bluuebunny/crossref_metadata_2025 huggingface dataset:
Root Growth and Dry Matter Distribution of Soybean as Affected by Phosphorus Stress, Nodulation, and Nitrogen Source1
Authors: Cassman K. G. , Whitney A. S. , Stockinger K. R.
Published: July 2010

In the field, plant root development is of primary importance under P deficient conditions. Two sand culture experiments were conducted to examine the effects of P stress, nodulation, and N source on the growth, dry matter distribution, and root development of ‘Clark 63’ soybean (Glycine max L. Merr.). In both experiments two levels of N (0 and 5.0 mM N) were employed: plants were either solely dependent upon symbiotic N fixation (N‐fixing), or primarily dependent upon uptake of combined N from the nutrient solution (N supplied). Nodule dry weight of N‐fixing plants grown at the highest P level (2.0 µ/ml) comprised 9% of total plant dry weight and 61% of root dry weight of 35‐day‐old soybeans. A decrease in the P supply inhibited nodule growth relatively more than either root or shoot growth. For N‐supplied soybean, a decrease in the P supply affected shoot growth relatively more than either nodule or root growth. When grown at intermediate P levels (0.02 to 0.5 µ/ml), the root + nodule:total plant dry weight ratio was similar in both N‐fixing and N‐supplied plants. However, the rootttotal plant dry weight ratio of N‐fixing plants was was less than that of N‐supplied plants at all P levels. There was an inverse relationship between nodule mass and total root length although the number of first‐order lateral roots on nodulated and nonnodulated plants was the same.

The data suggest that two functional equilibria operate in the N‐fixing plant, namely, the partitioning of dry matter between (i) the underground portion of the plant and the shoot and (ii) the root and nodules. Phosphorus stress affected the root‐nodule equilibrium relatively more than the partitioning of dry matter between below‐ground and above‐ground parts of the plant.
Inheritance of a Fertility Enhancer Factor from Pima Cotton when Transferred into Upland Cotton with Gossypium Harknessii Brandegee Cytoplasm1
Authors: Sheetz R. H. , Weaver J. B.
Published: July 2010

Present efforts towards the development of hybrid cotton in the United States are concentrated almost exclusively on the use of Gossypium harknessii Brandegee derived cytoplasmic male sterility. Fertility restoration is controlled by an incompletely dominant gene, leading to variable fertility in heterozygous F1 upland ✕ upland hybrid populations. However, G. barbadense L. apparently possesses a modifying gene(s) which enhances fertility expression when present in upland cytoplasmic malesterile ✕ upland restorer F1 hybrids.

Self‐pollinated seed, derived from a cross of male‐fertile plants of G. hirsutum L. in G. harknessii cytoplasm ✕ ‘Pima S‐4’ (G. barbademe), followed by three backcrosses to non‐restoring upland strains was planted in progeny rows in 1977. Individual fertile plants were selfed and testcrossed to six G. harknessii‐derived cytoplasmic male‐sterile strains to determine inheritance of the Pima enhancer factor. Testcrossed and selfed seed were planted in individual progeny rows in 1978 and segregation ratios analyzed.

Analysis of progenies showed that male fertility restoration in F1 G. hirsutum hybrids in G. harknessii cytoplasm is enhanced by adding a genetic factor from the G. barbadense genome. Fertility in hybrid populations heterozygous for the restorer gene which possess the enhancer factor is comparable, if not superior, to that of the homozygous restorer lines which do not have the enhancer factor.

Data strongly indicate that the enhancer factor derived from G. barbadense is controlled by a single gene expressing dominance. However, there is some indication that the enhancer may, in some instances at least, express incomplete dominance. The symbol E is proposed to denote the G. barbadense gene for fertility enhancement.
Variation Among Anther‐Derived Haploids from a Multiple Disease‐Resistant Tobacco Hybrid1
Authors: Burk L. G. , Chaplin J. F.
Published: July 2010

Numerous chromosome‐doubled haploids (dihaploids) were obtained from cultured anthers of a tobacco (Nicotiana tabacum L.) hybrid with multiple disease resistance. Field plot tests of dihaploid progenies were made in 1977 (in the absence of diseases), and some of the highyielding entries observed in 1977 were included in a 1978 planting. The selections grown in 1977 consisted of four groups based on their resistance or susceptibility to Tobacco Mosaic Virus (TMV) and Potato Virus Y (PVY).

Unlike dihaploids from inbreds, some of the dihaploids from the hybrid yielded significantly more than the midparent (MP). Four yielded more than the MP 1977, and six yielded more in 1978. Most of the entries that produced high yields in 1977 were also high‐yielding in 1978. Alkaloid values were extremely variable among dihaploid lines and highly uniform within them. Values for agronomic traits, averaged among entries in the group that was susceptible to TMV but resistant to PVY, indicated that the gene for PVY resistance was associated with increased yields and high grade indexes (values). Resistance to TMV or root knot (RK), caused by Meloidogyne incognita (Kofoid and White) Chitwood, was not particularly beneficial to the groups of entries that possessed those genes. However, individual entries with the same combinations of genes for resistance/susceptibility were found to be high‐yielding; some, contrary to expectation, also had high grade indexes. This finding suggests that large numbers of dihaploid lines should be evaluated to assure identification and selection of exceptional individuals for use as breeding stocks or as varietal candidates. The occurrence of exceptional in. dividuals from a hybrid anther source, coupled with the fact that a dihaploid is a true‐breeding, homozygous diploid, obtained in a single generation, offers encouragement for progress in breeding high‐yielding, disease: resistant tobacco.
Associations of Plant Symptoms and Pod Position with Phomopsis sojae Seed Infection and Damage in Soybean1
Authors: Hepperly P. R. , Sinclair J. B.
Published: July 2010

The frequency and severity of infections of Phomopsis sojae (Leh.), pod and stem blight fungus, were inversely related to pod height on soybean [Glycine max (L.) Merr.] plants for the cultivars ‘Chippewa 64’ ‘Hark’, and ‘Wells’. Phomopsis sojae seed damage was primarily found in the bottom third of plants and distribution of damaged seed was heavily skewed to the lowest bearing node. Overall USDA soybean grades were lowered for Chippewa 64 and Wells due to seed damage caused by P sojae. Disease ratings based on stem, pod, and seed symptoms were tested for their association with seed infection rates. Visible symptoms rating for seed was highly associated with rates of seed infection for all cultivars. Pod and stem symptom ratings were highly associated with seed infection rates in Chippewa 64 and Wells but not for Hark. Selective harvest of upper plant portions improved seed quality.
Phenotypic Thermal Stability of Rhizobitoxine‐induced Chlorosis and the Nodulation Controlling Gene, rj11
Authors: Devine T. E. , Breithaupt B. H.
Published: July 2010

The rj1 gene in soybeans (Glycine max L. Merrill), prevents nodulation with a broad range of strains of Rhizobium japonicum. Strains of R. japonicum that produce rhizobitoxine induced foliar chlorosis can nodulate rj1 plants in sand or vermiculite culture in the greenhouse. This study was undertaken to determine the effects of temperature on the expression of chlorotic symptoms and nodulation of rj1 plants, and to clarify the relationship between nodulation and chlorosis. Tests with plants cultured in Leonard jars in environmental control chambers maintained at 21, 27, and 32 C indicated that temperature modified the nodulation response of Clark rj1 soybeans with the chlorosis inducing strains 61 and 76. Chlorotic symptoms were beast evident at 21 C. Strain 61 produced good nodulation on rj1 plants at 21 C, but exhibited no induction of chlorosis at that temperature on the cultivar ‘Hawkeye.’ Strain 76 produced strong chlorotic symptoms on both the cultivars Hawkeye and ‘Peking’ at 32 C, but only a low level of nodulation with the rj1 plants. This differential effect of temperature on these two processes suggested that, while rhizobitoxine is correlated with both processes, separate control mechanisms with different temperature optima govern their expression.

Increasing the temperature from 21 to 32 C mitigated the expression of the ineffective nodulation response of the Rj1 gene with strain 61 in the cultivar Peking. Despite the low level of nodulation (3.6 nodules per plant) of strain 61 with Peking at 32 C, chlorotic symptoms were clearly apparent.
Resistance to a Necrotic Strain of Soybean Mosaic Virus in Soybean1
Authors: Kwon Shin Han , Oh Jeung Haing
Published: July 2010

Eighty‐nine entries from soybean [Glyclne max (L.) Merr.] germplasm collection and 47 cultivars were evaluated for resistance to necrotic infection by a strain of soybean mosaic virus (SMV‐N) in the field. Necrotic symptoms developed on 18 of the 136 entries with severity ranging from 4 to 86%. Many of the soybean cultivars evaluated were susceptible.

Five resistant lines or cultivars previously identified as resistant to SMV‐N in field test, ‘KEX‐2,’ ‘Kumgangdaerip,’ ‘# 31926,’ ‘KAS 390‐10,’ and ‘KAS 150‐5,’ were crossed with either susceptible cultlvars ‘Kwangkyo’ or ‘Tachisuzunari’ to study the inheritance of resistance. All the F2 progenies of these crosses segregated in a 3:1 ratio of susceptible to resistant plants, indicating that resistance was conferred by a single recessive gene.
Crossing Contamination along Contiguous Borders of Certified Alfalfa Seed Fields1
Authors: Brown D. E. , Kehr W. R. , Manglitz G. R. , Elgin J. H. , Ostazeski S. A.
Published: July 2010

Multiple pest resistant alfalfa (Medicago sativa L.) cultivars in commercial production were used to study cross‐pollination along contiguous borders using contrasting levels of disease and insect resistance. Twenty‐eight seed samples were obtained from each of 3 cultivars and 26 from the fourth cultivar. In 110 sample comparisons with foundation and certified lots, only five departures from expected levels of resistance were found. Departures appeared to be random in relation to distance from foreign pollen source and leafcutter bee, Megachile rotundata (F.), locations and were interpreted as sampling variations. Thus the data indicated that isolation requirements for production of certified seed in fields larger than 2 ha using M. rotundata (F.) as pollinators could be less stringent than current standards without sacrificing the integrity of the cultivar.
Carbohydrate Levels in Soybean Leaves During Reproductive Growth1
Authors: Egli D. B. , Leggett J. E. , Cheniae Audrey
Published: July 2010

The carbohydrate status of a soybean [Glycine max (L.) Merrill] leaf during reproductive growth is related to the interaction between the production of carbohydrate by photosynthesis and its utilltation by the developing seeds and other active sinks. This interaction between source and sink plays an important role in the production of yield. Leaf samples were collected from field grown soybeans, ‘Cutler 71,’for 3 years to investigate changes in levels of free sugars and starch during reproductive growth. Shade cloth that reduced the incident solar radiation by 60% was installed over plants at the beginning of the seed filling period for 2 years and leaf samples were collected from the 6th and/or 12th leaf position at weekly intervals. Changes in free sugar levels in the leaves during seed filling varied from an increase to no change to a decrease across the $ years. Starch leveis increased to a maximum and, in 2 of the 3 years, declined as the plant approached maturity. The increase in starch was associated with an increase in specific leaf weight. Leaves that were ready to abscise contained up to 8.5% starch. Shading reduced yield (19 to 32%) but had no effect the level of free sugars in the leaves. However, the shade caused an immediate reduction (within 5 to 8 days) the concentration of starch, to 13 to 28% below the control, and this difference in concentration was maintained throughout the remainder of the filling period. Although soybean leaves accumulate starch during the seed filling period, some of the starch is remobili~ed prior to leaf abscission and the amount in the abseised leaves does not represent a significant quantity relative to the seed yield.
Increased Leaf Area (Source) and Yield of Maize in Short‐season Areas1
Authors: Hunter R. B.
Published: July 2010

Assimilate supply (source) apparently limits grain yield of maize (Zea mays L.) grown in short‐season areas. One approach to increasing assimilate supply is to increase leaf area per plant. In this 2‐year study, leaf area of a short‐season, single‐cross, hybrid was manipulated by growing plants to tassel initiation under both a long and a short photoperiod. The plants were then transferred to the field. In both years the plants established under the long photoperiod were larger, having more leaves, bigger mean leaf size, and greater leaf area. The larger plants produced higher ear yields, presumably resulting from the greater assimilate supply associated with the greater plant leaf area. The data support the concept that in short‐season regions the selection of genotypes with greater leaf area should result in increased yields.
Breeding Methodology in Wheat. II. Productivity, Harvest Index, and Height Measured on F2 Spaced Plants for Yield Selection in Spring Wheat1
Authors: McVetty P. B. E. , Evans L. E.
Published: July 2010

Three crosses of spring wheat (Triticum aestivum L.) involving the cultivar ‘Glenlea’ as a common female parent were used to evaluate the use of productivity, harvest index, and height in a combined index selection procedure on F2 spaced‐plants as selection criteria to identify high‐yielding F4 bulks. A space‐planted and solid‐seeded trial of seven tall cultivars and seven semi‐dwarf cultivars (both groups including the parents involved in the crosses investigated), indicated that potentially high‐yielding tall cultivars could be selected from space‐planted populations using productivity. Semi‐dwarf cultivars (short cultivars), in contrast, could be selected from space‐planted populations using harvest index. Therefore, productivity was used as the selection criterion on tall F2 plants and harvest index was used as the selection criterion on short F2 plants for high yield potential. The results indicated that a combined index selection procedure utilizing productivity, harvest index, and height may be useful in increasing yield in spring wheat.
Inheritance of Resistance to Philippine Downy Mildew of Maize, Peronosclerospora philippinensis1
Authors: Kaneko K. , Aday B. A.
Published: July 2010

Various hypotheses on the mode of inheritance of resistance to downy mildew of maize (Zea mays L.) have been proposed on the basis of several studies, and it was suggested that the mode varied with the different epiphytotic conditions. Mode of inheritance of resistance to Philippine downy mildew (Peronosclerospora philippinensis), was investigated under experimental conditions, at different plant ages. The results show that the mode of inheritance of resistance to downy mildew changes from complete to partial dominance as the infection changes from very slight to severe, and at about 50% level of infection it becomes additive. Thereafter there is a shift to susceptibility showing partial to complete dominance. Such findings suggest that downy mildew resistance is governed by a polygenic system with a threshold nature.
Methanol Stress as a Test of Seed Vigor1
Authors: Musgrave M. E. , Priestley D. A. , Leopold A. C.
Published: July 2010

A pre‐germination treatment of seeds with methanolwater solutions is shown to mimic the effects of the accelerated aging treatment of soybeans (40 C, 100% RH). Similarities in germination data are presented for accelerated aging and methanol stress of peas (Pisum sativum L. cv. Alaska) and 7 cultivars of soybean [Glycine max (L.) Merr.]. Methanol stress is shown to bring about physiological lesions similar to those from accelerated aging, including increased membrane leakage, depressed cyanide sensitive respiration, and lowered chlorophyll synthesis in the cotyledons. The method is offered as a simple alternative to accelerated aging both in terms of seed testing and physiological studies.
Responses of Early Corn Inbreds to Photoperiod1
Authors: Rood S. B. , Major D. J.
Published: July 2010

Twelve early‐maturing inbred corn (Zea mats L.) lines were grown in controlled environments at photoperiods of 14, 16, 18, 19, 20, 21, 22, 23, or 24 hours. Days from emergence to anthesis increased as photoperiod increased for 10 of the 12 inbreds. The photoperiod response of the inbreds was adequately described by a three‐line model previously used for other plant species. Genotypic variability for the photoperiod response was identified.

The basic vegetative phase, which is the time from emergence to anthesls in optimal photoperiod conditions, ranged from 37 to 57 days. The photoperlod sensitivity, expressed in days delay per hour increase of photoperiod, ranged from 0 to 2.5. The maximum optimal photoperiod, which is the longest photoperiod at which no photoperiod‐induced delay in anthesls is observed, ranged from 14 to 24 hours, and the critical photoperiod, above which no further delay in anthesis occurs, ranged from 21 to 24 hours. The photoperiod‐induced phase varied from 0 to greater than 17 days. A lack of correlation between components of the photoperiod response suggests independent regulation of these components.
Classification of Environments and Genotypes in Wheat1
Authors: Ghaderi A. , Everson E. H. , Cress C. E.
Published: July 2010

Forty‐one genotypes (seven cultivars and 34 breeding lines) of winter wheat (Triticum aestivum L.) were planted in eight locations in each of 2 years. Test weight data were used to group locations according to their similarity of genotype ✕ location (G✕L) effects by cluster analysis. The results indicated that deletion of only one location from the variance analysis resulted in a group within which G ✕ L interaction was not significant. Such an analysis would be useful for the selection of testing sites for early generation testing and for development of genotypes with wide or narrow adaptability.

The cultivars were also grouped into 10 clusters with respect to their test weight similarity across the 16 environments (2 years and eight locations). Further, stability parameters, i.e., mean, regression coefficient, and deviations from regression were calculated for each genotype. Cluster analysis effectively grouped genotypes according to their stability responses. Three broad categories of genotypes were identified with respect to their stability characteristics. Cluster analysis could be a useful supplementary tool for the analysis of adaptation reactions of wheat genotypes for test weight.
Comparisons Among Populations of Maize for Growth at 13°C
Authors: Hardacre A. K. , Eagles H. A.
Published: July 2010

Six populations of maize (Zea mays L.), from high altitude sources in Mexico, Peru, and a high latitude source in Germany, and their crosses as males to two United States Corn Belt dent inbred lines (‘A619’ and ‘WI53R’) were compared for growth and survival at 13 C in a controlled environment with three U.S. Corn Belt dent hybrids (‘A632’ ✕ ‘A659,’ A619 ✕ A632, and WI53R ✕ A632).

The objective of this study was to determine if any of these populations had the ability to grow autotrophically at 13 C, a temperature which was expected to be below the minimum for autotrophic growth of U.S. Corn Belt dent cultivars.

At 13 C all plants grew heterotrophically utilizing seed reserves. However, major differences in the ability to grow autotrophicaly at 13 C existed among the genotypes studied. All genotypes containing germplasm from the high altitude Peruvian races ‘San Geronimo,’ ‘Huancavelicano,’ and ‘Confite Puneno’ were capable of autotrophic growth at l3 C as were genotypes from the CIMMYT (Centro Internacional de Mejoramiento de Maiz y Trigo) Pool 5. ‘Criollo die Toluca,’ predominantly of the high altitude Mexican race Conico, and ‘Bergenlaender,’ of the high latitude Norllhern Flint race, per se, were unable to grow at 13 C. However, their crosses with W153R and the cross A619 ✕ Criollo de Toluca were able to grow autotrophically at this temperature. Differences in growth rates existed between A619 and WI53R in crosses. Overall, crosses with W153R had the highest growth rates and crosses with A619 the lowest. The three U.S. Corn Belt dent hybrids did not grow autotrophically at 13 C.
Genetic Studies of Seed Oil in Cotton1
Authors: Kohel Russell J.
Published: July 2010

Twenty lines with high and low seed‐oil percentages were selected from 747 lines in the Upland cotton, Gossypium hisutum L., germplasm collection. These lines were used to transfer a range of seed‐oil percentage into agronomic backgrounds and to study its inheritance. The seed‐oil lines were crossed as females to five agronomic lines that included glanded and glandless types and fullseason and early‐maturing types. The characteristics determined were: (1) seed‐oil percentage, (2) seed index, (3) embryo percentage, (4) embryo‐oil percentage, (5) seed‐oil index, and (6) embryo index. Parental and F3 seeds (from F2 plants) were analyzed. Variability was significant for all characters. Differences among the maternal and paternal F33 arrays were highly significant. The maternal ✕ paternal interaction effects for seed‐oil index and embryo percentage were small but significant. Heritability estimates based on Fa genetic variability ranged from 42 to 66% for the characters measured. The heritability estimate for seed‐oil percentage was 35% when calculated by the standard‐unit regression (F33 on F22) method. These results established that seed oil is heritable and can be transferred readily. Variability for seedoil percentage of the seed‐oil parents exceeded that of the agronomic parents only slightly. Seed‐oil percentage was not as highly correlated with seed physical properties in the seed‐oil parents as it was in the agronomic parents. This result suggests that the seed‐oil parents offer unique germplasm for the modification of seed oil content.
Influence of Alfalfa Bud Mite on Growth of Alfalfa under Different Temperatures1
Authors: Ridland P. M. , Halloran G. M.
Published: July 2010

The influence of four temperatures (15, 20, 25, and 29 C) on the growth of alfalfa (Medicago sativa L) seedlings, initially infested with 10 alfalfa bud mites (Eriophyes medicaginis Keifer) per seedling, was studied.

Mite infestation caused significant reductions in dry weight of leaves and stems, petiole length, and leaf area of the seedlings at all temperatures. Dry weight reductions of infested seedlings were greatest at 25 and 29 C. The greatest reductions in stem and petiole length and leaf area occurred at 29 C. The reduction in total leaf area per plant due to mite infestation was similar at 15, 25 and 29 C but there was less reduction at 20 C.

The influence of bud mite infestation on the growth of alfalfa seedlings appears to be expressed mainly as a reduction of extension growth. This results in reduced leaf expansion and reduced elongation of the stem and petiole.
Drought Response of Winter Wheat Cultivars Grown under Field Stress Conditions1
Authors: Keim D. L. , Kronstad W. E.
Published: July 2010

Ten winter wheat cultivars (Triticum aestivum L.) were evaluated for grain yield and yield components under moisture stress conditions at three locations. Osmotic potential (Ψn.) was determined from leaf samples taken during the early part of grain filling. Consistent genetic differences were found for Ψn… Significant positive associations of Ψn with yield existed at two locations (r= 0.49 and 0.45). Path‐coefficient analysis indicated that Ψn. contributed positively to yield differences primarily by way of kernel weight at Pendleton, the least stressed site. Increased Ψn made contributions to high yield via spikelets/spike, kernels/spikelet, and kernel weight at Pilot Rock, a severely stressed site. High spike numbers had a tendency to be associated with low plant water status (low Ψn). At Heppner, the large direct effect on yield by spikes/m2 negated the small positive indirect effects of Ψn via the later‐developed yield components. In a growth analysis study at Pilot Rock, five cultivars were sampled over four time intervals from spike initiation to ripe stage. The mean Ψn decreased over time (‐ 17.1 to ‐ 31.8 bars). Cultivar Ψn values ranked consistently and differences became larger after the onset of high soil moisture stress (< ‐ 15 bars).

The drought‐resistant cultivar ‘Yamhill’ avoided drought stress by maintaining a high plant water status during reproductive development. The high growth rates during heading and anthesis and a high kernel weight indicated that this cultivar was less affected by high external water stress. The drought‐resistant cultivar ‘Wanser’ tolerated a high internal stress by maintaining a large number of tillers through development to harvest. Characterization of other cultivars also indicated that both avoidance and tolerance traits contributed to grain yield under drought stress.
Comparison of Narrow and Broad Leaflet Isolines of Soybean1
Authors: Mandl F. A. , Buss G. R.
Published: July 2010

We evaluated the effect of leaflet shape on the agronomic performance of soybeans, Glycine max (L) Merr., by using pairs of narrow and broad leaflet isolines with varied genetic backgrounds.

Results obtained from 1976 through 1978 indicated that the narrow leaflet isolines, on the average, were similar in seed yield to those with broad leaflets. Analyses over years showed the narrow leaflet isolines were significantly shorter and had smaller seeds. They were significantly earlier in 2 of the 3 years. Lodging scores were similar for both leaflet types. All differences were small and of little practical significance. We concluded that the narrow leaflet trait offers neither a yield advantage nor disadvantage compared with the broad leaflet trait.
Modification of Soybean Plant Architecture by Genes for Stem Growth Habit and Maturity1
Authors: Hartung R. C. , Specht J. E. , Williams J. H.
Published: July 2010

Soybean [Glycine max (L.) Merr.] plant architecture can be modified by genes conditioning stem termination and timing of flowering and maturity. Nearisogenic lines of the soybean cultivars ‘Clark’ and ‘Harosoy,’ which possessed various genes for stem termination and maturity, were evaluated for agronomic performance and plant architectural features in furrow irrigation culture for 2 years. Genes delaying flowering and maturity significantly increased the number of main stem nodes, stem length, lodging, branches per plant, and seeds per plant, but reduced seed weight. Genes hastening flowering and maturity had the opposite effects. The gene for semldeterminate stem growth (Dt2) significantly reduced the number of main‐stem nodes and stem length, but the reduction in lodging was not significant. Differences in yield and other traits between semideterminate and indeterminate types were not significant. The gene for determinate stem growth (dt1) severely reduced the number of main‐stem nodes, substantially reducing stem length and lodging. There were significantly fewer 3‐seed pods in the dt1 isolines, resulting in fewer seeds per plant. The lower seed yields of the dt1 isolines were not significantly different, however, from their indeterminate counterparts. Delaying flowering in the determinate types lessened the severe stem length reduction caused by dt1, but lodging resistance was maintained. However, there was no advantage with respect to yield because delayed flowering resulted in a shorter reproductive period which tended to reduce seed weight. The number of pods borne on the main stem of nodes 15 cm or less from the soil surface was significantly greater in the determinate types than in indeterminate or semideterminate types, although delays in maturity tended to lessen this effect. As a consequence, harvest losses could be significant in determinate cultivars grown in furrow irrigation culture.
Root Lipid Composition and Metabolism in Genetic Male‐Sterile Soybeans1
Authors: Wilson Richard F.
Published: July 2010

Genetic male‐sterile soybeans produced approximately 85% fewer pods than their fertile siblings. Reduced seed production presumably was responsible for prolonged retention of green leaves on male‐sterile plants and allowed more photosynthate to be diverted to the legume root system for utilization in metabolic processes or for conversion to metabolic storage reserves. Because lipids may function as either membrane components or metabolic storage products, the objective of this study was to determine if the secondary effects of male‐sterility were associated with patterns in root lipid composition and metabolism, and to describe any differences from those of the male‐fertile soybean roots. Sterile and fertile plants from a population of the male‐sterile (ms1) maintainer line [Glycine max (L.) Merr. cv. N69‐2774] were sampled in a replicated experimentat 10‐day intervals from flowering to maturity. The total root lipid content of male‐sterile and malefertile plants was found to be significantly different between 110 and 140 days after emergence (DAE). During that period the lipid in male‐sterile roots increased from 1.3 to 3 times that present in male‐fertile roots. At 140 DAE the level of triacylglycerol (TG) was 6.2 times greater in the male‐sterile roots, yet phospholipids were the major glycerolipid fraction in both genotypes throughout development. Within the phospholipid fraction at 140 DAE, the most striking differences between genotypes were the increase of phosphatidylglycerol (PG) and cardiolipin (DPG) in the male‐sterile roots, and the differences in the concentration of palmitoleic acid (16:1) and linolenic acid (18:3). Similar patterns in the concentration of 16:1 and 18:3 were observed in TG. At 140 DAE the concentration of 16:1 was greater in TG than in phospholipids, and also greater in male‐fertile root lipids than in the malesterile counterparts. Although no direct biochemical association was discovered between 16:1 and 18:3, the relation of 18:3 concentration between TG and phospholipids, and also between male‐fertile and malesterile root tissue was opposite to that described for 16:1. Radioactive acetate was incorporated primarily into phospholipids by both genotypes throughout development. The rate of incorporation into lipid was significantly lower in male‐fertile roots after 110 DAE. These results have shown that in the absence of a large seed sink, the lipid biochemistry of soybean root tissues was altered significantly as reflected in the increased levels of storage lipid and the biosynthesis of membrane lipid components.
Identification and Inheritance of Pigments in Wild Rice
Authors: Gutek L. H. , Woods D. L. , Clark K. W.
Published: July 2010

The identity and inheritance of anthocyanin pigments in the leaf sheath and staminate florets are not known in wild rice (Zizania aquatica L.). The objectives of this research were to identify the anthocyanins in wild rice and to initiate a study on the inheritance of these pigments. This information would facilitate studies on determining minimum isolation distances between varieties. In addition, color traits could be used as varietal markers. Spectroscopy and descending paper chromatography were used to identify the anthocyanins in the staminate florets and leaf sheath of wild rice. Cyanidin 3‐glucoside constituted approximately 75% and cyanidin 3‐rhamnoglucoside 25% of total anthocyanin content. Preliminary studies indicate that anthocyanin production is controlled by a dominant gene. Evidence suggesting the presence of a semidominant inhibitor gene is also discussed.
Seminal Root Morphology and Water Use of Wheat I. Environmental Effects1
Authors: Richards R. A. , Passioura J. B.
Published: July 2010

When wheat (Triticum aestivum L.) is growing predominantly on a limited supply of stored soil water, an increase in the axial resistance to water flow in the roots would conserve some of that water for the critical period during flowering and grain filling. This increase may be achieved by decreasing either the diameter of the main xylem vessel in the seminal axes or the number of seminal axes. The effects of different environments, or seed characters which are influenced by the environment, on both these seminal root characters are reported here. Few of the many factors studied had an effect. The most notable were grain size, drought, and temperature between germination and emergence, and drought when the seed was being produced. Neither root character showed any genotype‐environment interactions when contrasting genotypes were grown in different environments. This gives promise that selection for increased resistance could be done under controlled conditions.
Changes in Physiological Traits Associated With Grain Yield Improvement in Three Maize Breeding Programs1
Authors: Crosbie T. M. , Mock J. J.
Published: July 2010

Plant breeders and plant physiologists would like to know which plant traits have changed to permit new varieties to produce higher yields than older varieties. We studied crosses of improved and unimproved cycles from three recurrent selection programs conducted to increase grain yield in maize (Zea mays L.). Our research was conducted to study changes in several physiological traits that could be important to increased grain production.

Results suggested that an extended grain filling period and later plant senescence rather than an increased rate of grain filling was associated with grain yield increases in BS10(FR) x BS11(FR). Testcrosses of the improved Lancaster population produced more dry matter and translocated dry matter to developing kernels at a faster rate and for a longer period of time than did testcrosses of the unimproved population. Crosses of improved cycles of BSSS(R) and BSCBl(R) generally displayed more rapid filling periods and later plant senescence than did crosses of their unimproved cycles. Crosses of improved cycles generally produced more dry matter and translocated a larger percentage of dry matter to the grain.
The Seed Coat as a Control of Imbibitional Chilling Injury
Authors: Tully Raymond E. , Musgrave Mary E. , Leopold A. Carl
Published: July 2010

The imbibition of pea (Pisum sativum L.) seeds proceeds slowly in cold water, with little effect on subsequent vigor; soybean [Glycine max (L.) Merr.] seeds imbibe cold water rapidly, and suffer significant vigor loss. When the imbibitional rate of peas was increased by nicking the seed coats, the peas became susceptible to chilling injury. Conversely, when the rate of soybean imbibitionwas slowed with a solution of polyethylene glycol (PEG 6000), their susceptibility to imbibitional chilling was considerably lessened. Sensitivity to imbibitional chilling is thus a consequence of the rate of cold water uptake.

Cellular damage to cold‐imbibed peas and soybeans was assessed as inability to reduce triphenyl tetrazolium chloride (TTC). Peas showed only a low level of damage when imbibed with intact seed coats at 2 C, but increased damage when imbibed with nicked seed coats. Soybeans, however, showed considerable cellular damage when imbibed intact, and no further damage when imbibed with nicked seed coats. Pea seed coats thus offer considerable protection against rapid imbibition and chilling damage, whereas the soybean seed coat offers little.

Soybeans with black‐pigmented seed coats imbibed water more slowly than nonpigmented soybeans. Blackpigmented soybeans also showed less vigor loss following imbibition at 0 C, and exhibited no cellular damage as determined with TTC stain. Vigor of blackpigmented seeds after 23 C imbibition was less than that of nonpigmented, however, due to a slower rate of radicle penetration of the tougher black seed coats.
Limitations in the Use of Leaf Dry Weight and Leaf Number for Predicting Leaf Area of Soybeans1
Authors: Ogbuchi S. N. , Brandle J. R.
Published: July 2010

Equations relating leaf area to leaf dry weight and to leaf number were developed for soybeans [Glycine max (L.) Merr.] grown in windbreak‐sheltered and unsheltered plots during the 1978 and 1979 growing seasons. For each growing season, equations developed for a particular treatment were found to be accurate in predicting leaf area of independent samples taken from that treatment only. In a different treatment or growing season, the equations gave inaccurate estimates. This inaccuracy in predicting leaf area of plants grown in a different treatment or season was attributable to the differences in specific leaf area and leaf size. Our data indicate that prediction equations for soybean leaf area which utilize leaf dry weight and leaf number should not be used for soybeans grown in a different environment because of inaccuracy of estimates.
A Fourth Genetic Element to Facilitate Hybrid Cereal Production—A Recessive Tall in Rice1
Authors: Rutger J. N. , Carnahan H. L.
Published: July 2010

A recessive gene in rice (Oryza saliva L.) for elongated uppermost internode (eui), which effectively results in a recessive tall plant type, is described. The gene produces a near‐doubling in length of the uppermost internode, a 12% increase in panicle length, and little or no effect on other internodes or plant characters. It is proposed that this gene would be a useful fourth element which would complement the other three genetic elements∔cytoplasmic male sterility, maintainers, and restorers—generally used in hybrid seed production. The eui gene would be incorporated in pollen fertility restoring parents in hybrid seed production in situations where a semidwarf F1 generation is desired. The tall paternal plant type would be desirable for windblown pollen dispersal onto semidwarf female plants and the resulting hybrid plants would be semidwarf, unlike the usual case of tall hybrids from semidwarf by tall crosses. Additionally, its increased height would permit a co‐mingling of the hybrid parent seed stocks to maximize crossing and would facilitate mechanical removal of the paternal parent before mass harvest of the commercial hybrid seed.
Fertility of Hybrids between Two Geographic Races of Tall Fescue1
Authors: Hunt K. L. , Sleper D. A.
Published: July 2010

Increasing genetic variation by crossing geographic races is commonly recognized as desirable. The objectives were to determine the extent of sterility among American and Tunisian tall fescue (Festuca arundinacea Schreb.) F, hybrids. Genotypes from Portugal, France, and Algeria were selected as intermediate accessions and were mated to those adapted to America and Tunisia. Hybrids were separated into two groups based on the extent of meiotic irregularities. The most fertile hybrids (Group 1) had mean chromosome configurations of 0.65 univalents, 20.07 bivalents, 0.17 trivalents, and 0.18 quadrivalents. Group 2 had mean chromosome configurations of 4.90 univalents, 13.44 bivalents, 1.46 trivalents, 1.37 quadrivalents and occasional pentavalents and hexavalents. Pollen stainability of Group 1 hybrids ranged from 59 to 81% while Group 2 hybrids ranged from 1 to 13%. Seed germination ranged from 36 to 94% and 2 to 20% for Group 1 and 2, respectively. Only one genotype, B6‐13, showed the best attributes for donating Tunisian‐race genes to American cultivated tall fescue
Drought Resistance of Cowpea Improved by Selecting for Early Appearance of Mature Pods1
Authors: Hall A. E. , Grantz D. A.
Published: July 2010

We hypothesized that earlier partitioning of carbohydrate to reproductive parts by cowpeas [Vigna unguiculata L. (Walp.)] would result in improved drought resistance. We selected individual plants from adequately‐irrigated fields of the cultivar, California Blackeye No. 5 (CB5), and a land race of California Blackeyes, in southern California. The selection criterion was early appearance of mature pods.

Seeds of the selections and populations were bulked in a greenhouse. Phenology, growth, partitioning, and yield were examined at Riverside, Calif. over three summer growing seasons with both optimal irrigation and a treatment which received no irrigation or rainfall after seedling emergence. No differences were observed among the selections and populations in ability to extract water from the soil.

The selection from CB5 flowered earlier, and had substantially more dry matter in peduncles and pods during early stages of pod development, than CB5, in both irrigated and non‐irrigated conditions. At maturity, this selection had a higher harvest index and yielded 53% more seed than CB5, under non‐irrigated conditions, and a similar harvest index and seed yield as CB5 under irrigation.

In non‐irrigated conditions, the selection from the land race had more dry matter in peduncles and pods during early stages of pod development, a higher harvest index at maturity, and yielded 19% more dry seed than the land race. No significant differences were observed in earliness, partitioning, harvest index, or seed yield between this selection and the land race under irrigation. All strains had similar biomass production and seed yield under irrigation.
Sampling Stomatal Density in Alfalfa1
Authors: Carlson J. R. , Ditterline R. L. , Martin J. M. , Lund R. E.
Published: July 2010

Sample size requirements for stomatal density studies in alfalfa (Medicago sativa L.) are not documented. This study was conducted to refine sampling techniques and to determine whether the sampling required to estimate stomatal density is too extensive to use this trait as a possible rapid screening criterion for drought resistance in alfalfa.

Stomatal and epidermal cell counts were made on abaxial and adaxial leaflet surfaces sampled at three nodes from 10 stems of five alfalfa plants. These plants differed significantly in stomatal densities on abaxial and adaxial leaflet surfaces. Leaflets from the uppermost node sampled had higher stomatal densities than those from lower nodes.

Variability from counts on leaflets from stem to stem rather than variability in counts from microscopic field to microscopic field within a leaflet contributed most to overall imprecision in estimation of mean counts per plant. To increase precision and efficiency, efforts should thus be directed toward sampling leaflets on more stems and not toward more fields on a leaflet. Number of stem samples required to detect given differences between plants at specified probability levels have been tabulated.

Due to the large level of within‐plant variability for stomatal density in alfalfa, we decided that the sampling required was too extensive to pursue this trait in a breeding program for drought resistance.
Influence of Potassium‐Fertilization Rate and Form on Photosynthesis and N2 Fixation of Alfalfa1
Authors: Collins Michael , Duke Stanley H.
Published: July 2010

This study reports a growth chamber experiment conducted to investigate the influence of potassium (K) fertilization level (control, medium, high K) and form (KCI and K2SO4) on photosynthesis, carbohydrate concentration, and N2 fixation of alfalfa (Medicago sativa L.). Fertilization with high levels of K as K2SO4 increased shoot number per plant by 51% and increased shoot dry weight by 20% over the unfertilized control. Control plant herbage contained 1.28% reducing sugars (RS) compared with 0.78% RS in herbage of the high K‐high S treatment, indicating that K deficient plants accumulated these compounds in photosynthetic tissues. Chlorophyll concentration increased linearly in response to K application and net carbon exchange rate (CER) on a per plant basis was increased by average of 28% over the control. Nodule numbers per plant ranged from 28 for the control to 90 for the medium K‐high S treatment. Nitrogen‐fixation rate was enhanced by K fertilization and ranged from 12.3 nmoles ethylene/plant/minute for the control to 56.8 for the medium K‐medium S treatment. These results suggest that the increases in N2 fixation of alfalfa in response to K and S fertilization are a result of a number of factors including increased CER, increased nodule numbers, and enhanced carbohydrate movement from the shoot.
Resistance of Sweet Potato Cultivars to African Sweet Potato Weevil1
Authors: Hahn S. K. , Leuschner K.
Published: July 2010

Twenty sweet potato (Ipomoea batatas L.) cultivars, including two orange‐fleshed and 18 white‐fleshed types, were evaluated in the field for resistance to African sweet potato weevil (Cylas puncticollis Boh.). The cultivars showed significant differences in weevil resistance in separate evaluation of roots and shoots. Cultivars with the most resistant roots were ‘TIS 3053’ and ‘TIS 3030.’ Cultivars with the most resistant shoots were ‘TIS 2532,’ ‘TIS 3017,’ and TIS 3030. A highly significant correlation (r = 0.74) was noted between weevil damage ratings of roots and damage ratings of shoots.

A highly significant negative correlation between weevil root damage scores and root dry matter percentage was obtained (r = −0.56), but fresh root yield or average weight were not correlated with weevil damage.
Stormproof Boll in Upland Cotton III. Genotype‐Environment Interaction and Genetic Analysis1
Authors: Quisenberry J. E. , Dilbeck R. E.
Published: July 2010

Stormproofness (lock tenacity) of cotton (Gossypium hirsutum L.) was defined as the amount of force required to extract a locule of seedcotton from the bur of a mature boll. Six entries representing the range of variability in stormproofness of Upland cotton were grown in seven environments to study the relationship of the character to temperature and precipitation. In a separate experiment, a complete diallel set of crosses among the six entries was grown for 2 years to estimate general (GCA) and specific combining ability (SCA) associated with the inheritance of the stormproof trait.

In general, stormproofness increased as temperature during the boll maturation period decreased or seasonal precipitation increased. Temperature appeared to influence stormproofness more than precipitation, although responses among the entries varied. ‘Acala 1517 BR‐2,’ TM‐1, Contextum, and ‘Macha’ were more responsive to temperature than to precipitation. Unique Stormproof was about equally influenced by both variables, and ‘Lankart Sel. 57’ was most responsive to precipitation. Results from the genetic study revealed that significant GCA and SCA effects were associated with the expression of stormproofness, but that the SCA effects were small and hybrids tended to be intermediate between their respective parents. The GCA effects interacted with years primarily as a result of relative changes in lock tenacity between the stormproof and nonstormproof cultivars. A relationship between lock tenacity and the percentage of storm loss (seedcotton that fell on the ground) showed that hybrids between non stormproof cultivars may suffer relatively high storm losses.