Improve Fruit Set Research Articles

Enhanced vacuolar invertase activity and capability for carbohydrate import in GA-treated inflorescence correlate with increased fruit set in grapevine

Application of exogenous gibberellin (GA) has been widely used to improve fruit set in grapevine, although the underlying molecular mechanism remains unknown. In this work, GA application at 10 days before anthesis promoted fruit set of grapevine “Fenghou” (Vitis vinifera × V. labrusca) and increased sugar content and acid invertase activity in the ovary, especially vacuolar invertase (VIN) activity during fruit set, compared with the control. However, the GA biosynthesis inhibitor paclobutrazol (PAC) had the opposite effect. Tissue-specific expression analysis and in situ hybridization showed that transcripts of three acid invertase genes were primarily detected in the phloem of the flower and fruitlet. In contrast to the expression of the cell wall invertase gene, which was only induced before blooming, transcript accumulation of the VIN genes VvGIN1 and VvGIN2 was enhanced during fruit set by GA application. Nevertheless, PAC treatment reduced VvGIN1 transcript accumulation after anthesis, but had no significant effect on the VvGIN2 transcript level at the same time point. Interestingly, the effect of GA and PAC application on expression of VvPIN1-like and VvPIN3-like (auxin transporters) was similar to that on VvGIN1 after blooming. In addition, the inducibility of the VvGIN1 and VvGIN2 promoters by GA was demonstrated using transient expression assays in tobacco leaves. These results indicated that enhanced VIN activity and carbohydrate import into grapevine fruitlets by GA application contribute to the increased fruit set through increasing sink strength and sugar signaling activities, possibly by regulating polar auxin transport.

Influence of Foliar Application with Moringa (Moringa oleifera L.) Leaf Extract on Yield and Fruit Quality of Hollywood Plum Cultivar

This investigation was carried out during 2015 and 2016 seasons on twelve trees five years old of “Hollywood” plum trees (Prunus salicina Lindl.) grown in loamy clay soil in a private orchard at Ashmoun, Monofia, governorate, Egypt. Trees were sprayed with (0%, 4%, 5%, 6%) moringa (Moringa oleifera L.) leaf aqueous extract at full bloom stage+fruit setting stage+two weeks after fruit setting stage. Plums treated with 6% moringa leaf aqueous extract exhibited significantly higher setting, yield, fruit weight, firmness, color, Soluble Solid Content (SSC), Titrable Acidity (TA) ratio, ascorbic acid, anthocyanin content, antioxidant activity contents and reducing titrable acidity with reduced fruit drop as compared to all other treatments. It can be concluded that, foliar applications of 6% moringa leaf aqueous extract can be used effectively to improve fruit set, yield, fruit weight, firmness, color, soluble solids content, vitamin C, anthocyanin content and antioxidant activity of “Hollywood” plum.

‘Manzanillo’ olive (Olea europaea L.) tree response to bioregulators and foliar urea application and its interaction with high temperatures

Para mejorar el amarre y rendimiento de frutos en árboles de olivo se evaluaron biorreguladores y urea vía foliar durante tres ciclos y su interacción con altas temperaturas. Además, se llevó a cabo un análisis empírico de la inf luencia de temperaturas altas sobre el amarre de frutos. No se encontraron diferencias estadísticas en rendimiento (un ciclo) entre los tratamientos evaluados. Sobresaliendo Cytokin, Maxigrow y el Testigo con rendimientos superiores a 6.2 t.ha-1, así como mayor número de inf lorescencias, aunque fueron estadísticamente iguales. Los mismos tratamientos mostraron mayor amarre de frutos y los tratamientos menos efectivos resultaron ser Urea y Agromil-plus. Destacaron en uniformidad Agromil-plus y Biozyme-TFen todas las variables evaluadas, mostrando valores altos en frutos normales-FN (100 y 99.1 %, respectivamente) y las más bajas relaciones de frutos partenocárpicos-FP (FP/FN). En dos ciclos se obtuvieron FN con valores muy altos (> 90 %) en todos los tratamientos. Del análisis empírico resultó que en el año con temperaturas > 27 °C, se obtuvieron sólo FP, mientras que en años con temperaturas > y < 27 °C, se lograron FN y FP. La ocurrencia de las altas temperaturas, al inicio o al final de la f loración, inf luye de manera importante en el amarre de frutos.

Artificial spur extinction to regulate crop load and fruit quality of ‘Kalei’ apple

'Kalei' is a new scab-resistant apple cultivar released by the Department of Agriculture, Fisheries and Forestry, Queensland. It is a large apple (average weight 200 g) and trees are highly productive. Crop load management is important as overthinning and/or under-thinning can reduce yield and fruit quality. Artificial Spur Extinction (ASE) is a crop load management tool to regulate floral bud type and density just prior to the onset of spring budbreak. The impact of ASE on the productivity and quality of 'Kalei' was studied across three seasons at Applethorpe, Queensland, with trees on MM.106 and M.26 rootstocks trained as a Vertical Axis (2500 trees ha-1). ASE was compared with conventional (Conv) crop load management (no bud removal, and hand thinning seven to eight weeks after full bloom). In the ASE treatments, axillary buds borne on one-year old shoots were removed, whilst spur buds, and terminal buds of one-year old shoots (≥2.5 cm) were set to a predetermined bud density. ASE increased the proportion of terminal buds borne on shoots, compared with Conv management. ASE consistently improved fruit set, with fewer flower buds failing to set fruit and a higher proportion of flower buds setting 2 or 3 fruit. In 2012 and 2013, the mean fruit weight of 'Kalei' apples was greater with ASE than Conv management. By removing competing sinks early in the season using ASE, remaining fruitlets are given the space and resources to attain fruit size potential. No increase in yield was observed with ASE in both seasons. ASE increased 'Kalei' red blush coverage in 2013, but had no impact on flesh firmness, total soluble solids or dry matter content in 2012 or 2013.

Hydrogen cyanamide improves endodormancy release and blooming associated with endogenous hormones in ‘Summit’ sweet cherry trees

ABSTRACTA trial was conducted to verify the effect of hydrogen cyanamide (HC) application on endodormancy release and blooming of ‘Summit’ sweet cherry trees, as well as on endogenous gibberellic acids (GAs) and abscisic acid (ABA) levels which were identified and quantified by gas chromatography/mass spectrometry in branches with spurs. Results showed that HC efficiently hastened endodormancy release and budbreak, shortened blooming duration and improved fruit set. Furthermore, bioactive GAs play different roles in the process of endodormancy release and blooming. GA3 was recognised as the highest isomer of bioactive GA and was closely related with endodormancy release improved by HC treatment as well as GA4. GA7 displayed a rapid increase when buds went into the burst stage and associated with promoted budburst and blooming by HC treatment. GA1 showed irregular changes during this process. A higher GAs:ABA ratio was observed in HC-treated ‘Summit’ branches from endodormancy release until full bloom. However, a reciprocal pattern occurred thereafter due to senescence of the flowers.

A DIGE proteomic analysis of wheat flag leaf treated with TERRA-SORB® foliar, a free amino acid high content biostimulant

The flag leaf is the most important source of carbohydrate during wheat kernel filling. Around a 75% of all sugars stored in the kernel come from carbon fixed by this leaf. Terra-Sorb® foliar is an L-α-amino acid-based product from enzymatic hydrolysis for foliar application with a high ratio of free to total amino acids. Previous agronomical studies carried out on grassy, horticultural and tree crops have shown that the application of Terra-Sorb® increases photosynthetic plant activity and chlorophyll content, promotes rapid recovery from stress and improves fruit set. In this work, we have undertaken a proteomic approach to explore molecular mechanisms potentially involved in the stimulating effect of Terra-Sorb® Foliar on wheat yield when applied in commercial fields. Wheat plants at the flag leaf stage were treated, and a DIGE approach was used to compare the proteomes of treated vs. control plants in four biological replicates. Thirty-seven protein spots were found to change in abundance (ANOVA p The deregulated proteins identified were mainly related to the life cycle of Rubisco. Importantly, two proteins involved in the positive regulation of Rubisco activity, namely Rubisco activase, and the large subunit of Rubisco binding protein, were found up-regulated in treated plants, suggesting a better performance of Rubisco. Down-regulated proteins were of metabolic and anti-stress enzymes, including Cu/Zn superoxide dismutase that protects photosystem II from photooxidation. In conclusion, significant changes were shown to occur in the wheat flag leaf proteome upon Terra-Sorb® Foliar application. The deregulated proteins identified are directly or indirectly involved in the CO fixation which may correlate with the known stimulating effect of Terra-Sorb® Foliar of wheat yield, although further functional experiments are needed to validate the proposed hypothesis.

Impact of Cross- and Self-pollination on Fruit Set, Fruit Size, Seed Number, and Harvest Timing Among 13 Southern Highbush Blueberry Cultivars

Cross-pollination has been associated with improved fruit set, weight, and shortened time to ripening in southern highbush blueberry [SHB (Vaccinium corymbosum interspecific hybrids)]. Because of this, growers commonly plant two or more cultivars in small blocks to facilitate cross-pollination. However, many SHB cultivars may vary in the degree of improvement in each parameter after cross-pollination. Understanding the impacts of cross-pollination on a particular cultivar is crucial to forming planting recommendations, particularly as growers begin to transition to fields designed for machine harvest where large solid blocks would increase the harvest efficiency. The objective of this study was to examine the effects of cross- and self-pollination among 13 commonly planted or newly released SHB cultivars. Cross-pollination typically improved fruit set, fruit weight, and seed number while decreasing the average days to harvest. Cross-pollinated fruit always weighed more than self-pollinated fruit from the same cultivar, which was highly correlated to seed number per fruit. Although there was variation for each trait, interplanting with another unrelated cultivar sharing a similar bloom time remains the best recommendation to ensure early, high yield among these SHB cultivars.

Method of manipulating floral bud density affects fruit set responses in apple

Apple trees (Malus×domestica Borkh.) usually produce abundant flowers and fruit, and numbers must be reduced to achieve commercial targets of fruit size and quality. Profuse flowering and fruiting also creates high demand for a limited source of carbohydrates, which affects fruit set and development. Artificial spur extinction (ASE) uses hand-thinning of whole buds in late dormancy to reach targeted floral bud densities on every limb. ASE removes floral and vegetative sinks and potential leaf area. Consequently, ASE provides a useful tool to improve understanding of the physiological processes affecting fruit set. We investigated flowering, fruit set and yield of ‘Royal Gala’ trees treated with three thinning methods; ASE, flower cluster thinning (FCT) at pink bloom, and fruit thinning after final fruit set (Control). ASE and FCT were imposed at 2, 4 or 6 buds or flower clusters per cm2 branch cross-sectional area (BCA). Final fruit thinning on all three thinning methods was imposed at two fruit per bud on 2 budscm−2 BCA and a single fruit per bud on 4 and 6 budscm−2 BCA. Consequently, although the density of fruit-bearing buds differed between 2 and 4 budscm−2 BCA, fruit density did not. Compared with the Control, removal of floral sinks before flowering in ASE and FCT increased fruit set within flower clusters by more than 50% and increased harvest mean fruit weight by 18–32gfruit−1. Compared with FCT, ASE resulted in marginally lower fruit set but did not alter components of yield and had little effect on fruit quality. Results imply that manipulation of floral bud density may have beneficially altered carbon availability within floral spurs during early-season development. In FCT, reducing the density of flower clusters may have increased carbon availability to remaining fruit buds, improving their fruit set and development. In ASE, removal and uniform spatial distribution of buds may have improved irradiance of fruiting spurs, thereby increasing photosynthate availability to developing fruit on that spur, improving fruit set and development compared with the Control, achieving results similar to FCT. Despite large differences in natural fruit set brought about by normal seasonal differences in environment, ASE produced precise fruit set outcomes. This contrasts starkly with current commercial thinning practices that rely heavily on chemical thinning, and supports the use of ASE as a precision alternative to existing commercial crop load management.

English

In this study, we investigated the effects of 2,4-Dichlorophenoxy acetic acid (2,4-D) treatment on selected physiological parameters and fruit quality of wax apple fruits under field conditions. Foliar spray of 2,4-D at 0, 5, 10 and 20 mg L-1 concentrations were used from bud stage to the 3rd week of fruit development. Physiological parameters determined included net photosynthesis, stomatal conductivity, chlorophyll content and chlorophyll fluorescence. Net photosynthetic rate and photosynthetic efficiency via chlorophyll fluorescence significantly (p≤0.05) increased with 5 and 10 mg L-1 2, 4-D treatments. Furthermore, 5 mg L-1 2,4-D reduced bud and fruit drop, increased fruit weight and dry matter content in leaves. An improved fruit set, enhanced fruit growth, faster color development and advanced maturity were also recorded in treated plants. In addition, fruit yield increased by 39 and 48% with 5 and 10 mg L-1 2,4-D treatments, respectively. Fruit K+ content, total sugar, protein content and chalcone synthase (CHS) activities increased with 2,4-D treatments. Increased leaf soluble protein and elevated sucrose phosphate synthase (SPS) activity were also observed in 5 mg L-1 treated plants. Positive correlation between photosynthesis rate and SPS activity of leaves (R2=0.98) and between CHS activity and color development of fruits (R2=0.98) were recorded in 5 mg L-1 treatments. The results also suggested that 5 and 10 mg L-1 2,4-D treatments are promising for enhancing plant productivity and fruit quality in wax apple trees under field conditions.

THE EXPRESSION OF VVGA20OX1 AND VVGA3OX1 DURING FRUIT SET OF GRAPEVINE

Gibberellin plays an important role in fruit set in grapevine and is often used to improve berry fruit set percent. However, few studies have focused on the molecular mechanism(s) of how gibberellin improves fruit set. This research aims to explore the influence of gibberellin and paclobutrazol (PAC; an inhibitor of gibberellin biosynthesis) on grape berry fruit set. The expression of VvGA20ox1 and VvGA3ox1 were also analyzed. The result showed that application of gibberellin improved fruit set percent, PAC inhibited fruit set, and PAC inhibition was fully reversed with GA3 application. The fruit size of berries treated with gibberellin was smaller than controls. The expression of VvGA20ox1 and VvGA3ox1 showed different patterns; VvGA20ox1 seemed to be ubiquitously expressed, but VvGA3ox1 was expressed less in tendrils and stems. Before anthesis, VvGA20ox1 showed high expression, but it decreased after anthesis. VvGA20ox expression was lower in ovaries treated with gibberellin than PAC. This indicated that VvGA20ox1 may not or may negatively regulate gibberellin biosynthesis during grape berry fruit set. By contrast, the expression of VvGA3ox1 in inflorescence was low before anthesis, but expression increased rapidly after anthesis. Before anthesis, VvGA3ox1?s expression in inflorescences treated with gibberellin was higher than controls. After anthesis, there was no significant difference in VvGA3ox1 expression between control and gibberellin-treated berries. However, after using PAC, there was no difference with control before anthesis, but 8 days after anthesis, VvGA3ox1 expression in berries was much lower than control and gibberellin-treated berries, indicating that VvGA3ox1 may be involved in gibberellin biosynthesis during grape berry fruit set. There was no significant difference in tissue microstructure among different applications.

Fruit set and seed traits affected by N-phenyl-phetalamic acid in four grapevine (Vitis vinifera L.) cultivars

Grapes are an important horticultural crop that is popularly consumed in a variety of different forms; the fruit is eaten in at its immature stage, as ripe fruit and dried as raisins and vine leaves are also consumed. Therefore any research on ways to improve production of Iranian grapes in terms of quality and quantity is valuable. The main purpose of this study was to test the use of Phenyl Phetalamic Acid (PPA) to improve fruit set and quality. The experiment was designed as a factorial for four grapevine cultivars; 'Razeghi', 'Askari', 'Sefidaly' and 'Rishbaba' and three concentrations of PPA (0, 500, 1000 mg∙L -1 ). Treatments were arranged in a completely randomized design with three replications. The experiment was done in the Kashmar vineyard (Khorasan Razavi province) during 2010 spring. PPA treatment was applied by foliar spraying at the stage of 50 % anthesis. Results showed that PPA levels had a significant effect on evaluated cluster traits (weight, length and number) and berry (number, weight, length and diameter). Fruit set index (number of berries per cluster) was 263.11 for 'Sefidaly' followed by 113, 109.89 and 76.11 for 'Askari', 'Razeghi' and 'Rishbaba', respectively. 'Askari' and 'Razeghi' cultivars showed similar and insignificant reactions but their difference was significant compared to 'Rishbaba'. The effect was significant for interactions of traits for cluster, berry and seed except for number of berries per cluster. Based on these results, cluster characters were significantly and positively affected by PPA treatment at the concentration of 1000 mg∙L -1 . This concentration increased fruit set by 26.2 % compared to the control in all cultivars except for Askari. The PPA concentration 500 mg∙L -1 , observed as the most effective treatment for improved berry characters, provided its non-significant difference with 1000 mg∙L -1 . Seed number per berry decreased significantly in 'Askari' and 'Rishbaba' at 500 mg∙L -1 , which was considered positive in terms of quality. In summary, results determined that PPA had a positive effect on fruit as an auxin synergist. These improved berry characteristics are hypothesized to occur through a decrease in the dominance of apical buds that would allow more metabolites to be directed to development of fruit clusters, although further research is required.

Pollen ability and pollination in some olive(Olea europaeaL.) cultivars in Tunisia as affected by ‘on ’and ‘off ’years

The objective of this work was to assess the pollen viability, the pollen capacity (germination and tube growth) and the rate of fruit set in 19 cultivars of olive trees field-grown in Chott Mariem (Tunisia) after self-and free-pollination treatments during two seasons 2012 ('on'year) and 2013 ('off ’year). The pollen viability ranged from 60.5% for ‘Meski ’to 88.85% for ‘Gerboui ’during 2012 ('on'year) and between 97.47% for ‘Chetoui ’to 62.38% for ‘Meski ’in 2013 ('off ’year). All the cultivars increased their values of viability and germination during 2013 comparatively to 2012, with important consequences on the fertilization process measured by the initial fruit set rate. Concerning the pollination treatments, generally, the free-pollination improved fruit set when compared with self-pollination, especially for ‘Meski ’. However, a non-pollination of ‘Ascolana ’and ‘Tounsi ’was observed with all pollination modes and during the two years in Chott Mariem. Our results showed a high correlation between the rate of fruit set after self-and free-pollinations during the two years of study 2012 and 2013 (respectively, r2= 0.74 and 0.65). This study highlights some major remarkable differences among cultivars in terms of pollen abilities. In general, concerning the pollination efficiency of olive cultivars, the pollen viability can be an important characteristic to be considered as an indicative parameter of pollen development and functionality. Finally, this is a topic of particular importance for large-scale isolated plantings and in choosing the cultivars in new olive groves plantations.

IMPROVING FRUIT SET OF 'KORDIA' AND 'REGINA' SWEET CHERRY WITH AVG

Sweet cherry cultivars require different management strategies depending on whether they are prone to oversetting or have a tendency towards poor fruit set. The aim of this study was to investigate the efficacy of Retain® (15% a.i. (S)-trans-2- amino-4-[2-aminoethoxy]-3-butenoic acid hydrochloride, AVG) for improving fruit set on the difficult to set cultivars ‘Kordia’ and ‘Regina’ under Tasmanian conditions. Trials were established in commercial orchards of ‘Kordia’ in 2011/12 and ‘Regina’ in 2012/13. To evaluate the impact of application time, whole-tree applications of AVG were made separately by hydraulic hand lance at 30 and 80 percent bloom, or as a double application at 30 and 80 percent bloom. On each application date, AVG was applied at 75 or 112.5 g/ha to ‘Kordia’, and 75 or 150 g/ha to ‘Regina’. The surfactant Maxx™ was added to the spray solution at the label rate of 0.5 ml/L in ‘Kordia’, no surfactant was used in the ‘Regina’ orchard. AVG applications increased fruit set by 57 percent in ‘Kordia’ (from 9.7 to 15.3 %) and 33 percent in ‘Regina’ (from 23.1 to 30.7%), compared to untreated control trees. We found no significant differences between the two application rates, nor was there any effect of application timing. In the ‘Kordia’ orchard we recorded a significant (4.4%) reduction in fruit diameter in the AVG-treated trees. The double application also reduced size by 3.7% compared with a single application ( P < 0.01). However fruit size was increased slightly (2%) by the lower, but not the higher, rate of AVG in the ‘Regina’ trial ( P < 0.001). AVG reduced the incidence of rain-cracked fruit from 25% to 14% in the ‘Kordia’ orchard. Fruit firmness in ‘Kordia’ was significantly higher in AVG treated fruit than the control fruit (7%), but stem retention force was reduced by 16%. AVG had no effect on fruit color. AVG treated trees had significantly less starch in trunk tissue, from the time of pit hardening onwards, than control trees, implying that greater investment of tree carbohydrate reserves was associated with the relatively high fruit set. This work has demonstrated that AVG may be useful for improving fruit set (yield) in sweet cherry cultivars that are chronically low-yielding. Further work is needed to substantiate these results in different production regions and clarify the effect of AVG on fruit firmness.

Effect of Some Plant Growth Retardants on Vegetative Growth, Spurs and Fruiting of 'Le - Conte' Pear Trees

This study was carried out during two successive seasons 2012 and 2013 on 5 -years old 'Le Conte' pear trees grown under two types of soil. Selected trees were sprayed by some plant growth retardants such as, Paclobutrazol (Cultar) at 200 & 300 ppm conc., Mepiquat chloride at 150 & 250 ppm, Succinic acid at 150 & 300 ppm and control. Treatments were sprayed with the specified solutions till run off at three times: before flowering, after fruit set stage and two months after fruit set. That was at early March, mid April and mid May. Herein, fruit quality and vegetative growth parameters were determined at the time of harvest. Results showed that significantly increased fruit set and improved fruit quality compared with the control. It should be noted that the best results were recorded in sandy soil compared with the clay soil. The highest concentration in all treatments improved fruit set, yield and fruit quality.

IMPACT OF BORIC ACID SPRAYING DATE WITH DIFFERENT CONCENTRATIONS ON YIELD AND FRUIT QUALITY OF Pyrus communis cv. 'LE-CONTE' PEAR TREES

The aim of the study was to examine the response of pear (Pyrus communis, L.) trees to foliar applications of boric acid. The experiment was carried out during 2010-2011 and 2011-2012 seasons in a commercial orchard in El-Khatatba city, Monifia Governorate, Egypt on mature ‘Le-Conte’ pear trees grafted on Pyrus communis seedlings planted at a space of 5×5 m on a sandy soil under drip irrigation system and modified central leader trained. Annually, foliar sprays with boric acid were applied (i) at 1st September after harvest or (ii) at white bud stage before bloom. Spray treatments involved application of boric acid at a rate of 50, 100 or 150 ppm. Trees untreated with boric acid served as the control. The results revealed that foliar applications of boric acid after harvest or before full bloom at white bud stage increased boron concentration in flowers, fruit set percentage and fruit yield. Additionally, these applications resulted in higher mean fruit weight, size, length, diameter, firmness, seed number per fruit, soluble solids concentration and titratable acidity than those from the control trees. These findings indicate that pre-bloom and postharvest boric acid sprays are successful in increasing pear tree yielding and in improving fruit set. But, boric acid application at the rate of 150 ppm at 1st September after harvest was superior in this respect.

RESPONSE OF ‘BURLAT’ SWEET CHERRY TREES TO POSTHARVEST SPRAYS OF NITROGEN, BORON AND ZINC

The aim of the study was to examine effects of postharvest sprays of nitrogen (N), boron (B), and zinc (Zn) on reproductive response of sweet cherry (Prunus avium L.) trees, fruit quality and plant nutrition. The experiment was conducted during 2007–2009 in central Poland on mature ‘Burlat’ sweet cherry trees/F12, grown on a coarse-textured soil with low level of organic matter, and optimal soil reaction. Soil status of phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), Zn and copper (Cu) was optimal, whereas B – low. Sweet cherry trees were sprayed with boric acid-B, ethylenediaminetetraacetic acid (EDTA)-Zn, and urea-N at 30–40 d prior to initiation of leaf fall according to following schema: i) spray of N at a rate of 23 kg ha−1; ii) spray of B and Zn at a dose of 1.1 kg ha−1 and 0.5 kg ha−1, respectively; and iii) spray of N, B and Zn at the same rates as in the above spray combinations. The trees sprayed with water served as the control. The results showed that fall spray treatments had no influence on cold damage of flower buds, plant N status and soluble solids concentration in fruit. Postharvest spray of N and combined spray of N, B and Zn injured leaves in the fall but did not cause defoliation. Sprays of B and Zn with or without N increased status of Zn and B in fall leaves, and B in flowers and midsummer leaves. Those sprays also improved fruit set and yield. In one out of two years of the study, fall sprays of N with or without B and Zn decreased mean fruit weight. The above results indicate that only leaf-applied B in the fall improved reproductive response of sweet cherry trees. It is concluded that under conditions of B shortage in a soil and/or plant tissues, postharvest B sprays can be recommended in sweet cherry orchards to improve reproductive growth of the trees.

Split root fertigation enhances cucumber yield in both an open and a semi-closed greenhouse

We investigated the hypothesis that split root fertigation (SRF) approach could provide complementary benefits over traditional fertigation (TF) in terms of water use, vegetative growth and yield formation in the high radiation season and under two atmospheric conditions in a greenhouse. Plants of cucumber ( Cucumis sativus L. cv. Cumuli) were grown in a traditional high-wire cultivation system in a peat growing medium. In the SRF method the root system of a plant was separated into two compartments over the crop cycle. One compartment received fertigation solution with low EC (1.2 dS m −1) and the other compartment solution with high EC (3.5 dS m −1) value. In the TF method the EC value of fertigation solution was 2.4 dS m −1. The atmospheric conditions included an open (ventilated) and a semi-closed (cooled) greenhouse. The employment of cooling resulted in an enhancement of the average CO 2 in a semi-closed (810 ppm) over an open (530 ppm) greenhouse resulting in a yield improvement (37%). SRF improved water uptake in both atmospheric conditions and water use efficiency (WUE) in an open greenhouse. The water uptake in SRF was highest in the root part with the low EC values, namely 61% in the open and 66% in the semi-closed greenhouse. In both atmospheric conditions, SRF decreased flower abortion, leading to an improved fruit set with a small effect on vegetative growth. SRF increased yield by 21% in the open and 17% in the semi-closed greenhouse compared to TF in corresponding greenhouses.

Endogenous gibberellin levels during early fruit development of macadamia

Gibberellins play a key role in flower and fruit development, and fruits often contain high gibberellin concentrations. This study quantified endogenous gibberellins in flowers and immature fruits of the macadamia cultivars, H2 and 246, to assist in developing growth-regulator treatments for improving fruit set. GA 1, GA 3, GA 8, GA 9 and GA 20 was detected in flowers or fruits of both cultivars, and GA 4 were detected in flowers of cultivar 246. The timing of gibberellin accumulation was consistent between cultivars but total concentrations were very low (< 7 pmol g -1 fresh weight). Low gibberellin levels are consistent with the inability of the gibberellin-synthesis inhibitor, paclobutrazol, to influence fruit retention in macadamia.

Effect of pollination intensity, frequency and pollen source on fig ( Ficus carica L.) productivity and fruit quality

Yield and fruit quality in fig ( Ficus carica L.) are highly dependent on cultural practices especially caprification (pollination). However, this technique remains not well controlled in Tunisia. This study was conducted during two successive years, 2009 and 2010, to investigate different pollination conditions, i.e. number of caprifigs and repetitions of caprification on fruiting of two cultivars Bouhouli (San Pedro type) and Zidi (Smyrna type). In addition, the efficiency of four pollen sources was evaluated to identify the most effective pollinator for female cultivar Zidi. The following parameters were recorded: fruit number per shoot, fruit set, productivity, fruit characteristics and vegetative growth. Results indicated that caprification realized at four times with an interval of 4 days between each time could be efficient to improve fruit set (74.1 and 70.8% for Bouhouli and Zidi, respectively) and fruit quality (112 g per fruit, 19.4°Brix for Bouhouli, and 102 g per fruit, 20.3°Brix for Zidi). Compared with others caprifigs, the pollen of caprifig Djebba 2 resulted in higher productivity (6 fruits/20 cm), fruit weight (75.6–83.8 g), a large flesh thickness (23–25.1 mm) and better taste of fruits (16°Brix and 0.18% titrable acidity). These results suggested that caprifig Djebba 2 should be selected as the adequate pollinator for the edible Zidi fig in north-west Tunisia.

Effect of algae extract and yeast application on growth, nutritional status, yield and fruit quality of Keitte mango trees

This experiment was carried out during 2008 and 2009 seasons on Keitte mango trees grown in sandy soil under drip irrigation system in National Research Centre farm at El-Nobaria district, ElBehiera Governorate, Egypt. Experiment studied the effect of spraying trees with algae extract at ( 0.5, 1 and 2%) + yeast extract at (0.05, 0.1 and 0.2%) at full bloom stage on fruit set, fruit drop, fruit retention, tree yield, fruit quality and leaf mineral content. Results showed that spraying Keitte mango trees once at full bloom with algae at 2% combined with yeast at 0.2% was very effective in improving fruit set, fruit retention, yield as number of fruits or weight (kg) / tree and increased fruit length (cm), fruit width (cm), fruit weight (g), pulp/fruit percentage and enhanced total soluble solids (T.S.S.). Moreover, it reduced fruit drop and weight of peel and seed (g) comparing with the control. This treatment improved nitrogen, potassium and boron contents in the leaves. On the other hand, all treatments had no effect on leaf phosphorus percentage.