Dipartimento di Scienze Agrarie ed Ambientali, Università degli Studi di Perugia, Perugia, Italy.
Tree Physiol. 2011 Dec;31(12):1413-21. doi: 10.1093/treephys/tpr119.
Almond is often considered to be a moderately alternate-bearing species but historical yield data typically do not exhibit clear patterns of alternate bearing at the orchard level, while research has indicated that spurs (the main fruit bearing unit in almond trees) rarely produce fruit in two subsequent years. The objective of the present work was to analyze the bearing behavior of almond trees at both the orchard level and the individual spur level over multiple years to explain this apparent paradox. The 10-year yield patterns of three almond cultivars grown at three different sites within California were analyzed for tendencies of alternate bearing at the orchard level. At the individual spur level, data on spur viability, and number of flowers and fruits per spur were collected on 2400 individually tagged spurs that were observed over 6 years to characterize bearing at that level. At the orchard level one cultivar (Nonpareil) did exhibit a tendency for alternate bearing at one site (Kern) but other cultivars and sites did not. The orchard and the individual trees in which the spur population study was conducted showed tendencies for alternate bearing but the spur population did not. Only a relatively small percentage of the total tagged spur population bore fruit in any given year and therefore while individual fruiting spurs exhibited a high level of non-bearing after fruiting the previous year the spurs that did produce fruit in any year generally did not constitute enough of the total spur population to exhibit alternate bearing at the whole population level. Our results suggest that annual bearing fluctuations in almond are probably mainly due to year-to-year variations of parameters affecting fruit set and that high rates of fruit set in a given year may involve a larger-than-normal percentage of a spur population in fruit bearing. This would limit the size of the spur population available for flowering in the subsequent year and could cause alternate year bearing. However, from historical records, this would appear to be the exception rather than a normal circumstance. Therefore, almond should not be considered to be a strictly alternate-bearing species.
杏仁通常被认为是一种中度隔年结果的树种，但历史产量数据通常在果园水平上没有明显的隔年结果模式，而研究表明，短果枝（杏仁树的主要果实承载单位）很少连续两年结果。本研究的目的是分析杏仁树在多年时间内的果园水平和个体短果枝水平上的结实行为，以解释这一明显的悖论。分析了加利福尼亚三个不同地点种植的三个杏仁品种的 10 年产量模式，以研究果园水平上的隔年结果倾向。在个体短果枝水平上，对 2400 个单独标记的短果枝进行了结实活力、每短果枝花朵和果实数量的数据收集，这些短果枝在 6 年内进行了观察，以表征该水平的结实情况。在果园水平上，一个品种（Nonpareil）在一个地点（Kern）确实表现出隔年结果的倾向，但其他品种和地点则没有。果园和进行短果枝群体研究的个体树木表现出隔年结果的倾向，但短果枝群体没有。在任何给定的年份，只有相对较小比例的总标记短果枝群体结果，因此，虽然前一年结果的结果短果枝在前一年结果后表现出高水平的不结果，但在任何一年结果的短果枝通常没有构成足够的总短果枝群体，无法在整个短果枝群体水平上表现出隔年结果。我们的研究结果表明，杏仁的年度结实波动可能主要是由于影响果实结实的参数的逐年变化，而在给定年份的高果实结实率可能涉及比正常情况下更大比例的短果枝群体结果。这将限制次年开花的短果枝群体的大小，并可能导致隔年结实。然而，从历史记录来看，这似乎是例外而不是正常情况。因此，杏仁不应被视为严格的隔年结果树种。
