Percentage Of Ova Research Articles

Factors affecting intrafruit pattern of ovule abortion and seed production in Hormathophylla spinosa (Cruciferae)

We investigated the pattern of intrafruit seed production in Hormathophylla spinosa (Cruciferae) over a 7-yr period. H. spinosa fruit have two chambers, each chamber containing two ovules, and usually situate perpendicular to the infructescence axis with one chamber above the other. The percentage of ovules ripening to seeds is usually lower than 50%. In addition, we found a consistent position-dependence in seed ripening probability, since more than 90% of the ripe seeds are arranged in the lower chamber of the fruit. This pattern of seed production is not produced by the direct or indirect effect of seed predators, by pollen limitation or by nonrandom fertilizations. By contrast, fruit removal experiments showed that sibling rivalry can partially explain the seed production pattern, be the cause of the reduction in the seed number from the uppermost threshold of 50%. Moreover, experimental manipulations of fruit orientation suggest that the position-dependence in seed production is the cause but not the effect of seed ripening. We presume that some architectural effect is producing a significant increase in the ripening probability of the ovules arranged in the lower chamber, causing thus the observed pattern in the intrafruit seed production in H. spinosa and severely constraining the maximum number of seeds per fruit to two.

Pollen tube growth and early ovule development following self- and cross-pollination in Eucalyptus nitens

Controlled self- and cross-pollinations were conducted on flowers of five mature Eucalyptus nitens trees. Levels of self-sterility of the trees ranged from 25.8 to 93.6%. Pollen tube numbers in styles and ovule penetration by pollen tubes was investigated 2 weeks after pollination by fluorescence microscopy. There were no significant differences between treatments in the number of pollen tubes present in styles or in the percentage of ovules penetrated by pollen tubes. Embryology of material harvested 2 and 4 weeks after pollination was investigated by bright-field microscopy. Fertilisation had taken place by 2 weeks after pollination with nearly every ovule showing evidence of fertilisation. Cross-pollination resulted in a greater proportion of healthy, developing ovules, at both 2 and 4 weeks after pollination, compared with self-pollination. The proportion of degenerating ovules increased from 2 to 4 weeks after pollination. The reduced ability of E. nitens to set self-pollinated seed compared with cross-pollinated seed appears to be controlled by a post-zygotic mechanism. Differences in ovule size may potentially assist in the identification of trees incapable of setting self-pollinated seed.

Synchronisation of oestrus in dairy cows using prostaglandin F 2α, gonadotrophin-releasing hormone, and oestradiol cypionate

An oestrous synchronisation protocol was developed for use in lactating dairy cows using PGF 2α, GnRH, and oestradiol cypionate (ECP). In experiment 1, lactating dairy cows received two injections of PGF 2α (on days 0 and 11) (PP; n=10) or two injections of PGF 2α (days 0 and 11) and 100 μg of GnRH on day 3 (PGP; n=10). In experiment 2, cows were treated with PGP ( n=7), or PGP and 1 mg of ECP at the same time (PGPE 0; n=7) or 1 day after the second PGF 2α injection (PGPE 1; n=7). In experiment 3, 101 lactating dairy cows in a commercial herd were assigned to one of three treatments; PP, PGP, or PGPE 1. Follicular growth was measured by ultrasound in experiments 1 and 2. Every cow (experiments 1, 2, and 3) was blood sampled at selected intervals for progesterone and oestradiol assays and inseminated at oestrus. In experiment 1, a higher percentage of GnRH-treated cows ovulated after the first PGF 2α injection (90% versus 50%; P<0.05). The GnRH-treated cows tended to have a larger dominant follicle present at the time of the second PGF 2α injection (16.5±0.5 mm versus 15.0±0.7 mm; P<0.10). The percentage of cows that ovulated after the second PGF 2α injection was similar (60%). In experiment 2, cows treated with ECP had higher peak preovulatory concentrations of oestradiol in plasma (6.99±0.63 versus 3.63±0.63; P<0.01) following the second PGF 2α injection and a higher percentage ovulated (86% versus 43%; P<0.05). A higher percentage of PGPE 1-treated cows in experiment 3 were observed in standing oestrus and ovulated after the second PGF 2α injection (standing oestrus, 26.4, 34.3, and 62.6%, P<0.01; ovulated, 56, 63, and 78%, P<0.05; PP, PGP, and PGPE 1, respectively). In conclusion, the PGP protocol increased the number of cows that ovulated after the first PGF 2α injection and produced a more mature dominant follicle at the time of the second PGF 2α injection. Adding ECP to PGP (PGPE 1) enhanced the expression of oestrus and increased ovulation percentage. The combination of PGP and ECP is potentially a new method to routinely synchronise oestrus and ovulation in dairy cows.

Rabbit epididymal secretory proteins. II. Immunolocalization and sperm association of REP38.

Polyclonal antibody was used to partially characterize REP38, a major rabbit epididymal secretory protein. Western blot analyses and immunohistochemistry indicated that REP38 is only expressed in regions 5 and 6 of the epididymis (corpus epididy-midis) and is localized in the supranuclear region and microvilli of the principal cells in these regions. It was not expressed in other tissues of the body. In region 8 (cauda epididymidis), REP38 was detected in the luminal border and cytoplasm of scattered principal cells, indicating that it may be reabsorbed in this region. This protein accumulated on the sperm plasma membrane downstream of region 5 and was localized predominantly over the acrosomal and postacrosomal regions of the head and the middle piece. Although tightly bound to epididymal sperm, REP38 migrated to the equatorial segment under conditions in vivo that would promote capacitation. When tested in vitro, anti-REP38 IgG reduced the percentage of ova fertilized in a concentration-dependent manner, apparently by blocking sperm-egg fusion.

Characterization of Apomictic Potential in Guayule (Parthenium argentatum) In Vivo and In Vitro

Guayule (Parthenium argentatum Gray), a latex-producing perennial desert shrub and potential industrial crop for semiarid regions, exhibits reproductive modes ranging from sexual, self-sterile diploids to predominantly apomictic, self-compatible polyploids. The objectives of this study were to develop and evaluate a rapid, simple technique for characterizing apomictic potential (percentage of ovules that produce apomictic embryos) in guayule breeding lines. Initial in vivo experiments were based on an auxin test that permitted quantification of apomictic frequency in grasses. In our trials, floral application of NAA or IBA resulted in embryo production similar to that of open-pollinated controls, but 2,4-D inhibited embryo production. Breeding lines could be separated based on embryo production using an in vivo auxin test; however, accuracy of the results was questionable because 1) pollen release and insect activity within isolation bags prevented distinguishing between sexual and apomictic embryos, and 2) high temperatures and large humidity fluctuations could have affected results. Thus, in vitro flower culture was investigated using liquid medium, because it would provide better control of these factors. Flowers developed normally in vitro, except that pollen was not released from the anthers; therefore, any embryos produced in vitro were considered to be apomictic. Embryo production was similar on both Nitsch and Nitsch and Woody Plant Media. Addition of growth regulators inhibited embryo production. Embryo production was tested on Nitsch and Nitsch medium without growth regulators for seven breeding lines. Based on statistical analyses, four classes of apomictic potential were identified, ranging from none (sexual) to high. Chemical names used: 2,4-dichlorophenoxy acetic acid (2,4-D); indole-3-butyric acid (IBA); α-naphthaleneacetic acid (NAA).

Developmental Failure and Loss of Reproductive Capacity as a Factor in Extinction: A Nine-Year Study of Dedeckera Eurekensis (Polygonaceae)

Many long-lived perennial species exhibit lowered reproductive capacity. Early studies of reproductive success in Dedeckera eurekensis (Polygonaceae) demonstrated that the species exhibited extremely low reproductive success, low seed/ovule (S/O) ratios (i.e., the percentage of ovules that produce filled seeds; 2.5%), low germinability of filled seeds (3.5%), low seedling survivorship (11.1%), and lack of recruitment in natural populations. These results were attributed to genetic load, but this elicited controversy, prompting long-term studies of the relationship between the S/O ratio and environment. After nine years of monitoring, however, the S/O ratio had not changed significantly (2.7%), and there was no significant correlation between precipitation and the S/O ratio. Controlled field experiments demonstrated that neither resource availability nor other ecological factors significantly influenced embryo abortion rates. Controlled self-pollinations (N = 115) matured only one questionably filled seed, whereas intrapopulation cross-pollinations (N = 192) produced significantly more seed (S/O = 12.0 %). Previous pollination studies demonstrated that the species has no primary pollinators and is only rarely visited by a few generalist insects. However, the flowers typically self-pollinate in 2-3 days following anthesis. Strong inference suggests that the loss of reproductive capacity in D. eurekensis may be the result of inbreeding depression due to the superimposition of self-pollination on a normally outcrossed species carrying a high genetic/segregational load.

Embryo Sac Development and Fruit Set of 'Satohnishiki' Sweet Cherry as Affected by Temperature, GA3 and Paclobutrazol.

Effects of temperature and endogenous and exogenous gibberellins (GA) on embryo sac development and fruit set of 'Satohnishiki' sweet cherry were studied. Trees were grown in sunlit growth chambers kept at 15°C and 25°C from one month before anthesis to petal fall. At 25°C, the nucelli and embryo sacs degenerated more rapidly than at 15°C. When flowers were handpollinated with pollens of 'Takasago', fruit set was significantly lower at 25°C than at 15°C. Flowers which developed at 25°C had a higher endogenous gibberellin level than had those at 15°C. When bursting buds were sprayed with 10 and 100 ppm GA3, the percentage of ovules with degenerated embryo sac or nucellus increased considerably by 2 days after anthesis. But an application of paclobutrazol (PBZ) to bursting buds prolonged embryo sac longevity and increased fruit set. These results indicate that the endogenous GA may : 1) regulate the development of the nucellus and embryo sac in sweet cherry flowers, and 2) induce early embryo sac degeneration, which results in the low fruit set during periods of high temperature.

APPLICATION OF FOUR POLLINATION TECHNIQUES AND OF HORMONE TREATMENT FOR BYPASSING INTERSPECIFIC CROSSING BARRIERS IN LILIUM L.

Crosses between genotypes of the 3 commercially important groups of lilies, i.e. Lilium longiflorum Thunb., the Asiatic hybrids and the Oriental hybrids, are hampered by interspecific crossing barriers. Several methods have been developed to bypass pre-fertilization barriers or post-fertilization barriers in lily, e.g. the cut-style method and embryo rescue techniques. Five techniques were studied comparatively for their capacity to bypass barriers between different types of lilies: the grafted-ovary method, placental pollination, warm-water treatment, the mentor pollen technique and hormone treatment. For the grafted-ovary method, a compatible pollinated pistil was grafted one day after pollination on the ovary of another species. It appeared that the pollen tubes were not able to penetrate from one ovary into another ovary. After placental pollination, no embryo germination was found, even not when pre-pollinated styles were placed near the ovules. After a warm-water treatment (6 minutes of 50 C) of pistils, many seeds were harvested of self-pollinated flowers of L. longiflorum. However, interspecific crossing barriers could not be bypassed. The percentage of ovules with pollen tube penetration did not change by mixing pollen with radiated mentor pollen. It appeared that the mentor pollen were able to penetrate the ovules. After treating ovaries with 0.1% BAP, on average 6 embryos per flower of the cross L. longiflorum 'Gelria' x Asiatic hybrid 'Mont Blanc' could be rescued when ovule culture was started around 40 days after pollination.

The effect of medium composition on ovary-slice culture and ovule culture in intraspecific Tulipa gesneriana crosses

The effect of several media components on the germination percentage of ovules in intraspecific T. gesneriana L. crosses was studied by using two embryo rescue techniques, viz. ovary-slice culture followed by ovule culture and direct ovule culture. The addition of 9% sucrose to medium for ovary-slice culture, started at 3 or at 5 weeks after pollination (WAP), significantly improved the germination percentage as compared to 5% sucrose. The germination percentage did not differ between both sucrose concentrations (3% and 5%) used in ovule culture started 4 weeks later with ovules excised from the ovary-slices (at 9 WAP). Similar germination percentages were obtained with media containing the full or half of the concentrations of micronutrients and macronutrients of the MS-medium during ovary-slice culture and ovule culture. For direct ovule culture, started at 4, at 6, and at 8 WAP, the germination percentages did not differ between ovules cultured on media with 3%, 6% or 9% sucrose. The addition of the cytokinin BAP (0.01 or 0.1 mg l-1) had no effect on the germination percentage. The use of liquid-shaken culture resulted in germination percentages which were similar to those on agar-solidified media. Analysis of the carbohydrate concentration of the media revealed that, in both media for ovary-slice culture and for ovule culture, ultimately all sucrose is converted into glucose and fructose. The total concentration of carbohydrates decreased with 19%–48% in the media for ovary-slice culture, whereas the total concentration of carbohydrates did not decrease remarkably in media for ovule culture.

Ovular secretions in the micropylar canal of larches (Larix kaempferi and L. x eurolepis)

In Larix kaempferi (Lamb.) Carr. and L. × eurolepis A. Henry, a secretion fills the micropylar canal of the ovule during a period of archegonial development that ranges from central cell stage until fertilization. Dissection of the ovuliferous scales caused excess fluid to be exuded from the micropylar canal, forming a drop at the tip of the micropyle. This drop was collected, and its production was quantified. Drop volume was recorded, and the percentage of ovules with drops was counted. The maximum volume of 217 nL far exceeded the volume of the micropyle, which ranged between 18 ± 8 and 28 ± 7 nL (mean ± SD). Removal of drops resulted in further drops being secreted. No drops were produced in ovules that had aborted megagametophyte development.Key words: Larix, micropylar secretions, ovule development.

Seedlessness and Parthenocarpy inPistacia veraL. (Anacardiaceae): Temporal Changes in Patterns of Vascular Transport to Ovules

Pistacia vera‘Kerman’ (pistachio nut) typically produces high numbers of seedless or blank fruits. Patterns of vascular transport into fruits and ovules were studied over 3 years by following the movement of disodium fluorescein solution from cut branches into developing fruitlets. Early in the season, vascular conductivity is intact through to the chalazal end of the ovule. Soon afterwards, the percentage of ovules with vascular conductivity through to the chalaza declines, and in a variable fraction of fruits, movement of the fluorochrome solution becomes blocked either at the placenta or in the funiculus. Six to 9 weeks after anthesis there is blockage in 90 (1 year) to 100% (2 years) of fruits. Subsequently, vascular conductivity resumes in 83.3% (3 year mean) of ovules, a percentage that correlates well with the mean percentage of seeded nuts at harvest (77.5%). Ovules from fruits with dysfunctional vascular conduction early in the season are smaller than those with fully functional vascular tissue. At the time conductivity declines, a high percentage of those ovules with blocked vascular movement lack endosperm and appear to be unfertilized; none of the ovules that retain full vascular flow lack endosperm. Pollination using gamma-irradiated pollen (60Co, 1.0 kGy) led to a nearly three-fold increase in the production of blank nuts. The results indicate that fluorescein transport may be a valuable tool to predict the fate of ovules, and are consistent with the hypothesis that parthenocarpic fruit set may be an important factor in blank nut production in pistachio.

Micropylar exudates in Douglas fir - timing and volume of production

In Pseudotsuga menziesii, a secretion fills the micropylar canal about 7 weeks postpollination until fertilization. Micropylar volumes were measured and found to show variation. Dissection of the ovuliferous scales caused excess fluid to be exuded from the micropylar canal, forming a drop at the tip of the micropyle. This drop was collected, and its production quantified in three trees. Volume and percentage of ovules with drops were greatest when the archegonia in the female gametophyte were at central cell and/or egg cell stage. The volume of exuded drops far exceeded that of the micropyle. Production of subsequent drops by the ovules further confirms that the fluid is actively produced upon dissection

Stage-specific inhibition of cotton fiber development by adding α-amanitin to ovule cultures

When cotton (Gossypium hirsutum, DPL 90ne) ovules are removed from the carpel on the day of anthesis and placed on an appropriate medium, fiber cells will differentiatein vitro from the ovule epidermis. Alpha-amanitin, an inhibitor of poly (A)+ RNA synthesis was added to ovule cultures at selected times after culture initiation to determine the timing of events in fiber development. Replicate cultures were initiated from day of anthesis, cotton ovules with α-amanitin being added to media at final concentrations ranging from 0.05μg/ml to 5.0 μg/ml. After 21 d in culture, ovules were evaluated for fiber length, percentage of ovules producing fiber, fiber dry weight, and fiber cellulose content. Cultures treated with α-amanitin on the day of anthesis to 2 d postanthesis were prevented from forming normal numbers of fiber cells. Addition of α-amanitin to cultures between 2 and 10 d postanthesis reduced the length that fiber cells attained in culture after 21 d. Addition of α-amanitin to cultures at 4 d postanthesis had as much an effect on the accumulation of cellulose in the fiber cell wall as the later addition of the inhibitor at 8 to 10 d postanthesis. The inhibitory effect of α-amanitin on fiber growth was reversible when ovules were transferred to amanitin-free medium within 2 d after culture initiation. Ovules placed on media containing α-amanitin for 5 d or longer could not overcome the inhibitory effects when transferred to media lacking the inhibitor. These results indicate critical time periods when RNA transcripts important for specific phases of development are being synthesized.

Discovery of highly apomictic and highly amphimictic dihaploids in Allium tuberosum

To discover highly apomictic and amphimictic Allium tuberosum diploids, we evaluated the degree of apomixis in three dihaploids (2n=16, 2x), KaD2, TeD1 and GMD1, derived from highly apomictic tetraploids. The degree of apomixis, calculated as the percentage of diploid seedlings in the progeny obtained after cross-pollination with tetraploid cultivars, was 96% in KaD2, 7% in TeD1 and 39% in GMD1. In addition to this general index of apomictic nature, two analytical indices were evaluated in KaD2 and TeD1. The degree of diplospory, calculated as the percentage of endoreduplicated embryo-sac mother cells, was 96% in KaD2 and 2% in TeD1. The degree of parthenogenesis, calculated as the percentage of ovules with the egg cell developing parthenogenetically, was 98% in KaD2 and 10% in TeD1. Among angiosperms with gametophytic apomixis, KaD2 is the first diploid apomict whose reproductive mode has been fully described by these three quantitative indices of apomictic nature. And TeD1 is the first highly amphimictic plant found in the A. tuberosum complex. Although TeD1 is poorly fertile, the present results encourage further screening trials for highly fertile, highly amphimictic dihaploids, which may be effective counterparts to KaD2 in diploid-level cross experiments to genetically analyze apomixis in A. tuberosum.

Effects of pivalic acid and sodium pivalate on L-carnitine concentrations in the cauda epididymidis and on male fertility in the hamster.

In this study, administration of pivalic acid or its sodium salt was found to decrease the L-carnitine concentration in the epididymal lumen of the hamster; it also tested whether this decrease affected sperm cell motility, chromatin structure, or fertilizing capacity. Provision of pivalic acid or its sodium salt (20 mM or 40 mM) in the drinking water of mature male golden hamsters for 30 days reduced (by 72%, 75%, and 83% in three experiments) the L-carnitine concentration of the cauda epididymidis but did not inhibit sperm chromatin condensation, as assessed by flow cytometry. The treatments did not alter the location of motile sperm in the epididymidis nor did they appreciably affect the motility of sperm obtained from the distal cauda epididymidis. The numbers and percentage of ova that reached the 2-cell stage 36-40 h after uterine insemination with spermatozoa from control and treated hamsters served as a measure of sperm fertility. Treatment with pivalic acid or sodium pivalate did not render male hamsters infertile although it appeared to reduce the fertilizing ability of their spermatozoa. These results suggest that the high concentration of L-carnitine present in the lumen of the cauda epididymidis is not required for maturation of sperm chromatin or development of sperm motility.

EEECI OF LEAD EXPOSURE ON SOME SELECTED BIOCHEMICAL AND HAEMATOLOGICAL VARIABLES WITH SPECIAL REFERENCE TO REPRODUCTIVE TOXICITY IN FEMALE RABBITS.

The present study was designed to assess the effect of different levels of lead on ovarian activity and to elucidate some biochemical and haematological variables that can be associated with these levels. Immature female New Zealand rabbits were used, divided into four groups, each of six rabbits. Group I and II received low (5.4 mg/kg b. wt.) and high (10.8 mg / kg b.wt.) doses of lead acetate orally, respectively, daily for 5 days/week over a period of 8 weeks. Groups III and IV were kept as control. All groups (except group IV) were treated with 200 1.U pregnant mare serum gonadotrophin (PMSG) I/m, followed by i.m injection of 200 I.U human chorionic gonadotrophin (HCG), 48hrs after commencement of PMSG treatment. The results indicated that injection of PMSG followed by HCG had stimulated the ovarian activity of the control virgin does and elevated the total ovarian response, Metion rate and ovulation percentage. However, administration of low and high doses of lead acetate resulted in a significant decrease in total ovarian response, ovulation rate and ovulation percentage. Lead administration significantly decreased the levels of decteasereins and total lipids. However, a significant increase in the levels of triglycerides was obtained with low and high doses of lead. Cholesterol level was significantly increased with the high dose only. Estradiol-17β and progesterone were significantly decreased following oral administration of both doses of lead acetate. However, lead acetate administration resulted in a significant plasma of bolts were significantly increased with the low and high doses of lead acetate. However, haemoglobin concentration and response with profound changes in the biochemical, haematological and hormonal profiles

Sonographic visualization of the ovaries throughout pregnancy

To determine the frequency with which one or both normal ovaries can be visualized during a routine obstetric ultrasound examination. The population consisted of 5617 pregnant women at 5.0-39.9 weeks' gestation, studied cross-sectionally. The sonographic visualization rate for one or both normal ovaries, as well as their position above or below the level of the umbilicus, was recorded for one examination in each patient. The study population was divided into three groups according to gestational age: first trimester, 5.0-12.9 weeks; second trimester, 13.0-26.9 weeks; and third trimester, 27.0-39.9 weeks. There were 829, 3195, and 1593 women in the first, second, and third trimesters, respectively. Most women were examined transvaginally in the first trimester; transabdominal sonography was used in the second and third trimesters. The ability to visualize one or both ovaries declined significantly (P < .05) from the first trimester to the second, as well as from the second trimester to the third (P < .001). The percentage of ovaries that were visualized above the umbilicus increased from 2.4% in the first trimester to 10.1% in the second trimester (P < .001), and to 21.7% in the third trimester (P < .001). As gestational age advances, there is a significant reduction in the ultrasound visualization rate of normal ovaries. This investigation provides normative data for ovarian visualization throughout pregnancy that may be helpful in establishing ultrasound laboratory standards.

花柱切断受粉法によるテッポウユリ‘ジョージア’の花粉管伸長と種子形成に及ぼす予備受粉の効果

The present study was conducted to examine whether pre-pollination is effective in improving growth of pollen tubes and seed-sets of Lilium longiflorum 'Georgia' by comparing cut-style pollination (CSP) and stigmatic pollination (SP).1. Pollen tubes reached the basal end of the style by 48 hr in self-pollination of 'Georgia' and cross-pollination of 'Georgia' × 'Hinomoto' by CSP. Using the pre-pollination technique in CSP enhanced the growth of pollen tubes both in self-and cross-pollination.2. Generative cell division of pollen tubes in the style was observed 24 hr after pollination. In cross-pollination by SP, 78% of the pollen tubes had 2 sperm nuclei and 1 vegetative nucleus ('2 S + V'), while only 15% of these appeared in the self-combination. Using CSP, pollen tubes with '2 S+ V' were 32%in cross-and 9%in self-pollination. The percentages increased to 54% and 35%, respectively, when pollen of 'Hinomoto' was used in the pre-pollination treatment.3. In SP, numerous pollen tubes which penetrated the style grew in a bunch between two rows of ovules in an ovary ; they reached the ovules near the mid-region of the loculi. In CSP, pollen tubes elongated poorly in the ovary; only a few pollen tubes reached the ovules near the mid-region.4. Penetration of pollen tubes to the micropyle occurred in about 35% of the ovules in cross-pollination-1 by SP and in less than 10% of these by CSP. Pre-pollination in CSP effectively increased the percentage of ovules with a pollen tube in the micropyle.5. Only 3 full-seeds per capsule in self-and 6 in cross-pollination were obtained by CSP, whereas 11 and 23 seeds per capsule, respectively, were obtained as the result of pre-pollination.

Nutrients Affect Allocation to Male and Female Function in Abutilon theophrasti (Malvaceae)

In a pair of similar experiments, we examined the effects of varying substrate nutrient levels on several measures of male and female function in Abutilon theophrasti (Malvaceae). In the first trial, plants adjusted allocation to female function at several levels: number of flowers initiated, locule number, percentage of fruits matured, and percentage of ovules matured. In the second trial, plants were much larger, opened more flowers, and matured more fruit (in total but not on a percentage basis). However, in response to nutrient level, plants adjusted maternal investment at fewer levels than in the first trial. Seed mass varied between, but not within, trials. Little to no adjustment was seen in male characters within either trial, although flower number differed within trials and stamen number differed between trials. The lack of adjustment of paternal investment may be due to the fact that A. theophrasti is primarily an autogamous species. Between the two trials, growing conditions, primarily light intensity, varied and plants adjusted their allocation to reproduction differently, indicating plasticity in this trait.

Nutrients affect allocation to male and female function in Abutilon theophrasti (Malvaceae)

In a pair of similar experiments, we examined the effects of varying substrate nutrient levels on several measures of male and female function in Abutilon theophrasti (Malvaceae). In the first trial, plants adjusted allocation to female function at several levels: number of flowers initiated, locule number, percentage of fruits matured, and percentage of ovules matured. In the second trial, plants were much larger, opened more flowers, and matured more fruit (in total but not on a percentage basis). However, in response to nutrient level, plants adjusted maternal investment at fewer levels than in the first trial. Seed mass varied between, but not within, trials. Little to no adjustment was seen in male characters within either trial, although flower number differed within trials and stamen number differed between trials. The lack of adjustment of paternal investment may be due to the fact that A. theophrasti is primarily an autogamous species. Between the two trials, growing conditions, primarily light intensity, varied and plants adjusted their allocation to reproduction differently, indicating plasticity in this trait.