Feathering of ‘Doyenné du Comice’ pear in the nursery using repeat sprays of benzyladenine and gibberellins

Abstract: This work sets out to examine the effectiveness of a number of cytokinins or products with cytokinin-like activity, with and without additional sprays of gibberellins or leaf plucking, on the production of feathers (sylleptic shoots) on trees of the European pear cultivar ‘Comice’ in a fruit tree nursery. It covers the results from three successive years experimentation. In year 1, unsprayed trees of ‘Comice’/quince C (QC) had an average of 1.6 useful feathers per tree. Three applications of 1000–2000mgL−1 benzyladenine (BA) followed by three applications of 400mgL−1 GA4+7 resulted in over a fourfold increase in the number of feathers and a fivefold increase in the total length of feathers. Thidiazuron (TDZ) applications of 30–40mgL−1 followed by three applications of 400mgL−1 GA4+7 also resulted in an increase in feathering but were not as effective as BA sprays. Both spray treatments resulted in more spines on the trees. In year 2, feathering of ‘Taylor''s Gold Comice’/QC was enhanced by three BA sprays at 1500mgL−1, followed by three sprays of GA4+7 at 400mgL−1. Leaf plucking tended to improve feathering in the absence of GA4+7. BA sprays were more effective than sprays of TDZ at the concentrations used (30 and 60mgL−1). Sprays of GA4+7 without the use of cytokinins also stimulated feathering. Thorniness was linked with the use of GA4+7, not the cytokinins. In year 3, feathering of ‘Comice’/QC was enhanced by combinations of BA and GA (GA3 or GA4+7) sprays (four sprays of each applied sequentially) and these resulted in large, well-feathered trees. Thorniness was associated with the use of gibberellins rather than cytokinins. Thorniness was not reduced by the use of GA3 over the use of GA4+7; in fact it was made worse. However, GA3 was more effective at inducing feathering than GA4+7, so a similar thorniness score and feathering could be achieved by using 200mgL−1 GA3 as achieved with 400mgL−1 GA4+7. GA3 is additionally a cheaper product. Sprays of GA without the use of BA also stimulated feathering, although the height of these feathers in the tree were too high for commercial use because these sprays of GA were applied four weeks later than the BA sprays. Therefore, GA sprays applied earlier in the tree development may be sufficient to feather ‘Comice’ in the absence of BA. [Copyright &y& Elsevier]