Ovulation Length Research Articles

Growth of cotton fibre and ovules enhanced by IAA and NAA under in vitro conditions

An experiment was conducted at the tissue culture laboratory of MGM college ofAgricultural Biotechnology, Aurangabad (M.S.) during 2013-14 to evaluate the effects of different concentration levels of auxins viz., NAA and IAA on growth and quality of cotton (Gossipium hirsutum L.) ovules under in–vitro conditions. The experiment was laid out in Completely Randomized Design, 7 different concentration levels of auxins IAA and NAA. Auxins were tried at the levels of 0, 5, 10 and 15 μM conc. of each in culture of 2 DPAflowers of G. hirsutum Lusing Beasley and Ting (BT) medium. Cultures were maintained for 21 days and fibre length, fibre weight, ovule length and ovule weight were recorded. Different concentrations of auxins significantly influenced development of cotton ovules under in-vitro conditions. NAAat concentration of 15 μM was found significantlysuperior over rest ofthelevels of IAAand NAA in case of fibre length, ovule length and ovule weight whereas IAA concentration of 15 μM was found significantly superior over rest of other concentrations of IAA and NAA for increasing fibre weight.

Sexual Dimorphism and Gynoecium Size Variation in the Andromonoecious Shrub Caesalpinia gilliesii

The degree of sexual dimorphism in flowers and inflorescences can be evaluated early in flower development through the study of floral organ size co-variation. In the present work, the gynoecium-androecium size relationship was studied to assess the degree of sexual expression in flowers and inflorescences of the andromonoecious shrub Caesalpinia gilliesii. The co-variation pattern of floral organ sizes was compared between small and large inflorescences, under the hypothesis that inflorescence size reflected differential resource availability. Also, staminate and perfect flowers were collected from three populations and compared on the basis of gynoecium, ovule length, filament length, pollen size and number. The obtained results indicated that staminate and perfect flowers differed only in the gynoecium and ovule length, whereas filament length, pollen size, and number varied across populations. The gynoecium size was smaller and its variability was much higher in staminate than in perfect flowers, as explained by a recent hypothesis about pollinator-mediated gynoecium size selection acting upon perfect flowers. The analysis of the gynoecium-androecium size relationship during flower development, revealed a dissociation of gynoecium growth relative to other floral structures in some buds. Lower gynoecium-androecium regression slopes and smaller gynoecia length characterized smaller inflorescences, thus reflecting the fact that sexual expression was more male-biased. This trend is in agreement with a differential resource-related response at the inflorescence level, however, post-mating resource allocation and the inclusion of other modular levels may also help us to understand the variation in sexual dimorphism in this species.

Seedless-Seedless Grape Hybridization via In-Ovulo Embryo Culture.

The effect of berry sampling time and genotypic difference in stenospermocarpic seedless grapes on the recovery of viable embryos through in ovulo embryo culture was examined. In 5 open-pollinated seedless cultivars, berry weight increased consistently as the fruit developed, but the ovule length did not correspondingly increase, being either constant or shrinking. The recovery rate of viable embryos significantly increased as the days after anthesis proceeded, especially on the 40th day. During the culture, polyembryony was occasionally observed in some ovules. At the micropylar end of the ovule, most multiple embryos emerged adventitously from the hypocotyl-root axis of zygotic embryo. In 5 open-pollinated selections and 6 cultivars, veraison ranged from 49 to 66 days after anthesis. Varietal difference in the recovery of viable embryos from ovules sampled at veraison was significant, ranging from 0 to 24.7%. In a total of 20 crosses between seedless accessions, the recovery rate of viable embryos significantly varied from 2.7 to 47.0%. The rate of plant recovery in vitro ranged from 0.6 to 24.9%. F1 progenies produced through in ovulo embryo culture in seedless x seedless crosses segregated as follows ; completely seedless : perceptible seed traces : seeded=24 : 56 : 21.

Structural aspects of ovule and seed development and nonrandom abortion inMelilotus officinalis (Fabaceae)

Only one ovule matures into a seed inMelilotus officinalis. Although eight ovules form within an ovary, only the basal ovule develops into a mature seed, whereas the other ovules degenerate. The investigation of ovule and seed structure at different developmental stages and a comparison of quantitative characters of differently fated ovules within an ovary were undertaken by light, phase contrast, and fluorescence microscopy. In this species, campylotropous ovules develop simultaneously on marginal placentae in an apocarpous unilocular gynoecium. Megasporo- and megagametogenesis proceed normally and are completed in bud. The maturation of the Polygonum type embryo sac takes place after the flower opens. Shortly before fertilization, synergids show signs of degeneration in all ovules. At this stage, neither the structure nor the sizes of ovules within one ovary differ significantly. In spite of this, only the basal ovule develops into a seed. Rarely, one of the upper-situated ovules or the basal and another ovule mature into seeds. Seed enlargement is insignificant until the stage when globular embryo and nuclear endosperm are formed. At the seed-filling stage, other ovules have collapsed and the seed gradually comes to occupy the total volume of the pod. The fruit-to-seed length ratio decreases considerably during seed ripening. At fertilization, ovary length is four times greater than ovule length. In the mature state, the fruit and seed lengths are approximately equal. Seed size and weight diminish with an increase in seed number within a pod, although pod size remains constant. It is assumed that nonrandom abortion of young seeds inM. officinalis is under maternal control and is not related to structural abnormalities in ovule development or with limitation in pollen. We suppose that evolution of this species may have proceeded in the direction of a decrease in seed number and an increase in its sizes, which may play an important role in seed dispersal and seedling establishment.

Cytological and embryological studies inSetaria cordobensisHerrmann andSetaria leianthaHackel (Poaceae)

SUMMARYCytogenetics and embryology of Setaria cordobensis Herrmann and S. leiantha Hackel were investigated in four populations collected from different environments in Argentina. A somatic chromosome number of 2n = 36 was confirmed for S. leiantha and reported for the first time for S. cordobensis. Bivalent pairing was regular in pollen mother cell meiosis, but abnormalities such as dyads, triads and tetrads with micronuclei or non-conventional arrangement were described with different frequencies. A high degree of similarity between the two species was found investigating megasporangium, megasporogenesis and megagametogenesis. There were major differences in ovule length and width at anthesis. Both species follow a typical Polygonum development and no indicator of apomictic processes was noted.

Morphological Differences and Changes of the Gynoecium in Short-Lived Flowers of Rosa setigera Michaux and Their Relationship to Dioecy

Rosa setigera is unique within the genus because the plant is cryptically dioecious, the flowers of male and female plants appearing identical. Flowers produce no nectar, and the plants rely upon insects, which feed on or collect pollen, for pollination. The plants' gynoecia in both sexes are extremely similar; however, overall the synstigmatic length, synstylar length, ovary length, ovule length, and ovule width are greater in flowers of female plants than in flowers of male plants. Only the single stigma width of male plants was found to be greater than that of female plants. Furthermore, ovary volume, ovary width, ovule length, ovule width, and ovule volume in flowers of female plants increase over the period of 4 d of a flower's life (i.e., with petals), whereas in flowers of male plants those characters either decrease or remain relatively constant over the 4-d time period. No overall differences in synstigmatic width, synstylar width, single stigma length, synstigmatic area, and ovary width were found. The results indicate that dioecy may be a relatively recent occurrence in this species.

Stimulation of Pod and Ovule Growth of Soybean, Glycine max (L.) Merr. by 6-Benzylaminopurine

Flowers at distal nodes on soybean racemes usually fail to set pods and subsequently abscise. Physiological and histological studies were performed to determine the influence of 6-benzylaminopurine (BAP) on distal pod development. The pedicels of fully opened flowers on terminal racemes of field-grown IX93-100 soybean plants were treated three times with 200 mg kg-1 BAP in lanolin over a 6-d period. Racemes were then excised and 32P uptake was recorded for each flower position within a raceme; histological features of pedicels and ovules also were determined. Application of BAP increased pod and ovule length, width and weight at all four distal nodes (D, D-1, D-2, D-3) relative to controls treated with lanolin. Length and width of parietal endosperm cells were smaller in BAP-treated ovules at the most proximal node being studied (D-3), and greater numbers of parietal endosperm cells were observed at D-1 and D-3 nodes when compared to lanolin controls. Smaller amounts of starch were found in suspensor cells, endosperm, and integuments of lanolin-treated ovules, and starch depletion over time was observed within starch sheaths of pedicels from lanolin-treated pods when compared to BAP-treated tissues. BAP-treated racemes had more 32P uptake at the four most distal nodes. A higher rate of uptake (cpm mg-1 f. wt) was evident in ovules than in ovary tissues. These results suggest that for racemes otherwise destined to abscise, application of BAP promotes pod set and growth by stimulating ovule development.

A Flower and Pod Staging System for Soybean

Flower and pod abscission limit soybean yield. A system for quantifying flower and pod development based on the morphological appearance of the flower prior to and following anthesis has been developed to aid in studies of pod abscission. Changes in the appearance of the corolla, primarily the banner petal, are used to distinguish the different stages of the system. External pistil dimensions have been correlated with internal features for each stage of development. From anthesis to pod set, pistil length and weight increase almost two- and fivefold, respectively, and ovule development progresses from unfertilized egg cells to embryos surrounded by cellular endosperm. Pod dimensions are correlated with ovule length and width and embryo cell number. Flower and pod stages can be determined in situ, thus permitting non-destructive observation and experimental manipulation of flowers or pods without necessarily impeding their development. Stages have been identified that indicate precisely when pod set occurs and when young pods cease growing and ultimately abscise. This system of flower and pod staging is useful in studies designed to assess effects of abiotic or biotic stress and genetic factors on pod set and abortion.

Temperature Effects on Megagametophytic Development in Meadowfoam

Seed yield of meadowfoam (Limnanthes alba Benth.), an open‐pollinated winter annual, is partially determined by the number of seeds per flower. Each flower has the potential for five seeds, but typically an average of two seeds per flower has been measured in the cultivar Mermaid. The causes of less‐than‐maximum seeds per flower are not known. Therefore, an investigation of the effects of temperature on the growth rates of the unfertilized ovule and embryo sac and on megagametophytic structure was conducted. Treatment effects at 0, 48, 96, and 144 h postanthesis (HPA) under the regimes of 15/15, 24/15, and 33/15 °C alternating day/night were measured. Growth rate for embryo sac width, ovule width, embryo sac/ovule width growth rate (ESOWGR), embryo sac length, ovule length, and embryo sac/ovule length growth rate (ESOLGR) was significantly (P < 0.01) lower at 15/15 °C than at higher temperatures. Growth rate for embryo sac width, ESOWGR, and ESOLGR was significantly (P < 0.05) higher at 24/15 than at 33/15 °C. At anthesis, the number of flowers with four or five normal appearing megagametophytes was approximately the same in all temperature regimes. However, over time, with each warmer temperature regime there were increasing numbers of abnormal embryo sacs wherein the egg apparatus pulled away from the micropyle resulting in the megagametophyte appearing to float within the embryo sac. This temperature effect may explain some of the yearly variation in seed yield and suggest the need for timely pollinator management, especially during periods of rapid bloom when temperatures are typically above 24 °C.

Peach Fruit and Leaf Tissue Sensitivity to CGA 152811

Abstract Fruit tissue only was treated with concentrations of 0, 240, 360, 480, 600, 720, 840, and 960 ppm of (2-chloroethyl)methyl bis (phenyl methoxy) silane (CGA 15281) applied to 1/3, 1/2, and 2/3 of the fruit surface. Increased abscission of fruit occurred as ovule length increased from 3.5 mm to 13.3 mm when fruit alone were treated. Foliage sprays of the same concentrations with the fruit protected generally had no effect on fruit or leaf abscission. Application of 0.01 ml droplet of CGA 15281 to the abscission zone, peduncle, and fruit cheek caused little fruit removal, but produced chlorosis of the treated area on the fruit. The data suggest that fruit contact with CGA 15281 is necessary for fruit thinning.

The Relationship of Node Position to Bloom Date, Fruit Size, and Endosperm Development of the Peach, Prunus persica (L.) Batsch cv. Sullivan’s Elberta1

Abstract Fruits on uniform peach shoots selected from the periphery of trees were thinned to leave only those nodes of the terminal, intermediate, or basal regions of the shoot, or at 6” spacings along the shoot. The control consisted of unthinned shoots. During one year of the study the date of 90% bloom of buds at the various node positions and size of the subsequent fruit was determined. During the second year fruit volume and mean ovule length were determined for each thinning treatment. Flower buds from the terminal nodes were the first to bloom the resulting fruit were the largest at harvest. Conversely, buds at the basal nodes were the last to bloom and produced the smallest fruit. In treatments that included fruit from all node positions, the mean fruit volume was smaller than for shoots having fruit only at the terminal nodes. Mean ovule length was also influenced by node position.

Flowering Behavior and Seed Development in Four Desmodium Species1

AbstractA knowledge of flowering behavior and seed production would be helpful in formulating intra‐ and interspecific breeding programs of Desmodium species. Selections of D. canum (Gmel.) Schin. and Thell., D. intortum (Mill.) Urb., D. sandwicense E. Mey., and D. uncinatum (Jacq.) DC. were grown in controlled environments and in the glasshouse at Ithaca, New York to investigate plant response to photoperiod and to study ovule and seed development.D. sandwicense was day‐neutral. D. intortum and D. uncinatum flowered under short days of less than 12 hours. D. canum needed at least 12 hours to induce flowering under artificial light of 21,520 lux (2,000 ft‐c). The species is considered day‐neutral, however, since profuse flowering occurred under natural light of 15.2 hours and since it flowers under shorter days in tropical and subtropical areas. The four species had perfect flowers borne on indeterminate racemes. Anthers of D. canum dehisced in midafternoon with 14 to 15.2 hours of light in the glasshouse. Under 11 hours of light the other three species dehisced 6 to 8 hours before the end of the dark period in the growth chamber. A tripped flower wilted quickly and the standard petal folded over the stigma within 1 hour. Without pollinators, flowers generally did not trip, but seed set exceeded 50%.After fertilization, the ovule length:width ratio increased rapidly for 4 to 6 days, then declined as broadening occurred. The epicotyl, hypocotyl, and cotyledons became visible within 5 days. At 17 days after pollination seed coats became impermeable on drying of seeds. Before the seed reached maximum weight at about 28 days, 90% or more had hard seed coats. Seed were viable 20 days after fertilization when scarified, and germination rapidly increased thereafter to about 30 days. There was no dormancy period when seed were properly scarified.

Embryology of Agrostis interrupta (Gramineae)

Because of the characteristic morphology of the grass ovule, it is proposed that the end of the ovule opposite the micropyle be referred to as the basal end rather than the chalazal end. The ovule is hemianatropous, bitegmetic, and tenuinucellate. Both integuments are mostly two cells thick and exhibit some stretching of individual cells along the side of the ovule. This stretching is concomitant with increase in ovule length. The inner integument forms the micropyle and persists longer than the outer integument. Elimination of the outer integument is a result of stretching. The fruit wall is unlignified as a result of the transfer of the function of protection to the lemma. As evidenced by patterns of cell elongation, fruit elongation occurs first along the sides. There are few periclinal divisions in the nucellar protoderm, these occurring near the point of attachment of the ovule. Megasporogenesis and megagametogenesis are normal. Callose is associated with megaspore formation. The mature orientation of the megagametophyte, relative to the placenta, is obtained at approximately the two-nucleate state of development. Antipodal proliferation occurs before fertilization. After fertilization, large multinucleolate nuclei and multinucleate cells are seen in the antipodals. The cytological abnormalities seen in the antipodals may be associated with hormonal imbalance. The synergid, which will be penetrated by the pollen tube, develops a filiform apparatus before the other synergid. The pollen tube deposits sperm cells in a degenerated synergid. Endosperm is free nuclear and walls form first around the embryo. Starch appears at later developmental stages in the endosperm. When cellular, the endosperm grows by cell division at its periphery. There are two morphological axes within the grass ovule, that between the egg apparatus and the antipodals and that between the micropyle and basal end. In Agrostis interrupta, these two axes form a wide angle. Embryologically, A. interrupta is more similar to Avena. There are also embryological features that seem to characterize the Aveneae and Stipeae. Three general types of embryological similarities and differences can be discerned in the grasses, as well as in other plants: (1) similarities and differences that reflect relationships; (2) similarities of rare occurrence with no obvious taxonomic significance; (3) rare differences of no obvious taxonomic significance.

2-Chloroethylphosphonic Acid and 1,1,5,5-Tetramethyl-3-dimethylaminodithiobiuret as Chemical Thinners for Peach1

Abstract Foliar sprays of 2-chloroethylphosphonic acid (ethephon) at petal fall or when the ovules had grown to 4 or 9 mm resulted in an acceptable level of thinning on ‘Johnson’ and ‘Halford’ peach. Thinning of ‘Fay Elberta’ with ethephon occurred at the 5- to 9-mm ovule length. Foliar sprays of 1,1,5,5-tetramethyl-3-dimethylaminodithiobiuret (ER-3952) effectively thinned ‘Johnson’ and ‘Halford’ at the 4- to 9-mm ovule length but gave poor results with ‘Fay Elberta’.

Peach Cultivar Responses to Fruit Thinning with CPA1

Abstract Chemical thinning of peaches was conducted under orchard conditions using CPA,3 followed by standard hand thinning, on the cultivars ‘Jerseyqueen,’ ‘Sunhigh,’ ‘Redhaven’, ‘Sunqueen’ and ‘Rio Oso Gem.‘ Timing of the 3 sprays at 150 ppm was based on the water volume displacement of 100 fruits selected at random from each plot: a) at 200 ml displacement, b) at 280 ml, and c) at 280 ml plus 4 days. The control was hand thinned only. Ovule length was measured at each spray timing and found to be 7–10 mm at the 280 ml water displacement; both ovule length and water displacement techniques were used to time CPA sprays in over 2000 acres of New Jersey orchards in 1968. Timing of the CPA thinner for optimum effectiveness in this experiment varied with cultivar. Individual fruit weight was greater on CPA-thinned trees than on the controls for the cultivars ‘Redhaven,’ ‘Rio Oso Gem,’ ‘Sunqueen’ and ‘Sunhigh’ at harvest. Chemically thinned ‘Jerseyqueen’ did not show an increased mean fruit weight at harvest. Yield reductions occurred on ‘Sunhigh’ at the 280 ml timing and on ‘Redhaven’ at the 280 ml + 4 days timing, due apparently to subsequent over-thinning by hand. Shading increased the thinning effectiveness of CPA on all cultivars. ‘Jerseyqueen’ and ‘Redhaven’ were difficult to thin with CPA under the conditions of this experiment. ‘Rio Oso Gem’ was moderately difficult, while ‘Sunhigh’ and ‘Sunqueen’ were thinned readily.