Genetic control of biennial bearing in apple

Abstract

Although flowering in mature fruit trees is recurrent, floral induction can be strongly inhibited by concurrent fruiting, leading to a pattern of irregular fruiting across consecutive years referred to as biennial bearing. The genetic determinants of biennial bearing in apple were investigated using the 114 flowering individuals from an F1 population of 122 genotypes, from a ‘Starkrimson’ (strong biennial bearer)בGranny Smith’ (regular bearer) cross. The number of inflorescences, and the number and the mass of harvested fruit were recorded over 6 years and used to calculate 26 variables and indices quantifying yield, precocity of production, and biennial bearing. Inflorescence traits exhibited the highest genotypic effect, and three quantitative trait loci (QTLs) on linkage group (LG) 4, LG8, and LG10 explained 50% of the phenotypic variability for biennial bearing. Apple orthologues of flowering and hormone-related genes were retrieved from the whole-genome assembly of ‘Golden Delicious’ and their position was compared with QTLs. Four main genomic regions that contain floral integrator genes, meristem identity genes, and gibberellin oxidase genes co-located with QTLs. The results indicated that flowering genes are less likely to be responsible for biennial bearing than hormone-related genes. New hypotheses for the control of biennial bearing emerged from QTL and candidate gene co-locations and suggest the involvement of different physiological processes such as the regulation of flowering genes by hormones. The correlation between tree architecture and biennial bearing is also discussed.

A New Insight into Pruning Strategy in the Biennial Cycle of Fruiting: Vegetative Growth at Shoot and Whole-tree Level, Yield and Fruit Quality of Apple

“…'Golden Delicious', the plant material of this study, has been found susceptible to biennial bearing in the local conditions of the study . By diminishing competition between flower initiation and fruit formation, fruit growers can diminish the adverse effects of high yield on next year's flowering (Guitton et al, 2012;Smith and Samach, 2013). However, in the current experiment, neither blossom thinning Table 1.…”

Productive Performance of ‘Fuji’ Apple Trees on ‘Jm’ Series Rootstocks, in São Joaquim/Sc

“…Biennial bearing is characterized by large yields of small sized fruit in "on" years, and low yields, sometimes even no fruit, in "off" years (GUITTON et al, 2012). Alternate bearing is affected by cultivar (MONSElISE; GOlDSChMIDT, 1982) and rootstock (Jonkers 1979).…”

Examining growth, yield and bean quality of Ethiopian coffee trees : towards optimizing resources and tree management

“…For instance, production of 6 t of fresh berries ha -1 year -1 (yielding 1 t green coffee bean and 1.25 t dry pulp and parchment) exports 75 kg N, 11 kg P and 98 kg of K from coffee field (Van der Vossen 2005). Production of high fruit load without a concomitant balance in vegetative development leads to biennial bearing, means high fruit yields in 'n' year and low or no fruit yield in 'n+1' year (Guitton et al 2011) and branch die-back, i.e., descending branch death . Biennial bearing results in severe loss of both yield and quality of coffee beans.…”

“…Causes and consequences of bienniality may differ among fruit tree species. In apple, biennial bearing is attributed to competition between initiation of flowers for the next season and current fruit formation (Guitton et al 2011). In olive, it is controlled by the interaction between vegetative growth and fruit load.…”

“…At the time of flowering in the second year (early February 2013) there were also fewer or no flowers observed per node in trees with high fruit load. So a direct effect of developing fruits or seeds on formation of flower buds seems likely; in apple such competition is seen as a primary cause for biennial bearing (Dennis and Neilsen 1999;Guitton et al 2011). Further study would be needed to monitor accurately the dynamics of flower bud initiation and flower development.…”