When do apples stop growing, and why does it matter?

Abstract

Apples in the commercial food chain are harvested up to two weeks before maturity. We explore apple fruit development through the growing season to establish the point at which physical features differentiating those cultivars become evident. This is relevant both for the understanding of the growing process and to ensure that any identification and classification tools can be used both on ripened-on-tree and stored fruit. Current literature presents some contradictory findings on apple growth, we studied 12 apple cultivars in the Brogdale National Fruit Collection, UK over two seasons to establish patterns of growth. Fruit were sampled at regular time points throughout the growing season and four morphometrics (maximum length, maximum diameter, weight, and centroid size) were collected. These were regressed against growing degree days in order to appropriately describe the growth pattern observed. All four morphometrics were adequately described using log-log linear regressions, with adjusted R2 estimates ranging from 78.3% (maximum length) to 86.7% (weight). For all four morphometrics, a 10% increase in growing degree days was associated with a 1% increase in the morphometric. Our findings refine previous work presenting rapid early growth followed by a plateau in later stages of development and contrast with published expo-linear models. We established that apples harvested for commercial storage purposes, two weeks prior to maturity, showed only a modest decrease in size compared with ripened-on-tree fruit, demonstrating that size morphometric approaches are appropriate for classification of apple fruit at point of harvest.

Cytological characteristics of blueberry fruit development

“…Fruit growth curves mainly exhibit either a single "S" curve or a double "S" curve pattern. For fruits with a single "S" growth curve, the growth rate shows a "slow-fast-slow" trend, as observed in fruit trees like pears [ 25 ] and apples [ 26 ]. Fruits with a double "S" curve typically exhibit two rapid growth and development periods during fruit growth, with the growth rate displaying a "slow-fast-slow-fast-slow" trend, as observed in peaches [ 27 ], strawberries [ 28 ], grapes [ 29 ], and other fruit trees.…”

Assessment of the Quality of ‘Red Jonaprince’ Apples during Storage after Delayed Harvesting and 1-Methylcyclopropene (1-MCP) Preharvest and Postharvest Treatment

“…The impact of storage must also be taken into account while applying delayed harvesting, which results in shortening of the storage period, but it may also reduce the quality of fruits [4]. Once apples are harvested, some metabolic changes begin, but is should be noted that delayed harvesting means that fruit remains on the tree longer, which could contribute to increased size and mass of the fruits, and other related consequences [5]. For example, in the case of 'Golden Delicious' apples, after delayed harvesting, reduced firmness is observed as well [6].…”