bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Kernel Maturation on Subsequent Seedling Vigor in Maize1
Authors: Knittle K. H. , Burris J. S.
Published: July 2010

Production of high quality seed corn (Zea mays L.) would be facilitated by the harvesting of the seed at a kernel maturity which is highly correlated with maximum seedling vigor. This study attempted to correlate several kernel maturity indices with measures of seedling vigor in a maturing seed corn crop.

Hybrid seed samples were taken from two field locations of production of maternal parents ‘A632’, ‘Va26’, ‘B73’, and ‘Mo17’ from 35 days to 98 days after silking. Kernel maturity indices evaluated were: 1) fresh kernel respiration rates, 2) black layer development, 3) moisture percentage, and 4) dry weight accumulation. After drying, the seed was grown on moistened, rolled paper towels in the dark for seven days at 25 C. Vigor measurements included germination percentage, shoot dry weight, and root dry weight. Although germination percentages were high over all harvest dates, both shoot and root dry weight were highly dependent on date of harvest. Distinct vigor maxima and minima were noted, and the first and last sample dates never corresponded to maximum shoot and root dry weight. Dates of maximum vigor and kernel maturity patterns were specific for each hybrid. Maximum kernel dry weight was correlated with maximum shoot and root dry weight, and the range of kernel moisture percentage corresponding to initial attainment of maximum kernel dry weight was small.
Influence of Environment and Clipping on the Seed‐Yield Potential of Three Red Clover Cultivars1
Authors: Rincker C. M. , Dean J. G. , Garrison C. S. , May R. G.
Published: July 2010

Seed yields and components of seed yield of ‘Alaskland’ (single‐cut), ‘Kenland’ and ‘Sapporo’ (double‐cut) red clover (Trifolium pratense L.) cultivars were evaluated under clipping vs. no clipping treatments, at Prosser, Washington and at Shafter and Tehachapi, California to determine the influence of different environments on three different cultivars. These cultivars were grown in rows of 45 or 50 cm row width and irrigated when needed. Seed yields from undipped plants of these cultivars did not vary greatly at Prosser, whereas Kenland was superior at Shatter and Tehachapi. Clipping the first spring growth at 1/10 to 1/2 bloom significantly reduced seed yields and number of heads per m2 for all cultivars except Kenland at Prosser. Clipping significantly increased the number of florets per head for Sapporo and Kenland at all locations except Shafter, while reducing the number of florets for Alaskland at Tehachapi. Clipping increased the number of seeds per head for Sapporo and Kenland at Prosser but not at Shafter and Tehachapi. Clipping decreased the number of seeds per head for Alaskland at all locations. Clipping reduced the weight of 1,000 seeds except for Alaskland at Shatter. We conclude that in western environments removing a hay crop in red clover resulted in reduced seed yields of all cultivars in all locations, and that cultivars tended to perform better in environments similar to their origin. The environment at Shatter tended to influence components of seed yield in a manner unlike that of the other two environments.
Stomatal Diffusion Resistance in Three Ploidy Levels of Smooth Bromegrass1
Authors: Lea H. Z. , Dunn G. M. , Koch D. W.
Published: July 2010

Diurnal variations in stomatal resistance and the relationship of stomatal resistance to stomatal characters were investigated in tetraploid (4×), hexaploid (6×), and normal octoploid (8×) strains of Bromns inermis Leyss. Stomatal resistance of ‘Blair’ (8.6 sec/cm) was significantly higher than for the other six octoploid cultivars (5.8 to 6.5). The range of mean stomatal resistance between 0900 and 1600 hours (Eastern Standard Time) was approximately 4.0 to 9.0 sec/cm for 8×. Within a cultivar the diurnal pattern of stomatal resistance varied, dependent on the day of measurement; however, stomata of 4× and 6× plants consistently closed earlier in the evening than did 8× plants. Octoploid plants had the lowest mean stomatal resistance (5.1 sec/em), 6× intermediate (6.9), and 4× the highest (8.6), based on measurements between 0700 and 1930 hours for four measurement dates in June 1974.

A highly significant negative correlation (r = −0.58) was obtained between stomatal resistance, measured with a diffusion porometer, and total stomatal aperture estimated as the product of stomatal width ✕ length ✕ frequency. Stomatal width was the most important single factor in estimating total stomatal aperture (r = −0.92) and stomatal resistance (r = −0.54). Stomatal resistance was not affected significantly by leaf position on the culm.
Effect of the Twin‐seeded Character on Sorghum Performance1
Authors: Casady A. J. , Ross W. M.
Published: July 2010

The sorghum [Sorghum bicolor (L.) Moench] sessile spikelet normally contains two flowers. Usually, only the upper develops into a seed, but the lower also develops into a seed in some cultivars, resulting in twin seededness. A study of the influence of the twin‐seeded character on sorghum performance was made by use of isogenic lines. Isogenic single‐ and twin‐seeded A‐ and B‐lines of the sorghum cultivars ‘Combine Kafir‐60’ and ‘Redlan’ were developed by backcrossing. The twin‐seeded allele (Ts) caused sterility in some instances, especially in A‐lines. Attempts to develop twin‐seeded lines of ‘KS 24’ resulted in much sterility and multiple seededness of up to five seeds per spikelet.

Comparisons were made of isogenic single‐ and twinseeded counterparts of the sorghum hybrids ‘KS652’, ‘RS610’, ‘RS702’, ‘RS650’, 62MH248, and 55MH19 at Manhattan, Kans. and Mead, Neb. The percentage of spikelets with twin seed was influenced by genotype and environment. Twin seededness had no effect on days to 50% bloom, plant height, and panicles per plant. There was little evidence that twin seededness affected test weight, although it decreased seed weight and the number of seed‐bearing spikelets per panicle while increasing the number of seeds per panicle. Grain yields of the single‐ and twin‐seeded counterparts of RS610 and RS702 did not differ significantly, but twin‐seeded counterparts of the remaining hybrids yielded significantly less grain than the single‐seeded counterparts.
Characterization and Inheritance of a Spotted Leaf Trait in Alfalfa1
Authors: Azizi M. R. , Barnes D. K.
Published: July 2010

Few genetic markers are available in alfalfa (Medicago sativa L.) that do not reduce plant growth. A vigorous plant with spotted leaves was found in the ‘San Isidro’ variety. Spotted‐leaf plants were characterized by newly formed leaves that appeared normal but developed chlorotic spots within one week. Effects of two temperatures( 17 and 30 C) and three photoperiods (12‐ 16‐, and2 4‐hours) on the leaf‐spot trait were studied in both greenhouse and growth chambers. At 17 C the trait was readily expressed, but at 30 C no spotting occurred. Leaves developed at 30 C did not become spotted when subsequently exposed to 17 C. Conversely, spotted leaves that developed at 17 C did not show repair when exposed to 30 C. The development of spots was greatest with a 24‐hour light period. Cytological studies showed that palisade cells and a few spongy misspell cells of the spotted‐leaf tissue were deformed and deteriorated. The epidermal cells remained in tact.

Genetic studies conducted at 17 C with a 24‐hour footprint dicated that the spotted‐leaf trait was controlled by two tetrasomic genes with random chromosome inheritance. The SA— sbsbsbsb, SA— SB— and sasasasa sbsbsb genotypes produced normal plants. The sasasasa SBSB— genotypes produced spotted‐leaf plants. Incomplete penetrance in sasasasa SBsbsbsb plants produced about 20% spotted‐leaf plants. It was hypothesized that severity of spotting was controlled by modifying genes and was not closely associated with the dosage of the SB allele. The spotted‐leaf trait was not maternally inherited.
Backcross Breeding to Increase Fiber Strength of Cotton1
Authors: Meredith William
Published: July 2010

Three cycles of backcross breeding to increase fiber strength (T1) of cotton (Gossypium hirsutum L.) were studied at Stoneville, Miss. The objective was to measure the effectiveness of the backcross procedure for maintaining an adequate level of T1 and producing desirable combinations of yield and T1. The source of greater T1 was FTA 263‐20 (FTA) and the recurrent parent was ‘Deltapine 16’ (DPL 16). In each cycle, 480 F2 plants were grown. In both BC1F2 and BC2F2, 24 plants were selected. In BC1F3 and BC2F3, 12 and four progeny respectively, were used to initiate the next cycle. From each of the four families descending from the four selected BC2F3 progenies, 12 of 120 BC3F2 plants were selected. In 1974, four sets of families were grown at two locations with two replications each. In each replication of each set, two entries of DPL 16, FTA, and BC1F5 and BC2F4 parents, and one entry of each of the 12 BC3F3 progenies were evaluated for lint yield, yield components, and fiber properties.

Mean T1's for DPL 16, FTA, BC1F5, BC2F4, and BC3F3 were 193, 230, 220, 211, and 216, respectively. Therefore, a satisfactory level of T1 was maintained by the backcross procedure. Assuming yield and T1 were uncorrelated, the observed average line yield of BC3F3 was 9.8% less than expected. The decrease in expected yield was partially caused by a lower than expected lint percentage. Significant variability in lint yield was detected among the four sets. The family with highest yield was only 5.3% less than expected and also had above average T1 (T1 = 217). These results suggest moderate success in developing desirable combinations of yield and T1 by the backcross procedure.
Correlation of Field Emergence Rate and Seed Vigor Criteria in Barley Cultivars1
Authors: Ching T. M. , Hedtke Saundra , Boulger Mary C. , Kronstad Warren E.
Published: July 2010

Thirteen seed vigor parameters were compared in two 2‐row and four 6‐row barley (Hordeum vulgare L.) cultivars to determine selection criteria for predicting rate of field emergence. The materials also represented four spring and two winter types. Seed weight, 3‐day seedling adenosine triphosphate (ATP) content, 3‐day seedling total adenosine phosphates (TAP), 5‐day endosperm α‐amylase activity, 3‐day endosperm c~‐amylase activity, 4‐hour hydrated embryo TAP, 4‐day hydrated embryo ATP content, 7‐day seedling dry weight, 3‐day seedling dry weight, and 3‐day seedling shoot length were all significantly correlated (P≤0.01) with field emergence rate but in decreasing order, respectively. Based on the results of stepwise multiple regression analysis, it appeared that seed weight, 3‐day seedling ATP content, TAP content of hydrated embryo, and 7‐day seedling dry weight would be good seed vigor indices for predicting field emergence rate.
Field Studies of Boll Weevil Resistant Cotton Lines Possesing the Okra Leaf‐Frego Bract Characters1
Authors: Pieters Edward P. , Bird L. S.
Published: July 2010

Cotton lines (Gossypium hirsutum L.) possessing the okra leaf (L°L°) — frego bract (fg fg) characters were evaluated in a 3‐year field study in the Coastal Bend area of Texas. Two locations were used in 1974 and 1975 and one location in 1976. The number of squares (flower buds) with boll weevil (Anthonomus grandis Boheman) ovipositional punctures was recorded on a total of forty cotton lines.

Cotton lines possessing the okra leaf‐frego bract characters averaged about 60% fewer boll weevil ovipositional punctured squares than the broad leaf — normal bract cottons.
Relations between CO2 Exchange Rate, CO2 Compensation, and Mesophyll Resistance from a Simple Field Method1
Authors: Cary J. W.
Published: July 2010

An equation is developed that relates apparent photosynthesis to CO2 light compensation values, resistance to CO2 light compensation values, resistance to CO2 diffusion in air, and the apparent mesophyll resistance to CO2 transport. the equation also yields values for total photosynthesis and light respiration from measurements of apparaent photosynthesis. A simple method for measuring leaf CO2 exchange rates in the field with a hand‐operated syringe is described. Results obtained with this device and data published in recent literature are used with the new equation to show that photosynthesis be limited more by mesophyll resistance than by photorespiration.
Heritability of Flowering in Sugarcane1
Authors: Lyrene P. M.
Published: July 2010

The heritability of flowering was studied in sugarcane (Saccharum spp. L.) by observing the percentage of stools that flowered in 10 vegetatively propagated commercial clones, in 25 F1 populations obtained by crossing five of the clones as females with the other five used as males, and in S1 populations from the five paternal parents. All plants were field grown as spaced stools in a randomized block experiment with six replications. Populations within blocks were represented by 17 spaced stools each. Flowering frequency among parental clones ranged from 3.2% of all stools of CP 63‐588 and CP 70‐300 to 96.9% of all stools of CP 52‐68. Overall, 49% of all parental stools, 35% of all F1 seedlings, and 17% of all S1 seedlings flowered. Estimates of heritability obtained from F1‐ midparent regression were 54 to 60%. General combining ability was more important than specific combining ability in explaining the variance among F1 populations; the variance component for general combining ability was 4.4 times larger than that for specific combining ability.
Recurrent Selection for High Seed Weight in Cicer Milkvetch1
Authors: Townsend C. E.
Published: July 2010

Effectiveness of recurrent selection for high seed weight was determined in diallel cross and polycross populations of cieer milkvetch, Astragalus cicer L. To help prevent loss of vigor, selection was practiced for high vigor as well as high seed weight. In selecting parents of the second cycle from each population, selection pressure in one subpopulation was intense for mature‐plant vigor but was relaxed somewhat for seed weight. In the other subpopulation, selection pressures were reversed for the two characters.

In the first cycle of selection, mean seed weight of the diallel and polycross populations was 3.99 and 3.97 g/1,000 seeds, respectively. This represented an increase in seed weight of about 13% over the original population (3.51 g/1,000 seeds).

Two cycles of selection increased seed weight substautially. Mean seed weight of the four subpopulations ranged from 4.30 to 4.73 g/l,000 seeds, which represented increases of 22.5 to 34.8% over the original population. The percentage of increase in seed weight in cycle 2 over cycle 1 was greater for subpopulations in which selection pressure was higher for seed weight and lower for plant vigor. Vigor of some progenies in all subpopulations was high. A comparison of within‐plot variances for the subpopulations and clones indicated that genetic variance was still present after two cycles of selection. However, variance in the diallel snbpopulations was being depleted more rapidly than in the polycross subpopulations. This was attributed to the lower number of parents in the source population for the diallel group.
Intergenotypic Competition Between Rows and Within Blends of Soybeans1
Authors: Gedge D. L. , Fehr W. R. , Walker A. K.
Published: July 2010

Intergenotypic competition among soybean (Glycine max (L.) Merrill) cultivars was evaluated in competing row plots and in two‐component blends. The objectives were to determine the importance of intergenotypic competition on soybean performance in unbordered plots and to evaluate the use of estimates of interplot competition for predicting intergenotypic competition in blends. Five soybean cultivars, ‘Chippewa 64’, ‘Hark’, ‘Corsoy’, ‘Provar’, and ‘Amsoy’, were grown in three‐row plots with 25, 50, 75, and 100 cm between rows. The center row was the test cultivar, and the border rows were either the cultivar itself (pure stand) or one of the four other cultivars. All possible pairs of the five cultivars were tested in a northern and a central Iowa location for 2 years. The average change in yield caused by intergenotypic competition increased from 2.6% in 100‐cm rows to 17.6% in 25‐cm rows. Significant yield changes occurred at all row spacings, particularly when Amsoy was either the test cultivar or the competing cultivar. Maturity, height, and lodging were not significantly affected by competition at any row spacing. Soybean yield tests with cultivars and growing conditions similar to Iowa should use bordered plots if no bias from intergenotypic competition can be tolerated.

The soybean cultivars were grown in two‐component blends at the ratios 3:1, 1:1, and 1:3. The blends contained cultivars with different pubescence color so they could be harvested separately. The blends and pure stands of each cultivar were grown in bordered plots spaced 68 cm apart. The blend test was grown adjacent to the interplot competition test in all environments. Intergenotypic competition in blends was most closely predicted by competition between 25‐cm rows, but the relative competitive ability of cultivars in blends was not always the same as their relative competitive ability in adjacent rows.
Interspecific Hybrids Between Carthamus tinetorius and C. alexandrinus1
Authors: Estilai A.
Published: July 2010

Cultivated safflower C. tinctorius L. with n=12 was crossed to C. alexandrinus (Boiss. and Heldq;.) Ascher. with m=10, using both as male and female. Two F1 hybrids were obtained when C. tinctorius was the male parent. Analyses of the parents and their hybrids included studies of microsporocytes, pollen stainability, seed‐set, and pollen and corolla color. Meiosis was irregular in the hybrids, giving an average of 5.24 bivalents and 11.58 univalents at MI. At TII from one to six micronuclei were present, which may cause sterility of the hybrids. Low pollen stainability, lack of seed production, and poor chromosome pairing of the hybrids indicated that these two species are distantly related. Backcrossing of the sterile F1 plants to the cultivated safflower failed, precluding examination of the feasibility of obtaining cytoplasmic male sterility in this crop by interspecific hybridization of these two species, followed by backcrossing.
F1 Evaluation of Yield Potential in Hexaploid Triticale1
Authors: Salmon D.F. , Larter E.N. , Gustafson J.P.
Published: July 2010

Eight hexaploid triticale (X Triticosecale Wittmack) F1 populations were evaluated on the basis of yield in 1972 and 1973 at Winnipeg, Manitoba. In each year, one low‐, two intermediate‐, and one high‐yielding F1 populations were retained for F3 evaluation in an early‐generation yield trial. Comparisons were made of F1 and F3 yield rankings, also the number of high‐yielding F3 families produced by each F1 population. The results indicated that evaluation of crosses on the basis of F1 single plant yield was ineffective for the selection of crosses with a high yield potential in subsequent generations.
Effect of DPX 3778 on Anther Dehiscence in Pearl Millet1
Authors: Hanna Wayne W.
Published: July 2010

DPX 3778 [3‐(p‐chlorophenyl)‐6‐methoxy‐s‐triazine‐2, 4‐(1H, 3H)‐dione‐triethanolamine] was tested on pearl millet (Pennisetum americanum (L.) Leeke) to investigate its potential for preventing anther dehiscence. DPX 3778 prevented both anther exsertion and dehiscence in pearl millet. Pollen remained stainable and plump. Growth stage of the plant when the chemical was applied was very important. A 7.43 kg/ha application at the mid to late boot stage on inbreds ‘Tift 23DB’, ‘Tift 239DB2’, ‘Tift 13’, and ‘Tift 18DB’, followed by a second application at the same rate 5 to 6 days later, reduced selfed seed set to 2, 13, 5, and 30%, respectively. No female sterility or reduction in test weight of seed due to the chemical was observed. Application when plants were in the vegetative stage resulted in yellowing and loss of effectiveness at anthesis. A genotype response was observed among the four inbreds tested. DPX 3778 can be used effectively to produce hybrids in pearl millet.
Performance of Rice Composites Dimorphic for Plant Height and for Pubescence1
Authors: Dat Tran Van , Peterson M. L. , Rutger J. N.
Published: July 2010

The effects on yield of two contrasting rice (Oryza sativa L.) plant characteristics (tall vs. short, pubescent vs. glabrous) were studied. These plant types were developed from a cross between a pubescent short cultivar and a glabrous tall one with related parentage. Four plant types, glabrous short, glabrous tall, pubescent short, and pubescent tall, were selected in the F2 and increased in panicle rows in the F3. These panicle rows were composited and evaluated in broadcast plots in the F4.

The two short types produced grain yields about 10% greater than the two tall types at optimum N fertility levels. Differences were attributed to a combination of factors including greatly reduced lodging of short types, production of significantly more panicles per unit area, more grains per panicle, and a higher percentage of fertile florets (filled grains). The 100‐grain weight was similar for short and tall types.

The pubescent and glabrous leaf and hull characteristics did not affect grain yields significantly but number of grains per panicle and percent of sterile florets were significantly less in the pubescent than in the glabrous types. The four plant types were evaluated at six N fertility levels applied as urea. Rates of application were from 33.5 to 201 kg/ha with 33.5 kg increments. Optimum yields were obtained at 167.5 kg/ha. A progressive increase, in internode length occurred with N rate increments. The lower internodes (fourth and fifth from the top) elongated relatively more than upper ones with increased nitrogen fertilizer applications. Internodes of tall types elongated more than short types with increased N rates.
Comparison of Selection Efficiency for Grain Yield in Two Population Densities of Four Spring Wheat Crosses1
Authors: Nass H. G.
Published: July 2010

Selection efficiency for high‐yielding lines in four F2 populations of spring wheat (Triticum aestivum L.) was compared at two population densities based on plant head weight. The mean yield of F4 lines selected on the basis of high head weight as F2 plants was greater than that of lines with low head weight, with significant differences at the 5% level in a combined 2‐year analysis. The mean yields of lines selected at high population densities were greater than those of lines selected at low population densities, irrespective of plant head weight in the F2. Almost twice as many lines yielding in the top 15% in F4 were selected in F2 at high population densities than at low population densities. A considerably smaller number of high‐yielding lines were from the lowyielding category in F2. The results suggest that individual plant selection should be practiced at high population densities if the selected lines are to be subsequently evaluated at high population densities comparable to commercial seeding rates.
Minimum Sample Size for Estimating Progeny Mean and Variance1
Authors: Wu Kuo Kao , Heinz Don J. , Meyer Hans K. , Ladd Sheldon L.
Published: July 2010

Minimum sample size is defined as the minimum number of individuals necessary to estimate, with reasonable precision, mean and variance of a trait in a population.

Repeated random samples for various sample sizes were taken for each of four yield components in five sugarcane (Saccharum sp.) hybrid populations grown in two contrasting environments over 2 years in three selection stages. Means and variances of the samples were compared with those of the populations. Forty individuals from a population were found to be the minimum sample size required to estimate mean and variance for refractometer solids, stalk number, stalk diameter, or stalk length.
Competition Between Two Genotypes of Lima Bean With Morphologically Different Leaf Types1
Authors: Williams W. A. , Tucker C. I. , Guerrero F. P.
Published: July 2010

The canopy structure of lima bean (Phaseolus lunatus L.) was manipulated with the goal of increasing seed yield. Structure was varied by using two leaf types, willow‐leaflet and normal, in a replacement series (monocultures and mixtures with different proportions of the plant types) and at different total population densities in two field experiments. Yield was not improved by any of the mixtures. Mathematically calculated competition coefficients showed that they competed for the same resources and that the normal type dominated, with its dominance increasing with increasing population density. Leaf area profiles showed that these responses were associated with the preponderance of normal type leaves in the top strata of the canopy, leading to the conclusion that competition was primarily for light. Willow‐leaflet seems to be a character that is detrimental to yield both in mixture with normal and in monoculture.
Variability of Response to Low Levels of Inbreeding in a Population of Maize1
Authors: Burton J. W. , Stuber C. W. , Moll R. H.
Published: July 2010

Variability of inbreeding response was studied in four sets of eight inbred lines chosen at random from the maize (Zea mays L.) cultivar, ‘Indian Chief’. The eight lines in a set were mated in balanced pedigrees to generate groups of material having expected inbreeding coefficients of 0, 2/16, 3/16, 4/16, and 5/16. (The pedigrees were balanced with respect to the relative contribution of each line). In each pedigree, 20 samples were taken from the generation in which genotypes began segregating, so that 20 subpopulationsw ered erived for each level of inbreeding within each set. This material was evaluated in four environments with respect to grain yield, ear number,and ear height.

All four sets showed significant inbreeding depression in yield. None of the sets showed significant inbreeding depression in ear number, and only two sets showed significant depression in ear height. Inbreeding depression, when significant, was linearly rdated to the increase in F. Quadratic effects were not significant. The linear rate of inbreeding depression in yield was similar in all sets and averaged −0.36 q/ha per 1% increase in F. In all sets, there was much variability in response to inbreeding among the 20 subpopulations of a particular pedigree. The ranges of the 20 subpopulation means about each pedigree varied between 15 and 63% of the pedigree mean. Similar results were obtained with ear number and ear height. The variability was thought to be due to differences in genetic potential for inbreeding depression among the original genotypes sampled and genetic sampling error with inbreeding.
Relationships Among CO2‐exchange Rate and Plant Traits in Iowa Stiff Stalk S1ynthetic Maize Population1
Authors: Crosbie T. M. , Pearce R. B. , Mock J. J.
Published: July 2010

We measured CO2‐exchange rates (CER), morphological traits, and yield traits of 64 maize (Zea mays L.) inbred lines randomly derived from Iowa Stiff Stalk Synthetic (BSSS). Our experiments were grown for 2 years at one location. Genotypic correlations among these traits were calculated to determine if selection for high CER would cause correlated responses in other traits. We also studied possible physiological limitations to grain and dry matter yield of these inbreds.

Genotypic correlations between CER and plant traits were low, suggesting that one could develop high CER genotypes displaying various morphological traits. Nonsignificant correlations between CER and yield traits indicated CER was not the primary factor limiting yield of these inbreds. Correlations showed that dry matter yield was limited by amount of leaf area and by traits associated with efficient use of light energy. We concluded grain yield of these inbred lines was limited by sink size and by lack of a receptive sink because: 1) grain yield was highly correlated with ear length, ear diameter, 300‐kernel weight, and number of ears per plant and 2) potential dry‐matter production during grain filling was 208 g plant ‐1 compared with 49.6 g plant‐1 actually stored in the grain.
A Difference in N Use Efficiency in C3 and C4 Plants and its Implications in Adaptation and Evolution1
Authors: Brown R. H.
Published: July 2010

Plant species that fix CO2 by the C4 cycle have higher rates of CO2 uptake than species using the C3 photosynthetic carbon reduction cycle. Greater CO2 fixation capacity has been associated with reduced photorespiration, specialized leaf anatomy, and biochemical pathways that differ in C3 and C4 plants. The higher photosynthesis rate of C4 species also results in more dry matter production per unit of water transpired. This paper reviews published reports of productivity and N content of some C4 and C3 species. It hypothesizes that C4 plants have a greater N use efficiency (biomass production per unit of N in the plant) than do C3 plants. This difference presumably results from the relatively smaller investment of N in the photosynthetic carboxylation enzymes of C4 plants than of C3 plants. Some adaptive and evolutionary implications of such a hypothesis as well as limitations of supporting data are discussed.
Nitrogen and Dry Matter Accumulation by Kernels Formed at Specific Florets in Spikelets of Spring Wheat1
Authors: Simmons Steve R. , Moss Dale N.
Published: July 2010

Kernels formed at specific florets in central spikelets of the spring wheat (Triticum aestivum L.) cultivars ‘Era’ and ‘Kitt’ were compared in 1975 for N percentage, N content (mg), and dry weight (mg) per kernel. There was a lower N percentage in the third and fourth kernels of Era (numbered from the base of the spikelet) than in the first two. The third and fourth kernels of Kitt did not show this lower N percentage, however. In both genotypes the fourth kernel was noticeably smaller and contained much less N than any of the first three. When a fifth kernel was present, as with the genotype designated ‘8037’, that kernel, in turn, was substantially smaller and contained less N than the fourth. In 1976 kernel number per spike was systematically reduced in two ways for the genotypes Era and 8037, resulting in increased assimilate supply to the remaining kernels. Nitrogen percentage, N content, and dry weight of the remaining kernels from altered spikes were substantially greater than in corresponding kernels of intact spikes. The fourth and fifth kernels from the base of a spikelet in the altered spikes, however, were still much smaller and contained less N than the first three. Examination of the vascular connections in the rachilla for Era and 8037 revealed that the fourth and fifth kernels in a spikelet were served by much smaller diameter vascular bundles than the first three. In addition, all bundles that served the fourth and fifth kernels were ultimately connected to bundles that also served one or more of the first three. In contrast, some of the bundles that served each of the first three were independently linked to the rachis. Our results suggest that kernels formed in the fourth and more distal florets of central spikelets may be limited in their capacity to accumulate assimilate compared with the first three. This maybe a result of their position relative to the rachis and, possibly, dif. ferences in their growth potential.
Inheritance of Three Genes for Plant Color in American Pima Cotton1
Authors: Turcotte E. L. , Feaster Cral V.
Published: July 2010

Three new plant color mutants were found in American Pima cotton (Gossypium barbadense L.). These monogenicr ecessive mutantsw ere not alleles of 12 previously identified plant color mutants in Gossypium. In the field, two of these emerged with green cotyledons. The first six to eight true leaves were yellowishwhite to white, and subsequent leaves were progressively greener until midseason when the new leaves were practically a normal green. Greenhouse‐grown plants of these mutants were a normal green color over their lifespan, suggesting that the expression of the mutant color depended on cool temperatures such as that occurring in the field in April and May. We propose that these two mutantsb e nameda albivirescent‐1 and albivirescent‐2 and be given the gene symbols av1 and av2 The foliage of the third new Pima plant color mutant was light green throughout the life of the plant in the field or greenhouse, indicating that the expression of the gene was not affected by temperature. We propose that this mutant be named light green with the gene symbol ltg.
Use of 4‐Amino‐3,5,6‐trichloropicolinic Acid as an Auxin Source in Plant Tissue Cultures1
Authors: Colins G. B. , Vian W. E. , Phillips G. C.
Published: July 2010

The auxin‐like properties of 4‐amino‐3,5,6‐trichloropicolinic acid (picloram) were compared with those of other auxins in tissue cultures of wheat (Triticum aestivum), soybeans (Glycine max), tobacco (Nicotiana tabacum), and jackbean (Canavalia ensiformis) explants. Certain problems associated with the use of 2,4‐dichlorophenoxyacetic acid (2,4‐D) in tissue culture were not encountered when picloram was substituted for 2,4‐D in the culture medium of 2,4‐D‐requiring plant materials. Picloram performed as well or better than the auxins to which it was compared when used in plant tissue cultures. In general, picloram was more effective at low concentrations than the other auxins. The data indicate potential uses of picloram in routine callus cultures, in regeneration of plants from calli, and in research concerning the physiological development of plant tissues.
Soybean Pod Removal Alters Leaf Diffusion Resistance and Leaflet Orientation1
Authors: Koller H. R. , Thorne J. H.
Published: July 2010

Earlier work indicated that pod removal from soybean [Glycine max (L.) Merr.] led to increased stomatal dif. fusion resistance (r8) and reorientation of leaflets. In the present experiments, when rapidly growing pods were removed from growth chamber‐grown plants, diffusion porometer measurements showed that r8 of the upper leaf surface doubled within 24 hours and plateaued at 48 hours at approximately four times the normal r8. Stomatal diffusion resistance of the lower leaf surface increased by a smaller amount. The extent of stomatal closure on both leaf surfaces was generally proportional to the number of pods removed. The stomatal response was similar when pods were removed from the stem above or below the test leaf. The stomatal response occurred in a leaf even though the pods at that particular node remained on the plant. In the field, depoddinlged to slightly greater increases in r8 than in the growth chamber. In the growth chamber, leaflets of depodded plants rotated on their main axes to attain a near vertical orientation. Field‐grown plants did not exhibit a discernible leaflet reorientation following pod removal.
Selection Indices in Sugarcane1
Authors: Miller J. D. , James N. I. , Lyrene P. M.
Published: July 2010

Selection indices were constructed for four populations of sugarcane (Sacchanim sp.) and for combined data from the four populations. The average selection indices from the combined data were applied to a test population. When selection for metric tons per ha of cane (THC) was based on stalk length, stalk diameter, and stalk number, expected genetic advance was 89.0% of that obtained when selection was based on THC itself. When selection was for metric tons per ha of sucrose (THS), inclusion of Brix in the index along with the above traits gave 92.1% of the expected genetic advance obtained for selection based on THS itself.
Sorghum Stover Digestibility as Affected by Juiciness1
Authors: Schertz K. F. , Viera J. A. , Johnson J. W.
Published: July 2010

Most sorghum, Sorghum bicolor (L.) Moench, hybrids used for silage are juicy genetic types and, thus, are high in moisture. Contrasting dry types are available, and their merit as silage relative to juicy types needs to be ascertained. Genotypes with high and low moisture levels controlled by a single gene difference were compared to determine if their stover differed in digestibility when measured by in vitro dry matter disappearance (IVDMD). Dry matter content and IVDMD were determined for isogenic dry vs. juicy lines and hybrids produced by those lines. Samples of stover were taken at anthesis and at grain maturity and digested in vitro. Significant differences existed for stover dry matter content (62.1 to 79.8%) at both stages of development and for IVDMD at anthesis (57.7 to 63.2%). Isogenic pairs rarely differed significantly in IVDMD, indicating little, if any, advantage for juicy sorghum genotypes in this study.
Determining 1,000‐Seed Weight in Grain Sorghum1
Authors: Ross W. M. , Kofoid K. D.
Published: July 2010

Our objective was to determine the smallest seed sample size necessary to compute 1,000‐seed weight in grain sorghum, S. bicolor (L.) Moench. Samples of 125, 250, 500, and 1,000 seeds were analyzed from three different tests for 2 years at Mead, Nebr., 1974–75. There were 8, 12, and 24 genotypes in the three tests. Significant sample size differences were found in two tests, but they were small and of no practical importance. Genotype differences were significant in only one test. No significant genotype ✕ sample size interaction or significant genotype ✕ sample size ✕ year interaction was found. We concluded that 125‐seed samples generally would be adequate.
Evaluation of Grain Sorghum R Lines with a Single‐Cross vs. Inbred Line Testers1
Authors: Ross W. M. , Kofoid K. D.
Published: July 2010

Forty‐two Sorghum bicolor (L.) Moench ‘Martin’‐‘Wheatland’ three‐way crosses and their related single crosses were grown at Mead, Nebr. in 1975 and 1976 to identify superior fertility restoring (R) lines, evaluate the three female testers, and detect possible epistatic effects. The means of the three sets of hybrids differed significantly for date of bloom, plant height, but not grain yield. The mean performance of three‐way crosses was not different from expectations based on the means of single crosses. Two three‐way crosses for date of bloom, one for plant height, and one for yield deviated significantly from expectations, which may have been due to chance. The experiment did not indicate that epistasis was important in the lines tested. Selection of the best 21 males based on three‐way cross yields included 15 of the best 21 Martin hybrids and 15 of the best 21 Wheatland hybrids. The sterile F1 tester had greater seed production than the line testers.
Effect of Pod Removal on Abscisic Acid Levels in Soybean Tissue1
Authors: Ciha A. J. , Brenner M. L. , Brun W. A.
Published: July 2010

The seasonal profiles of free and conjugated abscisic acid (ABA) in seed, pod wall, and leaf tissue were determined using field‐grown control and depodded ‘Clay’ soybean (Glycine max (L.) Merr.) plants. Total seed ABA was initially high (13.0 /µg/g fresh weight) but decreased to 0.4 µg/g at maturity. The pod wall contained much less ABA than did seeds (ca. 0.5 µg/g). Pod wall ABA level was constant during development except for a twofold increase during final pod maturation. Leaves also contained much less ABA (< 1 µg/g) than did seeds. Upper canopy leaves contained more ABA than did lower canopy leaves. Depodding had no consistent effect on leaf ABA levels. Water stress caused an increase in ABA content in leaf tissue with no effect on pod wall tissue, while senescence increased ABA content hi pod walls with little effect on leaf tissue.
Reproductive Advantage Associated with Resistance to Soybean‐Cyst Nematode1
Authors: Luedders V. D. , Duclos L. A.
Published: July 2010

Cultivars of soybeans [Glycine max (L.) Merr.] resistant (R) and susceptible (S) to the soybean‐cyst nematode (Heterodera glycines Ichinohe) were grown separately and together on plots heavily infested with the nematodes and on noninfested plots. Two‐cultivar (R and S) mixtures in three maturity groups were grown at three densities for 3 years; each cultivar was also grown in pure stand. The mixtures of equal numbers of R and S seeds were made each year. The reproductive advantage of the R cultivar (i.e., the ratio between yield of R cultivar and yield of S cultivar) was always higher in the mixtures than in the pure stands and higher on infested than on noninfested soil. Since the selective advantage of the R cultivars was higher on soybean‐cyst nematode infested land, growing segregating populations for several generations on heavily infested land should increase the frequency of R plants. In such populations, segregation would also increase the frequency of R plants when some genes conditioning resistance were recessive, as in race 3 resistance.
Inheritance of the Associated Kernel Characters, High Lysine and Shrunken Endosperm, of the Barley Mutant Bomi, Risø 15081
Authors: Ullrich S. E. , Eslick R. F.
Published: July 2010

The shrunken endosperm trait of the induced high lysine mutant Risø 1508 of the cultivar ‘Bomi’ barley (Hordeum vulgate L.) was found to be inherited as a simple recessive gene that expresses xenia, and hence was designated sex3c. The gene was tentatively assigned to chromosome 7 by primary trisomic analysis. Linkage with the male‐sterile gene, msg19, and the short rachilla hair gene, s, indicates that sex3c is located near the centromere in the short arm of chromosome 7. The high lysine trait of Risø 1508 was closely associated with the shrunken endosperm trait with close linkage of two genes or pleiotropy as possible explanations for the association.
Heritability and Correlations of IVOMD, Maturity, and Plant Height in Rhodes Grass1
Authors: Quesenberry K. H. , Sleper D. A. , Cornell J. A.
Published: July 2010

Little information is available on variability and heritability of forage quality and digestibility in Rhodes grass (Chloris gayana Kunth). In this study, variability and heritability of in vitro organic matter digestibility (IVOMD) at 2 and 6 weeks of regrowth of 82 randomly selected plant introductions of Rhodes grass were examined in two growing seasons. The genotypic source of variance for 2 and 6 week regrowth digestibility was significant for both years. Mean IVOMD for 2 and 6‐week regrowth over both years was 72 and 57%, respectively. Although years were a significant source of variation for IVOMD, entries that ranked high for 6‐week IVOMD in year 1 were also consistently high in year 2. Simple correlation coefficients between 2‐ and 6‐week IVOMD in year 1 (r = 0.13) and year 2 (r = 0.35) although statistically significant (P < 0.01), were rather low. However, when the data were combined over years the correlation between 2‐week and 6‐week IVOMD was r = 0.58. In addition the genetic correlation between 2‐ and 6‐week IVOMD from analysis of covariance of both years data was rg = 0.75 indicating that certain genes influenced both 2‐ and 6‐week IVOMD. Broad sense heritability estimates of 2‐ and 6‐week IVOMD over both years were 13.7 and 42.5% respectively.

Significant variability was also found for maturity and plant height in both years. A highly significant positive correlation was found between maturity and plant height in year 1 (r = 0.76) and year 2 (r = 0.71). Heritability estimates for maturity and plant height derived from data averaged over both years were 74.3 and 66.3%, respectively. There was also a highly significant positive correlation (r = 0.71) between 6‐week regrowth digestibility and maturity.

Our results indicate that sufficient variability exists in this random sample of unselected Rhodes grass plant introductions to make selection for improved IVOMD feasible. Broad sense heritability estimates for IVOMD, maturity, and plant height were sufficiently high to suggest that relatively rapid initial progress could be made in selecting for these traits. The high positive correlation between 6‐week IVOMD and maturity suggests that selection for late maturing genotypes with high IVOMD should be possible.
Inheritance of Resistance to the Adult Pea Leaf Weevil in Austrian Winter Peas1
Authors: Nouri‐Ghanbalani G. , Auld D. L. , O'Keefe L. E. , Campbell A. R.
Published: July 2010

In recent years the pea leaf weevil (Sitona lineatus L.) has severely damaged the dry pea (Pisum sativum L.) crop in the Pacific Northwest. The defoliation of pea seedlings in the early spring by the adult pea leaf weevil results in severe stand depletion and reduced seed yield. The inheritance of resistance to the pea leaf weevil in Austrian winter peas [Pisum sativum subsp, arvense (L.) Poir] was studied by crossing in a non‐reciprocal diallel manner, eight genotypes that exhibited different levels of pea leaf weevil resistance. Parental and F2 seedlings were exposed to an average of 7.8 adult pea leaf weevils/seedling in the greenhouse and were rated for foliar damage and terminal leaflet injury. Twenty‐five selected F2 plants were progeny tested as F3 families. Data from parental lines and F2 populations were analyzed together and means separated by least significant differences. Diallel analyses indicate that differences in the pea leaf weevil resistance were due to specific combining ability. Very low estimated narrow sense heritabillties of —2.6 and —5.6% were estimated for foliar damage and terminal leaflet injury, respectively. This indicates that pea leaf weevil resistance could probably not be improved by selection within the populations that we studied. The F3 progeny test showed that selection was not successful in increasing the level of insect resistance.
Crytology and Morphology of a Tetraploid Sorghum Population Recovered from a Saccharum ✕ Sorghum Hybrid1
Authors: Gupta S. C. , Harlam J. R. , de Wet J. M. J.
Published: July 2010

Sugarcane (Saccharum sp.) with 2n = ca. 112 chromosomes was crossed with diploid (2n = 20) sorghum (Sorghum bicolor (L.) Moench), and their hybrids were backcrossed twice with diploid and twice with tetraploid (2n = 40) sorghum. The BC4 individuals, so obtained, were selfed twice to produce a recovered tetraploid sorghum population (BC4F3). Fifty‐one BC4F3 individuals, sugarcane and the sorghum parents, were studied cytologically and morphologically. Irregular cytological behavior of recovered sorghum plants, characterized by an increase in bivalent formation and decrease in tetravalent formation at diakinesis (in comparison to their tetraploid ‘Rio’ sorghum parent) indicated that the sorghum chromosomes may be contaminated with sugarcane genetic material. Morphological data were analyzed by cluster analysis, principal component analysis, univariate analysis of variance, F‐test, and t‐test to study the variability in the hybrid populations and to test the significance of morphological differences among groups. Modified recovered tetraploid sorghums had various combinations of Saccharum characteristics superimposed on a basic Sorghum morphology. Sixteen of 26 plant characters studied were influenced by sugarcane genetic material to varying degrees and frequencies. The presence of these sugarcane characters in recovered sorghums indicated intergenomic genetic exchange.
Microscopic Observations on Cuticle from Trichomeless. tr, and Normal, Tr, Pearl Millet1
Authors: Hanna Wayne W. , Akin Danny E.
Published: July 2010

Leaves of trichomed (Tr) and trichomeless (tr) pearl millet were studied with both electron and light micm scopy to determine morphological differences that may account for the differences in transpiration rate, pest resistance, and penetration of rumen microbes through the leaf surface between the two lines. Slight differences were observed in cuticle thickness. Encrustation of epidermal cell walls in tr cuticle indicate chemical differences between tr and Tr cuticle. The cuticle of Tr plants had 3X and 1.3X as many cracks of the adaxial and abaxial leaf surfaces, respectifely, as that of tr plants. This helps to explain why tr leaves transpire less water than Tr leaves and why there is more penetration of rumen microbes through the surface of Tr leaves as compared to tr leaves.