15, 30, and 35°C during most of the lag phase. Before the start of the EGFP some kernels were transferred to each of the other temperature regimes while others remained at the original temperatures. When 30°C was maintained through the lag phase and EGFP, kernel mass was 77% of that observed for kernels from field‐grown ears. Temperature extremes (15 or 35°C) during either period of kernel development reduced final kernel mass, however, an unfavorable thermal environment during the lag phase caused the most reduction. Detrimental effects sustained in the lag phase prevailed when kernels were transferred to a more conducive (30°C) thermal environment during EGFP. Regardless of temperature during the EGFP, final kernel mass was 3 to 10 times higher when the lag phase temperature was 30°C. The data also showed that duration of EGFP was mediated primarily by prevailing temperature during EGFP while kernel growth rate during the EGFP was mediated in part by thermal history during the lag phase. High levels of soluble sugars were found in the endosperm during both stages of kernel development under adverse thermal environments (15 or 35°C). This suggested that low substrate level was not the cause of the reduced kernel growth rate and lower kernel weight observed at these temperatures. High temperature during the lag phase appeared to have the greatest negative effect on endosperm starch deposition during EGFP even when a favorable EGFP temperature (30°C) was provided. These data show that temperature extremes during the lag phase may mediate final kernel size by reducing endosperm sink capacity established during the lag phase or by reducing starch deposition in endosperm cells during the subsequent EGFP.
Effect of Cultivar and Planting Pattern on Yield and Apparent Harvest Index in Soybean1
Authors: Walker A. K. , Fioritto R. J.
Published: July 2010

Three determinate soybean [Glycine max (L.) Merr.] cultivars were recently released because of their yield superiority to indeterminate cultivars when planted in narrow rows. The objective of our study was to determine if this yield advantage was because determinate cultivars had higher apparent harvest indices (ratio of seed yield to mature plant weight) than indeterminate cultivars when planted in narrow rows. Eight indeterminate and three determinate cultivars were grown in three environments with two planting patterns. The wide‐row planting pattern had 76‐cm rows with 38.9 viable seeds/m2 and the narrow‐row planting pattern had 19‐cm rows with 52.7 viable seeds/m2. Characters examined were maturity, mature plant population, seed yield, and apparent harvest index. Only seed yield had a significant cultivar by planting pattern interaction. Several indeterminate and the three determinate cultivars showed a high yield response to the narrow‐row planting pattern. An 18% average yield increase resulted from decreasing row widths from 76 to 19 cm. The apparent harvest indices of the determinate cultivars were similar to the apparent harvest indices of several indeterminate cultivars in both planting patterns. Other factors such as total dry matter production and final plant population may be as important as apparent harvest index in determining seed yield for determinate cultivars.
Pressure‐Volume Characteristics of Genotypes of Three Wheatgrass Species1
Authors: Frank A. B. , Barker R. E. , Berdahl J. D.
Published: July 2010

A need exists for drought tolerant forages that can produce acceptable yields on limited water. Techniques to accurately predict performance under drought stress are essential for selection of drought tolerant forages. Objectives of this study were to measure water relations of important forage species using the pressure volume (P‐V) method and to evaluate its usefulness predicting drought tolerance. The study was conducted using clonal selections of crested wheatgrass [Agropyron desertorum (Fisch.) Schult.], western wheatgrass (A. smithii Rydb.), and intermediate wheatgrass [A. intermedium (Link) Haloc.]. Pressure‐volume measurements were made using a pressure chamber on plants grown in both field and glasshouse environments. Data from the P‐V curves for initial turgor loss point, osmotic potential at full hydration and leaf water potential at zero pressure potential indicated differences among genotypes for all three species of wheatgrasses. Although only a limited number of genotypes were evaluated results appear more promising for selecting genotypes for drought tolerance in western than in crested or intermediate wheatgrasses. Species comparisons based on data from the P‐V relationship shows that genotypes of crested and western exhibit water relations that coincide with their greater drought tolerance. The P‐V technique requires a high labor input and will require modifications for practically evaluating large breeding populations for drought tolerance.
Relationship of N Deposition to Grain Yield and N Response of Three Maize Hybrids1
Authors: Tsai C. Y. , Huber D. M. , Glover D. V. , Warren H. L.
Published: July 2010

Three maize (Zea mays L.) hybrids were evaluated for their grain yield under different levels of spring‐applied anhydrous ammonia fertilizer. The N content in the vegetative tissues and grain was analyzed at the midsilk stage and at 60 days after pollination. Of the three hybrids tested, B14 ✕ Oh43 (intermediate type) responded to moderate levels of N fertility, B73 ✕ Mol7 (high‐fertility type) had a great response to additional N, and Pioneer 3732 (low‐fertility type) performed well under low levels of N fertilizer but reached maximum yield with only 67 kg N/ha. There are at least three factors affecting grain yield which distinguish the high‐fertility from low‐fertility type hybrids. These include 1) ability to absorb additional N fertilizer after the midsilk stage, 2) rate and duration of grain fill, and 3) rate of zein synthesis (kernel N sink) affected by N fertilizer. When the kernel genotpye of Pioneer 3732 was modified by pollinating with pollen from B73 ✕ Mol7, the developing F1 kernels not only had grain protein concentration higher than Pioneer 3732 F2 kernels but had dry matter accumulation kinetics complementary to Pioneer 3732 and B73 ✕ Mol7. This complementation resulted in larger kernels than those obtained with selfed kernels of either hybrid. This result indicates the kernel sink is more important than the vegetative source in affecting kernel weight and grain yield.
A Quantitative Sampling Method for Airborne Sweet Corn Pollen under Field Conditions1
Authors: Flottum P. K. , Robacker D. C. , Erickson E. H.
Published: July 2010

The rate of pollen dehiscence in a sweet corn (Zea mays L.) plot was measured using a Rotorod Sample®. Samples were taken from 0700 to 1230 h for 3 days during anthesis. Totals were averaged over the 3 days, and the resulting composite data were used to develop a sampling protocol accurate for determining the rate of pollen release. Results showed that a 10‐min sampling period, with a frequency of at least once every half hour was required to accurately reflect the pollen release rate.
An Examination of the Digital Fibrograph Length Uniformity Index1
Authors: Krowicki R. S. , Ramey H. H.
Published: July 2010

The Digital Fibrograph length uniformity index is usually misinterpreted. The theoretical maximum for this index is 51.28. The theoretical maximum index requires that: 1) all cotton (Gossypium sp.) fibers within the beard being scanned by the Fibrograph have the same length, 2) that the fibers are randomly caught and held, and 3) that the optical scan of the beard begin at the point of holding. The latter condition does not exist, because the scan of the beard begins at 3.81 mm from the point of holding. The result is that maximum possible uniformity index is increased to 56.0 for 40 mm and to 60.7 for 20 mm fibers. Direct comparisons of the uniformity index are valid only in a narrow range of fiber lengths.
Yield Testing Cool‐Season Forage Grasses in Pure Stands vs. Binary Mixtures with Alfalfa1
Authors: Casler M. D. , Drolsom P. N.
Published: July 2010

Cool season perennial forage grasses are grown in pure stands and in mixtures with other grasses or legumes. Differential environmental and competitive effects between pure and mixed stands may cause interactions with cultivars or breeding lines. Our objective was to compare the productivity of cultivars of four cool‐season perennial forage grasses in pure stands and binary mixtures with alfalfa (Medicago sativa L.). Cultivars of orchardgrass (Dactylis glomerata L.), smooth bromegrass (Bromus inermis Leyss.), tall fescue (Festuca arundinacea Schreb), and timothy (Phleum pratense L.) were grown in replicated trials in pure stands and binary mixtures with alfalfa at five Wisconsin locations for up to three seasons. Differences among cultivars were significant for 12 of 38 species‐environment combinations in pure stands and eight in mixed stands. Coefficients of variation were slightly higher for pure stands, while the square root of broad sense heritability showed no consistent differences between stand types. Rank correlations for cultivar yield between the two stand types were generally nonsignificant for all species, except timothy. Both stand types were about equally susceptible to cultivar ✕ environment interaction, except cultivar ✕ year interaction for timothy. We concluded that additional replication is necessary to obtain the desired level of precision in forage yield trials. With the possible exception of timothy, recommendations of superior grass cultivars in alfalfa mixtures should be based on mixed stand performance.
Genetic Variability for Root Characters in Alfalfa Populations Differing in Winterhardiness1
Authors: Pederson G. A. , Hill R. R. , Kendall W. A.
Published: July 2010

A sample of plants from each of six alfalfa (Medicago sativa L.) cultivars with different levels of winterhardiness were used as parents in an experiment to obtain information on genetic variability for shoot dry weight, root diameter, number of lateral roots, root branching, and root dry weight. Cultivar intracrosses (from intercrossing plants within each cultivar) and intercrosses (from crossing plants in each cultivar with plants from the other five cultivars) were included in the experiment and analyzed as if the entries were in a diallel cross. Intercross and intracross progenies were evaluated in gravel culture tanks in the greenhouse and for two seedling years in the field. In the field experiment, intracross means were significantly greater than cultivar intercross means for root dry weight, root diameter at the crown, root diameter at 15 cm, and shoot dry weight. Intercross and intracross means did not differ significantly for number of lateral roots or for tap root branching. Cultivar intracrosses differed significantly only for number of lateral roots. General combining ability effects were significant for each of the traits measured in the field, but genotype ✕ year interactions were also very large. Correlations between field and greenhouse measurements of root traits were generally small and nonsignificant. Differences among cultivar intracrosses were significant for each trait measured in the greenhouse, but significant combining ability effects were detected only for shoot number. Observed differences for root characteristics did not correlate well with hardiness levels from the cultivars in either the greenhouse or field experiments.
Effect of Recurrent Selection for Stalk Crushing Strength on Agronomic Characteristics and Soluble Stalk Solids in Maize1
Authors: Colbert T. R. , Darrah L. L. , Zuber M. S.
Published: July 2010

Our objectives were to determine responses to selection for crushing strength and the associated changes in yield, stalk strength, field stalk lodging, flowering dates, and soluble stalk solids. The MoSQA and MoSQB maize (Zea mays L.) synthetics that had undergone five cycles of recurrent selection for high and low stalk crushing strength were used. Selection for high crushing strength in MoSQA and MoSQB did not affect grain yield and significantly decreased stalk lodging. Soluble stalk solids and days to flowering were significantly increased in MoSQB. Selection for low crushing strength reduced grain yield in MoSQB but not in MoSQA, increased stalk lodging in MoSQB, and caused slightly earlier flowering and a decline in soluble stalk solids in MoSQA. Grain yield was positively correlated with crushing strength (r = 0.50**) and soluble solids (r = 0.41**) but atively correlated with natural occurring stalk lodging (r = ‐0.60**) (**Significant at the 0.01 level.). The negative relationship may have occurred because significant changes in yield occurred only for selection for low crushing strength in MoSQB. Stalk crushing strength was negatively correlated with stalk lodging and positively correlated with flowering dates and soluble stalk solids. Stalk lodging was negatively correlated with flowering dates and stalk soluble solids. Flowering dates were positively correlated with stalk soluble solids. The observed relationships between soluble stalk solids and other traits agree with other reported results on stalk quality. The high experimental error and erratic behavior of estimates of soluble stalk solids among cycles of selection indicate either an insufficient sample size or a lack of precision in determination.
Patterns of Reproductive Abscission, Seed Yield, and Yield Components in Soybean1
Authors: Heindl Josephine C. , Brun William A.
Published: July 2010

Field studies were conducted in 1981 and 1982 to determine patterns of flowering and reproductive abscission for nodes on the main stem of soybean [Glycine max (L.) Merr.] and to relate these patterns to seed yield components at nodes in various levels of the canopy. ‘Evans,’ an indeterminate, Maturity Group 0 cultivar was used. Individual flowers were tagged at anthesis and monitored through abscission or pod maturity. Date of anthesis and date of flower or pod abscission were recorded. Percent abscission was calculated on a per node basis. Number of mature pods, seeds/pod, and seed weight/pod were recorded for each main stem node. Data are reported as averages over nodes within four sections of the stem, each of which included approximately one‐fourth of the flowering nodes. Seed weight/node and seed weight/section were significantly greater in the middle two sections than in the top or bottom sections in both years. Pods at nodes in the middle two sections accounted for at least 75% of the main stem yield. Flowers produced per node generally varied only slightly among the sections, so percent abscission was the main determinant of pods/node. Pods/node varied as much as 300% among sections, whereas individual seed weight varied less than 35%. The primary cause of differences in number of pods/node and therefore in productivity of nodes in various stem sections was differential flower and pod abscission.
Effect of Divergent Selection for Root Weight on Genetic Variation for Root and Shoot Characters in Alfalfa1
Authors: Pederson G. A. , Kendall W. A. , Hill R. R.
Published: July 2010

Thirty plants each from two hardy (‘Grimm’ and ‘Teton’), two moderately hardy (‘Saranac’ and ‘Lahontan’), and from two nonhardy (‘Moapa’ and ‘Mesa Sirsa’) alfalfa (Medicago sativa L.) cultivars were grown in a simulated growing season environment in plant growth chambers. Shoots and roots were harvested five times during this simulated growing season. From each cultivar, one plant with an accumulated fresh root weight consistently greater and one plant with an accumulated fresh root weight consistently less than the cultivar mean were selected and crossed in a 12 × 12 diallel. Diallel progenies were evaluated in two greenhouse trials to determine the effects of selection for high and low root weight on the expression of related vigor traits in the progenies of the selected parents. Progenies from high‐rootweight (HRW) selections had greater root diameters, root branching, and shoot weights than did progenies from low‐rootweight (LRW) selections in both greenhouse trials. Root weight and shoot number were greater in progenies from high than from low‐root‐weight selections in the greenhouse trial conducted in the spring. Differences between progenies of high and low‐root‐weight parents tended to be greater for parents from Mesa Sirsa and Moapa than for parents from the other cultivars. Progenies from HRW selections had greater root diameter, root dry weight, and shoot dry weight when the parent was used as a female than when it was used as a male. The opposite trend was observed for progenies of LRW selections—means were greater when the parent was used as a male than when used as a female. Maternal effects for root diameter, root weight, and shoot weight were expressed with greater intensity in plants evaluated in the spring than in those evaluated in the fall. The presence of maternal effects for certain root characteristics in alfalfa could complicate selection for root traits.
Heritabilities of Grain Yield of Common Bean in Sole Crop and in Intercrop with Maize1
Authors: Zimmermann Maria J. O. , Rosielle Arnold A. , Waines J. Giles
Published: July 2010

Standard unit heritabilities for grain yield of common bean (Phaseolus vulgaris L.) were determined for F2‐derived F4 and F5 progenies and for F2 individual plants and their F3 progenies of three common bean crosses. Standard unit heritabilities were determined by correlating F2‐derived F4 line grain yields with F2‐derived F5 line grain yields. Heritabilities were determined for direct selection (F4 and F5 lines in the same cropping system) and indirect selection (F4 and F5 lines in different cropping systems). Selection gains were also estimated for direct selection, indirect selection, and for selection based on the means of both systems. Parent‐offspring genotypic correlations were determined for the F2‐derived F4 and F5 progenies. Standardized correlated responses to selection for grain yield based on selection for harvest index were estimated for F2 individual plants. Standard unit heritabilities were larger in intercrop than in sole crop. The difference in heritability between cropping systems was larger for F2 plants than for the F2‐derived F4 progenies. Direct selection in intercrop and sole crop was always superior to indirect selection in the alternate cropping system. Indirect selection in intercrop for sole crop gave the lowest gains. Direct selection in intercrop or in sole crop gave the highest genetic gains in each respective cropping system. Selection on the mean of both systems gave gains in each system almost as high as those of direct selection. Selection in sole crop for improvement in the mean of both systems resulted in lower gains than selection on the mean of both systems, but was better than selection in intercrop. Standardized correlated responses in grain yield by selection for harvest index were larger in intercrop than in sole crop. Single plant selection for yield may be effective for beans which are intercropped.
Variation in Plants Regenerated from Tissue Culture of Tetraploid Alfalfa Heterozygous for Several Traits1
Authors: Groose R. W. , Bingham E. T.
Published: July 2010

Plants were regenerated from callus and suspension cultures of two tetraploid (2n = 4x = 32) alfalfa (Medicago sativa L.) genotypes bred to be heterozygous for four heritable traits: i) anthocyanin pigmentation in flowers and other plant parts as conditioned by the basic color factor gene, C2, ii) the multifoliolate leaf trait, iii) ability to regenerate from tissue culture, and iv) cytoplasmic male‐sterility conditioned by nuclear fertility‐restorer genes. Regenerated plants were examined for shifts in expression of these traits, as well as for any other shifts in vigor, fertility, morphology or ploidy. In one callus culture cycle, 21% of 116 regenerated plants were classified as variant for one or more characters. At least 11% of regenerates lost one or more chromosomes in this callus culture cycle, with chromosome numbers among deficient plants ranging from 28 to 31. Two apparent shifts to octoploidy occurred. Approximately 60% of variant regenerates exhibited a change in chromosome number. Other variants were not due to a simple change in chromosome number. A white‐flowered variant was the result of an unstable recessive mutation of the functional C2 allele. The frequency of somaclonal variants regenerated after suspension culture was comparable to that found after callus culture. Reculture of a 28‐chromosome variant did not result in a shift toward euploidy among 113 plants regenerated.
Estimation of Epicuticular Wax Amounts in Wheat Using Wide‐Line Proton Magnetic Resonance1
Authors: Johnson Douglas A. , Tonnet M. Lorraine , Richards Richard A.
Published: July 2010

Epicuticular wax is an important component of the plant cuticle and contributes to functions such as conservation of water, minimization of leaching losses, and protection from injury due to various environmental factors. Because the gravimetric and colorimetric procedures in some cases may be limited in their use in plant selection programs or studies concerning the significance of epicuticular wax, wide‐line proton magnetic resonance (PMR) was investigated as an alternative technique for the determination of amount of epicuticular wax. Epicuticular wax from field‐grown wheat (Triticum aestivum L. and T. turgidum L. durum) was extracted and then dissolved in carbon tetrachloride for reading by PMR. Carbon tetrachloride was used as the solvent because it does not itself give a PMR signal. Amounts of epicuticular wax determined by the PMR method were highly correlated (r2 = 0.99) with those assayed by the gravimetric procedure over a wide range of wax contents (0.001 to 0.178 g). Close correlations (r2 = 0.99) between PMR reading and amount of wax were also found with beeswax and Carbowax‐4000, suggesting that the technique is applicable to waxes other than wheat wax. The PMR method is an alternative technique for the rapid, accurate estimation of wheat wax amounts and is applicable in plant selection programs.
Genotypic Variation for Resistance to Preharvest Sprouting in Soybean1
Authors: Dougherty R. W. , Boerma H. R.
Published: July 2010

Preharvest sprouting in soybean [Glycine max (L.) Merr.] can reduce seed quality and germination. To determine the amount of genotypic variation for resistance to preharvest sprouting, the percentage of pods ruptured by sprouting seed (PR) and pod rupture adjusted for initial seed germination (APR) were measured on 40 genotypes for 3 years. The pods were produced in the field and screened for resistance in the greenhouse by using a mist chamber. Pods were misted for 4‐rain periods 22 times/ day for 7 days. Genotypic variation within maturity groups was found for PR, APR, post‐treatment seed germination (PTSG), and post‐treatment seed quality. Genotypes with the most resistance to preharvest sprouting were: D65‐8232 (impermeable seed coat) and ‘Hale 3’, Maturity Group (MG) V; ‘Lancer’ ‘Tracy’, MG VI; ‘McNair 800’, MG VII; and ‘Dowling’, MG VIII. The partial correlation coefficient, with the effect of year and maturity removed, between APR and PTSG was negative (r = −0.39). Resistance to preharvest sprouting was associated with slower water uptake by seed. The presence of pubescence on the pod was also associated with less preharvest sprouting.
A Growth Retardant Improves Performance of Soybeans Relay Intercropped with Winter Wheat1
Authors: Jeffers Daniel L.
Published: July 2010

When soybeans [Glycine max (L.) Merr.] are relay intercropped with winter wheat (Triticum aestivum L.), the soybeans may grow excessively tall and interfere with wheat harvesting. The objective of this study was to evaluate a chemical growth retardant, BTS44584, for its effects on soybean growth and yield. In relay intercropping the chemical was used at varying rates as a soybean seed treatment or as a foliar treatment at the second trifoliolate stage, either broadcast sprayed on both wheat and soybeans using a hand‐carried five nozzle boom or directly sprayed on soybean foliage only, using a single wand and nozzle. As a seed treatment the growth retardant was also evaluated for its compatibility with the fungicide, pyroxyfur, and for its growth and yield effects on monocropped soybeans. In relay intercropping seed or foliar spray treatments retarded soybean growth such that height at the time of wheat harvesting was significantly less than for untreated soybeans. The chemical treatments prevented substantial combine defoliation of intercropped soybeans as occurred with controls during wheat harvesting. Height of treated soybeans at maturity ranged from 11 to 32 cm taller than untreated soybeans resulting partly from this defoliation of untreated plants and partly from delayed development and continued vegetative growth of treated soybeans. Maturity of treated soybeans was delayed an average of 3 to 11 days depending on method and rates of application. Seed yields from treated soybeans were not significantly larger than those from the untreated in most instances, the exceptions being those receiving the 0.5 g/kg seed treatment and those receiving the directed foliar sprays. Seed treatment with 0.1 to 0.5 g/kg would be the preferred method on the basis of efficacy, ease of application and economy. Pyroxyfur and BTS44584 were found to be compatible as seed treatments. In monoculture soybean growth and yield were decreased by BTS44584 seed treatments ranging from 0.1 to 2.5 g/kg of seed.
Effects of Plant Smoothness on Agronomic Traits of Upland Cotton—Fiber Properties1
Authors: Lee Joshua A.
Published: July 2010

Glabrousness in upland cotton (Gossypium hirsutum L.) confers resistance to certain insects and decreases trash in ginned lint. Such plant smoothness has been associated with reductions in lint percentage and fiber yield, but there is little information on the effects of the phenotype on fiber properties. Two complete diallel sets involving various combinations of smoothness and pilosity alleles were grown in randomized, complete blocks in North Carolina in 1982 in four replications per location. The first set was generated by intercrossing the allelic pairs, Sms11 and sm1, and Sm2 and sm2 in all possible combinations, and the second by intercrossing the allelic pairs Sm2 and sm2, and Sm, and sm41. Increasing the number of Sm alleles in a given cotton increases plant smoothness, whereas the completely recessive phenotype (all sm alleles), imparts normally pubescent, the phenotype of ‘Coker 310’, the cultivar used as background. Within the two diallels 2.5% fiber span length varied from 26.9 to 30.1 mm with the lowest values associated with the Sm2 allele. Fifty percent span length varied from 13.0 to 14.3 mm but was significantly various only in the first diallel, and the variation for 50% span length in that particular set did not relate to degree of plant smoothness. The entries with the shortest 2.5% span length tended to have the highest fiber uniformity index. Micronaire values above 5 were associated with some of the entries homozygous for Sm2 and fiber tenacity showed a deficiency where the Sms11 allele was homozygous. There were significant estimates for general and specific effects for some of the traits, particularly with entries harboring the Sm2 ✕ sm2 contrasts, and evidence for maternal and reciprocal (maternal ✕ embryonic) effects for some traits. There was no consistent evidence that degree of plant smoothness related to disturbances in any fiber trait, but evidence that specific smoothness alleles were accompanied by fiber quality deficits.
Genetic Variation in Acid Detergent Fiber, Neutral Detergent Fiber, Hemicellulose, Crude Protein, and Their Relationship with In Vitro Dry Matter Digestibility in Tall Fescue1
Authors: Soh A. C. , Frakes R. V. , Chilcote D. O. , Sleper D. A.
Published: July 2010

Breeding for improved forage quality in tall fescue (Festuca arundinaceae, Schreb.) has received scant attention. The aim of this study was to generate information on genetic variability and how it varies with seasons, years, locations, and planting arrangements for acid detergent fiber (ADF), neutral detergent fiber (NDF), hemicellulose (HCL), and crude protein (CP) and also on the relationships of these analytical components with in vitro dry matter digestibility (IVDMD) and to formulate a selection program for improvedigestibility in tall fescue. A combining ability ✕ environment analysis was made on data collected from spring, summer and fall harvests in 1977 and 1978, from six tall fescue parent clones and their 15 single‐cross hybrids which were planted in rows in Corvallis, Oreg. and in rows and swards in Columbia, Mo. General combining ability (GCA) predominated for all measured quality characteristics. Of the genotype‐environment interactions, only GCA ✕ harvest effects were important. The high coefficients of determination for hybrid progeny performance due to GCA (r2gca) and generally low parent‐progeny regressions suggest that GCA of the parents is a better predictor of hybrid progeny performance than actual parental performance. Acid detergent fiber is a more transmissable trait than NDF, IVDMD, HCL, or CP. Acid detergent fiber and NDF were well correlated with IVDMD while HCL and CP were not. The results indicate that a selection program based on progeny testing for GCA for low ADF in row plantings in one location for all harvest seasons over I or 2 years would efficiently and conveniently result in rapid indirect selection improvement for digestibility in tall fescue.
Inheritance of Flower Color in Guayule1
Authors: Estilai A.
Published: July 2010

Five sexual diploid guayule (Parthenium argentatum Gray) plants, two with purple and three with white flower color were selfed, open‐pollinated, and crossed in all possible combinations. Except for one white parent which produced two plants, the parents failed to produce progenies by selfing. All of the parents produced progenies upon open‐pollination. Due to the existence of a sporophytic system of incompatibility in diploid guayule, only compatible crosses produced F1 plants. Crosses among white parents produced only white progenies. Reciprocal crosses between two purple parents produced fifty purple and one white plants. Crosses between purple and white parents produced either all white or white and purple progenies in 1:1 ratio. These results and the results obtained from the open‐pollination of the parents indicated that purple flower color is a recessive trait which is controlled by one pair (p controlling purple and P controlling white) of genes. The presence of modifiers accounting for the light to dark purple variability in flower color is postulated also. Purple flower color is expected to serve as a valuable genetic marker especially in studies directed toward the determination of the degree of apomixis in guayule.
Effect of Weather Variables During Maturation on Preharvest Sprouting of Hard White Wheat1
Authors: Nielsen M. T. , McCrate A. J. , Heyne E. G. , Paulsen G. M.
Published: July 2010

Susceptibility to preharvest sprouting is a major disadvantage of hard white winter wheats (Triticum aestivum L.) as compared with most hard red winter wheat cultivars in the Great Plains. Experiments were initiated to determine differences in susceptibility among genotypes and to identify weather variables affecting preharvest sprouting. Seven white wheat lines and a popular red wheat cultivar were grown at several Kansas locations for 2 years. α‐Amylase enzyme activity was determined in grain from mature spikes before and after treatment with simulated rain. Multiple regression and stepwise regression analyses were used to determine the influence of accumulated temperatures, diurnal temperature fluctuations, and accumulated precipitation on α‐amylase activity before and after the rain treatment. The white wheat lines were uniformly susceptible to preharvest sprouting and the red wheat cultivar was more resistant, α‐Amylase activity before rain treatment was low 1 year and was high at all except one site the 2nd year, but activity in grain from all locations increased after rain treatment both years. Daily temperature fluctuations before physiological maturity and precipitation after physiological maturity significantly affected α‐amylase activity in wheat grain that was not treated with simulated rain. Regression coefficients of weather factors showed sprouting was increased by large daily temperature fluctuations, low daily temperatures, and high precipitation. We concluded that weather factors before as well as after physiological maturity affect preharvest sprouting resistance.
Temperature Effects on Vegetative and Reproductive Development of Peanut1,2
Authors: Ketring D. L.
Published: July 2010

Optimum temperature for growth of most peanut (Arachis hypogaea L.) genotypes is near 30°C. During the 1980 growing season, temperatures ranged from 35 to 40°C for many days in USA peanut producing regions, and severe crop losses attributable to the high temperatures and drought occurred. Experiments were initiated to determine the effect of temperature separate from drought on peanut development. Plants were grown in controlled environments at 30/25°C, 12/12 h light/dark temperatures to obtain a population of plants with uniform development. Measurements of individual leaf areas, leaf dry weights, and seedling height were made 21 days after planting to establish plant growth state. Then temperature treatments, based on temperatures expected to occur during the summer peanut growing season in the southwest USA, were begun. Temperature during the dark period was held constant at 22°C for all treatments. Temperatures during the light period were 30, 32, and 35°C. The 35°C treatment decreased individual leaf areas and dry weights at both 63 and 91 days after planting. Plants harvested at 91 days after planting showed reduced total leaf area and stem elongation was decreased in two experiments at 35°C. The highest temperature treatment significantly reduced the number of subterranean pegs. Mature seed weight was reduced and significantly so in two of three experiments, once for each cultivar tested. Thus, a temperature of 35°C was shown to have an inhibitory effect on peanut development even when plants were grown under well‐watered conditions. An evaluation of eight peanut genotypes showed genotypic variation in response to the 35°C temperature treatment. Selection for peanuts with improved heat tolerance may be possible.
Taproot‐Elongation Rates of Soybean Cultivars in the Glasshouse and Their Relation to Field Rooting Depth1
Authors: Kaspar T. C. , Taylor H. M. , Shibles R. M.
Published: July 2010

Deeper rooting should improve soybean [Glycine max (L.) Merr.] water stress avoidance by increasing water uptake from deep soil strata. Because taproots are initially the deepest segment of soybean root systems, soybean genotypes with rapidly elongating taproots may have deeper root systems than genotypes with slowly elongating taproots. Taproot‐elongation rates of 105 soybean cultivars from Maturity Groups I, II, and III were measured in a glasshouse using clear plastic tubes filled with vermiculite and then inclined 15°. Taproot‐elongation rates within a maturity group differed among cultivars by as much as 1.3 cm/day. Seed weight within a seedlot and seed source also influenced the taproot‐elongation rate of a cultivar. Selected Maturity Group II cultivars with either faster or slower taproot‐elongation rates in the glasshouse were grown in the Ames rhizotron and in field plots. Excavation of rhizotron compartments 49 days after planting revealed that roots of faster elongators were 10 cm deeper than those of slower elongators. In field plots 56 days after planting, the faster elongating group was 9 cm deeper and had more roots at 150 cm than did the slower elongating group. The two groups did not differ significantly, however, 72 days after planting. The group of cultivars with faster elongation rates also depleted soil‐water below 120 cm slightly more than did the slower group.
Stress Tolerance in Soybeans. I. Evaluation of Three Screening Techniques for Heat and Drought Tolerance1
Authors: Bouslama M. , Schapaugh W. T.
Published: July 2010

Three screening techniques for characterizing drought tolerance were evaluated using 20 soybean [Glycine max (L.) Merr.] genotypes. These techniques involved: 1) germinating seed in polyethylene glycol‐600 (PEG) at −0.6 MPa osmotic pressure, 2) subjecting seedlings to PEG‐600 at −0.6 MPa osmotic pressure in hydroponic solution for 14 days, and 3) a heat tolerance test based on the cellular membrane thermostability. Genotypic variability associated with drought tolerance was demonstrated by the evaluation techniques. Based on these procedures, 2 of the 20 cultivars tested were relatively drought tolerant, 2 were relatively susceptible, and the remaining cultivars fell into an intermediate group. Highly significant correlations were found between the hydroponic seedling and heat tolerance tests, indicating that both drought and heat tolerance were identified in the same cultivars under the conditions of this study. It is doubtful that the seed germination test could be used as a reliable procedure for identifying drought tolerant cultivars because it tended to reflect differences in seed quality and had no relation to field performance. Although reproducibility and consistency of genotypic differences did exist using the heat tolerance tests, comparisons with more yield data are needed to evaluate this technique. Of the three procedures evaluated in this study, the hydroponic seedling test seemed to be the most reliable and potentially useful as a means for screening for drought tolerance in soybeans.
Combining Ability and the Selection of Parents for Interspecific Oat Matings1
Authors: Cox D. J. , Frey K. J.
Published: July 2010

Ten accessions of Avena sterilis L. (males) were tested as sources of genes for improving productivity of cultivated oats (A. sativa L.). They were mated with six A. sativa (females) cultivars from the north central USA, and populations of F2‐derived lines in F3 from these matings were evaluated for grain yield and biomass at three locations in Iowa and vegetative growth index at one location. Maximum specific combining ability (SCA) effects exceeded maximum general combining ability (GCA) effects for all traits in both males and females. The SCA sums of squares were intermediate in magnitude between the GCA sums of squares for males and females. Transgressive segregates, one LSD0.005 above the high parent, were derived from every parent for each trait. However, there was a greater percentage of significantly high transgressive segregates for biomass and vegetative growth index than for grain yield (9.8, 9.0, and 3.1%, respectively). Performances of the A. sterilis accessions and A. sativa cultivars per se generally were good predictors of mean progeny performance for each trait. However, the production of extreme progeny types was more closely associated with the mean genotypic variance of a parent, as calculated over the array of matings, than with that of parental performance per se.
Potential Use of Alien Germplasm for Maize Improvement1
Authors: Cohen J. I. , Galinat W. C.
Published: July 2010

Plant breeders have demonstrated the potential ability of exotic and alien germplasm to enhance particular qualitative genetic traits of maize, (Zea mays L.). Results from such programs include the incorporation of genes that condition resistance to pathogens or insect pests. Fewer examples exist which provide information on how alien and exotic germplasm affect quantitative traits, although studies have shown it is possible to increase heterosis or to expand the level of genetic divergence between breeding populations by using such germplasm. However, in either case, most breeders prefer current, elite inbreds with known combining ability as sources for inbred development and for improvement of hybrid performance. Alien germplasm was evaluated for its effects on quantitative traits by crossing seven substitution lines, each containing various segments of germplasm from teosinte (Zea mexicana), with three testers, and measuring the effects on maize hybrids. A performance trial was used for this evaluation from which data were collected for 12 traits on 23 hybrids. Significant differences in grain yield and heterosis were obtained between the means of the three testers and among the various substitution line hybrids. One tester, Havels‐(20 + 2Tr7), contained an extra disomic chromosome from Tripsacum dactyloides. Hybrids with this tester had a combining ability value 8% higher than the isogenic control. The highest yielding hybrids were the teosinte A158‐substitution lines involving the Florida and Durango teosinte types crossed with the Havels testers. The two highest yields occurred from crossing the Havels tester containing the Tripsacum chromosome with the A158‐Florida 4,9 and the A158‐Florida 9 teosinte substitution lines.
Causes of Square Abscission in Cotton in Arizona1
Authors: Mauney Jack R. , Henneberry T. J.
Published: July 2010

Cotton (Gossypium hirsutum L.) plantings sometimes abscise large numbers of flower buds (squares). Many environmental and nutritive stresses and insect or disease damage are known to induce this abscission. To determine the specific causes of abscission in Arizona the squares were examined visually under a ✕ 10 stereomicroscope. Symptoms that indicated the cause of the abscission were observed to fall into four categories: 1) dissolution of tissues due to plant bug (primarily Lygus spp.) feeding, 2) soft rot due to thrips (Thysanoptera spp.) activity, 3) tunnels due to lepidopterous larvae feeding, and 4) desiccation without physical damage indicating physiological stresses. Each week during three seasons (1978 to 1980) the abscised squares were subdivided among these categories. Prior to 15 July the primary cause of abscission was Category 1 with a minor fraction due to Categories 2 and 4. After 15 July Category 3 became more important and Category 2 was seldom observed. In only two sampling periods during the 3 year study did Category 4 exceed half of the abscised squares. Correlation of the Category 1 symptoms with lygus bug population in the field at the beginning of the week of sampling was high (r = 0.94 P < 0.05). The regression analysis indicated a feeding rate of 1.7 squares insect−1 per day−1. Temperature correlation on lygus feeding was not significant. The study showed that visual symptoms of damage can be used to categorize abscised squares by the causal agent and that large variation within and between years occurs.
Grain‐Filling Duration and Yield in Spring Barley1
Authors: Metzger Debra D. , Czaplewski Steven J. , Rasmusson Donald C.
Published: July 2010

Several studies of various crop species have suggested the possibility of identifying an optimum grain‐filling duration for improving grain yield. Accordingly, a research program on grainfilling duration and its relationship to grain yield in barley (Hordeum vulgare L.) was initiated at the University of Minnesota, St. Paul in 1970. Two and three cycles of crossing and selection were used to incorporate variability for grain‐filling duration into improved genetic backgrounds. Ultimately, lines from four populations were grown in field trials in 1979, 1980, and 1982 to study the relationship between grain‐filling duration and grain yield. These lines were selected to assure diversity for grainfilling duration, while having similar maturity. Significant differences among genotypes for grain‐filling duration were found in all populations. Long duration lines spent an average of 3 to 7 days longer in the grain‐filling period than short duration lines. Although grain‐filling duration varied with environment, the long and short duration classes remained distinct. In spite of the consistent differences in grain‐filling duration there was no significant association between grain‐filling duration and yield in these populations. Failure to detect a yield advantage due to differences in grain‐filling duration in lines with similar maturity suggests that any advantage derived from alteration of the grain‐filling period may have been outweighed by the coincident change in length of the vegetative period. Genetic differences among lines for traits other than grain‐filling duration, such as synchrony of anthesis, may have limited our ability to find an association between grain‐filling duration and yield. Based on our research, selection for an optimum grain‐filling duration to improve grain yield does not appear to be a worth while objective for upper midwestern‐type barleys.
Genetic Analysis of Egyptian Glandless Cotton1
Authors: Kohel R. J. , Lee J. A.
Published: July 2010

The Egyptian cotton (Gossypium barbadense L.) strain, ‘Bahtim 110’, is glandless due to the expression of a dominant allele at a single locus while the glandless condition found in Upland cotton (G. hirsutura L.) is due to the expression of recessive alleles at two loci. The gene conditioning the glandless character in the Egyptian strain was found to be an allele at the Gl2 locus and was designated Gl2•. Potential use of this gene in glandless cottonseed breeding programs is discussed.