Biennial bearing in apple cultivars

ABSTRACT Biennial bearing is the process in fruit trees by which one year of high fruit load is followed by a very low load or no production the next year. In apple growing, this is a troublesome problem, because of the negative effect on crop yield accumulated over the years, fruit quality, and plant physiology. The objective of this study was to evaluate the biennial bearing of nine apple cultivars, grafted on two rootstocks using of the biennial bearing index (BBI). The indices were calculated for the scion cultivars Maxi-Gala, Gala Real, Royal Gala, Fuji Select, Fuji Suprema, Mishima, Daiane, and Cripps Pink based on the yields from the harvests from 2008 to 2013. The apple cultivars exhibited no significant alternate production, considering the range of variation of the index. For the M-9 rootstock, cv. Fuji Suprema showed the highest BBI. For Marubakaido/M-9, Baigent, Mishima, Fuji Select, and Maxi-Gala showed the highest indices. There was no correlation between the biennial bearing index and the stem cross section of the scion cultivars, regardless of the rootstock used.摘要 隔年结果（biennial bearing）是指果树在某一年结果负载量偏高后，次年结果负载量极低甚至绝产的现象。在苹果栽培领域，该现象是一类棘手的生产难题，因其会对多年累积的作物产量、果实品质以及植株生理状态造成负面影响。本研究旨在借助隔年结果指数（biennial bearing index, BBI），评估嫁接于两种砧木的9个苹果品种的隔年结果特性。研究基于2008至2013年的收获产量，对供试接穗品种Maxi-Gala、Gala Real、Royal Gala、Fuji Select、Fuji Suprema、Mishima、Daiane及Cripps Pink的隔年结果指数进行了计算。综合该指数的变异范围来看，供试苹果品种未表现出显著的交替结果特性。对于M-9砧木，Fuji Suprema品种的隔年结果指数最高。针对Marubakaido/M-9复合砧木，Baigent、Mishima、Fuji Select及Maxi-Gala的隔年结果指数最高。无论采用何种砧木，隔年结果指数与接穗品种的茎干横截面积均无相关性。