Parthenocarpic Fruit Set Research Articles

CPPU and BA, with and without Pollination, Affect Set, Growth, and Quality of Muskmelon Fruit

Solutions of CPPU and BA were applied to ovaries of melon (Cucumis melo) flowers with or without pollination, and the effects on fruit set, growth, and sugar content were investigated. Treatment with CPPU increased fruit set in both seeded and seedless melons. Even at low concentrations, CPPU had a strong effect on fruit set in the seeded melons. In seedless melons, CPPU induced 100% parthenocarpic fruit set when applied with 10 mg·L–1; lower concentrations were much less effective. Treatment with BA increased fruit set in seeded melons, but was not particularly effective in the absence of pollination. During the first 10 days after anthesis, CPPU promoted fruit growth, but between 8 and 13 days after anthesis, the growth rate was lower than in the controls. Treatment with CPPU had little effect upon soluble solids (SS) levels in seeded fruit. SS content was significantly lower in seedless than in seeded fruit; this difference was larger in the placenta than in the mesocarp. Sucrose levels of both seeded and seedless fruits were consistently higher than glucose and fructose levels. High concentrations of CPPU reduced sucrose levels in the placenta of seedless fruit. These results indicate that seeds play an important role in sugar accumulation and melon fruit growth during later stages of development. Chemical names used: [1-(2-chloro-4-pyridyl)-3-phenylurea] (CPPU); 6-benzylaminopurine (BA).

High temperatures and parthenocarpic fruit set: Misunderstandings about the pepino breeding system

SummaryThe sensitivity of pepino (Solanum muricatum Aiton) to high temperatures, together with the variability in the expression of parthenocarpy among cultivars, have led to confusion about its breeding system. We have studied, under greenhouse conditions, the effect of two temperature regimes (T25 and T35) on parthenocarpic fruit set in three pepino clones; a strong parthenocarpic clone, a non-parthenocarpic clone, and the hybrid between them. The T25 regime (25°C maximum, 10–14°C minimum) was shown to be close to the optimum regime for pepino fruit set. High temperatures of T35 (maximum of 35°C) completely hampered fruit set of the non-parthenocarpic clone, but did not affect fruit set of either the parthenocarpic clone or the hybrid. High temperatures reduced pollen fertility and pollen release from the anthers in all clones, but had no significant adverse effects on pollen germination or pollen tube growth in the style. The percentage of seedless fruit varied greatly with the temperature regime, and is therefore not a good index of parthenocarpic fruit set ability. This ability can be exploited to expand the areas suitable for pepino cultivation and the possible growing cycles. The re-interpretation of published data, together with our own experimental results confirm that Solanum muricatum is a predominantly self-pollinating species.

Parthenocarpy induced by N-(2-chloro-4-pyridyl)- N′-phenylurea (CPPU) prevents flower abortion in Chinese white-flowered gourd ( Lagenaria leucantha)

Flower abortion under unfavorable weather conditions is a serious problem in commercial production of cucurbitaceous crops in spite of artificial pollination. The effects of naphthaleneacetic acid (NAA), gibberellic acid (GA 3), N-(2-chloro-4-pyridyl)- N′-phenylurea (CPPU), 6-benzylaminopurine (BA), N, N′-diphenylurea (DPU) and N-(4-pyridyl)- N′-phenylurea (4-PU) on fruit set in unpollinated and pollinated ovaries of Chinese white-flowered gourd ( Lagenaria leucantha) were studied with the aim of increasing fruit set. Among the tested compounds, only CPPU showed high activity in inducing parthenocarpy and all the parthenocarpic fruit developed to normal size. The parthenocapy percentage induced by CPPU was as high as 100% within the tested concentration (10–100 mg l −1) and was not significantly altered by application time from 2 days before anthesis to two days after anthesis. NAA and GA 3 induced parthenocarpic fruit set in 37.5% and 45.5% of treated ovaries respectively, however, they could not induce parthenocarpic fruits of normal size. DPU, 4-PU and BA treatments had little effects on unpollinated ovaries. NAA, however, improved fruit set of pollinated ovaries but did not accelerate fruit growth. A contrary trend was observed in GA 3 treatment. CPPU also increased fruit set and fruit growth of pollinated ovaries. Treating all ovaries on a plant or alternate ovaries increased fruit yield by 91.3% and 83.3%, respectively, but reduced fruit size.

Parthenocarpy in Summer Squash

Summer squash (Cucurbita pepo L.) cultivars were compared for ability to set parthenocarpic fruit. Some cultivars set no parthenocarpic fruit and others varied in the amount of fruit set when not pollinated. The degree of parthenocarpy varied with season, but the relative ranking of cultivars for parthenocarpy was generally similar. Cultivars with the best parthenocarpic fruit set were of the dark green, zucchini type, but some cultivars of other fruit types also set parthenocarpic fruit. A summer squash cultivar was developed that combines a high rate of natural parthenocarpy with multiple disease resistance. Yield of summer squash plants grown under row covers that excluded pollinating insects was as much as 83% of that of insect-pollinated plants in the open.

Induction of Parthenocarpy in Rosa Canina and Diospyros Lotus by the application of growth regulators

The effect of indole-3-acetic acid (IAA) and gibberellic acid (GA3) applications on parthenocarpic fruit set in Rosa canina and Diospyros lotus was investigated. GA3 induced parthenocarpic fruit set in both plants, but IAA only in D. lotus. Maturation of seedless fruits was earlier than the seeded fruits. GA3 caused a decrease in the fresh mass and size of both fruits. IAA induced an increase in the fresh mass and size in parthenocarpic fruit of D. lotus.

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.

The Inheritance of Parthenocarpy and Associated Traits in Pepino

Parthenocarpy in pepino (Solanum muricatum Aiton) can overcome poor fruit set caused by pollination deficiencies. In two families involving a parthenocarpic parent (Pp), a nonparthenocarpic parent (Pnp), and the generations Pp⊗, Pnp⊗, F1, BCp, BCnp, and F2, we studied three traits that are often confused: parthenocarpy, efficiency of parthenocarpy over seeded fruit set, and the degree of facultative parthenocarpy. Plants were trained to two stems (A and B). On stem A we emasculated six flowers per truss; three were pollinated and the other three were left unpollinated. We considered that a plant was parthenocarpic if it set one or more seedless fruit similar in size and shape to those seeded, and nonparthenocarpic if it only set seeded fruit. The efficiency of parthenocarpy over seeded fruit set was measured with a parthenocarpic fruit set index (PFSI), defined as twice the ratio of seedless to total fruit on stem A. In stem B all flowers were left to self-pollinate naturally. We quantified the degree of facultative parthenocarpy as the percentage of seedless fruit of the total. Parthenocarpy is controlled by one dominant gene for which we propose the symbol P. Parthenocarpic fruit set in the homozygote PP was as efficient as the seeded one (PFSI ≈ 1); in the heterozygote Pp it was less efficient (PFSI ≈ 0.6). The dose of gene P explained the differences found between generations for the PFSI and made it possible to predict the PFSI of a given generation from the proportions of PP and Pp genotypes. Although for the Pp hybrids parthenocarpic fruit set was less efficient than the seeded one, their ability to set seedless fruit in conditions of deficient pollination, together with their high degree of heterosis, makes them agronomically useful. The degree of facultative parthenocarpy seemed to be a complex trait with low heritability. In environments unfavorable for pollination, parthenocarpic genotypes set seedless fruit, thus ensuring crop production and yield stability. Using the degree of facultative parthenocarpy to classify plants for parthenocarpy is not recommended. Developing parthenocarpic cultivars can help spread this crop and stabilize yields.

植物生長調節物質によるキウイフルーツ「ヘイワード」の単為結果誘起について

Effects of various plant growth regulators on parthenocarpic fruit set and subsequent growth of 'Hayward' kiwifruit [Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson var. deliciosa] were investigated.Higher percentages of parthenocarpic fruit set were obtained at harvest when N- (2-chloro-4-pyridy1) -N'-phenylurea (CPPU) at 1, 2, 5 and 10 ppm was applied three times; 1 day before anthesis (DBA) and 2 times at about weekly intervals after anthesis. The size of the mature parthenocarpic fruits induced with CPPU was equal to or larger (weight) than that of the hand-pollinated fruits, and the treated fruits matured a few days earlier.Triple applications of GA3 or GA4 at 1000 ppm induced about a 20% set of parthenocarpic fruit. The size of mature GA3- or GA4-treated fruits was about 12% (weight) of that of the hand-pollinated control. Double applications of 500 ppm t-zeatin (z), and single and double applications of N6-benzyladenine (BA) at 500 or 1000 ppm respectively induced 60% and 20% to 40% set of parthenocarpic fruit, the size of the mature Z- and BA-treated fruits respectively being about 9% and 2% to 3% (weight) of that of the handpollinated ones.To obtain nearly a 100% set of parthenocarpic fruit as well as fruit sizes similar to those of hand-pollinated fruits at harvest, flowers and growing fruits should be sprayed with CPPU 3 times at 2 ppm, 1 DBA then 7 and 14 days after anthesis (DAA), or twice at 5 ppm, 1 DBA and 7 DAA, or once at 10 ppm, 1 DBA.

Investigation on the Fertilization Biology of Santa Maria and June Beauty Summer Pear Cultivars

In this study, fertilization biology of Santa Maria and June Beauty summer pear cultivars, grown under Adana ecological conditions, were investigated. In addition to these two cultivars Prococe di Fiorano was taken as pollinators. In order to determine the pollinator ability of these cultivars, the polen viability, germination capacity and production level of pollens were tested in vitro. Viability of the pollens was determined by TTC and FDA tests. In vitro pollen germination experiments with 'hanging drop' method were done in 0, 5, 10, 15 and 20 % sucrose solutions. In addition, pollen production of the cultivars were detemined by using 'hemacytometric method'. The percentage of fruit-set obtained from free-, self- and cross-pollination experiments, determined in vitro. In order to determine the parthenocarpic fruit settings ability, the flowers were emasculated and isolated. Additionally, the fruit sizes and the number of seeds per fruit determined in all experiments. Santa Maria has given the best results on the pollen viability and germination test. The most suitable pollen germination media were 10 and 15 % sucrose solutions depending on the cultivars. The highest pollen production level was obtained from Santa Maria. After cross-pollinations, it was found that Santa Maria and June Beauty were good pollinators for each other. Moreover, Santa Maria cv. was found to have a tendency for parthenocarpic fruit set.

Molecular expression of genes involved in parthenocarpic fruit set in tomato

Molecular expression of genes involved in parthenocarpic fruit set in tomato

Molecular expression of genes involved in parthenocarpic fruit set in tomato

To characterize the phenomenon of natural parthenocarpy in tomato (Lycopersicon esculentum Mill.) two different approaches have been followed. At a developmental level, the ovary weights of three non‐parthenocarpic lines and three near‐isogenic parthenocarpic (pat‐2) lines were compared. Four developmental stages were considered: flower bud, preanthesis, anthesis and 4 days after anthesis. The parthenocarpic lines displayed ovary weights higher than their respective non‐parthenocarpic lines from preanthesis to 4 days after anthesis. A molecular approach involved comparison of in vitro translation products from flower RNAs taken from the same developmental stages of non‐parthenocarpic and near‐isogenic parthenocarpic (pat‐2 and pat‐3/pat‐4) lines. Analysis by two‐dimensional polyacrylamide gel electrophoresis showed the differential expression of a 30‐kDa product in parthenocarpic materials from preanthesis to anthesis. These results suggest that the physiological and molecular events responsible for parthenocarpy begin at the preanthesis stage, before the flower is completely mature and receptive to pollination. The differential expression of this in vitro translation product in pat‐2 and pat‐3/pat‐4 genotypes also suggests a common or confluent molecular basis in genetically controlled parthenocarpy.

Parthenocarpic Fruit Set in Summer Squash

Low temperatures typical of early season production promote female sex expression and reduce male flower formation in summer squash. In addition, some summer squash cultivars do not produce sufficient male flowers for good fruit set early in the season in New York. Parthenocarpic fruit set could increase early season yield as well as at times when bee activity is restricted by wet weather or by row covers. More than 30 Cucurbita pepo cultivars and breeding lines were evaluated for their ability to produce parthenocarpic fruit over the past 3 years. Pistillate flowers were closed before anthesis to prevent pollination. In 1992, 66% of all the entries set parthenocarpic fruit where as 40% displayed the same pattern in 1993 and 81% in 1994. Varieties with the best parthenocarpic fruit set included Black Beauty, Black Magic, Black Jack, and Chefini Hybrid, all zucchini types. Most yellow-fruited cultivars had poor fruit set but the precocious yellow cultivar Gold Rush had good parthenocarpic fruit set in 1992 and 1993. In 1994, floating row covers placed over the plants 1 week after planting confirmed the results of the previous two seasons. This indicates that certain varieties of summer squash consistently set parthenocarpic fruit. These varieties may be most useful for early season production or for production under plastic tunnels or row covers where pollinator activity is restricted. In addition, our results indicate that it is possible to breed parthenocarpic squash of different fruit colors and types.

Strong synergistic effects of gibberellins with the synthetic cytokinin N-(2-chloro-4-pyridyl)-N-phenylurea on parthenocarpic fruit set and some other fruit characteristics of apple

The induction of parthenocarpic fruit set was investigated using the apple cvs. Golden Delicious and Jonagold. The gibberellins GA3, GA4, GA5 and GA7 and the synthetic phenylurea-type cytokinin CPPU (N-(2-chloro-4-pyridyl)-N-phenylurea), were applied alone and in combination to unpollinated flowers at the end of petal fall. Gibberellins induced only a marginal final set of parthenocarpic fruits. CPPU sprays were more effective, particularly in the first year. When applied in combination, CPPU and gibberellins had a positive synergistic effect on parthenocarpic fruit set and fruit size, but a negative effect on flower induction the next year. After CPPU + GA sprays, percent fruit set was similar, or greater, compared to natural pollinated trees. The parthenocarpic fruits induced by CPPU + GA had an increased length to diameter ratio. CPPU stimulated, and GA4 and GA7 reduced, the russeting of the parthenocarpic fruits. The internal quality of the fruits was hardly affected, but Ca-deficiency symptoms occurred more frequently in parthenocarpic fruits.

FRUIT FIRMNESS OF PARTHENOCARPIC VERSUS NONPARTHENOCARPIC PICKLING CUCUMBER CULTIVARS.

Parthenocarpic pickling cucumbers may be advantageous to conventional nonparthenocarpic cultivars due to their higher fruiting capacity and ability to produce fruit under poor pollination conditions. The processing quality, particularly firmness, of parthenocarpic pickling cucumbers has been questionable. Fruit firmness of six parthenocarpic and six nonparthenocarpic cultivars was evaluated in 1992 at Brooks, Oregon. Plots covered with floating row covers, to prevent pollination and ensure parthenocarpic fruit set, were compared with noncovered plots. Parthenocarpic cultivars were significantly softer than nonparthenocarpic cultivars. Cultivars within the parthenocarpic and nonparthenocarpic types were significantly different from one another. Fruit produced under row covers were significantly firmer than those which were pollinated. Cultivars which were firmer under the row cover tended to be firmer in the absence of row cover. Floating row covers allow firmness and parthenocarpic fruiting ability to be evaluated concurrently.

カキ結果枝における着果位置と受粉果実の有無が‘富有’と‘平核無’の単為結果に及ぼす影響

Influence of flower location (distal, mid- or basal) on a shoot thinned to 3 flowers and whether or not the flowers were pollinated on the set of parthenocarpic fruit of kaki (Diospyros kaki L. f.) cvs. Fuyu and Hiratanenashi was investigated. The purpose was to clarify the relation between the set of parthenocarpic fruits and the relative sink strength of parthenocarpic and seeded fruits located at different positions on the same shoot.1. Fruit set of pollinated and non-pollinated flowers was highest at the distal position and lowest at the basal one on a shoot.2. The set of parthenocarpic fruits on the distal position on the shoot with non-pollinated 3 flowers was higher than that of seeded fruits at any position on the shoot with pollinated 3 flowers.3. Seeded fruits set at a greater frequency than did the parthenocarpic fruits on the same shoot.4. The parthenocarpic fruit set of non-pollinated 3 flowers on a shoot, especially at the upper position, decreased with decreasing length of shoot.5. There was a significant difference in seedless fruit growth among the fruiting positions ; many smaller fruits tended to abscise.6. Whether or not a parthenocarpic fruit set depended on its position and the presence of a seeded fruit on the same shoot. The variations in setting patterns of parthenocarpic fruits were very similar in 'Fuyu' and 'Hiratanenashi'.We concluded that 1) a dominant factor of the variation of parthenocarpy in 'Fuyu' was more environmental than hereditary, 2) there was no significant difference in hereditary characteristics of parthenocarpy between 'Fuyu' and 'Hiratanenashi', 3) fruit drop of seedless fruit was induced by competition among fruits, and 4) the set of parthenocarpic fruits was achieved when the relative sink strength of seedless fruit was stronger than that of competing fruits.

Endogenous levels of IAA in relation to parthenocarpy in cucumber ( Cucumis sativus L.)

The role of endogenous indole-3-acetic acid (IAA) on parthenocarpic fruit set in cucumber was investigated. Parthenocarpic fruit set was closely related to the accumulation of IAA in the ovary. Application of N-1-napthylphthylamic acid (naptalam) and 2,3,5-triiodobenzoic acid (TIBA), auxin transport inhibitors, to the ovary or peduncle significantly increased the IAA content in the ovary. Exogenously applied auxins, naphthaleneacetic acid (NAA) and 4-chlorophenoxyacetic acid (4-CPA), gibberellic acid (GA 3) and cytokinins, N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) and 6-benzylaminopurine (BA), also increased it. It is suggested that endogenous IAA is the main hormonal factor for parthenocarpic fruit set and exogenously applied hormones are considered to promote IAA accumulation in the ovary.

Parthenocarpic Fruit Set and Endogenous Indole-3-acetic Acid Content in Ovary of Cucumis sativus L.

Parthenocarpic Fruit Set and Endogenous Indole-3-acetic Acid Content in Ovary of Cucumis sativus L.

BRANCH AUTONOMY AND BLANKING IN PISTACHIO

An average of >20% seedless (blank) fruit are produced annually in Pistacia vera cv. Kerman. The degree of blank production was reportedly not related to individual tree yields and, therefore, was not thought to be resource limited (Crane, J.C., 1973. HortSci. 8:388-390). In two crop years, we studied the variability in percentage blanking among individual shoots characterized by widely varying leaf area to fruit (L/F) ratios. L/F ratios were related inversely to the percentage of blank fruit produced. Thus, individual branches behaved somewhat autonomously with respect to blanking. Our data are consistent with the view that embryo development was resource-limited. Although `Kerman' exhibits the potentiality for parthenocarpic fruit set, the hissed distribution of seedless fruit within the tree presumably indicates that blanking is an example of stenospermocarpy. Blanking does not result primarily from inadequate pollination under typical field conditions.

Absorption, Translocation, and Metabolism of Et-IAA in Relation to Fruit Set and Growth of Day-neutral Strawberry

Abstract Single applications of auxins that normally induce parthenocarpic fruit set in June-bearing and everbearing strawberries (Fragaria × ananassa Duch) (e.g., NAA, 2-NOA, and IAA) do not induce set in the day-neutral cultivar Fern. The only auxin found to date that induces set in day-neutrals with a single application is Et-IAA. The translocation and metabolism of [14C]Et-IAA applied to receptacles was followed in order to gain insight into mechanisms involved in set. Ninety to ninety five percent of the recovered 14C activity remained in the receptacles throughout set and initial development (0 to 6 days) after Et-IAA application. Growth of treated receptacles followed the rapid metabolism of [14C]Et-IAA. Twelve hours after application, 16% of the radioactivity remained in the Et-IAA fraction. This level decreased to <5% by 144 hr after application. The majority of the radioactivity (55–60%) was contained in highly polar compounds. Little activity was recovered in the free IAA fraction. Chemical names used: 1-naphthaleneacetic acid (NAA); 2-naphthoxyacetic acid (2-NOA); 1H-indole-3-acetic acid (IAA); IAA ethyl ester (Et-IAA).

Hormone directed sucrose transport during fruit set induced by gibberellins in Pisum sativum

A new system has been developed to study hormone‐directed transport in intact plants during parthenocarpic fruit set induced by gibberellins. Gibberellic acid (GA3) and gibberellin A1 (GA1) applied to unpollinated ovaries of pea (Pisum sativum L. cv. Alaska) promoted sucrose transport from the leaf to the site of hormone application. In vivo experiments showed an early (30 min) accumulation of [14C]‐sucrose in ovaries of pea stimulated by gibberellins. This activation of sucrose transport appears to be mediated by gibberellins (GA1, GA3), increasing both loading of phloem with sucrose in the leaf (source) and sucrose unloading in the ovary (sink). The ability of pea tissue segments to take up sucrose in vitro was not affected by the hormonal treatment.