Response of secondary bloom of ‘Bartlett’ pear (Pyrus communis L.) to pruning

Summary

Type V secondary bloom of pear (Pyrus communis L.) is associated with pruning and is frequently infected by fire blight (Southwick et al., 2000). The goal of this research was to determine which pruning practices would most likely be associated with subsequent Type V secondary bloom. Pruning date, shoot age, type of pruning cut and shoot orientation were varied and effect on Type V secondary bloom assessed. In both 1998 and 1999, dormant pruning was more likely to result in Type Vs than summer pruning or pruning one month after harvest. Pruning one week after harvest in 1998 was as likely to lead to Type Vs as dormant pruning, but was less likely in 1999. The likelihood that Type Vs would occur was lowest from 49 to 89.d from full bloom (DFB) and at 175 DFB in 1998. The lowest likelihood of Type Vs in 1999 was found on shoots pruned at 83 or 185 DFB. The likelihood for Type Vs rose with increasing shoot age from one to four years, but there was no difference between three- and four-year old shoots. In 1998, stub cuts (severe heading) were more likely to have Type Vs than head cuts when pruning two year old shoots, but not for one year old shoots. In 1999, type of pruning cut had an inconsistent effect on the likelihood for Type Vs and was not the same for each shoot age. NAA applied to summer pruned shoots completely prevented Type Vs from occurring and almost completely stopped Type Vs when applied to dormant pruning cuts. Summer pruning from 50 to 90 DFB or pruning one month after harvest and the application of NAA to pruning wounds may be strategies for reducing the occurrence of Type V secondary bloom.     

Response of ‘Early Imperial’ Mandarins to Selective Harvesting

All cv Early Imperial mandarin fruits with circumferences 14 cm or more were removed in the first week of May or in July and the remaining fruits as well as those from the controls were picked in the last week of August. Increases in fruit circumference and in fruit weight were recorded only on the trees selectively picked in May, suggesting a minimum time requirement for sizing after removing about 25% to 40% of the fruit. Changes in palatability, colour, puffiness and dryness with time indicated that selective harvesting should not be practised beyond late August to avoid dryness and puffiness.     

Improving the postharvest performance of cut spray ‘Prince’ carnations by vase treatments with nano-silver and sucrose

The postharvest performance of cut spray-type carnations (Dianthus caryophyllus L.) is often limited by the opening, longevity, and coloration of individual florets, and is apparently related to water stress and sugar deficiency. In this study, we found that, compared with deionised water-treated controls, the vase life of cut spray ‘Prince’ carnations was extended by 2.1–4.6 days when held in vase solutions containing1–5 mg L^–1 nano-silver (NS). Moreover, combination treatments with 5 mg L^–1 NS and 2%, 3%, or 4% sucrose consistently further prolonged the vase life, prominently promoted floret opening, and increased the bright pink coloration of petals, thereby markedly enhancing quality performance. Overall, the 5 mg L^–1 NS plus 3% sucrose treatment provided the longest vase life extension (6.6 days) compared with the control, and significantly increased the anthocyanin content in floret petals. Besides, we also showed that the treatment with 5 mg L^–1 NS alone or 5 mg L^–1 NS plus 3% sucrose significantly enhanced their vase solution uptake and relative fresh weight. Further, scanning electron microscopy observations revealed that the NS vase treatments evidently alleviated vascular occlusion by inhibiting bacterial colonisation and biofilm formation on their stem-end cut surfaces and in the xylem vessels.     

Girdling of early season ‘Mayfire’ nectarine trees

The effect of four times of limb girdling on fruit and tree response was examined on ‘Mayfire’ nectarine (Prunus persica (L.) Batsch). Girdling prior to Stage II of fruit growth reduced the lag phase associated with Stage II, and caused peak fruit growth rates to occur earlier in the season than on later girdled or ungirdled trees. Optimum response was obtained by girdling prior to Stage II, when fruit seed length was approximately 10 mm. Girdling at this time increased fruit weight by 22.5% and more than doubled the percentage of fruit in the largest three size categories. Maturity, measured as soluble solids concentration, was increased by 42%. Shoot extension growth was reduced only by early girdling. Leaf weight per unit area was increased, and leaf nutrient concentrations were decreased by all girdling treatments. Leaf conductance to water vapour (g,) was not affected when measured 8 days prior to and 78 days after harvest. Fifteen days after harvest, g, was decreased in all girdling treatments.     

Breeding of a new pear cultivar‘Xinli No.11’北大核心CSCD

‘Xinli No.11’is a new pear cultivar,which was bred by crossing‘Kuerlexiangli pear’as the female parent and‘Yali’as the male parent. Five single plant was initially selected in 1989 for theirs strong adaptability,good quality and different maturity charateristics,and then a single plant number‘75-4-1’was finally selected for its better comprehensive quality,early fruiting,high yield,strong cold resistance and stable agronomic traits charateristics,After regional adaptability testing at three sites (including Korla area,Tarim area and Yanqi area) over five years from 2014 to 2018,it was finally selected in 2018. We applied for the registration as a new cultivar in April 2018 and got identification certificate from Trees Variety Approval Committee of Xinjiang Uygur Autonomous Region in November 2019 and named‘Xinli No.11’. The canopy was conical under natural conditions,the young trees growth potential was flourishing. Leaves were ovoid and eiiipse with average 11.30 cm length and 9.08 cm width,petiole was 3.95 cm in length. Leaf color was dark green. Flowers were pale pink,the relative position of petals was separated. The petal shape was oval,pollen was abundant.It was mainly on the short branch in the fields with ratio of 64%. The average setting rate of single flower was 35.4% and the setting rate of single inflorescene was 86.2% under the condition of natural pollination. The fruit was gourd shape and regular,shed calyx. The average single fruit weights was 181.2 g. The ground col- or of fruit skin was green yellow. The fruit skin was smooth and shining,the peel was thin,the fruit dot was middle-small and was not obvious. The fruit flesh was creamy white,fine and crisp. It was juicy,sour-sweet flavor and tasted delicious along with aromas. The fruit quality was excellent. The content of soluble solid,soluble sugar,titratable acid and vitamin C was 13.42% ,10.41% ,0.108% and 41.9 mg · kg- 1 fresh,respectively. The sarcocarp hardness was 4.66 kg · cm- 2. The vigor of growth of‘Xinli No.11’was middle,germinating capability was high,branch development capability was middle. The fruit development period was about 140 to 150 days,the growth period per year was 210 days,and the fruit was ripening in early or middle of September in Korla,China. It can be stored in cold storage conditions for 5 to 6 months. It has the characters of early fruiting and high yield,the production of 3-4 year old tree was 2-3 times compared to‘Kuerlexiangli pear’. It began flowering after 2 years of planting and the average yield of individual plant was 9.7 kg at 4 years after planting,and it had better adaptability and strong cold resistance (can survive minus 28 ℃ low temperature). The orchard should with mild saline-alkaline and well drained soil. The suitable planting space in the rows and plants are (4-5) m×(3-4) m and 4 m×1.5 m,respectively. The suitable tree shape was evacuation and thin-long spindle. ‘Xinli No.11’has high rate of fruit setting under natural conditions,fruit thinning should be carried out within three weeks after fallen petal with a standard of leaving fruit with good shape and bright color without any diseases and pests and mechanical injuries. The fertilizer should be provided properly according to the period of growth and development and the tree age,and the water should be provided properly according to the soil moisture,both drip irrigation and flood irrigation are available. Grapholitha molesta,Cydia pomonella and Valsa canker should be regard as the most important pests and diseases and controled by scientific using physical and chemical technology according to their occurrence rule. © 2019 Journal of Fruit Science     

Performance of ‘Coscia’ pear (Pyrus communis) on seven rootstocks in a warm climate

Summary

The vegetative and reproductive performance of ‘Coscia’ pear (Pyrus communis L.) growing on seven rootstocks [OHF 69, OHF 97, OHF 513 and BP 1 (P. communis), clonal seedling (Davis AxB) of P. betulifolia, and quince BA 29 and EMA (Cydonia oblonga)] were compared over an 8-year period. The trial was conducted at the Experimental Orchard Farm Station in northern Israel, on a well-drained soil with pH 7.5. Trees were planted in December 1998 at a distance of 4.0 m 2.0 m, and trained with a central axis. The most vigorous trees were on P. betulifolia seedling, followed by BP 1 and the three OHF rootstocks (69, 97, 513). All the above rootstocks demonstrated greater vigour than quince BA 29 or EMA. The reason for this effect, at least in part, appeared to be the excellent water status (high midday stem water potential values) of trees on P. betulifolia in comparison with the other rootstocks. The highest cumulative yields per tree were harvested from trees on P. betulifolia and BP 1, followed by the three OHF rootstocks (69, 97, 513). However, the highest cumulative yield of large fruit (> 60 mm) was obtained from trees on P. betulifolia, followed by the OHF series and BP 1. The two quince rootstocks had the lowest cumulative yield, and the lowest yield of large fruit. A positive correlation was found between the vigour of the tree, as affected by the rootstock, and both total yield and fruit size. We conclude that, in a warm climate, yield efficiency is not the only parameter that should be taken into account, and building a strong tree for the weak scion cultivar is the first requirement for establishing an orchard. Fruit quality at harvest and during cold storage were examined for fruit from three rootstocks only. The highest soluble solids content values at harvest were obtained in fruit grown on quince EMA, compared to values for BP 1 and P. betulifolia fruit.     

Response of the phenylpropanoid pathway to Venturia inaequalis infection in maturing fruit of ‘Braeburn’ apple

Summary

This study investigated the activities of key enzymes in the phenylpropanoid pathway and the accumulation of phenolic products in apple peel in response to infection with Venturia inaequalis [(Cooke) G. Wint.]. We compared healthy apple peel with apple peel showing symptomatic scab lesions, and with peel tissue from 1 – 2 mm around the scab lesions in fruit 1 month before maturity [140 d after full bloom (DAFB)] and at physiological maturity (175 DAFB). Infection with V. inaequalis enhanced the synthesis of some phenolic compounds. Compared to healthy peel, scab lesion tissue had ≤ 3.1-times higher hydroxycinnamic acid content, ≤ 1.3-times higher dihydrochalcone content, and ≤ 3.9-times higher flavan-3-ol content. Scab lesions showed slightly higher phenylalanine ammonia-lyase, chalcone synthase, chalcone isomerase, flavonol synthase, and dihydroflavonol 4-reductase activities. The total amount of phenolics remained relatively stable between the two sampling dates, except for epicatechin and caffeic acid which decreased in amount toward fruit maturity, and levels of catechin which increased in more mature fruit. During fruit maturation, only chalcone synthase and chalcone isomerase activities decreased in all tissues examined. This study showed that the phenylpropanoid pathway in apple fruit peel changed significantly following infection with the apple scab pathogen.     

Preliminary trials to examine the effects of ethephon as a thinner of ‘Gala’ and ‘Jonagold’ apples

Trials in southern Tasmania examined the thinning effects of ethephon on ‘Gala’ and ‘Jonagold’ apples. Untreated controls were compared with ethephon thinning sprays applied at full bloom at 50,100,200,400,800 and 1 600 mg I“1 to both cultivars. Thinning of both cultivars was related to the concentration of the spray and in most cases logistic models were fitted. Thinning effectiveness was largely reflected in increased fruit weight and size. The ‘Gala’ fruit was still not large enough for Australian markets. Ethephon at 200 mg I“1 effectively thinned ‘Jonagold’ and produced the required increases in fruit size and weight. ‘Jonagold’ was overthinned by the high concentrations of ethephon, but this was not reflected in increased fruit weight and size. Ethephon also reduced vegetative growth at the higher concentrations which was considered an advantage. More work is required to establish specific recommendations for either cultivar.     

The thinning effect of benzyladenine on red ‘Fuji’ apple trees

A trial, at the Grove Research Station in southern Tasmania, studied the thinning effect of benzyladenine (BA) on five year old red ‘Fuji’ apple trees. Untreated control trees were compared with trees treated at four timings, from full bloom (FB) to 30 d after full bloom (AFB), with four concentrations of BA (50, 100, 200 or 400 mg I-1). The most effective time of thinning was 20 d AFB, when increasing concentration also increased thinning. Further advantages of this successful thinning were reflected in better fruit size and weight. At 30 d AFB high concentrations of BA depressed fruit weight. Return bloom was improved significantly by both 20 and 30 d. AFB sprays with a concentration effect at 20 d AFB. Timing of sprays had no effect on the incidence of russet which was increased only by applications of 400 mg l-1. Both the higher concentrations and later timings resulted in an increase in shoot numbers and total growth. Reduction in mean shoot length was related more to the concentration of BA used than to differences in the timing of sprays. BA has shown potential as a thinner for red ‘Fuji’ apple at 20 d AFB.     

Fate of photosynthates from spur leaves of ‘Nijisseiki’ pear during the period of rapid fruitgrowth

Summary

Spurs of ‘Nijisseiki’ pear (Pyrus pyriflora Nakai) were allowed to assimilate _10033;CO₂ at 87.d after anthesis (DAA) and at 108 DAA during the period of rapid fruit growth. Then the spurs were sampled periodically until fruit harvest time to trace the time course and amount of movement of assimilates from spur leaves to individual organs in the spur. The amount of _10033;C absorbed by fruit within 3.d after labelling was constant until harvest, regardless of the labelling date. However, the total amount of _10033;C in the spur decreased continually until harvest.Of the total amount of _10033;C recovered in the spur labelled at 87 DAA, by harvest, 43.2% of 13C was found in the fruit flesh (cortex of receptacle), 5% in the core (pith of receptacle 1 pericarp 1 seeds), 5.6% in spur stem, 5.4% in the source leaves, and 40.8% was respired and exported from the spur. Of total amount of initial _10033;C labelled at 108 DAA, at harvest, the proportion of _10033;C translocated to flesh, core, stem, respired, and remaining in leaves was 61%, 6.1%, 3.0%, 24% and 5.4%, respectively. Photosynthates fixed by the spur early in the rapid growth stage of the fruit contribute more to the formation of starch and structural materials and less to solublecarbohydrates in fruit than do those fixed later.     

Flower bud thinning in ‘Rojo Liso’ cactus pear

Summary

The export of cactus pear fruit from Mexico has increased over the last decade, with growing consumer demand for larger and higher quality fruit. Growers are concerned that yields decrease when fruit thinning is used to increase fruit size. Our objective was to assess the effects of flower bud (FB) thinning on the pre-harvest and post-harvest attributes and yields of ‘Rojo Liso’ cactus pear (Opuntia ficus-indica) fruit. The experiments were conducted in 2005 and 2006. The treatments used were: 1) no thinning, considered as the control; 2) thinning every second bud (T1); or 3) thinning two out of every three buds (T2). Marketable fruit (having an equatorial diameter > 5 cm) in the thinned treatments increased compared to the unthinned controls in both seasons. Thinning did not reduce fruit yield. Fruit quality was similar among treatments, both at harvest and after storage, except for the soluble solids concentrations which were higher in both the T1 and T2 treatments in 2005. Fruit weight loss in storage was similar among treatments. Flower bud thinning can therefore be recommended for commercial use.     

Prohexadione–Ca inhibits vegetative growth of ‘Smoothee Golden Delicious’ apple trees

Experiments to test the effectiveness of prohexadione–Ca as a growth inhibitor in apple trees have been carried out for 3 years in the Middle Ebro Valley (Spain). Also, effects on fruit quality and flower initiation were evaluated. The application of 100–400 mg l⁻¹ of prohexadione–Ca between 12 and 30 days after full bloom (DAFB) to ‘Smoothee Golden Delicious’/M9 apple trees resulted in the inhibition of shoot growth, the effect increasing with concentration, and a greater inhibition was obtained when the trees were first sprayed 12–20 DAFB. A second spray was usually needed to avoid a regrowth of the shoots. The effectiveness of the second application was related to the concentration applied and the date of the first spray. The relative increase in trunk-cross-sectional area was not affected by the growth inhibitor. No negative effects on yield and fruit quality were found except for a reduction of soluble solid content. Flower initiation in the following year was not affected. Concentrations of 100–200 mg l⁻¹ applied shortly after full bloom should be recommended, bearing in mind that a second application might be necessary 6–8 weeks later.     

Effect of agar,galactomannan and indole-butyric acid on in vitro rooting of the pear cultivar ‘Durondeau’ and apple rootstock cultivar ‘Marubakaido’

Summary

The influence of partial substitution of agar by galactomannans in culture media supplemented with different concentrations of indole-3-butyric acid (IBA) was studied on in vitro rooting of pear (Pyrus communis L.) cultivar ‘Durondeau’ and apple rootstock (Malus prunifolia Borkh.) cultivar ‘Marubakaido’. The galactomannans applied were obtained from Cassia fastuosa (cassia) and Cyamopsis tetragonolobus (guar gum) seeds. The results obtained with mixtures of agar and galactomannan (3 g l^–1 each) were compared with those from media solidified with a standard concentration of agar (6 g l^–1). The rooting of pear shoots was enhanced significantly in the presence of a mixture of agar plus cassia galactomannan compared to medium solidified with agar only. The modified media promoted a higher number of roots than the control, and increased the percentage of rooted shoots. A maximum of 84.8% rooting was obtained on half-strength MS medium (¹?2MS) supplemented with 0.49 µM IBA and solidified with a blend of agar plus cassia galactomannan. For the apple rootstock, only the number of roots per shoot was influenced significantly by the addition of galactomannan to the rooting medium. The highest number of roots per shoot was 16.67 on ¹?2MS medium gelled with a mixture of agar plus guar galactomannan supplemented with 4.90 µM IBA. The behaviour of the agar-galactomannan gel and the possibility of reduced costs when compared with systems containing only agar, suggest new biological and commercial applications for galactomannans.     

A comparison of high- and low-volume spray techniques in the thinning of ‘Golden Delicious’ apples

A trial at the Grove Research Station, southern Tasmania in 1989-90 examined the thinning of mature ‘Golden Delicious’ apple trees. High-volume sprays were applied at 6,0001 ha^-1 as air blast or vertical boom using NAA at 10mg l^-1 4d after full bloom (AFB) and 18 d AFB. Carbaryl at 1,000 mg l^-1 and thiram at 1200 mg l^-1 were also applied as combined sprays, 30 and 38 d AFB. These high-volume sprays were compared with unsprayed controls and Micron and Micronair low volume sprayers at 200 and 1,1000 l ha^-1. The dosages of the low volume applications were equilibrated to apply the same rates of chemical per hectare as the high-volume sprays, and the timing was the same. All spray treatments reduced crop load to acceptable levels when compared with the overcropped controls. There were no consistent differences between treatments for number of fruit per cm² limb area except that the lowest volume Micron spray thinned significantly less than most other treatments. Considering the number of fruit per 100 blossom clusters the airblast spray was the only treatment to be significantly better than the Micron at 2001 ha^-1. These numbers were reflected in mean fruit weight with the control fruit being significantly lighter than any sprayed fruit. The air blast treatment produced significantly heavier fruit than all other treatments, apart from the other high volume treatment. Fruit size distribution (FSD) showed significant differences between the control and all the spray treatments. The airblast treatment produced significantly more fruit in the 80 mm or larger category than all treatments, apart from the vertical boom application. These preliminary results suggest that although low-volume sprays can thin apple trees, the use of ultra low volumes (ULV) should be explored using machines capable of controlled droplet application (CDA). This may ultimately lead to less chemical being applied per hectare.     

Molecular markers to distinguish ‘Thar Shoba’, a variety of khejri [Prosopis cineraria (L.) Druce], from trees in natural populations

Prosopis cineraria (L.) Druce, commonly called khejri, is an important multipurpose, leguminous tree of the Thar Desert. ‘Thar Shoba’ is a variety of khejri without thorns which was developed as a vegetable. In order to develop markers for varietal identification, 80 RAPD primers were tested, of which nine were polymorphic between ‘Thar Shoba’ and trees in a natural population of khejri. Phenetic analysis revealed that ‘Thar Shoba’ formed a separate cluster from the natural population with similarity coefficients of 0.57–0.78. The 10-mer primers OPBE05, OPBA13, OPA12, and OPA14 were each found to differentiate ‘Thar Shoba’ from the natural population by one amplicon. These differential amplicons were sequenced and SCAR markers were developed based on the sequences that differentiated ‘Thar Shoba’ from the natural population. Natural populations of khejri from different regions of the Thar Desert, and clonally multiplied ‘Thar Shoba’ plants in the ICAR-CIAH bud-wood genebank, were used to validate these primers. These markers will be useful in further developing the bud-wood genebank, and for certification, identification, and protection of the khejri variety ‘Thar Shoba’.     

Controlling growth of ‘Delicious’ apple trees with low- dosage applications of Uniconazole or BAS111

Foliar applications of 30, 60 or 120 mg I-1 uniconazole were made to ‘Delicious’ apple trees at full bloom or one, two or three weeks after full bloom. Application at full bloom reduced fruit weight and length/diameter ratio more than when applied two or more weeks after full bloom. In another experiment, a single application of uniconazole was applied to ‘Delicious’ trees three weeks after full bloom at 15, 30, 60, 120, 240 or 480 mg I-1. Posages of 240 or 480 mg I-1 controlled vegetative growth to about 50% of the control values at ten weeks after treatment. Thereafter, the rate of shoot elongation was similar to that of the controls. The lowest dosage to reduce vegetative growth was 15 mgl-1. In a third experiment, uniconazole was compared with BAS111 for controlling vegetative growth of ‘Delicious’ trees. Uniconazole or BAS111 applied six times at 350 mgl'1 reduced growth to 46% and 81% of that of the controls, respectively. Increasing the rate of surfactant from 0.1% to 1.0% reduced growth by an additional 8%. Growth reduction in the year of treatment was similar following uniconazole treatments of 350 mg l_l applied three times or 35 mg I-' applied six times.     

Regeneration from in-vitro leaves of ‘Conference’ and other pear cultivars (Pyrus communis L.)

Summary

Regeneration of shoots from in-vitro grown leaf tissues of the pear cv. Conference was achieved at rates of up to 40%. The highest regeneration percentage was achieved using a phytohormone combination of benzylamino purine (5 mg 1^?1) and 1-naphthalene acetic acid (1.0 mg 1^?1) on a basal medium of Murashige and Skoog, to which had been added 200 mg I^?1 of the antibiotic cefotaxime. The percentage regeneration was reduced when a higher concentration of cefotaxime (400 mg 1^?1) was used. Cefotaxime had little beneficial effect on regeneration at a lower concentration of 1-naphthalene acetic acid (0.5 mg l^?1). Regenerated shoots were easily micropropagated, rooted and transplanted to soil. To date, the plants have a true-to-type phenotypic appearance. Regeneration was also achieved with other cultivars—‘Abbé Fetel’, ‘Doyenne d’Hiver’, ‘Doyenne du Comice’ and ‘Passé Crassane’—but percentage regeneration was lower and, apart from ‘Passé Crassane’, the regenerated shoots were weak and could not be subcultured.     

Physiological responses and quality attributes of Japanese pear ‘Kosui’ fruit kept in low oxygen atmospheres

Summary

Japanese pear ‘Kosui’ fruits were stored under a continuous flow of 0%, 1%, 3%, 5% and 10% O₂ (balance N₂) or air for 7 d at 20°C to study the effects of low O₂ on their physiological responses and quality attributes. Low O₂ treatments did not significantly influence changes in skin colour and soluble solids content. However, weak off-flavours were detected in the fruits stored at 0% O₂ on day 3, and the intensity of these off-flavours increased as storage progressed. The concentrations of acetaldehyde in fruit increased throughout the storage period. The ethanol concentration was greatly increased in fruits stored at 0% O₂. Moreover, ethanol concentrations were much higher than those of acetaldehyde and remained very low during storage in air, but their concentration were just slightly increased in fruits exposed to 1%, 3%, 5% and 10% O₂. Pyruvate decarboxylase activity was greatly increased in fruits exposed to 1% and 3% O₂, while its activity in fruits exposed to 5% and 10% O₂ were only slightly higher than that of the control and at 0% O₂ at the same level as the control. Alcohol dehydrogenase (ADH) activity greatly increased in fruit exposed to 0%, 1%, 3% and 5% O₂, while at 10% O₂, ADH was only slightly higher than the control. Changes in ADH isozymes correlated well with changes in ADH activity. The homogenate pH of fruits exposed to 1%, 3%, 5% and 10% O₂ and air remained constant, while in fruit stored at 0% O₂ their pH increased. The potential for using low O₂ atmospheres to help in maintaining the quality of Japanese pear ‘Kosui’ is discussed.     

Increase in first-flush flowering of ‘Meiwa’ kumquat,Fortunella crassifolia Swingle,trees by paclobutrazol

Paclobutrazol (PP 333) ((2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl-)pentan-3-ol) sprayed at 1000 mg l⁻¹ on 23 April and also on 8 May, during the flower bud induction stage, remarkably increased the first-flush flowering of ‘Meiwa’ kumquat, Fortunella crassifolia Swingle. Flowering of the second flush was decreased by the paclobutrazol treatment. As a result, the total number of first- and second-flush flowers was also somewhat decreased by the treatment, although it was not significantly different from the control. The number of newly emerged shoots and new leaves was not affected by the treatment. Paclobutrazol slightly decreased the length of the shoots. Applications of 3000 mg l⁻¹ daminozide, on the same dates, slightly decreased first-flush flowering, increased second-flush flowering, and somewhat reduced the length of the shoot. It was concluded that paclobutrazol induced flower bud differentiation. Paclobutrazol may be used commercially to increase early flowering of kumquat trees.