Kitren Glozer

Detection of genetic diversity among populations of sweet cherry (Prunus avium L.) by AFLPs

Summary The high degree of polymorphism of AFLPs provides an efficient system for identification and genome analysis of sweet cherry (Prunus avium) cultivars and selections. The cultivars of sweet cherry have usually been characterized by assessment of phenotypic and pomological traits. AFLP markers were employed to identify 38 sweet cherry accessions and estimate the genetic diversity among this material. Ten of 18 tested primer combinations were informative with up to 80 bands per primer combination. Seven to 33% of the amplfied bands were polymorphic depending upon primer combination. Allcultivars and selections tested could be clearly identified. The objective of this work was to demonstrate the usefulness of molecular markers in revealing the genetic diversity among different sweet cherry genotypes.

The effects of Apogee® on shoot growth, secondary flowering, fire blight, fruit quality, yield and return bloom in ‘Bartlett’ pear growing in California

Summary Apogee® sprays were applied to mature ‘Bartlett’ pear (Pyrus communis L.) trees as single or multiple sprays during the growing seasons of 1999 to 2003 at concentrations of 420 g ha–1 (125 mg –1) or 840 g ha–1 (250 mg–1): both reduced vegetative shoot growth. Two sprays of 840 g ha–1 applied 3–3.5 weeks apart were most effective and reduced shoot growth by approximately 40%. An application made 2 d after fall bloom was ineffective and led to more vegetative shoot growth. Single sprays of Apogee® made within 9–28 d after full bloom (DAFB) were equally effective in reducing vegetative shoot growth. Bourse shoot growth was reduced 43% by 3 April, 2001 (8 DAFB) treatment of 840 g ha–1 when bourse and vegetative shoots ranged from 2.5 to 7.5 cm in length. Subsequent single applications of 840 g ha–1 Apogee® (on April 12 or 23, 2001) did not reduce bourse shoot growth significantly. Vegetative shoot growth was also reduced by 12% (9 d after treatment) and by 38% (approximately one month after treatment) by 840 g ha–1 Apogee® applied on 3 April, 2001, (8 DAFB). In 2002, bourse shoot growth was controlled most effectively by split applications (840 + 420 g ha–1 or 840 2 g ha–1, 9 April and 24 May) and by 840 g ha–1 Apogee®, applied at 2.5 to 7.5 cm shoot growth (9 April). These split applications, as well as girdling, decreased shoot strikes in 2002, the year after treatment. Split applications of 840 g ha–1 Apogee® made in April to early May were most effective in controlling both vegetative and bourse shoot growth in most years, although single applications of Apogee® were effective in some years. Subsequent flushes of shoots tended to be controlled by split applications with the second application timed to the emergence of new shoots. Apogee® was not consistently effective in reducing the incidence of Type I or Type V secondary flowers in these trials. Single or multiple sprays of Apogee® had no measurable or consistent effect on return bloom, fruit size or shape, firmness, percentage soluble solids, or yield per tree over the period of these experiments. Apogee® appears to have promise as a shoot growth control agent in ‘Bartlett’ pear growing in California, USA, without deleterious effects.

Use of gibberellin to delay maturity and improve fruit quality of 'French' prune.

Summary Gibberellin (GA) increased firmness of ‘French‘ prune (Prunus domestica L.) when applied preharvest at a rate of 31 or 62 mg 1‒1 in 1997,1998 and 1999. Most effective application dates corresponded with a fruit soluble solids (SS) of 11% to 13% in 1997 and 1998, but with 15% in 1999. The development of SS was temporarily delayed by some of the GA treatments, but was generally similar to the control by harvest time. In 1997, fruit firmness remained higher than the control and extended fruit maturity for up to 7 d by either 31 or 62 mg 1‒1 GA applied at 13% SS, or by 62 mg 1‒1 GA applied at 16% SS. In 1998, fruit firmness was increased by treatment with either 31 or 62 mg 1‒1 GA at 11.5% SS or 31 mg 1‒1 at 16% SS. In 1999, harvest was extended by 3 d due to greater fruit firmness by 31 mg 1‒1 GA applied at 11% or 13% SS, or by 62 mg 1‒1 GA applied at 13% or 15% SS. GA treatments did not affect fruit drop, dried fruit size, or yield. Bloom was delayed by application of GA in 1997 and 1998, particularly with later treatments and with the higher rate. Return bloom in 1998 was not affected by GA treatment in 1997. In 1999,31 mg 1‒1 GA at 11.5% SS resulted in greater return bloom than the control, but bloom of other treatments had similar return bloom as the control. Fruit set was unaffected by the application dates and concentrations tested.

GA and Ethephon Have Limited Effect on Secondary Bloom in ‘Bartlett’ Pear

Abstract GA3, GA4+7 + BA or ethephon was applied in the spring or summer 1997, 1998 and 1999 to reduce secondary bloom in ‘Bartlett’ pear (Pyrus communis L.). Reduction of secondary bloom could reduce associated fire blight (Erwinia amylovora [Burrill] Winslow et al.) infections. The number of Type I secondary bloom was reduced by 400 mg·L−1 GA3, applied between 33 and 97 DAFB, dates which also reduced normal bloom and fruit set. Summer timings of GA3 at 100 mg·L−1 or GA4+7 + BA at 200 mg·L−1 reduced the number of Type V secondary bloom with no difference between GA3 and GA4+7. Ethephon applied one month after harvest in 1997 and 1998 reduced Type Vs in 1998 but not in 1999. Ethephon also reduced fruit set in 1999. Use of GAs to reduce Type V secondary bloom in a fire blight management program may be possible.