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The European apricot (Prunus armeniaca) cultivar 'Earlicot' has high economic potential due to its high-quality fruit and early yields. 'Earlicot' has recently been introduced into Israeli orchards. The climate in Israel is relatively warm, although cold enough for cultivating high-quality stone fruit. However, the full potential of this new apricot cultivar was not being realised. The aim of this work was to understand the reasons for the low performance of 'Earlicot' and to identify methods to overcome them. In a 2-year study, we observed that 'Earlicot' flowered poorly. The problem of poor flowering and hence fruit-set was improved and yields tripled following application of the gibberellin inhibitor, uniconazole, at 500 mg 1-1 [1% (v/v) Magic™] during the period of floral differentiation (mid-May). In addition, we found significant positive relationships between the proximity of 'Earlicot' trees to the polleniser 'Earlygold' and the efficiency of fertilisation, as determined by the genetic marker S8-RNase, the fruit-set percentage, and fruit yield. We also identified the early apricot flowering cultivar '311' to be a fully-compatible polleniser for 'Earlicot'. Full-compatibility for cross-pollination will assure high fruit yields in 'Earlicot'. [ABSTRACT FROM AUTHOR]

Calyx cracking in 'Pink Lady' apple (Malus x domestica Borkh.) results in substantial economic losses. 'Pink Lady' apple trees were sprayed with various rates and combinations of synthetic gibberellins (GA3, or GA4 plus GA7) and a synthetic cytokinin (6-benzyladenine; BA) at different phenological stages, starting at 60 d after full bloom (DAFB) until 150 DAFB, to determine if the incidence of cracking could be reduced. The experiments were conducted in Northern Israel between 2008 - 2011. The percentages of fruit with calyx cracking decreased following three applications of 0.2% (v/v) Superlon™ (i.e., 40 mg 1-1 BA plus 40 mg 1-1 GA4+7) at 14 d intervals, starting at 60 DAFB. GA3 or GA4+7 alone had no effect on cracking. In addition, the Superlon™ treatments resulted in increases in epidermal cell density at the calyx end, which may have contributed to the increased elasticity of the peel, thus preventing crack formation. No change was observed in cuticle thickness. Fruit quality was not affected by 0.2% (v/v) Superlon™ at harvest, or after 5 months of controlled atmosphere (CA) storage. However, fruit size increased, probably due to the effect of BA. The results from semi-commercial multiple applications of 0.2% (v/v) Superlon™ supported its use in orchards of 'Pink Lady' that tend to suffer from calyx cracking. [ABSTRACT FROM AUTHOR]

'Cripp's Pink' apple often develops a poor colour at commercial harvest, resulting in economic loss. To determine if fruit colour could be improved without advancing ripening, 'Cripp's Pink' apple trees were sprayed with various synthetic auxins at different phenologic stages, from 30 d after bloom (30 DAB) until 150 DAB. The experiments were conducted in the North of Israel, from 2006 to 2008. Application of 50 mg l' of the synthetic auxin 2,4-dichlorophenoxypropionic acid (2,4-DP), as its butoxyethyl ester (Power™), or as its potassium salt 2,4-DP-P (Prigan™), at approx. 60 DAB, increased the rate of endogenous ethylene production by the fruit. This was accompanied by an increased concentration of anthocyanins in the fruit skin, and a higher percentage of red blush, without causing the fruit drop that is usually associated with increased levels of ethylene. Although both auxins accelerated fruit maturation, neither had any negative effects on fruit quality at harvest, or after 6 months of storage - at 0°C. The effects were specific to 2,4-DP (and 2,4-DP-P). Several other synthetic auxins such as 2,4-dichlorophenoxyacetic acid (2,4-D), naphthaleneacetic acid (NAA), 2,4-D plus NAA, and naphthaleneacetamide (NAD) plus NAA, had no effect on the red skin colour of 'Cripp's Pink' apple. 2,4-DP sprays therefore represent an effective treatment to improve the colour of 'Cripp's Pink' apple at commercial harvest, without adversely affecting other fruit quality attributes. [ABSTRACT FROM AUTHOR]

The commercial apricot cultivar 'Canino', grown in Israel, is self-compatible and therefore sets large numbers of small fruit. Chemical thinning of blooms and fruitlets is not efficient in stone fruit, therefore hand-thinning of fruitlets has become normal commercial practice, although this is expensive, time-consuming, and not efficient. During 2006 - 2008, applications of uniconazole [a.i., E-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl-1-penten-3-ol)] at 50 - 100 mg l-1 [0.1 - 0.2% (v/v) Magic™ at 30% of full bloom (FB), reduced fruit-set by approx. 50%. As a result, the time spent in hand-thinning was reduced, the crop load was reduced, and a larger fruit size was achieved (i.e., an 80 - 100% increase in fruit > 50 mm). No impairment in return bloom the following year was observed. [ABSTRACT FROM AUTHOR]

Peaches and nectarines belong to a self-pollinating species and therefore tend to set a large number of small fruit. Chemical-thinning is not efficient in stone fruit. Consequently hand-thinning of fruitlets has become the commercial practice, although it is very expensive and not efficient at this stage. Over five consecutive years (2003 - 2007), application of 25 mg 1-1 GA3 to the basal part of shoots during flower bud induction (60 d after full bloom ) reduced flowering of 'Snow-Queen', 'Queen-Giant', and 'Arctic Mist' nectarines, and `Scarlet-Snow' peach in the following season. As a result, the time spent on hand-thinning was reduced by Ca. 50%, and the yields of large fruit increased approx. two-to-three fold. Ripening of 'Queen-Giant' nectarine fruit was delayed slightly, and the incidence of internal breakdown following storage was reduced. Since the effect of the GA3 treatment lasted for only 1 year, it is suggested that it should be applied annually. [ABSTRACT FROM AUTHOR]

The two main pear cultivars grown in the warm climate of Israel, ‘Spadona’ and ‘Coscia’, produce relatively small fruit. Over five consecutive years (2001 - 2005), the application of 0.12% (v/v) BoleroTM [8.6 mg l-1 gibberellic acid (GA3) plus 6 mg 1-1 2,4-dichiorophenoxyacetic acid (2,4-D) plus 6 mg 1-1 naphthaleneacetic acid (NAA)] at full-bloom, caused an appreciable and significant increase in fruit size without any deformation of the calyx-end, which is typical of GA3 treatment when applied at the same phenological stage to improve fruit set. GA3 alone did not increase fruit size. Application of 0.125% (v/v) Perlan™ [25 mg 1-1 benzyladenine (BA) plus 25 mg 1-1 GA4+7] at full-bloom + 14 d, increased fruit size via stimulation of fruit cell division (BA) and fruit cell enlargement (GA4+7), with no negative effect on fruit shape. [ABSTRACT FROM AUTHOR]

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 UHF 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. [ABSTRACT FROM AUTHOR]

The only commercial apricot cultivar grown in Israel, 'Canino', produces relatively small fruit. Over three consecutive years (2003-2005), application of 25 - 50 mg l-1 2,4-dichlorophenoxypropionic acid [2,4-DP; as its butoxyethyl ester (Power™)], 15 mg l-1 3,5,6-trichloro-2-pyridyloxyacetic acid [3,5,6-TPA; as the free acid (Maxim®)], or 25 - 40 mg 2,4-dichiorophenoxyacetic acid (2,4-D) plus 30-50 mg l-1 naphthaleneacetic acid (NAA; 0.3% - 0.5% Amigo™), at the beginning of pit-hardening, when the widest diameter of the fruit was 25 mm, caused appreciable and significant increases in fruit size and total yield. Anatomical studies revealed that the main effect of these synthetic auxins was via direct stimulation of fruit cell enlargement. None of the above auxins had any negative effect on fruit quality, either at harvest or after 1 month of storage at 0°C, or on return yield in the following year. Two other synthetic auxins formulations: 2,4-D (Hadranol™) and 2,4-dichiorophenoxypropionic acid [2,4-DP-P; as its potassium salt (Prigan™)] increased fruit size, but had detrimental effects on fruit quality at harvest and during storage. [ABSTRACT FROM AUTHOR]

‘Red Delicious’, the main apple cultivar grown in Israel, and ‘Jonathan’, grown on a smaller scale, are prone to substantial pre-harvest drop. Spraying both cultivars with the synthetic auxin 3,5,6-trichloro-2-pyridyl-oxyacetic acid (3,5,6-TPA) reduced pre-harvest fruit drop and increased yield. Application of 40 mg l-1 3,5,6-TPA 2 weeks before anticipated harvest (WBH), or 30 mg l-1 3,5,6-TPA at 4 and 2 WBH gave the best results, and were as effective as 2,4,5- trichloro-phenoxypropionic acid (2,4,5-TP) which was the commercial product commonly in use until being withdrawn. There were no negative effects on fruit quality at harvest, or during 8 months of storage. Therefore 3,5,6-TPA can be recommended for routine use on ‘Red Delicious’ and ‘Jonathan’ apples in Israel. [ABSTRACT FROM AUTHOR]

The effects of the synthetic cytokinin N-(2-chloro-4-pyridyl);N′-phenylurea (CPPU) on fruit development and the storage-life of litchi (Litchi chinensis Sonn.) cv. ‘Mauritius’ were examined in Israel over 5 years, CPPU at 5 – 10 mg l-1, applied to green or slightly red fruitlets (25 or 30 mm in diameter), delayed harvesting by 2–3 weeks compared with control trees. At harvest, CPPU-treated fruit that attained a red colour comparable to that of earlier harvested control fruit, were 20–25% larger with total soluable solid contents:titratable acidity (SSC:TA) ratios more than 50% higher than the controls. Despite their high SSC:TA ratios, CPPU-fruit stored well for 6 weeks at 1°C due to reduced browning, lower decay development and less aril discolouration, and maintained an acceptable flavour. These results suggest that CPPU can be used to extend the harvest season for litchi fruit. [ABSTRACT FROM AUTHOR]

The two main apple cultivars grown in the warm climate of Israel, ‘Delicious’ and ‘Golden Delicious’, produce relatively small fruits. Over four consecutive years (2001–2004), application of 10 mg l-1 N-(2-chloro-4-pyridyl);N′-phenylurea (CPPU) or 50 mg l-1 benzyladenine (BA), 2 weeks after full-bloom, when fruitlet diameter was 10 mm, caused an appreciable (> 50%) and significant increase in fruit size with only slight (BA) or no (CPPU) effect on fruit thinning. We therefore conclude that the main effect of these cytokinins was via direct stimulation of fruit cell division. Neither cytokinin had any effect on fruit shape or seed number, nor on fruit quality at harvest or in storage at 0°C, nor on return bloom or yield in the following year. [ABSTRACT FROM AUTHOR]

In Israel, European pear (Pyrus communis L.) is grown in warm, sub-optimal climate conditions and the yield is low. Commercial orchards consist of 'Spadona' as the main cultivar, and 'Coscia', 'Gentile' and 'Spadochina' as its pollinators. In a previous study, it was found that these three pollinators were semi-compatible with 'Spadona'. In the present study, the fertilisation efficiency of the cultivars was compared using hand- and open-pollination. Differences in fertilisation efficiency characteristics (including seed number per fruit) were inconsistent, apart from an increase in 'Spadona' fruit diameter when pollinated by 'Spadochina'. Hence, these results indicate that 'Spadochina' exerted metaxenia, a phenomenon which has not been described previously in European pear. However, this difference is not sufficient for the desired increase in yield. Therefore, a comparison between a fullye and two semi-compatible pollinators was carried out. Since 'Spadona' could not serve as a female parent in this kind of experiment, due to the S-RNase allele content of the cultivars, 'Coscia' served as the female parent, 'Gentile' as the fully-compatible pollinator, and 'Spadona' and 'Spadochina' as the semi-compatible pollinators. As this pear-couple composition is not included in orchard designs, only hand-pollination experiments could be carried out. The trial revealed a high and significant increase in fruit set and seed set by fully-compatible compared to semi-compatible pollinators. [ABSTRACT FROM AUTHOR]

Apple (Malus domestica) has a gametophytically determined self-incompatibility system, which limits inbreeding. As a consequence, apple trees depend on cross-fertilization for fruit-set, which may be enhanced by honeybees (Apis mellifera). In this study honeybee pollination effectiveness and setting potential of two important apple cultivars, 'Smoothee Golden Delicious' and 'Topred Red Delicious', were investigated to shed light on the high fruit-sets and yields of 'Smoothee', as compared with 'Topred'. Analysis of floral features and honeybee behaviour revealed that the differences between the two cultivars in flower size and nectar traits did not affect honeybee visitation frequency, which was the same for both cultivars. Due to the wide basal gaps between the stamen filaments in 'Smoothee' and 'Topred' flowers, which enabled "sideworking", a low proportion of "topworkers" was found in both cultivars. Yet, more than double the number of "topworkers" was found in 'Smoothee', as compared to 'Topred', probably because of the wider diameter of the stamen filament spread of the 'Smoothee' flowers, facilitating nectar collection from the top and thus increasing pollination effectiveness. 'Smoothee' fruit-set was significantly higher than 'Topred' in all stages of flower development, in accordance with the assumption that 'Topred' has a shorter ovule longevity than 'Smoothee'. However, higher fruit-set of 'Smoothee' flowers pollinated before anthesis, at the "Balloon" stage, was also found. This implies that the high fruit-set and fertility of 'Smoothee' are also due to additional genetic features. [ABSTRACT FROM AUTHOR]

The Japanese plum (Prunus salicina Lindl.) belongs to the Rosaceae, which carries the gametophytic selfincompatibility system. Therefore, commercial plum orchards must contain at least two cultivars, which are able to fertilize each other. However, the S-allele content, which determines the fertilization compatibility, has not yet been identified in most of the Japanese plum varieties. This lack of knowledge may lead to cases of reduced yields due to semi, instead of full, compatibility. In the present study, five S-alleles were cloned from three Japanese plum cultivars. The genes were isolated, from genomic DNA, by applying the PCR (Polymerase Chain Reaction), resulting in fragments containing exons, as well as introns. Four of the five clones turned out to be new alleles: from ’Wickson’ S3 and S6, and from ’Royal-Zee’, S4 and S5. The fifth allele, S/, which was isolated from ’Red-Beaut’, has been cloned previously as a cDNA sequence from ’Sordum’ (named Sa, GenBank accession no. AB026981). Sequence analysis revealed an identity of approximately 85% between the exons of the clones, whereas the introus exhibited a much lower identity. The highest degree of identity to a non-Japanese plum gene was displayed by the S2 - RNase of sweetcherry Prunus avium (74–88% identity). Based on these findings, unique pairs of primers were designed allowing for PCR analysis for each of the cloned alleles. PCR with these primers was carried out to identify the level of compatibility between ’Royal-Zee’ and three of its common pollenizers. It revealed that ’Black-Diamond’ and ’Angeleno’ are semi-compatible, since they shared S4 and S5 with ’Royal-Zee’, respectively, whereas ’Black-Gam’ was found to be fully compatible. [ABSTRACT FROM AUTHOR]

The European pear (Pyrus communis) belongs to the Rosaceae, which carries the gametophytic self-incompatibility fertilization system (GSI). GSI is haplotype specific and controlled by the S-locus. The S-locus carries a multi-allelic gene that encodes for RNase (S-RNase), which is involved in executing pollen rejection in a specific manner. The different S-alleles also serve for molecular identification of the S-haplotypes. Orchards of trees carrying GSI contain at least two cultivars, which are fertilization-compatible with each other. However, compatibility may be full when the cultivars differ in both their S-loci or partial when they share one of the two S-loci. Semi-compatibility between cultivars can lead to yield reduction, since half of the pollinator's pollen is rejected. Identification of semicompatibility according to yield levels is not always trivial, since many factors are involved in yield production. On the contrary, the application of molecular analysis, for the identification of S-RNase alleles can clearly determine the genetic compatibility between cultivars. Many S-alleles of Rosaceae fruit trees have been identified, but only a few of them are from European pear cultivars. In Israel the yield of the European pear is relatively low. To elucidate if semiS-allele compatibility could provide the explanation, the S-allele content of the four cultivars grown in the Israel was determined. It was found that ’Spadona’, the main cultivar carries the alleles Sj and Sk, and its pollinators, ’Coscia’, ’Gentile’ and ’Spadochina’ carry Sb-Sk, Si-Sj and Sk-Sl, respectively. Thus, each of the pollinators shares one of the ’Spadona’ S-alleles and therefore is semi-compatible with it. All of the alleles are new, apart from Sb, which has been identified previously by Zuccherelli et al. (2002). To identify potential fully compatible pollinators for ’Spadona’, five additional cultivars that are being considered for introduction into the Israel pear orchard were analysed. It was discovered that ’Bon Rouge’, ’Doctor Jill Guyot’, ’Forelle’ and ’Red Clapp’ are semi-compatible and that ’Lawson’ is fully compatible with ’Spadona’. In this latter analysis, three additional European pear S-alleles, Sm, Sn and So were identified. [ABSTRACT FROM AUTHOR]