Removal of the Most Developed Flowers Influences Fruit Set, Quality, and Yield of Apple Clusters

Abstract

<jats:p>The apical or king (K) flower in the apple (<jats:italic>Malus ×domestica</jats:italic> L. Borkh.) cluster usually develops and blooms first and also has a greater sink potential. For this reason, resources are primarily used by the K fruit, and this is also one of the reasons why most thinning practices tend to favor K fruit set. However, it is not always possible to retain the K flower and remove the lateral ones. This study was undertaken to determine if the removal of the most developed flowers in the cluster influences yield or quality compared to that obtained in a whole cluster. The treatments were made in `Golden Delicious' and `Royal Gala' apple cultivars, within a wide range of flower densities for each cultivar. The factor tested was the intensity of flower removal (FRI); the treatments consisted in removing one, two, or three flowers in each cluster. Flower density was used as a covariate in an analysis of covariance to account for differences in flower densities in response to FRI treatments. In all experiments the covariate was not significant; therefore FRI effect was not affected by flower density. `Golden Delicious' and `Royal Gala' had similar responses to flower removal, so that when at least three flowers in a cluster remained, fruit set and cluster yield were similar to whole clusters. Only when two or fewer poorly developed flowers remained after FRI treatments, yield was reduced by as much as 25%. Fruit from FRI clusters were even heavier than those from whole clusters, due to reduced competition among the fruit, so that the growth potential of fruit from the first and second lateral flowers was similar to clusters with K fruit, in clusters where the K flower had been removed.</jats:p>

Influence of Reproductive Impairment of Most Developed Flowers on Fruit Set and Fruit Quality in Pear

“…Results obtained for SR2 and SR4 suggest that clusters in which all fl owers are undamaged have a similar ability to set as those in which the pollination has been thwarted in two or four fl owers (SR2 and SR4 treatments, respectively). These results agree with previous research available for apple (Ferree et al, 2001;Goffi net et al, 1996;Miranda et al, 2005) in which well developed lateral fl owers had a similar setting ability as the most developed fl ower or whole clusters. Seed number at harvest and fruit shape in this study were not affected in SR2 and SR4 treatments.…”

“…In conclusion, flower position in the cluster had little infl uence on shape, size, or seed content, and the growth potential of fruit from partially damaged clusters in their most developed fl owers seems to be similar to that of undamaged clusters, as previously found in apple (Ferree et al, 2000(Ferree et al, , 2001Goffi net et al, 1996;Miranda et al, 2005). Our results show that two generally taken for granted assumptions, i.e., 1) thinning has to be preferentially selective, so that the fi rst fl owers in the cluster have to be kept and 2) the loss of the most developed fl owers in the cluster leads to lower yields, seem to have no sound basis, at least when thinning is performed at bloom stages.…”

“…This result indicates that those clusters had a similar ability to be pollinated and form viable seeds as undamaged clusters under natural autogamy ('Blanquilla' treatments) as well as under crosspollination ('Conference' treatments). Ferree et al (2001) and Miranda et al (2005) found similar results for some apple cultivars. This Table 2.…”

“…When apple clusters were hand-thinned leaving a single fruit of known position within the cluster, there were no statistical differences among fl ower positions in fruit weight, fruit size or seed count at harvest (Ferree et al, 2001;Goffi net et al, 1996), concluding that early thinning allows the most mature lateral fl owers to achieve an equal size to that of the king fl owers. A recent study which compared the set and yield of whole apple clusters with that obtained for thinned clusters in which only the king fl ower had been removed, or in which more than two lateral fl owers were left alone in the cluster (Miranda et al, 2005), found that the growth potential of fruit from the fi rst and second lateral fl owers was similar to clusters with the king fl ower. The authors are unaware of any similar research conducted in pear cultivars, whose study implies further diffi culty as a consequence of the presence of parthenocarpy.…”

Unravelling pest infestation and biological control in low-input orchards: the case of apple blossom weevil

“…and 'Royal Gala') which removed 1-3 of the five flowers per cluster found that when at least three flowers remained, fruit set and yield were similar in non-manipulated and manipulated clusters (Miranda et al 2005). Yield reduction was only observed when two or fewer flowers per cluster remained.…”